U.S. patent application number 12/537896 was filed with the patent office on 2010-02-04 for fused heterocycles.
This patent application is currently assigned to Sepracor Inc.. Invention is credited to James M. Dorsey, Qun Kevin Fang, Robert J. Foglesong, Michele L. R. Heffernan, Seth C. Hopkins, Cyprian O. Ogbu, Mustapha Soukri, Kerry L. Spear.
Application Number | 20100029741 12/537896 |
Document ID | / |
Family ID | 40342283 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100029741 |
Kind Code |
A1 |
Dorsey; James M. ; et
al. |
February 4, 2010 |
FUSED HETEROCYCLES
Abstract
This invention provides methods of improving cognitive function
by administering to a subject a therapeutically effective amount of
a fused heterocycle having the formula: ##STR00001## in which
R.sup.1 is a member selected from the group consisting of H,
substituted or unsubstituted arylalkyl and substituted or
unsubstituted heteroarylalkyl. R.sup.2 is a member selected from
the group consisting of H substituted or unsubstituted alkenyl,
substituted or unsubstituted arylalkyl and substituted or
unsubstituted heteroarylalkyl. R.sup.3 is a member selected from
the group consisting of H, C.sub.1-C.sub.6 substituted or
unsubstituted alkyl, substituted or unsubstituted arylalkyl and
substituted or unsubstituted heteroarylalkyl. R.sup.4 is a member
selected from OH and O.sup.-X.sup.+, in which X.sup.+ is positive
ion which is a member selected from organic positive ions and
inorganic positive ions. Substituted or unsubstituted arylalkyl and
substituted or unsubstituted heteroarylalkyl moieties have the
formula: ##STR00002## in which Ar is a member selected from the
group consisting of substituted or unsubstituted aryl and
substituted or unsubstituted heteroaryl. The index n is an integer
from 1 to 4.
Inventors: |
Dorsey; James M.; (Durham,
NC) ; Heffernan; Michele L. R.; (Worcester, MA)
; Fang; Qun Kevin; (Wellesley, MA) ; Foglesong;
Robert J.; (Durham, NC) ; Hopkins; Seth C.;
(Clinton, MA) ; Ogbu; Cyprian O.; (Durham, NC)
; Soukri; Mustapha; (Raleigh, NC) ; Spear; Kerry
L.; (Concord, MA) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS LLP (SF)
One Market, Spear Street Tower, Suite 2800
San Francisco
CA
94105
US
|
Assignee: |
Sepracor Inc.
Marlborough
MA
|
Family ID: |
40342283 |
Appl. No.: |
12/537896 |
Filed: |
August 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11833903 |
Aug 3, 2007 |
7579370 |
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12537896 |
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11825093 |
Jul 2, 2007 |
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11833903 |
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60806391 |
Jun 30, 2006 |
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60842465 |
Sep 5, 2006 |
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60914293 |
Apr 26, 2007 |
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Current U.S.
Class: |
514/412 |
Current CPC
Class: |
A61K 31/407 20130101;
A61P 25/04 20180101; A61P 25/24 20180101; A61P 25/00 20180101; A61P
25/28 20180101; A61P 25/16 20180101; A61P 25/08 20180101; A61P
25/18 20180101; C07D 491/04 20130101; A61P 29/00 20180101; A61P
43/00 20180101; C07D 495/04 20130101 |
Class at
Publication: |
514/412 |
International
Class: |
A61K 31/407 20060101
A61K031/407; A61P 25/00 20060101 A61P025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 2008 |
US |
PCT/US08/71642 |
Claims
1. A method of treating a subject for a condition selected from
loss of memory, loss of cognition and a combination thereof, said
method comprising administering to said subject a therapeutically
effective amount of a D-amino oxidase inhibitor having the formula:
##STR00012## in which R.sup.1 is a member selected from the group
consisting of H, and substituted or unsubstituted arylalkyl;
R.sup.2 is a member selected from the group consisting of H, and
substituted or unsubstituted arylalkyl; and R.sup.4 is a member
selected from OH and O.sup.-X.sup.+ wherein X.sup.+ is a positive
ion which is a member selected from organic positive ions and
inorganic positive ions, wherein substituted or unsubstituted
arylalkyl has the formula: ##STR00013## in which Ar is substituted
or unsubstituted aryl; and n is an integer from 1 to 4.
2. The method according to claim 1 wherein said condition is a
result of Alzheimer's disease.
3. The method according to claim 1 wherein said condition is a
result of schizophrenia.
4. The method according to claim 1 wherein said D-amino oxidase
inhibitor is administered to said subject as a pharmaceutical
composition in unit dosage form comprising, per dosage unit, a
pharmaceutically acceptable carrier and a daily dosage of said
D-amino oxidase inhibitor in an amount of about 0.1 mg to about
7000 mg.
5. The method according to claim 4 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 50 mg to about 500 mg.
6. The method according to claim 5 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 1 mg to about 100 mg.
7. The method according to claim 6 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 25 mg to about 50 mg.
8. The method according to claim 4 wherein said unit dosage is an
oral dosage form.
9. The method according to claim 6 wherein oral dosage form is a
member selected from a tablet and a capsule.
10. A method of treating a subject for a condition selected from
loss of memory, loss of cognition and a combination thereof, said
method comprising administering to said subject a therapeutically
effective amount of a D-amino oxidase inhibitor as a pharmaceutical
composition comprising, in single or divided doses, a
pharmaceutically acceptable carrier and a daily dosage from about
0.1 mg to about 7000 mg of said D-amino oxidase inhibitor, said
D-amino oxidase inhibitor having the formula: ##STR00014## in which
R.sup.1 is a member selected from the group consisting of H, and
substituted or unsubstituted arylalkyl; R.sup.2 is a member
selected from the group consisting of H, and substituted or
unsubstituted arylalkyl; and R.sup.4 is a member selected from OH
and O.sup.-X.sup.+ wherein X.sup.+ is a positive ion which is a
member selected from organic positive ions and inorganic positive
ions, wherein substituted or unsubstituted arylalkyl has the
formula: ##STR00015## in which Ar is substituted or unsubstituted
aryl; and n is an integer from 1 to 4.
11. The method according to claim 10 wherein said condition is a
result of Alzheimer's disease.
12. The method according to claim 11 wherein said condition is a
result of schizophrenia.
13. The method according to claim 10 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 50 mg to about 500 mg.
14. The method according to claim 13 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 1 mg to about 100 mg.
15. The method according to claim 14 wherein said D-amino oxidase
inhibitor is present in said pharmaceutical composition in an
amount of about 25 mg to about 50 mg.
16. The method according to claim 10 wherein said unit dosage is an
oral dosage form.
17. The method according to claim 16 wherein oral dosage form is a
member selected from a tablet and a capsule.
18. A method of claim 1 wherein R.sup.1 is H; R.sup.2 is H; and
R.sup.4 is a member selected from OH and O.sup.-X.sup.+ wherein
X.sup.+ is a positive ion which is a member selected from organic
positive ions and inorganic positive ions.
19. The method according to claim 18 wherein said condition is a
result of Alzheimer's disease.
20. The method according to claim 18 wherein said condition is a
result of schizophrenia.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 11/833,903, filed Aug. 3, 2007, which is a
continuation-in-part of U.S. patent application Ser. No.
11/825,093, filed Jul. 2, 2007, which claims priority to U.S.
Provisional Patent Application No. 60/806,391 filed on Jun. 30,
2006, U.S. Provisional Patent Application No. 60/842,465 filed on
Sep. 5, 2006, and U.S. Provisional Patent Application No.
60/914,293 filed on Apr. 26, 2007, each of which is incorporated
herein by reference in its entirety for all purposes.
FIELD OF THE INVENTION
[0002] This invention relates to enzyme inhibitors and methods of
treating diseases and conditions, wherein modulation of D-amino
acid oxidase activity, D-serine levels, D-serine oxidative products
and NMDA receptor activity in the nervous system of a mammalian
subject is effective, along with a reduction in undesirable side
effects.
BACKGROUND OF THE INVENTION
[0003] The enzyme D-amino acid oxidase (DAAO) metabolizes D-amino
acids, and in particular, metabolizes D-serine in vitro at
physiological pH. DAAO is expressed in the mammalian brain and
periphery. D-Serine's role as a neurotransmitter is important in
the activation of the N-methyl-D-aspartate (NMDA) selective subtype
of the glutamate receptor, an ion channel expressed in neurons,
here denoted as NMDA receptor.
[0004] NMDA receptors mediate many physiological functions. NMDA
receptors are complex ion channels containing multiple protein
subunits that act either as binding sites for transmitter amino
acids and/or as allosteric regulatory binding sites to regulate ion
channel activity. D-serine, released by glial cells, has a
distribution similar to NMDA receptors in the brain and acts as an
endogenous ligand of the allosteric "glycine" site of these
receptors (Mothet et al., PNAS, 97:4926 (2000)), the occupation of
which is required for NMDA receptor operation. D-serine is
synthesized in brain through serine racemase and degraded by
D-amino oxidase (DAAO) after release.
[0005] Small organic molecules, which inhibit the enzymatic cycle
of DAAO, may control the levels of D-serine, and thus influence the
activity of the NMDA receptor in the brain. NMDA receptor activity
is important in a variety of disease states, such as schizophrenia,
psychosis, ataxia, ischemia, several forms of pain including
neuropathic pain, and deficits in memory and cognition.
[0006] DAAO inhibitors may also control production of toxic
metabolites of D-serine oxidation, such as hydrogen peroxide and
ammonia. Thus, these molecules may influence the progression of
cell loss in neurodegenerative disorders. Neurodegenerative
diseases are diseases in which CNS neurons and/or peripheral
neurons undergo a progressive loss of function, usually accompanied
by (and perhaps caused by) a physical deterioration of the
structure of either the neuron itself or its interface with other
neurons. Such conditions include Parkinson's disease, Alzheimer's
disease, Huntington's disease and neuropathic pain.
N-methyl-D-aspartate (NMDA)-glutamate receptors are expressed at
excitatory synapses throughout the central nervous system (CNS).
These receptors mediate a wide range of brain processes, including
synaptic plasticity, that are associated with certain types of
memory formation and learning. NMDA-glutamate receptors require
binding of two agonists to induce neurotransmission. One of these
agonists is the excitatory amino acid L-glutamate, while the second
agonist, at the so-called "strychnine-insensitive glycine site", is
now thought to be D-serine. In animals, D-serine is synthesized
from L-serine by serine racemase and degraded to its corresponding
ketoacid by DAAO. Together, serine racemase and DAAO are thought to
play a crucial role in modulating NMDA neurotransmission by
regulating CNS concentrations of D-serine.
[0007] Known inhibitors of DAAO include benzoic acid,
pyrrole-2-carboxylic acids, and indole-2-carboxylic acids, as
described by Frisell, et al., J. Biol. Chem., 223:75-83 (1956) and
Parikh et al., JACS, 80:953 (1958). Indole derivatives and
particularly certain indole-2-carboxylates have been described in
the literature for treatment of neurodegenerative disease and
neurotoxic injury. EP 396124 discloses indole-2-carboxylates and
derivatives for treatment or management of neurotoxic injury
resulting from a CNS disorder or traumatic event or in treatment or
management of a neurodegenerative disease. Several examples of
traumatic events that may result in neurotoxic injury are given,
including hypoxia, anoxia, and ischemia, associated with perinatal
asphyxia, cardiac arrest or stroke. Neurodegeneration is associated
with CNS disorders such as convulsions and epilepsy. U.S. Pat. Nos.
5,373,018; 5,374,649; 5,686,461; 5,962,496 and 6,100,289, to
Cugola, disclose treatment of neurotoxic injury and
neurodegenerative disease using indole derivatives. None of the
above references mention improvement or enhancement of learning,
memory or cognition.
[0008] WO 03/039540 to Heefner et al. and U.S. Patent Application
Nos. 2005/0143443 to Fang et al. and 2005/0143434 to Fang et al.
disclose DAAO inhibitors, including indole-2-carboxylic acids, and
methods of enhancing learning, memory and cognition as well as
methods for treating neurodegenerative disorders. Patent
Application No. WO/2005/089753 discloses benzisoxazole analogs and
methods of treating mental disorders, such as schizophrenia.
However, a need for additional drug molecules that are effective in
treating memory defects, impaired learning, loss of cognition, and
other symptoms related to NMDA receptor activity, remains. The
present invention addresses this and other needs.
SUMMARY OF THE INVENTION
[0009] The invention provides novel inhibitors of D-amino acid
oxidase that are useful in the prevention and treatment of a
variety of diseases and/or conditions including neurological
disorders, pain, ataxia, and convulsion.
[0010] In a first aspect, the present invention provides a compound
having a structure according to Formula (I):
##STR00003##
in which R.sup.1 is H, substituted or unsubstituted arylalkyl or
substituted or unsubstituted heteroarylalkyl. The symbol R.sup.2 is
represents H, substituted or unsubstituted alkenyl, substituted or
unsubstituted arylalkyl or substituted or unsubstituted
heteroarylalkyl. R.sup.3 is H, C.sub.1-C.sub.6 substituted or
unsubstituted alkyl, substituted or unsubstituted arylalkyl or
substituted or unsubstituted heteroarylalkyl. The radical R.sup.4
represents OH or O.sup.-X.sup.+, wherein X.sup.+ is a positive ion
which is a member selected from organic positive ions and inorganic
positive ions. The invention also includes salts, hydrates,
solvates and prodrugs of the compounds of Formula I.
[0011] In the context of Formula I, substituted or unsubstituted
arylalkyl and substituted or unsubstituted heteroarylalkyl have the
formula:
##STR00004##
in which Ar is substituted or unsubstituted aryl or substituted or
unsubstituted heteroaryl. The index n is an integer from 1 to
4.
[0012] In a preferred embodiment, the compound according to Formula
I is incorporated into a pharmaceutical formulation along with one
or more pharmaceutically acceptable diluent, excipient, carrier,
etc. Those of skill in the art will recognize the overlap in the
terms "diluent", "excipient" and "carrier".
[0013] In a further aspect the invention provides a method for
treating or preventing a disease or condition which is a member
selected from a neurological disorder, pain, ataxia and convulsion.
The method includes administering to a subject in need thereof a
therapeutically effective amount of a compound of Formula (I) or a
pharmaceutically acceptable salt or solvate thereof.
DETAILED DESCRIPTION OF THE INVENTION
I. Definitions
[0014] Where substituent groups are specified by their conventional
chemical formulae, written from left to right, they optionally
encompass substituents resulting from writing the structure from
right to left, e.g., --CH.sub.2O-- optionally also recites
--OCH.sub.2--.
[0015] The term "alkyl," by itself or as part of another
substituent, means, unless otherwise stated, a straight or branched
chain, or cyclic hydrocarbon radical, or combination thereof, which
may be fully saturated, mono- or polyunsaturated and can include
di- and multivalent radicals, having the number of carbon atoms
designated (i.e. C.sub.1-C.sub.10 means one to ten carbons).
Examples of saturated hydrocarbon radicals include, but are not
limited to, groups such as methyl, ethyl, n-propyl, isopropyl,
n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl,
(cyclohexyl)methyl, cyclopropylmethyl, homologs and isomers of, for
example, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. An
unsaturated alkyl group is one having one or more double bonds or
triple bonds. Examples of unsaturated alkyl groups include, but are
not limited to, vinyl, 2-propenyl, crotyl, 2-isopentenyl,
2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1-
and 3-propynyl, 3-butynyl, and the higher homologs and isomers. The
term "alkyl," unless otherwise noted, is also meant to include
those derivatives of alkyl defined in more detail below, such as
"heteroalkyl" with the difference that the heteroalkyl group, in
order to qualify as an alkyl group, is linked to the remainder of
the molecule through a carbon atom. Alkyl groups that are limited
to hydrocarbon groups are termed "homoalkyl".
[0016] The term "alkenyl" by itself or as part of another
substituent is used in its conventional sense, and refers to a
radical derived from an alkene, as exemplified, but not limited by,
substituted or unsubstituted vinyl and substituted or unsubstituted
propenyl. Typically, an alkenyl group will have from 1 to 24 carbon
atoms, with those groups having from 1 to 10 carbon atoms being
generally preferred.
[0017] The term "alkylene" by itself or as part of another
substituent means a divalent radical derived from an alkane, as
exemplified, but not limited, by
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2--, and further includes those
groups described below as "heteroalkylene." Typically, an alkyl (or
alkylene) group will have from 1 to 24 carbon atoms, with those
groups having 10 or fewer carbon atoms being preferred in the
present invention. A "lower alkyl" or "lower alkylene" is a shorter
chain alkyl or alkylene group, generally having eight or fewer
carbon atoms.
[0018] The terms "alkoxy," "alkylamino" and "alkylthio" (or
thioalkoxy) are used in their conventional sense, and refer to
those alkyl groups attached to the remainder of the molecule via an
oxygen atom, an amino group, or a sulfur atom, respectively.
[0019] The term "heteroalkyl," by itself or in combination with
another term, means, unless otherwise stated, a stable straight or
branched chain, or cyclic hydrocarbon radical, or combinations
thereof, consisting of the stated number of carbon atoms and at
least one heteroatom selected from the group consisting of O, N, Si
and S, and wherein the nitrogen and sulfur atoms may optionally be
oxidized and the nitrogen heteroatom may optionally be quaternized.
The heteroatom(s) O, N and S and Si may be placed at any interior
position of the heteroalkyl group or at the position at which the
alkyl group is attached to the remainder of the molecule. Examples
include, but are not limited to, --CH.sub.2--CH.sub.2--O--CH.sub.3,
--CH.sub.2--CH.sub.2--NH--CH.sub.3,
--CH.sub.2--CH.sub.2--N(CH.sub.3)--CH.sub.3,
--CH.sub.2--S--CH.sub.2--CH.sub.3, --CH.sub.2--CH.sub.2,
--S(O)--CH.sub.3, --CH.sub.2--CH.sub.2--S(O).sub.2--CH.sub.3,
--CH.dbd.CH--O--CH.sub.3, --Si(CH.sub.3).sub.3,
--CH.sub.2--CH.dbd.N--OCH.sub.3, and
--CH.dbd.CH--N(CH.sub.3)--CH.sub.3. Up to two heteroatoms may be
consecutive, such as, for example, --CH.sub.2--NH--OCH.sub.3 and
--CH.sub.2--O--Si(CH.sub.3).sub.3. Similarly, the term
"heteroalkylene" by itself or as part of another substituent means
a divalent radical derived from heteroalkyl, as exemplified, but
not limited by, --CH.sub.2--CH.sub.2--S--CH.sub.2--CH.sub.2-- and
--CH.sub.2--S--CH.sub.2--CH.sub.2--NH--CH.sub.2--. For
heteroalkylene groups, heteroatoms can also occupy either or both
of the chain termini (e.g., alkyleneoxy, alkylenedioxy,
alkyleneamino, alkylenediamino, and the like). Still further, for
alkylene and heteroalkylene linking groups, no orientation of the
linking group is implied by the direction in which the formula of
the linking group is written. For example, the formula
--CO.sub.2R'-- represents both --C(O)OR' and --OC(O)R'.
[0020] The terms "cycloalkyl" and "heterocycloalkyl", by themselves
or in combination with other terms, represent, unless otherwise
stated, cyclic versions of "alkyl" and "heteroalkyl", respectively.
Additionally, for heterocycloalkyl, a heteroatom can occupy the
position at which the heterocycle is attached to the remainder of
the molecule. A "cycloalkyl" or "heterocycloalkyl" substituent may
be attached to the remainder of the molecule directly or through a
linker, wherein the linker is preferably alkylene. Examples of
cycloalkyl include, but are not limited to, cyclopentyl,
cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, cycloheptyl, and the
like. Examples of heterocycloalkyl include, but are not limited to,
1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl,
3-piperidinyl, 4-morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl,
tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl,
1-piperazinyl, 2-piperazinyl, and the like.
[0021] The terms "halo" or "halogen," by themselves or as part of
another substituent, mean, unless otherwise stated, a fluorine,
chlorine, bromine, or iodine atom. Additionally, terms such as
"haloalkyl," are meant to include monohaloalkyl and polyhaloalkyl.
For example, the term "halo(C.sub.1-C.sub.4)alkyl" is mean to
include, but not be limited to, trifluoromethyl,
2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, and the
like.
[0022] The term "aryl" means, unless otherwise stated, a
polyunsaturated, aromatic, substituent that can be a single ring or
multiple rings (preferably from 1 to 3 rings), which are fused
together or linked covalently. The term "heteroaryl" refers to aryl
groups (or rings) that contain from one to four heteroatoms
selected from N, O, S, Si and B, wherein the nitrogen and sulfur
atoms are optionally oxidized, and the nitrogen atom(s) are
optionally quaternized. A heteroaryl group can be attached to the
remainder of the molecule through a heteroatom. Non-limiting
examples of aryl and heteroaryl groups include phenyl, 1-naphthyl,
2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl,
3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl,
4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl,
4-isoxazolyl, 5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl,
2-furyl, 3-furyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl,
4-pyridyl, 2-pyrimidyl, 4-pyrimidyl, 5-benzothiazolyl, purinyl,
2-benzimidazolyl, 5-indolyl, 1-isoquinolyl, 5-isoquinolyl,
2-quinoxalinyl, 5-quinoxalinyl, 3-quinolyl, and 6-quinolyl.
Substituents for each of the above noted aryl and heteroaryl ring
systems are selected from the group of acceptable substituents
described below.
[0023] For brevity, the term "aryl" when used in combination with
other terms (e.g., aryloxy, arylthioxy, arylalkyl) optionally
includes both aryl and heteroaryl rings as defined above. Thus, the
term "arylalkyl" optionally includes those radicals in which an
aryl group is attached to an alkyl group (e.g., benzyl, phenethyl,
pyridylmethyl and the like) including those alkyl groups in which a
carbon atom (e.g., a methylene group) has been replaced by, for
example, an oxygen atom (e.g., phenoxymethyl, 2-pyridyloxymethyl,
3-(1-naphthyloxy)propyl, and the like).
[0024] Each of the above terms (e.g., "alkyl," "heteroalkyl,"
"aryl" and "heteroaryl") optionally include both substituted and
unsubstituted forms of the indicated radical. Preferred
substituents for each type of radical are provided below.
[0025] Substituents for the alkyl and heteroalkyl radicals
(including those groups often referred to as alkylene, alkenyl,
heteroalkylene, heteroalkenyl, alkynyl, cycloalkyl,
heterocycloalkyl, cycloalkenyl, and heterocycloalkenyl) are
generically referred to as "alkyl group substituents," and they can
be one or more of a variety of groups selected from, but not
limited to: substituted or unsubstituted aryl, substituted or
unsubstituted heteroaryl, substituted or unsubstituted
heterocycloalkyl, --OR', .dbd.O, .dbd.NR', .dbd.N--OR', --NR'R'',
--SR', -halogen, --SiR'R''R''', --OC(O)R', --C(O)R', --CO.sub.2R',
--CONR'R'', --OC(O)NR'R'', --NR''C(O)R', --NR'--C(O)NR''R''',
--NR''C(O).sub.2R', --NR--C(NR'R''R''').dbd.NR'''',
--NR--C(NR'R'').dbd.NR''', --S(O)R', --S(O).sub.2R',
--S(O).sub.2NR'R'', --NRSO.sub.2R', --CN and --NO.sub.2 in a number
ranging from zero to (2m'+1), where m' is the total number of
carbon atoms in such radical. R', R'', R''' and R'''' each
preferably independently refer to hydrogen, substituted or
unsubstituted heteroalkyl, substituted or unsubstituted aryl, e.g.,
aryl substituted with 1-3 halogens, substituted or unsubstituted
alkyl, alkoxy or thioalkoxy groups, or arylalkyl groups. When a
compound of the invention includes more than one R group, for
example, each of the R groups is independently selected as are each
R', R'', R''' and R'''' groups when more than one of these groups
is present. When R' and R'' are attached to the same nitrogen atom,
they can be combined with the nitrogen atom to form a 5-, 6-, or
7-membered ring. For example, --NR'R'' is meant to include, but not
be limited to, 1-pyrrolidinyl and 4-morpholinyl. From the above
discussion of substituents, one of skill in the art will understand
that the term "alkyl" is meant to include groups including carbon
atoms bound to groups other than hydrogen groups, such as haloalkyl
(e.g., --CF.sub.3 and --CH.sub.2CF.sub.3) and acyl (e.g.,
--C(O)CH.sub.3, --C(O)CF.sub.3, --C(O)CH.sub.2OCH.sub.3, and the
like).
[0026] Similar to the substituents described for the alkyl radical,
substituents for the aryl and heteroaryl groups are generically
referred to as "aryl group substituents." The substituents are
selected from, for example: substituted or unsubstituted alkyl,
substituted or unsubstituted aryl, substituted or unsubstituted
heteroaryl, substituted or unsubstituted heterocycloalkyl, --OR',
.dbd.O, .dbd.NR', .dbd.N--OR', --NR'R'', --SR', -halogen,
--SiR'R''R''', --OC(O)R', --C(O)R', --CO.sub.2R', --CONR'R'',
--OC(O)NR'R'', --NR''C(O)R', --NR'--C(O)NR''R''',
--NR''C(O).sub.2R', --NR--C(NR'R''R''').dbd.NR'''',
--NR--C(NR'R'').dbd.NR''', --S(O)R', --S(O).sub.2R',
--S(O).sub.2NR'R'', --NRSO.sub.2R', --CN and --NO.sub.2, --R',
--N.sub.3, --CH(Ph).sub.2, fluoro(C.sub.1-C.sub.4)alkoxy, and
fluoro(C.sub.1-C.sub.4)alkyl, in a number ranging from zero to the
total number of open valences on the aromatic ring system; and
where R', R'', R''' and R'''' are preferably independently selected
from hydrogen, substituted or unsubstituted alkyl, substituted or
unsubstituted heteroalkyl, substituted or unsubstituted aryl and
substituted or unsubstituted heteroaryl. When a compound of the
invention includes more than one R group, for example, each of the
R groups is independently selected as are each R', R'', R''' and
R'''' groups when more than one of these groups is present.
[0027] Two of the substituents on adjacent atoms of the aryl or
heteroaryl ring may optionally be replaced with a substituent of
the formula -T-C(O)--(CRR').sub.q-U-, wherein T and U are
independently --NR--, --O--, --CRR'-- or a single bond, and q is an
integer of from 0 to 3. Alternatively, two of the substituents on
adjacent atoms of the aryl or heteroaryl ring may optionally be
replaced with a substituent of the formula
-A-(CH.sub.2).sub.r--B--, wherein A and B are independently
--CRR'--, --O--, --NR--, --S--, --S(O)--, --S(O).sub.2--,
--S(O).sub.2NR'-- or a single bond, and r is an integer of from 1
to 4. One of the single bonds of the new ring so formed may
optionally be replaced with a double bond. Alternatively, two of
the substituents on adjacent atoms of the aryl or heteroaryl ring
may optionally be replaced with a substituent of the formula
--(CRR')S--X--(CR''R''').sub.d--, where s and d are independently
integers of from 0 to 3, and X is --O--, --NR'--, --S--, --S(O)--,
--S(O).sub.2--, or --S(O).sub.2NR'--. The substituents R', R', R''
and R''' are preferably independently selected from hydrogen or
substituted or unsubstituted (C.sub.1-C.sub.6)alkyl.
[0028] As used herein, the term "acyl" describes a substituent
containing a carbonyl residue, C(O)R. Exemplary species for R
include H, halogen, substituted or unsubstituted alkyl, substituted
or unsubstituted aryl, substituted or unsubstituted heteroaryl, and
substituted or unsubstituted heterocycloalkyl.
[0029] As used herein, the term "fused ring system" means at least
two rings, wherein each ring has at least 2 atoms in common with
another ring. "Fused ring systems may include aromatic as well as
non aromatic rings. Examples of "fused ring systems" are
naphthalenes, indoles, quinolines, chromenes and the like.
[0030] As used herein, the term "heteroatom" includes oxygen (O),
nitrogen (N), sulfur (S) and silicon (Si), boron (B) and phosphorus
(P).
[0031] The symbol "R" is a general abbreviation that represents a
substituent group, e.g., one that is selected from substituted or
unsubstituted alkyl, substituted or unsubstituted heteroalkyl,
substituted or unsubstituted aryl, substituted or unsubstituted
heteroaryl, and substituted or unsubstituted heterocycloalkyl
groups.
[0032] The phrase "therapeutically effective amount" as used herein
means that amount of a compound, material, or composition
comprising a compound of the present invention which is effective
for producing some desired therapeutic effect by inhibition of DAAO
in at least a sub-population of cells in an animal and thereby
blocking the biological consequences of that pathway in the treated
cells, at a reasonable benefit/risk ratio applicable to any medical
treatment.
[0033] The term "pharmaceutically acceptable salts" includes salts
of the active compounds which are prepared with relatively nontoxic
acids or bases, depending on the particular substituents found on
the compounds described herein. When compounds of the present
invention contain relatively acidic functionalities, base addition
salts can be obtained by contacting the neutral form of such
compounds with a sufficient amount of the desired base, either neat
or in a suitable inert solvent. Examples of pharmaceutically
acceptable base addition salts include sodium, potassium, calcium,
ammonium, organic amino, or magnesium salt, or a similar salt. When
compounds of the present invention contain relatively basic
functionalities, acid addition salts can be obtained by contacting
the neutral form of such compounds with a sufficient amount of the
desired acid, either neat or in a suitable inert solvent. Examples
of pharmaceutically acceptable acid addition salts include those
derived from inorganic acids like hydrochloric, hydrobromic,
nitric, carbonic, monohydrogencarbonic, phosphoric,
monohydrogenphosphoric, dihydrogenphosphoric, sulfuric,
monohydrogensulfuric, hydriodic, or phosphorous acids and the like,
as well as the salts derived from relatively nontoxic organic acids
like acetic, propionic, isobutyric, maleic, malonic, benzoic,
succinic, suberic, fumaric, lactic, mandelic, phthalic,
benzenesulfonic, p-tolylsulfonic, citric, tartaric,
methanesulfonic, and the like. Also included are salts of amino
acids such as arginate and the like, and salts of organic acids
like glucuronic or galactunoric acids and the like (see, for
example, Berge et al., Journal of Pharmaceutical Science, 66: 1-19
(1977)). Certain specific compounds of the present invention
contain both basic and acidic functionalities that allow the
compounds to be converted into either base or acid addition
salts.
[0034] When a residue (such as R.sup.4 in this application) is
defined as "O.sup.-", then the formula is meant to optionally
include an organic or inorganic cationic counterion. Preferably,
the resulting salt form of the compound is pharmaceutically
acceptable.
[0035] The neutral forms of the compounds are preferably
regenerated by contacting the salt with a base or acid and
isolating the parent compound in the conventional manner. The
parent form of the compound differs from the various salt forms in
certain physical properties, such as solubility in polar solvents,
but otherwise the salts are equivalent to the parent form of the
compound for the purposes of the present invention.
[0036] In addition to salt forms, the present invention provides
compounds, which are in a prodrug form. Prodrugs of the compounds
described herein are those compounds that readily undergo chemical
changes under physiological conditions to provide the compounds of
the present invention. For instance, prodrugs for carboxylic acid
analogs of the invention include a variety of esters. In an
exemplary embodiment, the pharmaceutical compositions of the
invention include a carboxylic acid ester. In another exemplary
embodiment, the prodrug is suitable for treatment/prevention of
those diseases and conditions that require the drug molecule to
cross the blood brain barrier. In a preferred embodiment, the
prodrug enters the brain, where it is converted into the active
form of the drug molecule. In another example, a prodrug is used to
enable an active drug molecule to reach the inside of the eye after
topical application of the prodrug to the eye. Additionally,
prodrugs can be converted to the compounds of the present invention
by chemical or biochemical methods in an ex vivo environment. For
example, prodrugs can be slowly converted to the compounds of the
present invention when placed in a transdermal patch reservoir with
a suitable enzyme or chemical reagent.
[0037] Certain compounds of the present invention can exist in
unsolvated forms as well as solvated forms, including hydrated
forms. In general, the solvated forms are equivalent to unsolvated
forms and are encompassed within the scope of the present
invention. Certain compounds of the present invention may exist in
multiple crystalline or amorphous forms ("polymorphs"). In general,
all physical forms are of use in the methods contemplated by the
present invention and are intended to be within the scope of the
present invention. "Compound or a pharmaceutically acceptable salt,
hydrate, polymorph or solvate of a compound" intends the inclusive
meaning of "or", in that materials meeting more than one of the
stated criteria are included, e.g., a material that is both a salt
and a solvate is encompassed.
[0038] Certain compounds of the present invention possess
asymmetric carbon atoms (optical centers) or double bonds; the
racemates, diastereomers, geometric isomers and individual isomers
are encompassed within the scope of the present invention.
Optically active (R)- and (S)-isomers may be prepared using chiral
synthons or chiral reagents, or resolved using conventional
techniques. When the compounds described herein contain olefinic
double bonds or other centers of geometric asymmetry, and unless
specified otherwise, it is intended that the compounds include both
E and Z geometric isomers. Likewise, all tautomeric forms are
included.
[0039] The compounds of the present invention may also contain
unnatural proportions of atomic isotopes at one or more of the
atoms that constitute such compounds. For example, the compounds
may be radiolabeled with radioactive isotopes, such as for example
tritium (.sup.3H), iodine-125 (.sup.125I) or carbon-14 (.sup.14C).
All isotopic variations of the compounds of the present invention,
whether radioactive or not, are intended to be encompassed within
the scope of the present invention.
[0040] In the context of the present invention, compounds that are
considered to possess activity as DAAO inhibitors are those
displaying 50% inhibition of the enzymatic activity of DAAO
(IC.sub.50) at a concentration of not higher than about 100 .mu.M,
preferably, not higher than about 10 .mu.M, more preferably not
higher than about 1 .mu.M and most preferably not higher than about
100 nM.
[0041] The term "neurological disorder" refers to any condition of
the central or peripheral nervous system of a mammal. The term
"neurological disorder" includes neurodegenerative diseases (e.g.,
Alzheimer's disease, Parkinson's disease and amyotrophic lateral
sclerosis), neuropsychiatric diseases (e.g. Schizophrenia and
anxieties, such as general anxiety disorder). Exemplary
neurological disorders include MLS (cerebellar ataxia),
Huntington's disease, Down syndrome, multi-infarct dementia, status
epilecticus, contusive injuries (e.g. spinal cord injury and head
injury), viral infection induced neurodegeneration, (e.g. AIDS,
encephalopathies), epilepsy, benign forgetfulness, closed head
injury, sleep disorders, depression (e.g., bipolar disorder),
dementias, movement disorders, psychoses, alcoholism,
post-traumatic stress disorder and the like. "Neurological
disorder" also includes any condition associated with the disorder.
For instance, a method of treating a neurodegenerative disorder
includes methods of treating loss of memory and/or loss of
cognition associated with a neurodegenerative disorder. Such method
would also include treating or preventing loss of neuronal function
characteristic of neurodegenerative disorder.
[0042] "Pain" is an unpleasant sensory and emotional experience.
Pain classifications have been based on duration, etiology or
pathophysiology, mechanism, intensity, and symptoms. The term
"pain" as used herein refers to all categories of pain, including
pain that is described in terms of stimulus or nerve response,
e.g., somatic pain (normal nerve response to a noxious stimulus)
and neuropathic pain (abnormal response of a injured or altered
sensory pathway, often without clear noxious input); pain that is
categorized temporally, e.g., chronic pain and acute pain; pain
that is categorized in terms of its severity, e.g., mild, moderate,
or severe; and pain that is a symptom or a result of a disease
state or syndrome, e.g., inflammatory pain, cancer pain, AIDS pain,
arthropathy, migraine, trigeminal neuralgia, cardiac ischaemia, and
diabetic peripheral neuropathic pain (see, e.g., Harrison's
Principles of Internal Medicine, pp. 93-98 (Wilson et al., eds.,
12th ed. 1991); Williams et al., J. of Med. Chem. 42: 1481-1485
(1999), herein each incorporated by reference in their entirety).
"Pain" is also meant to include mixed etiology pain, dual mechanism
pain, allodynia, causalgia, central pain, hyperesthesia,
hyperpathia, dysesthesia, and hyperalgesia.
[0043] "Somatic" pain, as described above, refers to a normal nerve
response to a noxious stimulus such as injury or illness, e.g.,
trauma, burn, infection, inflammation, or disease process such as
cancer, and includes both cutaneous pain (e.g., skin, muscle or
joint derived) and visceral pain (e.g., organ derived).
[0044] "Neuropathic pain" is a heterogeneous group of neurological
conditions that result from damage to the nervous system.
"Neuropathic" pain, as described above, refers to pain resulting
from injury to or dysfunctions of peripheral and/or central sensory
pathways, and from dysfunctions of the nervous system, where the
pain often occurs or persists without an obvious noxious input.
This includes pain related to peripheral neuropathies as well as
central neuropathic pain. Common types of peripheral neuropathic
pain include diabetic neuropathy (also called diabetic peripheral
neuropathic pain, or DN, DPN, or DPNP), post-herpetic neuralgia
(PHN), and trigeminal neuralgia (TGN). Central neuropathic pain,
involving damage to the brain or spinal cord, can occur following
stroke, spinal cord injury, and as a result of multiple sclerosis.
Other types of pain that are meant to be included in the definition
of neuropathic pain include pain from spinal cord injury,
neuropathic cancer pain, HIV/AIDS induced pain, phantom limb pain,
and complex regional pain syndrome. In a preferred embodiment, the
compounds of the invention are of use for treating neuropathic
pain. An exemplary compound of use in this embodiment is a compound
according to Formula I in which each of R.sup.1-R.sup.3 is
hydrogen, and R.sup.4 is selected such that the compound is a free
acid or salt thereof.
[0045] Common clinical features of neuropathic pain include sensory
loss, allodynia (non-noxious stimuli produce pain), hyperalgesia
and hyperpathia (delayed perception, summation, and painful
aftersensation). Pain is often a combination of nociceptive and
neuropathic types, for example, mechanical spinal pain and
radiculopathy or myelopathy.
[0046] "Acute pain", is the normal, predicted physiological
response to a noxious chemical, thermal or mechanical stimulus
typically associated with invasive procedures, trauma and disease.
It is generally time-limited, and may be viewed as an appropriate
response to a stimulus that threatens and/or produces tissue
injury. "Acute pain", as described above, refers to pain which is
marked by short duration or sudden onset.
[0047] "Chronic pain" occurs in a wide range of disorders, for
example, trauma, malignancies and chronic inflammatory diseases
such as rheumatoid arthritis. Chronic pain usually lasts more than
about six months. In addition, the intensity of chronic pain may be
disproportionate to the intensity of the noxious stimulus or
underlying process. "Chronic pain", as described above, refers to
pain associated with a chronic disorder, or pain that persists
beyond resolution of an underlying disorder or healing of an
injury, and that is often more intense than the underlying process
would predict. It may be subject to frequent recurrence.
[0048] "Inflammatory pain" is pain in response to tissue injury and
the resulting inflammatory process. Inflammatory pain is adaptive
in that it elicits physiologic responses that promote healing.
However, inflammation may also affect neuronal function.
Inflammatory mediators, including PGE.sub.2 induced by the COX2
enzyme, bradykinins, and other substances, bind to receptors on
pain-transmitting neurons and alter their function, increasing
their excitability and thus increasing pain sensation. Much chronic
pain has an inflammatory component. "Inflammatory pain", as
described above, refers to pain which is produced as a symptom or a
result of inflammation or an immune system disorder.
[0049] "Visceral pain", as described above, refers to pain which is
located in an internal organ.
[0050] "Mixed etiology" pain, as described above, refers to pain
that contains both inflammatory and neuropathic components.
[0051] "Dual mechanism" pain, as described above, refers to pain
that is amplified and maintained by both peripheral and central
sensitization.
[0052] "Causalgia", as described above, refers to a syndrome of
sustained burning, allodynia, and hyperpathia after a traumatic
nerve lesion, often combined with vasomotor and sudomotor
dysfunction and later trophic changes.
[0053] "Central" pain, as described above, refers to pain initiated
by a primary lesion or dysfunction in the central nervous
system.
[0054] "Hyperesthesia", as described above, refers to increased
sensitivity to stimulation, excluding the special senses.
[0055] "Hyperpathia", as described above, refers to a painful
syndrome characterized by an abnormally painful reaction to a
stimulus, especially a repetitive stimulus, as well as an increased
threshold. It may occur with allodynia, hyperesthesia,
hyperalgesia, or dysesthesia.
[0056] "Dysesthesia", as described above, refers to an unpleasant
abnormal sensation, whether spontaneous or evoked. Special cases of
dysesthesia include hyperalgesia and allodynia,
[0057] "Hyperalgesia", as described above, refers to an increased
response to a stimulus that is normally painful. It reflects
increased pain on suprathreshold stimulation.
[0058] "Allodynia", as described above, refers to pain due to a
stimulus that does not normally provoke pain.
[0059] The term "pain" includes pain resulting from dysfunction of
the nervous system: organic pain states that share clinical
features of neuropathic pain and possible common pathophysiology
mechanisms, but are not initiated by an identifiable lesion in any
part of the nervous system.
[0060] The term "Diabetic Peripheral Neuropathic Pain" (DPNP, also
called diabetic neuropathy, DN or diabetic peripheral neuropathy)
refers to chronic pain caused by neuropathy associated with
diabetes mellitus. The classic presentation of DPNP is pain or
tingling in the feet that can be described not only as "burning" or
"shooting" but also as severe aching pain. Less commonly, patients
may describe the pain as itching, tearing, or like a toothache. The
pain may be accompanied by allodynia and hyperalgesia and an
absence of symptoms, such as numbness.
[0061] The term "Post-Herpetic Neuralgia", also called
"Postherpetic Neuralgia" (PHN), is a painful condition affecting
nerve fibers and skin. It is a complication of shingles, a second
outbreak of the varicella zoster virus (VZV), which initially
causes chickenpox.
[0062] The term "neuropathic cancer pain" refers to peripheral
neuropathic pain as a result of cancer, and can be caused directly
by infiltration or compression of a nerve by a tumor, or indirectly
by cancer treatments such as radiation therapy and chemotherapy
(chemotherapy-induced neuropathy).
[0063] The term "HIV/AIDS peripheral neuropathy" or
"HIV/AIDS-related neuropathy" refers to peripheral neuropathy
caused by HIV/AIDS, such as acute or chronic inflammatory
demyelinating neuropathy (AIDP and CIDP, respectively), as well as
peripheral neuropathy resulting as a side effect of drugs used to
treat HIV/AIDS.
[0064] The term "Phantom Limb Pain" refers to pain appearing to
come from where an amputated limb used to be. Phantom limb pain can
also occur in limbs following paralysis. It is usually chronic in
nature. It is similar in nature to the limb pain experienced by
patients with paralysis following spinal cord injury.
[0065] The term "Trigeminal Neuralgia" (TN) refers to a disorder of
the fifth cranial (trigeminal) nerve that causes episodes of
intense, stabbing, electric-shock-like pain in the areas of the
face where the branches of the nerve are distributed (lips, eyes,
nose, scalp, forehead, upper jaw, and lower jaw). It is also known
as the "suicide disease".
[0066] The term "Complex Regional Pain Syndrome (CRPS)," formerly
known as Reflex Sympathetic Dystrophy (RSD), is a chronic pain
condition. The key symptom of CRPS is continuous, intense pain out
of proportion to the severity of the injury, which gets worse
rather than better over time. CRPS is divided into type 1, which
includes conditions caused by tissue injury other than peripheral
nerve, and type 2, in which the syndrome is provoked by major nerve
injury, and is sometimes called causalgia.
[0067] The term "Fibromyalgia" refers to a chronic condition
characterized by diffuse or specific muscle, joint, or bone pain,
along with fatigue and a range of other symptoms. Previously,
fibromyalgia was known by other names such as fibrositis, chronic
muscle pain syndrome, psychogenic rheumatism and tension
myalgias.
[0068] The term "convulsion" refers to a CNS disorder and is used
interchangeably with "seizure," although there are many types of
seizure, some of which have subtle or mild symptoms instead of
convulsions. Seizures of all types may be caused by disorganized
and sudden electrical activity in the brain. Convulsions are a
rapid and uncontrollable shaking. During convulsions, the muscles
contract and relax repeatedly.
II. Introduction
[0069] The present invention relates to novel inhibitors of the
enzyme D-amino acid oxidase. These compounds are useful for
treating or preventing any disease and/or condition, wherein
modulation of D-serine levels, and/or its oxidative products, is
effective in ameliorating symptoms. Inhibition of the enzyme can
lead to increases in D-serine levels and a reduction in the
formation of toxic D-serine oxidation products. Thus, the invention
provides methods for the treatment or prevention of neurological
disorders. For example, the invention provides methods of enhancing
learning, memory and/or cognition, for treating or preventing loss
of memory and/or cognition associated with neurodegenerative
diseases (e.g., Alzheimer's disease) and for preventing loss of
neuronal function characteristic of neurodegenerative diseases.
Further, methods are provided for the treatment or prevention of
pain, ataxia, and convulsion.
III. Compositions
A. Fused Heterocycles
[0070] The heterocyclic inhibitors of the invention are
characterized by a variety of core-moieties.
[0071] In a first aspect, the present invention provides a compound
having a structure according to Formula (I):
##STR00005##
in which R.sup.1 is H, substituted or unsubstituted arylalkyl or
substituted or unsubstituted heteroarylalkyl. The symbol R.sup.2 is
represents H, substituted or unsubstituted alkenyl, substituted or
unsubstituted arylalkyl or substituted or unsubstituted
heteroarylalkyl. R.sup.3 is H, C.sub.1-C.sub.6 substituted or
unsubstituted alkyl, substituted or unsubstituted arylalkyl or
substituted or unsubstituted heteroarylalkyl. The radical R.sup.4
is OH or O.sup.-X.sup.+, wherein X.sup.+ is positive ion which is a
member selected from organic positive ions and inorganic positive
ions. The invention also includes salts, hydrates, solvates and
prodrugs of the compounds of Formula I.
[0072] In the context of Formula I, substituted or unsubstituted
arylalkyl and substituted or unsubstituted heteroarylalkyl have the
formula:
##STR00006##
in which Ar is substituted or unsubstituted aryl or substituted or
unsubstituted heteroaryl. The index n is an integer from 1 to
4.
[0073] In a preferred embodiment, the compound according to Formula
I is incorporated into a pharmaceutical formulation along with one
or more pharmaceutically acceptable diluent, excipient, carrier,
etc. Those of skill will recognize that there is overlap between
the terms "diluent", "excipient" and "carrier".
1. Synthesis of Fused Furan Pyrrole Analogs
[0074] Exemplary fused furan pyrrole analogs of the present
invention are prepared using a procedure such as those outlined in
Schemes 1, 2 and 3 below.
##STR00007##
##STR00008##
##STR00009##
[0075] The fused furan pyrrole derivatives of the invention may be
prepared by Suzuki coupling of a halogenated furan aldehyde and an
appropriate boronic acid. Condensation of the resulting furan
intermediate and 2-azidoacetate, followed by cyclization and
saponification of the ester group affords the desired carboxylic
acid analog (Schemes 1 and 2). Similarly, Suzuki coupling of a
halogenated 4H-furo[3,2-b]pyrrole-5-carboxylic acid ester, followed
by saponification, affords the desired carboxylic acid analog
(Scheme 3).
C. Pharmaceutical Compositions
[0076] While compounds of the present invention can be administered
as the raw chemical, it is preferable to present them as a
pharmaceutical composition. According to a further aspect, the
present invention provides a pharmaceutical composition comprising
a compound of Formula (I) or a pharmaceutically acceptable salt,
hydrate or solvate thereof, together with one or more
pharmaceutical carrier and optionally one or more other therapeutic
ingredients. The carrier(s) are "acceptable" in the sense of being
compatible with the other ingredients of the formulation and not
deleterious to the recipient thereof. The term "pharmaceutically
acceptable carrier" includes vehicles, diluents, excipients and
other elements appropriate for incorporation into a pharmaceutical
formulation.
[0077] The formulations include those suitable for oral, parenteral
(including subcutaneous, intradermal, intramuscular, intravenous
and intraarticular), rectal and topical (including dermal, buccal,
sublingual and intraocular) administration, as well as those for
administration by inhalation. The most suitable route may depend
upon the condition and disorder of the recipient. The formulations
may conveniently be presented in unit dosage form and may be
prepared by any of the methods well known in the art of pharmacy.
All methods include the step of bringing into association a
compound or a pharmaceutically acceptable salt or solvate thereof
("active ingredient") with the carrier which constitutes one or
more accessory ingredients. In general, the formulations are
prepared by uniformly and intimately bringing into association the
active ingredient with liquid carriers or finely divided solid
carriers or both and then, if necessary, shaping the product into
the desired formulation. Oral formulations are well known to those
skilled in the art, and general methods for preparing them are
found in any standard pharmacy school textbook, for example,
Remington: The Science and Practice of Pharmacy, A. R. Gennaro, ed.
(1995), the entire disclosure of which is incorporated herein by
reference.
[0078] Pharmaceutical compositions containing compounds of Formula
(I) may be conveniently presented in unit dosage form and prepared
by any of the methods well known in the art of pharmacy. Preferred
unit dosage formulations are those containing an effective dose, or
an appropriate fraction thereof, of the active ingredient, or a
pharmaceutically acceptable salt thereof. The magnitude of a
prophylactic or therapeutic dose typically varies with the nature
and severity of the condition to be treated and the route of
administration. The dose, and perhaps the dose frequency, will also
vary according to the age, body weight and response of the
individual patient. In general, the total daily dose ranges from
about 0.1 mg per day to about 7000 mg per day, preferably about 1
mg per day to about 100 mg per day, and more preferably, about 25
mg per day to about 50 mg per day, in single or divided doses. In
some embodiments, the total daily dose may range from about 50 mg
to about 500 mg per day, and preferably, about 100 mg to about 500
mg per day. It is further recommended that children, patients over
65 years old, and those with impaired renal or hepatic function,
initially receive low doses and that the dosage is titrated based
on individual responses and/or blood levels. It may be necessary to
use dosages outside these ranges in some cases, as will be apparent
to those in the art. Further, it is noted that the clinician or
treating physician knows how and when to interrupt, adjust or
terminate therapy in conjunction with individual patient's
response.
[0079] It should be understood that in addition to the ingredients
particularly mentioned above, the formulations of this invention
may include other agents conventional in the art having regard to
the type of formulation in question, for example those suitable for
oral administration may include flavoring agents.
[0080] Formulations of the present invention suitable for oral
administration may be presented as discrete units such as capsules,
cachets or tablets each containing a predetermined amount of the
active ingredient; as a powder or granules; as a solution or a
suspension in an aqueous liquid or a non-aqueous liquid; or as an
oil-in-water liquid emulsion or a water-in-oil liquid emulsion. The
active ingredient may also be presented as a bolus, electuary or
paste.
[0081] A tablet may be made by compressing or molding the compound
of Formula (I), optionally using one or more additional ingredient.
Compressed tablets may be prepared by compressing in a suitable
machine the active ingredient in a free-flowing form such as a
powder or granules, optionally mixed with a binder, lubricant,
inert diluent, lubricating, surface active or dispersing agent.
Molded tablets may be made by molding in a suitable machine a
mixture of the powdered compound moistened with an inert liquid
diluent. The tablets may optionally be coated or scored and may be
formulated so as to provide sustained, delayed or controlled
release of the active ingredient therein. Oral and parenteral
sustained release drug delivery systems are well known to those
skilled in the art, and general methods of achieving sustained
release of orally or parenterally administered drugs are found, for
example, in Remington: The Science and Practice of Pharmacy, pages
1660-1675 (1995).
[0082] Formulations for parenteral administration include aqueous
and non-aqueous sterile injection solutions which may contain
anti-oxidants, buffers, bacteriostats and solutes which render the
formulation isotonic with the blood of the intended recipient.
Formulations for parenteral administration also include aqueous and
non-aqueous sterile suspensions, which may include suspending
agents and thickening agents. The formulations may be presented in
unit-dose or multi-dose containers, for example sealed ampoules and
vials, and may be stored in a freeze-dried (lyophilized) condition
requiring only the addition of a sterile liquid carrier, for
example saline, phosphate-buffered saline (PBS) or the like,
immediately prior to use. Extemporaneous injection solutions and
suspensions may be prepared from sterile powders, granules and
tablets of the kind previously described. Formulations for rectal
administration may be presented as a suppository with the usual
carriers such as cocoa butter or polyethylene glycol. Formulations
for topical administration in the mouth, for example, buccally or
sublingually, include lozenges comprising the active ingredient in
a flavored basis such as sucrose and acacia or tragacanth, and
pastilles comprising the active ingredient in a basis such as
gelatin and glycerin or sucrose and acacia.
[0083] The pharmaceutically acceptable carrier may take a wide
variety of forms, depending on the route desired for
administration, for example, oral or parenteral (including
intravenous). In preparing the composition for oral dosage form,
any of the usual pharmaceutical media may be employed, such as,
water, glycols, oils, alcohols, flavoring agents, preservatives,
and coloring agents in the case of oral liquid preparation,
including suspension, elixirs and solutions. Carriers such as
starches, sugars, microcrystalline cellulose, diluents, granulating
agents, lubricants, binders and disintegrating agents may be used
in the case of oral solid preparations such as powders, capsules
and caplets, with the solid oral preparation being preferred over
the liquid preparations. Preferred solid oral preparations are
tablets or capsules, because of their ease of administration. If
desired, tablets may be coated by standard aqueous or nonaqueous
techniques. Oral and parenteral sustained release dosage forms may
also be used.
[0084] Exemplary formulations, are well known to those skilled in
the art, and general methods for preparing them are found in any
standard pharmacy school textbook, for example, Remington, THE
SCIENCE AND PRACTICE OF PHARMACY, 21 st Ed., Lippincott.
[0085] Since one aspect of the present invention contemplates the
treatment of the disease/conditions with a combination of
pharmaceutically active agents that may be administered separately,
the invention further relates to combining separate pharmaceutical
compositions in kit form. The kit comprises two separate
pharmaceutical compositions: a compound of the present invention,
and a second pharmaceutical compound. The kit comprises a container
for containing the separate compositions such as a divided bottle
or a divided foil packet. Additional examples of containers include
syringes, boxes, bags, and the like. Typically, the kit comprises
directions for the administration of the separate components. The
kit form is particularly advantageous when the separate components
are preferably administered in different dosage forms (e.g., oral
and parenteral), are administered at different dosage intervals, or
when titration of the individual components of the combination is
desired by the prescribing physician.
[0086] An example of such a kit is a so-called blister pack.
Blister packs are well known in the packaging industry and are
being widely used for the packaging of pharmaceutical unit dosage
forms (tablets, capsules, and the like). Blister packs generally
consist of a sheet of relatively stiff material covered with a foil
of a preferably transparent plastic material. During the packaging
process recesses are formed in the plastic foil. The recesses have
the size and shape of the tablets or capsules to be packed. Next,
the tablets or capsules are placed in the recesses and the sheet of
relatively stiff material is sealed against the plastic foil at the
face of the foil which is opposite from the direction in which the
recesses were formed. As a result, the tablets or capsules are
sealed in the recesses between the plastic foil and the sheet.
Preferably the strength of the sheet is such that the tablets or
capsules can be removed from the blister pack by manually applying
pressure on the recesses whereby an opening is formed in the sheet
at the place of the recess. The tablet or capsule can then be
removed via said opening.
[0087] It may be desirable to provide a memory aid on the kit,
e.g., in the form of numbers next to the tablets or capsules
whereby the numbers correspond with the days of the regimen which
the tablets or capsules so specified should be ingested. Another
example of such a memory aid is a calendar printed on the card,
e.g., as follows "First Week, Monday, Tuesday, . . . etc. . . .
Second Week, Monday, Tuesday, . . . " etc. Other variations of
memory aids will be readily apparent. A "daily dose" can be a
single tablet or capsule or several pills or capsules to be taken
on a given day. Also, a daily dose of a compound of the present
invention can consist of one tablet or capsule, while a daily dose
of the second compound can consist of several tablets or capsules
and vice versa. The memory aid should reflect this and aid in
correct administration of the active agents.
[0088] In another specific embodiment of the invention, a dispenser
designed to dispense the daily doses one at a time in the order of
their intended use is provided. Preferably, the dispenser is
equipped with a memory-aid, so as to further facilitate compliance
with the regimen. An example of such a memory-aid is a mechanical
counter which indicates the number of daily doses that have been
dispensed. Another example of such a memory-aid is a
battery-powered micro-chip memory coupled with a liquid crystal
readout, or audible reminder signal which, for example, reads out
the date that the last daily dose has been taken and/or reminds one
when the next dose is to be taken.
IV. Methods
A. Methods for Treatment or Prevention
[0089] In a further aspect the invention provides a method for
treating or preventing a disease or condition which is a member
selected from a neurological disorder, pain, ataxia and convulsion.
The method includes administering to a subject in need thereof a
therapeutically effective amount of a compound of Formula (I) or a
pharmaceutically acceptable salt, hydrate, prodrug or solvate
thereof:
[0090] In an exemplary embodiment, the subject is preferably not in
need of treatment for a condition, which is a member selected from
a H.sub.4-receptor mediated disease, a monocyte chemoattractant
protein-1 (MCP-1) receptor mediated disease, type-2 diabetes,
insulin resistance, syndrome X, hyperinsulinaemia,
hyperglucagonaemia, cardiac ischemia, obesity, artherosclerosis,
diabetic neuropathy, diabetic nephropathy, diabetic retinopathy,
cataracts, hypercholesterolemia, hypertriglyceridemia,
hyperlipidemia, hyperglycemia, hypertension, tissue ischemia and
myocardial ischemia.
[0091] In another embodiment, the subject is preferably not in need
of inhibiting glycogen phosphorylase.
[0092] Subjects for treatment according to the present invention
include humans (patients) and other mammals in need of therapy for
the stated condition.
[0093] Compounds of the invention possess unique pharmacological
characteristics with respect to inhibition of DAAO and influence
the activity of the NMDA receptor in the brain, particularly by
controlling the levels of D-serine. Therefore, these compounds are
effective in treating conditions and disorders (especially
CNS-related disorders), which are modulated by DAAO, D-serine
and/or NMDA receptor activity. In one embodiment, compounds of the
invention are associated with diminished side effects compared to
administration of the current standards of treatment.
[0094] Accordingly, the present invention relates to methods for
increasing the concentration of D-serine and/or decreasing the
concentration of toxic products of D-serine oxidation by DAAO in a
mammal. Each of the methods comprises administering to a subject in
need thereof a therapeutically effective amount of a compound of
the invention, for example those of Formula (I), or a
pharmaceutically acceptable salt, hydrate, prodrug or solvate
thereof.
[0095] Compounds of the invention are typically more selective than
known DAAO inhibitors, including indole-2-carboxylates, and
demonstrate higher selectivity for DAAO inhibition relative to
binding at the NMDA receptor's D-serine binding site. The compounds
also exhibit an advantageous profile of activity including good
bioavailability. Accordingly, they offer advantages over many
art-known methods for treating disorders modulated by DAAO,
D-serine or NMDA receptor activity. For example, unlike
conventional antipsychotic therapeutics, DAAO inhibitors can
produce a desirable reduction in the cognitive symptoms of
schizophrenia. Conventional antipsychotics often produce
undesirable side effects, including tardive dyskinesia
(irreversible involuntary movement disorder), extra pyramidal
symptoms, and akathesia, and these may be reduced or eliminated by
administering compounds of the invention.
[0096] Compounds of the present invention may also be used in
conjunction with therapy involving administration of D-serine or an
analog thereof, such as a salt of D-serine, an ester of D-serine,
alkylated D-serine, D-cycloserine or a precursor of D-serine, or
can be used in conjunction with therapy involving administration of
antipsychotics, antidepressants, psychostimulants, and/or
Alzheimer's disease therapeutics.
[0097] The compounds of the invention may also be used in
conjunction with therapy involving administration of antipsychotics
(for treating schizophrenia and other psychotic conditions),
psychostimulants (for treating attention deficit disorder,
depression, or learning disorders), antidepressants, nootropics
(for example, piracetam, oxiracetam or aniracetam),
acetylcholinesterase inhibitors (for example, the physostigmine
related compounds, tacrine or donepezil), GABA analogs (e.g.,
gabapentin) or GABA receptor modulators, Alzheimer's disease
therapeutics (e.g., nemantine hydrochloride) and/or analgesics (for
treating of persistent or chronic pain, e.g. neuropathic pain).
Such methods for conjoint therapies are included within the
invention.
Conditions and Disorders
[0098] In one embodiment, the compounds of the present invention
are useful for the treatment of neurological disorders, pain (e.g.,
neuropathic pain), ataxia and convulsion. Neurological disorders
include neurodegenerative diseases (e.g., Alzheimers disease) and
neuropsychiatric disorders (e.g., schizophrenia).
Neuropsychiatric Disorders
[0099] Neuropsychiatric disorders include schizophrenia, autism,
and attention deficit disorder. Clinicians recognize a distinction
among such disorders, and there are many schemes for categorizing
them. The Diagnostic and Statistical Manual of Mental Disorders,
Revised, Fourth Ed., (DSM-IV-R), published by the American
Psychiatric Association, provides a standard diagnostic system upon
which persons of skill rely, and is incorporated herein by
reference. According to the framework of the DSM-IV, the mental
disorders of Axis I include: disorders diagnosed in childhood (such
as Attention Deficit Disorder (ADD) and Attention
Deficit-Hyperactivity Disorder (ADHD)) and disorders diagnosed in
adulthood. The disorders diagnosed in adulthood include (1)
schizophrenia and psychotic disorders; (2) cognitive disorders; (3)
mood disorders; (4) anxiety related disorders; (5) eating
disorders; (6) substance related disorders; (7) personality
disorders; and (8) "disorders not yet included" in the scheme.
[0100] ADD and ADHD are disorders that are most prevalent in
children and are associated with increased motor activity and a
decreased attention span. These disorders are commonly treated by
administration of psychostimulants such as methylphenidate and
dextroamphetamine sulfate.
[0101] The compounds (and their mixtures) of the present invention
are also effective for treating disruptive behavior disorders, such
as attention deficit disorder (ADD) and attention deficit
disorder/hyperactivity (ADHD), which is in accordance with its
accepted meaning in the art, as provided in the DSM-IV-TR.TM..
These disorders are defined as affecting one's behavior resulting
in inappropriate actions in learning and social situations.
Although most commonly occurring during childhood, disruptive
behavior disorders may also occur in adulthood.
[0102] Schizophrenia represents a group of neuropsychiatric
disorders characterized by dysfunctions of the thinking process,
such as delusions, hallucinations, and extensive withdrawal of the
patient's interests from other people. Approximately one percent of
the worldwide population is afflicted with schizophrenia, and this
disorder is accompanied by high morbidity and mortality rates.
So-called negative symptoms of schizophrenia include affect
blunting, anergia, alogia and social withdrawal, which can be
measured using SANS (Andreasen, 1983, Scales for the Assessment of
Negative Symptoms (SANS), Iowa City, Iowa). Positive symptoms of
schizophrenia include delusion and hallucination, which can be
measured using PANSS (Positive and Negative Syndrome Scale) (Kay et
al., 1987, Schizophrenia Bulletin 13:261-276). Cognitive symptoms
of schizophrenia include impairment in obtaining, organizing, and
using intellectual knowledge which can be measured by the Positive
and Negative Syndrome Scale-cognitive subscale (PANSS-cognitive
subscale) (Lindenmayer et al., 1994, J. Nerv. Ment. Dis.
182:631-638) or with cognitive tasks such as the Wisconsin Card
Sorting Test. Conventional antipsychotic drugs, which act on the
dopamine D.sub.2 receptor, can be used to treat the positive
symptoms of schizophrenia, such as delusion and hallucination. In
general, conventional antipsychotic drugs and atypical
antipsychotic drugs, which act on the dopamine D.sub.2 and
5HT.sub.2 serotonin receptor, are limited in their ability to treat
cognitive deficits and negative symptoms such as affect blunting
(i.e., lack of facial expressions), anergia, and social
withdrawal.
[0103] Disorders treatable with the compounds of the present
invention include, but are not limited to, depression, bipolar
disorder, chronic fatigue disorder, seasonal affective disorder,
agoraphobia, generalized anxiety disorder, phobic anxiety,
obsessive compulsive disorder (OCD), panic disorder, acute stress
disorder, social phobia, posttraumatic stress disorder,
premenstrual syndrome, menopause, perimenopause and male
menopause.
[0104] Compounds and compositions of the present invention are also
effective for treating eating disorders. Eating disorders are
defined as a disorder of one's appetite or eating habits or of
inappropriate somatotype visualization. Eating disorders include,
but are not limited to, anorexia nervosa; bulimia nervosa, obesity
and cachexia.
[0105] In addition to their beneficial therapeutic effects,
compounds of the present invention provide the additional benefit
of avoiding one or more of the adverse effects associated with
conventional mood disorder treatments. Such side effects include,
for example, insomnia, breast pain, weight gain, extrapyramidal
symptoms, elevated serum prolactin levels and sexual dysfunction
(including decreased libido, ejaculatory dysfunction and
anorgasmia).
Learning, Memory and Cognition
[0106] Generally, compounds of the invention can be used for
improving or enhancing learning and memory. Patients, who may
benefit from such treatment, include those exhibiting symptoms of
dementia or learning and memory loss. Individuals with an amnesic
disorder are impaired in their ability to learn new information or
are unable to recall previously learned information or past events.
The memory deficit is most apparent on tasks to require spontaneous
recall and may also be evident when the examiner provides stimuli
for the person to recall at a later time. The memory disturbance
must be sufficiently severe to cause marked impairment in social or
occupational functioning and must represent a significant decline
from a previous level of functioning. The memory deficit may be
age-related or the result of disease or other cause. Dementia is
characterized by multiple clinically significant deficits in
cognition that represent a significant change from a previous level
of functioning, including memory impairment involving inability to
learn new material or forgetting of previously learned material.
Memory can be formally tested by measuring the ability to register,
retain, recall and recognize information. A diagnosis of dementia
also requires at least one of the following cognitive disturbances:
aphasia, apraxia, agnosia or a disturbance in executive
functioning. These deficits in language, motor performance, object
recognition and abstract thinking, respectively, must be
sufficiently severe in conjunction with the memory deficit to cause
impairment in occupational or social functioning and must represent
a decline from a previously higher level of functioning.
[0107] Compounds of the invention are useful for preventing loss of
neuronal function, which is characteristic of neurodegenerative
diseases. Therapeutic treatment with a compound of the invention
improves and/or enhances memory, learning and cognition. In one
embodiment, the compounds of the invention can be used to treat a
neurodegenerative disease such as Alzheimer's, Huntington's
disease, Parkinson's disease and amyotrophic lateral sclerosis, as
well as MLS (cerebellar ataxia), Down syndrome, multi-infarct
dementia, status epilecticus, contusive injuries (e.g. spinal cord
injury and head injury), viral infection induced neurodegeneration,
(e.g. AIDS, encephalopathies), epilepsy, benign forgetfulness, and
closed head injury.
[0108] Compounds of the invention are useful for treating or
preventing loss of memory and/or cognition associated with a
neurodegenerative disease. The compounds also ameliorate cognitive
dysfunctions associated with aging and improve catatonic
schizophrenia
[0109] Alzheimer's disease is manifested as a form of dementia that
typically involves mental deterioration, reflected in memory loss,
confusion, and disorientation. In the context of the present
invention, dementia is defined as a syndrome of progressive decline
in multiple domains of cognitive function, eventually leading to an
inability to maintain normal social and/or occupational
performance. Early symptoms include memory lapses and mild but
progressive deterioration of specific cognitive functions, such as
language (aphasia), motor skills (apraxia) and perception
(agnosia). The earliest manifestation of Alzheimer's disease is
often memory impairment, which is required for a diagnosis of
dementia in both the National Institute of Neurological and
Communicative Disorders and Stroke--Alzheimer's Disease--and the
Alzheimer's Disease and Related Disorders Association
(NINCDS-ADRDA) criteria (McKhann et al., 1984, Neurology
34:939-944), which are specific for Alzheimer's disease, and the
American Psychiatric Association's Diagnostic and Statistical
Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria, which
are applicable for all forms of dementia. The cognitive function of
a patient may also be assessed by the Alzheimer's disease
Assessment Scale-cognitive subscale (ADAS-cog; Rosen et al., 1984,
Am. J. Psychiatry 141:1356-1364). Alzheimer's disease is typically
treated by acetylcholine esterase inhibitors such as tacrine
hydrochloride or donepezil. Unfortunately, the few forms of
treatment for memory loss and impaired learning available at
present are not considered effective enough to make any significant
difference to a patient, and there is currently a lack of a
standard nootropic drug for use in such treatment.
[0110] Other conditions that are manifested as deficits in memory
and learning include benign forgetfulness and closed head injury.
Benign forgetfulness refers to a mild tendency to be unable to
retrieve or recall information that was once registered, learned,
and stored in memory (e.g., an inability to remember where one
placed one's keys or parked one's car). Benign forgetfulness
typically affects individuals after 40 years of age and can be
recognized by standard assessment instruments such as the Wechsler
Memory Scale. Closed head injury refers to a clinical condition
after head injury or trauma. Such a condition, which is
characterized by cognitive and memory impairment, can be diagnosed
as "amnestic disorder due to a general medical condition" according
to DSM-IV.
[0111] Compounds and compositions of the invention are also
effective for treating cerebral function disorders. The term
cerebral function disorder, as used herein, includes cerebral
function disorders involving intellectual deficits, and may be
exemplified by senile dementia, Alzheimer's type dementia, memory
loss, amnesia/amnestic syndrome, epilepsy, disturbances of
consciousness, coma, lowering of attention, speech disorders,
Parkinson's disease and autism.
Pain
[0112] The compounds of the invention are useful to treat any kind
of acute or chronic pain. In a preferred embodiment, the compounds
of the invention are useful to treat chronic pain. In a
particularly preferred embodiment, the compounds of the invention
are useful to treat neuropathic pain. The term neuropathic "pain"
includes central neuropathic pain, involving damage to the brain or
spinal cord, such as may occur following stroke, spinal cord
injury, and as a result of multiple sclerosis. It also includes
peripheral neuropathic pain, which includes diabetic peripheral
neuropathic pain, post-herpetic neuralgia (PHN), and trigeminal
neuralgia (TN). It also includes dysfunctions of the nervous system
such as Complex Regional Pain Syndrome (CRPS), formerly known as
Reflex Sympathetic Dystrophy (RSD), and causalgia, and neuropathic
pain symptoms such as sensory loss, allodynia, hyperalgesia and
hyperpathia. It further includes mixed nociceptive and neuropathic
pain types, for example, mechanical spinal pain and radiculopathy
or myelopathy, and the treatment of chronic pain conditions such as
fibromyalgia, lower back pain and neck pain due to spinal nerve
root compression, neuropathic cancer pain, HIV/AIDS induced pain,
and phantom limb pain. In another preferred embodiment, the
compounds of the invention are useful for chronic migraine
prophylaxis.
[0113] Other conditions and disorders include, but are not limited
to, autism, childhood learning disorders, depressions, anxieties,
sleep disorders. Compounds of the invention may also be useful for
the treatment of neurotoxic injury that follows cerebral stroke,
thromboembolic stroke, hemorrhagic stroke, cerebral ischemia,
cerebral vasospasm, hypoglycemia, amnesia, hypoxia, anoxia,
perinatal asphyxia and cardiac arrest.
[0114] The term "treating" when used in connection with the
foregoing disorders means amelioration, prevention or relief from
the symptoms and/or effects associated with these disorders and
includes the prophylactic administration of a compound of the
invention, a mixture thereof, or a pharmaceutically acceptable salt
of either, to substantially diminish the likelihood or seriousness
of the condition.
B. Models of Disease
[0115] In animals, several established models of learning and
memory are available to examine the beneficial cognitive enhancing
effects and potential related side effects of treatment.
Descriptions of tests that may be employed to assess changes in
cognition in non-human species are given in the following
references and references cited therein. Each of the following
references is incorporated by reference into this application in
their entirety: Sarter, M., Intern. J. Neuroscience, 1987,
32:765-774; Methods and Findings in Experimental and Clinical
Pharmacology 1998, 20 (3), 249-277; Indian Journal of Pharmacology
1997, 29 (4), 208-221. The tests include the Morris water maze
(Stewart and Morris, In "Behavioral Neuroscience. A Practical
Approach. Volume I", 1993, R. Saghal, Ed., 107-122; Morris, R.
Journal of neuroscience methods 1984, 11 (1), 47-60), delayed
non-match to sample (Bontempi, B, et al, Journal of Pharmacology
and Experimental Therapeutics 2001, 299 (1), 297-306; Alvarez, P;
Zola-Morgan, S; Squire, L. R. Proc Natl Acad Sci USA. 1994 7; 91
(12), 5637-41), delayed Alternation (also called delayed
non-matching to position; Roux, S; Hubert, I; Lenegre, A;
Milinkevitch, D; Porsolt, R D. Pharmacol Biochem Behav. 1994 49
(3), 83-8; Ohta, H; Ni, X. H.; Matsumoto, K; Watanabe, H, Jpn J
Pharmacol. 1991, 56 (3), 303-9), social discrimination models
(Engelmann, M; Wotjak, C. T; Landgraf R. Physiol Behav. 1995, 58
(2), 315-21), social recognition test (also called delay-induced
forgetting; Lemaire, M; Bohme, G. A.; Piot. O; Roques, B. P.;
Blanchard, J. C. Psychopharmacology (Berl). 1994, 115 (4):435-40),
contextual fear conditioning (Barad, M; Bourtchouladze, R; Winder,
D G; Golan, H; Kandel, E. Proc Natl Acad Sci USA. 1998, 95 (25),
15020-5; Bourtchouladze, R.; Frenguelli, B.; Blendy, J.; Cioffi,
D.; Schutz, G.; Silva, A. J. Cell, 1994, 79, 59-68), novel object
recognition (Ennaceur, A.; Delacour, J. Behav. Brain Res. 1988, 31,
47-59; Ennaceur, A.; Cavoy, A.; Costa, J. C.; Delacour, J. Behav.
Brain Res., 1989, 33, 197-207), and conditioned fear extinction
(Walker, D L; Ressler, K J; Lu, K. T., Davis, M., J Neurosci. 2002,
22 (6), 2343-51; Davis, M.; Ressler, K.; Rothbaum, B. O.;
Richardson, R. Biol. Psychiatry, 2006, 60, 369-375).
[0116] The Morris water maze is one of the best-validated models of
learning and memory, and it is sensitive to the cognitive enhancing
effects of a variety of pharmacological agents. The task performed
in the maze is particularly sensitive to manipulations of the
hippocampus in the brain, an area of the brain important for
spatial learning in animals and memory consolidation in humans.
Moreover, improvement in Morris water maze performance is
predictive of clinical efficacy of a compound as a cognitive
enhancer. For example, treatment with cholinesterase inhibitors or
selective muscarinic cholinergic agonists reverse learning deficits
in the Morris maze animal model of learning and memory, as well as
in clinical populations with dementia. In addition, this animal
paradigm accurately models the increasing degree of impairment with
advancing age and the increased vulnerability of the memory trace
to pre-test delay or interference which is characteristic of
amnesiac patients.
[0117] Contextual fear conditioning is a form of associative
learning in which animals learn to fear a new environment (or an
emotionally neutral conditioned stimulus) because of its temporal
association with an aversive unconditioned stimulus (US), such as a
foot shock. When exposed to the same context or conditioned
stimulus at a later time, conditioned animals show a variety of
conditioned fear responses, including freezing behavior. Because
robust learning can be triggered with a single training trial,
contextual fear conditioning has been used to study temporally
distinct processes of short-term and long-term memory. Contextual
fear conditioning is believed to be dependent on both the
hippocampus and amygdala function.
[0118] Another example of learning is called fear extinction, a
process exhibited in both human and animals, including rodents.
Extinction of fear refers to the reduction in the measured level of
fear to a cue previously paired with an aversive event when that
cue is presented repeatedly in the absence of the aversive event.
Extinction of fear is not the erasure of the original fear memory,
but instead results from a new form of learning that acts to
inhibit or suppress the original fear memory (Bouton, M. D.;
Bolles, R. C. J. Exp. Psychol. Anim. Behav. Process. 1979, 5,
368-378; Konorski, J. Inegrative Activity of the Brain: An
Interdiscipinary Approach, 1967, Chicago: The University of Chicago
Press; Pavlov, I. P. Conditioned Reflexes. 1927, Oxford, United
Kingdom: Oxford University Press). The literature also suggests
that glutamate acting at the N-methyl D-aspartate (NMDA) receptor
is critically involved in learning and memory (Bear, M. F. Proc.
Nat. Acad. Sci. 1996, 93, 13453-13459; Castellano, C.; Cestari, V.;
Clamei, A. Curr. Drug Targets, 2001, 2, 273-283; Morris, R. G.;
Davis, S.; Butcher, S. P. Philos. Trans. R Soc. Lond. B Biol. Sci.
1990. 329, 187-204; Newcomer, J. W.; Krystal, J. H. Hippocampus,
2001, 11, 529-542). There is also evidence that the NMDA receptor
is involved with extinction of fear. For example, NMDA antagonists
such as 2-amino-5-phosphopentanoic acid (APV) are known to block
fear extinction (Davis, M.; Ressler, K.; Rothbaum, B. O.;
Richardson, R. Biol. Psychiatry, 2006, 60, 369-375; Kehoe, E. J.;
Macrae, M.; Hutchinson, C. L. Psychobiol. 1996, 24, 127-135; Lee,
H.; Kim, J. J. J. Neurosci. 1998, 18, 8444-8454; Szapiro, G.;
Vianna, M. R.; McGaugh, J. L.; Medina, J. H.; Izquierdo, I.
Hippocampus, 2003, 13, 53-58), and NMDA agonists (such as the
partial agonist D-cycloserine), are known to facilitate fear
extinction (Davis, M.; Ressler, K.; Rothbaum, B. O.; Richardson, R.
Biol. Psychiatry, 2006, 60, 369-375; Ledgerwood, L.; Richardson,
R.; Cranney, J. Behav. Neurosci. 2003, 117 341-349; Walker, D. L.;
Ressler, K. J.; Lu K.-T.; Davis, M. J. Neurosci. 2002, 22,
2343-2351). Additional experimental conditions for fear extinction
tests may be found in the references cited in this paragraph, and
are incorporated by reference.
[0119] In human exposure therapy, a patient is repeatedly exposed
for prolonged periods to a feared object or situation in the
absence of aversive consequences. As a result, the patient is often
able to face their feared cues or situations with less fear and
avoidance (extinction retention) due to the learning that took
place during exposure therapy (extinction training). It has been
shown that agents, such as D-cycloserine, that improve extinction
in animals also improve the effectiveness of exposure-based
psychotherapy. Examples of exposure based cognitive-behavioral
therapy (CBT) improved by agents that improve extinction include
exposure to phobic objects as therapy for phobia disorders (For
acrophobia, see Davis, M.; Ressler, K.; Rothbaum, B. O.;
Richardson, R. Biol. Psychiatry, 2006, 60, 369-375; Ressler, K. J.;
Rothbaum, B. O.; Tannenbaum, L.; Anderson, P.; Graap, K.; Zimand,
E.; Hodges, L.; Davis, M. Archives Gen. Psychiatry 2004, 61,
1136-1144), exposure to phobic situations as therapy for panic
disorders (For social anxiety disorder, see Hoffmann, S. G.;
Meuret, A. E.; Smits, J. A.; Simon, N. M.; Pollack, M. H.;
Eisenmenger, K.; Shiekh, M.; Otto, M. W. Arch. Gen. Psychiatry
2006, 63, 298-304; Hofmann, S. G.; Pollack, M. H.; Otto, M. W. CNS
Drug Reviews 2006, 12, 208-217), recollection of traumatic memories
as therapy for Post-Traumatic Stress Disorder, exposure to cues
associated with drug cravings as therapy for drug addiction, and
exposure to cues associated with smoking as therapy for smoking
cessation. Because of the cognitive, learning aspects associated
with psychotherapy based treatment for disorders such as phobias,
anxiety, Post-Traumatic Stress Disorder, and Addiction, compounds
of the invention are useful as an adjunct with psychotherapy for
the treatment of these conditions. Clinically, compounds of the
invention are useful as an adjunct to shorten the number of therapy
sessions required or improve the therapeutic outcome of
therapy.
[0120] In humans, methods for improving learning and memory may be
measured by such tests as the Wechsler Memory Scale and the
Minimental test. A standard clinical test for determining if a
patient has impaired learning and memory is the Minimental Test for
Learning and Memory (Folstein et al., J. Psychiatric Res. 12:185,
1975), especially for those suffering from head trauma, Korsakoff's
disease or stroke. The test result serves as an index of
short-term, working memory of the kind that deteriorates rapidly in
the early stages of dementing or amnesiac disorders. Ten pairs of
unrelated words (e.g., army-table) are read to the subject.
Subjects are then asked to recall the second word when given the
first word of each pair. The measure of memory impairment is a
reduced number of paired-associate words recalled relative to a
matched control group. Improvement in learning and memory
constitutes either (a) a statistically significant difference
between the performance of treated patients as compared to members
of a placebo group; or (b) a statistically significant change in
performance in the direction of normality on measures pertinent to
the disease model. Animal models or clinical instances of disease
exhibit symptoms which are by definition distinguishable from
normal controls. Thus, the measure of effective pharmacotherapy
will be a significant, but not necessarily complete, reversal of
symptoms. Improvement can be facilitated in both animal and human
models of memory pathology by clinically effective "cognitive
enhancing" drugs which serve to improve performance of a memory
task. For example, cognitive enhancers which function as
cholinomimetic replacement therapies in patients suffering from
dementia and memory loss of the Alzheimer's type significantly
improve short-term working memory in such paradigms as the
paired-associate task. Another potential application for
therapeutic interventions against memory impairment is suggested by
age-related deficits in performance which are effectively modeled
by the longitudinal study of recent memory in aging mice.
[0121] The Wechsler Memory Scale is a widely used pencil-and-paper
test of cognitive function and memory capacity. In the normal
population, the standardized test yields a mean of 100 and a
standard deviation of 15, so that a mild amnesia can be detected
with a 10-15 point reduction in the score, a more severe amnesia
with a 20-30 point reduction, and so forth. During the clinical
interview, a battery of tests, including, but not limited to, the
Minimental test, the Wechsler memory scale, or paired-associate
learning are applied to diagnose symptomatic memory loss. These
tests provide general sensitivity to both general cognitive
impairment and specific loss of learning/memory capacity (Squire,
1987). Apart from the specific diagnosis of dementia or amnestic
disorders, these clinical instruments also identify age-related
cognitive decline which reflects an objective diminution in mental
function consequent to the aging process that is within normal
limits given the person's age (Diagnostic and Statistical Manual of
Mental Disorders, 4.sup.th Edition, DSM IV, American Psychiatric
Association, 1994). As noted above, "improvement" in learning and
memory within the context of the present invention occurs when
there is a statistically significant difference in the direction of
normality in the paired-associate test, for example, between the
performance of therapeutic agent treated patients as compared to
members of the placebo group or between subsequent tests given to
the same patient.
[0122] In animals, many established models of schizophrenia are
available to examine the beneficial effects of treatment; many of
which are described in the following references, as well as
references cited within, and are incorporated by reference: Saibo
Kogaku 2007, 26 (1), 22-27; Cartmell, J.; Monn, J. A.; Schoepp, D.
D. J. Pharm. Exp. Ther. 1999, 291 (1), 161-170; Rowley, M; Bristow,
L. J.; Hutson, P. H. J. Med. Chem. 2001 15; 44 (4), 477-501; Geyer,
M. A.; Ellenbroek, B; Prog Neuropsychopharmacol Biol Psychiatry
2003, 27 (7): 1071-9; Geyer, M. A.; Krebs-Thomson, K; Braff, D. L.;
Swerdlow, N. R. Psychopharmacology (Berl). 2001 156 (2-3):117-54;
Jentsch, J. D.; Roth, R. H. Neuropsychopharmacology 1999, 20
(3):201-25. The tests include Prepulse Inhibition (Dulawa, S. C.;
Geyer, M. A. Chin J Physiol. 1996, 39 (3): 139-46), PCP stereotypy
test (Meltzer et al (In "PCP (Phencyclidine): Historical and
Current Perspectives", ed. E. F. Domino, NPP Books, Ann Arbor,
1981, 207-242), Amphetamine stereotypy test (Simon and Chermat, J.
Pharmacol. (Paris), 1972, 3, 235-238), PCP hyperactivity (Gleason,
S. D.; Shannon, H. E. Psychopharmacology (Berl). 1997, 129
(1):79-84) and MK-801 hyperactivity (Corbett, R; Camacho, F; Woods,
A. T.; Kerman, L. L.; Fishkin, R. J.; Brooks, K; Dunn, R. W.
Psychopharmacology (Berl). 1995, 120 (1):67-74.
[0123] The prepulse inhibition test may be used to identify
compounds that are effective in treating schizophrenia. The test is
based upon the observations that animals or humans that are exposed
to a loud sound will display a startle reflex and that animals or
humans exposed to a series of lower intensity sounds prior to the
higher intensity test sound will no longer display as intense of a
startle reflex. This is termed prepulse inhibition. Patients
diagnosed with schizophrenia display defects in prepulse
inhibition, that is, the lower intensity prepulses no longer
inhibit the startle reflex to the intense test sound. Similar
defects in prepulse inhibition can be induced in animals via drug
treatments (scopolamine, ketamine, PCP or MK-801) or by rearing
offspring in isolation. These defects in prepulse inhibition in
animals can be partially reversed by drugs known to be efficacious
in schizophrenia patients. It is felt that animal prepulse
inhibition models have face value for predicting efficacy of
compounds in treating schizophrenia patients.
[0124] In animals, many established models of pain are available to
examine the beneficial effects of treatment; many of which are
reviewed in Methods in Pain Research, CRC Press, 2001, Kruger, L.
(Editor). Tests of acute pain include the tail flick (d'Amour and
Smith, J. Pharmacol. Exp. Ther. 1941, 72, 74-79), hot plate (Eddy,
N. B.; Leimbach, D. J Pharmacol Exp Ther. 1953, 107 (3):385-93),
and paw withdrawal tests. The phenylbenzoquinone writhing assay is
a measure of peritoneovisceral or visceral pain. Persistent pain
tests, which use an irritant or foreign chemical agent as the
nociceptive stimulus, include the formalin test (Wheeler-Aceto, H;
Cowan, A Psychopharmacology (Berl). 1991, 104 (1):35-44), Freund's
adjuvant (Basile, A. S. et al Journal of Pharmacology and
Experimental Therapeutics 2007, 321 (3), 1208-1225; Ackerman, N. R.
et al; Arthritis & Rheumatism 1979, 22 (12), 1365-74),
capsaicin (Barrett, A. C. et al Journal of Pharmacology and
Experimental Therapeutics 2003, 307 (1), 237-245), and carrageenin
models. These models have an initial, acute phase, followed by a
second, inflammatory phase.
[0125] Neuropathic pain models are reviewed in Wang and Wang,
Advanced Drug Delivery Reviews 2003, and include the Spinal Nerve
Ligation (SNL) model (also called the Chung Model; Kim, S. H.;
Chung, J. M. Pain 1992 50 (3):355-63; Chaplan et al., Journal of
Neuroscience Methods 1994, 53 (1):55-63; Chaplan S R, Bach F W,
Pogrel J W), Chronic Constriction Injury (CCI) model (also called
the Bennett Model; Bennett, G. J; Xie, Y. K Pain 1988 33
(1):87-107), Progressive Tactile Hypersensitivity (PTH) model
(Decosterd, I. Pain, 2002, 100 (1), 155-162; Anesth. Analg. 2004,
99, 457-463), Spared Nerve Injury (SNI) model (Decosterd, I. Pain,
2002, 100 (1), 155-162; Anesth. Analg. 2004, 99, 457-463), the
lumbar nerve ligation model (Ringkamp, M; Eschenfelder, S; Grethel,
E. J.; Habler, H. J., Meyer, R. A., Janig, W., Raja, S. N. Pain,
1999, 79 (2-3), 143-153), and streptozocin--or chemotherapy induced
diabetic neuropathy (Courteix, C.; Eschalier, A.; Lavarenne, J.
Pain, 1993, 53 (1), 81-88; Aubel, B. et al Pain 2004, 110 (1-2),
22-32).
[0126] Opioids, such as morphine, display robust efficacy in models
of acute pain, such as the tail flick and hot plate tests, as well
as in both the initial, acute phase and the second, inflammatory
phase of persistent pain tests, such as the formalin test. Opioids
also display efficacy in neuropathic pain models, such as the
Spinal Nerve Ligation (SNL) model. The general analgesic effects of
opiate compounds such as morphine in neuropathic pain models,
however, are suggested by the increase in paw withdrawal threshold
(PWT) in both the injured and the contralateral (uninjured) paw.
Compounds that are useful specifically for the treatment of
persistent or chronic pain states (e.g., neuropathic pain), such as
gabapentin, tend to display efficacy in models of persistent
inflammatory and neuropathic pain, such as the formalin (second
phase) and SNL models. Compounds of this type, however, tend to
increase PWT in the SNL model in only the injured paw. In addition,
these compounds fail to display efficacy in acute tests such as the
tail flick test and the hot plate test, and also fail to display
efficacy in the initial, acute phase of the formalin test. The lack
of effect of compounds in the acute pain tests supports the notion
that the antinociceptive action of these compounds is related to
specific mechanisms associated with a central sensitized state
following injury. As a result, compounds that are efficacious in
neuropathic pain model(s), such as the SNL (Chung) model, and the
second phase of the formalin test, but are not efficacious in acute
pain models, such as hot plate and tail flick, or in the first
phase of the formalin test suggest that these compounds are more
likely to be effective in persistent and chronic, rather than
acute, pain states (see Table 1). In addition, their ability to
increase PWT in the SNL model should be specific for the
ipsilateral (injured) paw. Relevant references follow, and are
included by reference. Singh, L. et al, Psychopharmacology, 1996,
127, 1-9. Field, M. J. et al Br. J. Pharmacol. 1997, 121,
1513-1522. Iyengar, S. et al, J. Pharmacology and Experimental
Therapeutics, 2004, 311, 576-584. Shimoyama, N. et al Neuroscience
Letters, 1997, 222, 65-67. Laughlin, T. M. et al J. Pharmacology
and Experimental therapeutics, 2002, 302, 1168-1175. Hunter, J. C.
et al European J. Pharmacol. 1997, 324, 153-160. Jones, C. K. et al
J. Pharmacology and Experimental therapeutics, 2005, 312, 726-732.
Malmberg, A. B.; Yaksh, T. L. Anesthesiology, 1993, 79, 270-281.
Bannon, A W et al Brain Res., 1998, 801, 158-63.
[0127] In a preferred embodiment, the compounds of the invention
are useful for the treatment of persistent or chronic pain states
(e.g., neuropathic pain). As described above, such compounds may be
profiled in vivo by evaluating their efficacy in models of both
acute and neuropathic pain. Preferred compounds demonstrate
efficacy in neuropathic pain models, but not in acute pain
models.
TABLE-US-00001 TABLE 1 Profile of morphine and gabapentin in a
variety of animal models Animal Model Morphine Gabapentin Acute
Pain Hot plate + - Tail flick + - Formalin (early phase) + - Tissue
Injury/Inflammatory Pain Formalin (second phase) + + Carrageenan +
+ Nerve Injury/Neuropathic Pain Spinal Nerve Ligation (SNL; Chung)
+ + Chronic Constriction Injury (CCI; Bennet) + +
[0128] There are various animal models with chronic brain
dysfunctions thought to reflect the processes underlying human
epilepsy and seizures/convulsions, such as those described in
Epilepsy Res. 2002 June; 50 (1-2):105-23. Such chronic models
include the kindling model of temporal lobe epilepsy (TLE),
post-status models of TLE in which epilepsy develops after a
sustained status epilepticus, and genetic models of different types
of epilepsy. Currently, the kindling model and post-status models,
such as the pilocarpine or kainate models, are the most widely used
models for studies on epileptogenic processes and on drug targets
by which epilepsy can be prevented or modified. Furthermore, the
seizures in these models can be used for testing of antiepileptic
drug effects. A comparison of the pharmacology of chronic models
with models of acute (reactive or provoked) seizures in previously
healthy (non-epileptic) animals, such as the maximal electroshock
seizure test, demonstrates that drug testing in chronic models of
epilepsy yields data which are more predictive of clinical efficacy
and adverse effects.
[0129] The following examples are provided to illustrate selected
embodiments of the invention and are not to be construed as
limiting its scope.
EXAMPLES
General Procedures
General Procedure 1: Synthesis of Fused Pyrrole Analogs
##STR00010##
[0131] In the above Scheme, ring A represents any substituted or
unsubstituted 5-membered, aromatic ring. Exemplary aromatic rings
include furans.
A) Condensation of an Aldehyde with Ethyl Azidoacetate
[0132] A solution of the aldehyde (e.g., 1.61 g, 8.41 mmol) and
about 4 to about 7 equivalents of ethyl azidoacetate (e.g., 4.34 g,
33.7 mmol) in anhydrous EtOH (e.g., 10.5 mL) was added dropwise to
a solution of sodium (e.g., 0.8 g) in anhydrous EtOH (e.g., 50.0
mL) at a temperature between about 0.degree. C. and about
-45.degree. C. (typically between about -10 and about -5.degree. C.
(e.g., NaCl/ice)). The reaction mixture was stirred for about 1
hour (h) while the temperature was maintained below 0.degree. C.
and was then allowed to warm to ambient temperature (e.g.,
overnight). The mixture was quenched with a cold solution of
saturated aqueous NH.sub.4Cl or was diluted with water (e.g., 0.5
L). The product was extracted with diethyl ether or ethyl acetate
(EtOAc) (e.g., 3.times.0.2 L) and the combined organic phases were
washed with saturated aqueous NaCl solution (2.times.0.1 L), dried
(e.g., over Na.sub.2SO.sub.4) and filtered. The solvent was removed
in vacuo to give the ethyl azidoacrylate. Alternatively, the
solvent was reduced in vacuo (e.g., to about 50 mL) and the
resulting solution was used in the next reaction step.
B) Cyclization of the Ethyl Azidoacrylate
[0133] A solution of the above ethyl azidoacrylate in o- or
m-xylene (e.g., 150 mL) was heated to reflux for a time period
between about 15 minutes (min) and 14 h (typically about 1 h). The
reaction mixture was then allowed to cool to ambient temperature.
The solution was concentrated in vacuo and the crude product was
purified (e.g., silica gel column chromatography) to give the fused
pyrrole ethyl ester.
General Procedure 2: Saponification of Ethyl and Methyl-Esters
##STR00011##
[0135] To a solution or suspension of the ester (e.g., 0.33 g, 1.2
mmol) in MeOH or EtOH (e.g., 16.5 mL) was added an aqueous base,
such as 10M NaOH (e.g., 0.6 mL, 6 mmol), 5M KOH (e.g., 1.2 mL, 6
mmol) or 1M LiOH (e.g., 6 mL). The solution was heated to a
temperature between about 80.degree. C. and refluxed for a time
period between about 30 min and about 20 h (e.g., 5 h). The
reaction mixture was cooled to rt and was then acidified. In one
example, the mixture was poured into water (e.g., 200 mL) and the
pH of the resulting mixture was adjusted to about pH 1-2 with HCl.
In another example, excess solvent was removed in vacuo and the
residue was dissolved in 5% citric acid (e.g., 15 mL). In yet
another example, the solvent was removed in vacuo and the residue
was dissolved in a saturated solution of NH.sub.4Cl (e.g., 15 mL).
The acidified solution was then extracted (e.g., 3.times.100 mL
EtOAc) and the combined organic layers were washed (e.g., with
brine), dried (e.g., over Na.sub.2SO.sub.4), filtered and
concentrated in vacuo to give the carboxylic acid.
Example 1
Synthesis of Fused Furan Pyrrole Analogs
1.1. Synthesis of Intermediate Aldehydes
1.1.a) Synthesis of 4-phenethyl-furan-2-carbaldehyde
[0136] A solid mixture of 4-bromo-2-furaldehyde (1.50 g, 8.57
mmol), PdCl.sub.2(PhCN).sub.2 (197 mg, 0.514 mmol) and CuI (65.0
mg, 0.343 mmol) was flushed under an argon stream for 1 minute
(min). A solution of HP(t-butyl).sub.3BF.sub.4 (298 mg, 1.03 mmol)
and diisopropylamine (1.80 mL, 12.9 mmol) in dioxane (9 mL) was
added to the solid mixture followed byphenylacetylene (1.13 mL,
10.3 mmol). The reaction was allowed to stir at room temperature
(rt) under an atmosphere of argon for 15 hours (h) before being
filtered through a plug of silica gel with ethyl acetate (EtOAc).
The solution was then concentrated in vacuo and chromatographed
over silica gel to give 4-phenylethynyl-furan-2-carbaldehyde as a
colorless oil (1.54 g, 92%). R.sub.f=0.35 (1:9 heptane/EtOAc);
.sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm 9.68 (d, J=0.5 Hz,
1H) 7.90 (s, 1H) 7.48-7.55 (m, 2H) 7.35-7.40 (m, 3H) 7.33 (d, J=0.7
Hz, 1H).
[0137] To a solution of 4-phenylethynyl-furan-2-carbaldehyde (1.54
g, 7.84 mmol) in MeOH was added palladium on carbon (Pd/C) (154 mg,
10% Pd by weight). A vacuum was applied to the reaction mixture and
back filled with H.sub.2 4 times. The reaction was then allowed to
stir at rt for 14 h under an atmosphere of H.sub.2 before being
filtered through a plug of Celite.RTM. with EtOAc. The reaction was
then concentrated in vacuo to give 4-phenethyl-furan-2-carbaldehyde
as a colorless oil (1.53 g, 97%). .sup.1H NMR (400 MHz, CDCl.sub.3)
.delta. ppm 9.59 (d, J=0.6 Hz, 1H) 7.40 (d, J=0.8 Hz, 1H) 7.28-7.34
(m, 2H) 7.20-7.26 (m, 1H) 7.14-7.20 (m, 2H) 7.05 (d, J=0.6 Hz, 1H)
2.87-2.94 (m, 2H) 2.78-2.85 (m, 2H).
1.1.b) Synthesis of 5-benzyl-furan-2-carbaldehyde
[0138] A solution of Pd(OAc).sub.2 (64 mg, 0.29 mmol),
triphenylphosphine (TPP) (0.30 g, 1.1 mmol) and isopropanol (3.6
mL) in acetonitrile (7.4 mL) was added to a solid mixture of
2-boronic acid-5-furaldehyde (0.80 g, 5.7 mmol),
diethylbenzylphosphonate (1.5 g, 6.3 mmol) and K.sub.3PO.sub.4 (1.8
g, 8.6 mmol). The reaction mixture was flushed with a stream of
nitrogen and heated to 80.degree. C. overnight. The mixture was
then cooled to room temperature and filtered through a plug of
silica gel with ethyl acetate. The organic solution was then
concentrated in vacuo and the resultant solid was chromatographed
over silica gel to give 5-benzyl-furan-2-carbaldehyde as a brown
solid (0.37 g, 65%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm
9.56 (s, 1H) 7.29-7.38 (m, 3H) 7.24-7.28 (m, 2H) 7.17 (d, J=3.5 Hz,
1H) 6.19 (d, J=3.6 Hz, 1H) 4.07 (s, 2H).
1.1.c) Synthesis of 4-benzyl-furan-2-carbaldehyde
[0139] The title compound was synthesized from
5-formylfuran-3-boronic acid pinacol ester (878 mg, 3.95 mmol), and
benzyl diethyl phosphate (1.25 g, 5.14 mmol) using the same
conditions used to synthesize 5-benzyl-furan-2-carbaldehyde, with
the exception that TPP and Pd(OAc).sub.2 were dissolved in 2:1
CH.sub.3CN/isopropyl alcohol. Purification by flash chromatography
yielded 4-benzyl-furan-2-carbaldehyde as a white solid (300 mg,
41%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm 9.56 (s, 1H)
7.29-7.38 (m, 3H) 7.24-7.28 (m, 2H) 7.17 (d, J=3.5 Hz, 1H) 6.19 (d,
J=3.6 Hz, 1H) 4.07 (s, 2H).
1.1.d) Synthesis of 4-vinylfuran-2-carbaldehyde
[0140] The title compound was synthesized from
4-bromo-furan-2-carbaldehyde (1.1 g, 6.29 mmol) and vinylboronic
acid dibutyl ester (1.67 mL, 7.54 mmol) using the same conditions
used to synthesize 5-benzyl-furan-2-carbaldehyde, with the
exception that the reaction was run in N,N-dimethylformamide (DMF)
(20 mL). Purification by flash chromatography (0-30% EtOAc in
heptane) provided 4-vinylfuran-2-carbaldehyde as an orange oil;
Yield 282 mg (37%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm
5.31 (dd, J=10.88, 0.93 Hz, 1H), 5.61 (dd, J=17.57, 0.54 Hz, 1H),
6.56 (dd, J=17.55, 10.91 Hz, 1H), 7.37 (s, 1H), 7.67 (s, 1H), 9.66
(d, J=0.59 Hz, 1H).
1.1.e) Synthesis of (Z)-4-(prop-1-enyl)furan-2-carbaldehyde
[0141] The title compound was synthesized from
4-bromo-furan-2-carboxaldehyde (1.1 g, 6.3 mmol, 1 equiv) and
cis-propene boronic acid (0.65 g, 7.5 mmol, 1.2 equiv) using the
conditions to synthesize 5-benzyl-furan-2-carbaldehyde, with the
exception that the reaction was run in DMF (20 mL). The resulting
residue was purified via ISCO Companion (0-25% EtOAc/heptane over
30 min, retention time of product: 23-26 min) to give
(Z)-4-(prop-1-enyl)furan-2-carbaldehyde (0.4130 g, 48% yield).
LC/MS m/e 136.8 (M+H). .sup.1H NMR (400 MHz, CD.sub.3CN) .delta.
(ppm): 9.59 (d, J=0.63 Hz, 1H), 7.83 (s, 1H), 7.42 (s, 1H), 6.23
(dd, J=11.40, 1.68 Hz, 1H), 5.79-5.89 (m, 1H), 1.87 (dd, J=7.10,
1.78 Hz, 3H).
1.1.f) Synthesis of (E)-4-styrylfuran-2-carbaldehyde
[0142] The title compound was synthesized from
4-bromo-furan-2-carboxaldehyde (1.1 g, 6.3 mmol, 1 equiv) and
trans-phenylvinyl-boronic acid (1.4 g, 9.4 mmol, 1.5 equiv) using
the conditions used to synthesize 5-benzyl-furan-2-carbaldehyde,
with the exception that the reaction was run in DMF (25 mL). The
resulting residue was purified via ISCO Companion (0-30%
EtOAc/heptane) and preparative HPLC using the Chromeleon
purification system (0.1% formic acid/1% acetonitrile mixture in
water (aqueous phase) and methanol (no modifier added--organic
phase) using a 50 mm Dynamax HPLC C-18 column at 28 mL/min (initial
gradient of 40% methanol and increasing to 100% over 7 min))
afforded a clean product, retention time of product: 3.4-3.6 min.
Amount of (E)-4-styrylfuran-2-carbaldehyde isolated: 89.1 mg (7%
yield). .sup.1H NMR (400 MHz, CD.sub.3CN) .delta. (ppm): 9.62 (d,
J=0.59 Hz, 1H), 7.91 (s, 1H), 7.63 (d, J=0.63 Hz, 1H), 7.50-7.55
(m, 2H), 7.35-7.42 (m, 2H), 7.26-7.32 (m, 1H), 7.08 (s, 2H).
1.2. Synthesis of Intermediate Esters
[0143] The following ethyl esters were synthesized from the
indicated aldehyde according to General Procedure 1A (to yield an
intermediate acrylate) followed by General Procedure 1B.
1.2.a) Synthesis of ethyl 4H-furo[3,2-b]pyrrole-5-carboxylate
[0144] The title compound was synthesized from 2-furaldehyde (1.44
g, 15.0 mmol) and was purified by silica gel column chromatography
(0 to 25% EtOAc in heptane over 25 min) to give ethyl
4H-furo[3,2-b]pyrrole-5-carboxylate as a pink solid (0.330 g, 12%).
R.sub.f=0.42 (50:50 heptane/EtOAc); .sup.1H NMR (400 MHz,
CDCl.sub.3) .delta. (ppm) 8.63 (s, 1H) 7.53 (s, 1H) 6.81 (s, 1H)
6.47 (s, 1H) 4.36 (q, J=7.1 Hz, 2H) 1.38 (t, J=7.1 Hz, 3H).
1.2.b) Synthesis of ethyl
3-phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylate
[0145] A) 2-Azido-3-(4-phenethyl-furan-2-yl)-acrylic acid ethyl
ester was synthesized from 4-phenethyl-furan-2-carbaldehyde (1.53
g, 7.64 mmol) to give a colorless oil (0.718 g, 30%) after
purification by silica gel column chromatography. .sup.1H NMR (400
MHz, CDCl.sub.3) .delta. ppm 7.28-7.34 (m, 2H) 7.17-7.25 (m, 4H)
6.99 (s, 1H) 6.81 (s, 1H) 4.35 (q, J=7.1 Hz, 2H) 2.86-2.94 (m, 2H)
2.73-2.80 (m, 2H) 1.38 (t, J=7.1 Hz, 3H).
[0146] B) The title compound was prepared from
2-azido-3-(4-phenethyl-furan-2-yl)-acrylic acid ethyl ester and was
purified by silica gel column chromatography to give ethyl
3-phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylate as a white solid
(613 mg, 94%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm 7.48
(br s., 1H) 7.28-7.39 (m, 4H) 7.23-7.26 (m, 2H) 6.67 (d, J=1.8 Hz,
1H) 4.30 (q, J=7.1 Hz, 2H) 2.90-2.99 (m, 4H) 1.36 (t, J=7.2 Hz,
3H).
1.2.c) Synthesis of ethyl
2-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate
[0147] A) 2-Azido-3-(5-benzyl-furan-2-yl)-acrylic acid ethyl ester
was prepared from 5-benzyl-furan-2-carbaldehyde (295 mg, 1.58 mmol)
and was purified by silica gel column chromatography to give a
brown oil (35.0 mg, 7%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta.
ppm 7.30-7.36 (m, 3H) 7.24 (d, J=0.6 Hz, 2H) 7.09 (dd, J=3.4, 0.4
Hz, 1H) 6.21-6.24 (m, 1H) 6.05-6.08 (m, 1H) 4.35 (q, J=7.1 Hz, 2H)
4.05 (s, 2H) 1.35-1.39 (m, 3H).
[0148] B) The title compound was prepared from
2-azido-3-(5-benzyl-furan-2-yl)-acrylic acid ethyl ester and was
purified by silica gel column chromatography to afford ethyl
2-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate as a tan solid (17 mg,
53%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm 8.61 (br. s.,
1H) 7.31-7.37 (m, 2H) 7.23-7.31 (m, 3H) 6.74 (dd, J=1.6, 0.9 Hz,
1H) 6.10 (d, J=0.9 Hz, 1H) 4.34 (q, J=7.1 Hz, 2H) 4.07 (s, 2H) 1.37
(t, J=7.1 Hz, 3H).
1.2.d) Synthesis of ethyl
3-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate
[0149] A) 2-Azido-3-(4-benzyl-furan-2-yl)-acrylic acid ethyl ester
was synthesized from 4-benzyl-furan-2-carbaldehyde (0.300 g, 1.61
mmol) and purified to give a pale yellow oil (135 mg, 28%). .sup.1H
NMR (400 MHz, CD.sub.3CN) .delta. ppm 7.42 (d, J=0.9 Hz, 1H) 7.30
(d, J=7.1 Hz, 2H) 7.19-7.28 (m, 3H) 7.00 (s, 1H) 6.75 (s, 1H) 4.29
(q, J=7.1 Hz, 2H) 3.79 (s, 2H) 1.32 (t, J=7.1 Hz, 3H).
[0150] B) The title compound was prepared from
2-azido-3-(4-benzyl-furan-2-yl)-acrylic acid ethyl ester and was
purified by silica gel column chromatography to afford ethyl
3-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate as a brown solid (52
mg, 43%). .sup.1H NMR (400 MHz, CD.sub.3CN) 8 ppm 9.57 (br. s., 1H)
7.40 (s, 1H) 7.28-7.35 (m, 4H) 7.19-7.27 (m, 1H) 6.68 (d, J=1.8 Hz,
1H) 4.26 (q, J=7.1 Hz, 2H) 3.92 (s, 2H) 1.27-1.34 (m, 3H).
1.2.e) Synthesis of ethyl
3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylate
[0151] A) Ethyl 2-azido-3-(4-vinylfuran-2-yl)acrylate (398 mg, 52%)
was synthesized from 4-vinylfuran-2-carbaldehyde (0.4 g, 3.28 mmol)
and was purified by flash chromatography (Isco CombiFlash, 0-5%
EtOAc/heptane). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm 1.39
(t, J=7.13 Hz, 3H), 4.36 (q, J=7.13 Hz, 2H), 5.23 (dd, J=10.88,
1.22 Hz, 1H), 5.58 (dd, J=17.52, 1.17 Hz, 1H), 6.55 (dd, J=17.57,
10.88 Hz, 1H), 6.81 (s, 1H), 7.25 (s, 1H), 7.46 (s, 1H); LCMS-MS
(ESI+) 205.86 (M-N.sub.2).
[0152] B) The title compound was synthesized from ethyl
2-azido-3-(4-vinylfuran-2-yl)acrylate and was purified by flash
column chromatography (Isco CombiFlash, 0-30% EtOAc/heptane) to
afford ethyl 3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylate as a white
solid (215 mg, 62%). .sup.1H NMR (400 MHz, CDCl.sub.3) .delta. ppm
1.40 (t, J=7.13 Hz, 3H), 4.38 (q, J=7.13 Hz, 2H), 5.35 (d, J=10.93,
Hz, 1H), 5.52 (d, J=17.57 Hz, 1H), 6.63 (dd, J=17.57, 10.88 Hz,
1H), 6.80 (d, J=1.66 Hz, 1H), 7.53 (s, 1H); LCMS-MS (ESI+) 205.85
(M+H).
1.2.f) Synthesis of (Z)-ethyl
3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylate
[0153] A) (Z)-ethyl
2-azido-3-(4-((Z)-prop-1-enyl)furan-2-yl)acrylate (663 mg, 87%) was
synthesized from (Z)-4-(prop-1-enyl)furan-2-carbaldehyde (0.4130 g,
3.7 mmol, 1 eq.) and was purified via ISCO Companion (0-20%
EtOAc/heptane over 19 min, retention time: 3-6 min). .sup.1H NMR
(400 MHz, CD.sub.3CN) .delta. (ppm): 7.63 (s, 1H), 7.21 (s, 1H),
6.78 (s, 1H), 6.20 (dd, J=11.37, 1.61 Hz, 1H), 5.71-5.82 (m, 1H),
4.31 (q, J=7.13 Hz, 2H), 1.86 (dd, J=7.13, 1.76 Hz, 3H), 1.33 (t,
J=7.13 Hz, 3H).
[0154] B) The title compound was synthesized from (Z)-ethyl
2-azido-3-(4-((Z)-prop-1-enyl)furan-2-yl)acrylate (0.6633 g) and
purified via ISCO Companion (0-30% EtOAc/heptane over 30 min,
retention time: 26-29 min) to give (Z)-ethyl
3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylate (145 mg, 25%).
LC/MS m/e 219.8 (M+H). .sup.1H NMR (400 MHz, CD.sub.3CN) .delta.
(ppm): 9.70 (s, 1H), 7.65 (s, 1H), 6.72 (d, J=1.71 Hz, 1H),
6.30-6.37 (m, 1H), 5.82-5.94 (m, 1H), 4.24-4.34 (m, 2H), 1.88 (dd,
J=7.05, 1.78 Hz, 3H), 1.30-1.36 (m, 3H).
1.2.g) Synthesis of (E)-ethyl
3-styryl-4H-furo[3,2-b]pyrrole-5-carboxylate
[0155] A) (E)-Ethyl 2-azido-3-(4-styrylfuran-2-yl)acrylate (36.1
mg, 26%) was synthesized from (E)-4-styrylfuran-2-carbaldehyde
(0.0891 g, 0.5 mmol) and was purified via ISCO Companion (0-50%,
EtOAc/heptane, over 35 min, retention time: 3-8 min). .sup.1H NMR
(400 MHz, CD.sub.3CN) .delta. (ppm): 7.71 (s, 1H), 7.47-7.54 (m,
3H), 7.34-7.40 (m, 2H), 7.24-7.30 (m, 1H), 6.99-7.10 (m, 2H), 6.79
(s, 1H), 4.32 (q, J=7.13 Hz, 2H), 1.34 (t, J=7.10 Hz, 3H).
[0156] B) The title compound was prepared from (E)-ethyl
2-azido-3-(4-styrylfuran-2-yl)acrylate (36.1 mg) and was purified
via preparative HPLC using the Chromeleon purification system
(60-100% methanol/0.1% formic acid-1% acetonitrile in water, 50 mm
Dynamax C-18 column at 28 mL/min over 7 min, retention time 3.5-3.8
min) to give (E)-ethyl 3-styryl-4H-furo[3,2-b]pyrrole-5-carboxylate
(18.1 mg, 55% yield). .sup.1H NMR (400 MHz, CD.sub.3CN) .delta.
(ppm): 10.07 (s, 1H), 7.75 (s, 1H), 7.57-7.62 (m, 2H), 7.40 (t,
J=7.61 Hz, 2H), 7.26-7.32 (m, 1H), 7.09-7.22 (m, 2H), 6.78 (d,
J=1.71 Hz, 1H), 4.33 (q, J=7.13 Hz, 2H), 1.36 (t, J=7.13 Hz,
3H).
1.5. Synthesis of Carboxylic Acids from Esters
1.5.a) Synthesis of 4H-Furo[3,2-b]pyrrole-5-carboxylic acid
(11)
[0157] The title compound was synthesized from ethyl
4H-furo[3,2-b]pyrrole-5-carboxylate (0.33 g, 1.84 mmol) according
to General Procedure 2 and was purified by silica gel column
chromatography (0 to 100% EtOAc in heptane over 30 min) to give
4H-furo[3,2-b]pyrrole-5-carboxylic acid 11 as a light pink solid
(0.200 g, 72%). R.sub.f=0.07 (1:1 heptane/EtOAc); .sup.1H NMR (400
MHz, (CD.sub.3).sub.2SO) .delta. (ppm) 12.34 (s, 1H) 11.48 (s, 1H)
7.75 (s, 1H) 6.68 (s, 1H) 6.57 (s, 1H).
1.5.b) Synthesis of 3-phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylic
acid (17)
[0158] The title compound was prepared from ethyl
3-phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylate (265 mg, 0.935
mmol) according to General Procedure 2 to give
3-phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid 17 as a tan
solid (117 mg, 49%). .sup.1H NMR (400 MHz, (CD.sub.3).sub.2SO)
.delta. ppm 12.34 (br s., 1H) 11.68 (s, 1H) 7.51 (s, 1H) 7.25-7.32
(m, 4H) 7.15-7.22 (m, 1H) 6.63 (d, J=1.7 Hz, 1H) 2.91-2.99 (m, 2H)
2.73-2.81 (m, 2H).
1.5.c) Synthesis of 2-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic
acid (24)
[0159] The title compound was prepared from ethyl
2-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate (17 mg, 63 .mu.mol)
according to General Procedure 2 to give
2-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid 24 (13 mg, 87%) as
a tan solid. .sup.1H NMR (400 MHz, (CD.sub.3).sub.2SO) .delta. ppm
12.17 (br. s., 1H) 11.36 (s, 1H) 7.19-7.36 (m, 5H) 6.59 (dd, J=1.7,
0.9 Hz, 1H) 6.29 (d, J=0.8 Hz, 1H) 4.04 (s, 2H).
1.5.d) Synthesis of 3-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic
acid (26)
[0160] The title compound was prepared from ethyl
3-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylate (52 mg, 0.19 mmol)
according to General Procedure 2 to give
3-benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid 26 as a tan solid
(41 mg, 87%). .sup.1H NMR (400 MHz, (CD.sub.3).sub.2SO) .delta. ppm
12.32 (br. s., 1H) 11.60 (s, 1H) 7.57 (s, 1H) 7.33-7.38 (m, 2H)
7.25-7.31 (m, 2H) 7.15-7.21 (m, 1H) 6.63 (d, J=1.5 Hz, 1H) 3.84 (s,
2H). HPLC 99%. LCMS 242 (M+H).
1.5.e) Synthesis of 3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid
(32)
[0161] The title compound was synthesized from ethyl
3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylate (100 mg, 0.49 mmol)
according to General Procedure 2 and was purified by flash
chromatography (Isco CombiFlash, 0-40% EtOAc/heptane) to give
3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid 32 (36 mg, 42%).
.sup.1H NMR (400 MHz, CD.sub.3OD) .delta. ppm 5.29 (dd, J=11.03,
0.73 Hz, 1H), 5.81-5.88 (m, 1H), 6.59-6.68 (m, 1H), 6.72 (s, 1H),
7.63 (s, 1H); LCMS-MS (ESI-) 175.8 (M-H); HPLC (UV=99.2%),
(ELSD=100%).
1.5.f) Synthesis of
(Z)-3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylic acid
(46)
[0162] The title compound was synthesized from (Z)-ethyl
3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylate (0.1445 g, 68
mmol) according to General Procedure 2 and was purified by
preparative HPLC using a Chromeleon purification system (50-100%
over 7 min methanol/0.1% formic acid-1% acetonitrile in water, 50
mm Dynamax C-18, 28 mL/min) to give
(Z)-3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylic acid 46
(40.4 mg, 32% yield). LC/MS m/e 189.8 (M-H). Purity by HPLC: 99.1%
(UV); 100% (ELSD). .sup.1H NMR (400 MHz, CD.sub.3OD) .delta. (ppm):
7.64 (s, 1H), 6.72 (s, 1H), 6.32-6.38 (m, 1H), 5.81-5.91 (m, 1H),
1.91 (dd, J=7.03, 1.76 Hz, 3H).
1.5.g) Synthesis of (E)-3-Styryl-4H-furo[3,2-b]pyrrole-5-carboxylic
acid (48)
[0163] The title compound was synthesized from (E)-ethyl
3-styryl-4H-furo[3,2-b]pyrrole-5-carboxylate (0.0181 g, 0.071 mmol)
according to General Procedure 2A and was purified via preparative
HPLC (Chromeleon purification system, 40-100% over 7 min,
methanol/0.1% formic acid-1% acetonitrile in water, 50 mm Dynamax
C-18, 28 mL/min, retention time of product: 3.9-4.0 min) to give
(E)-3-styryl-4H-furo[3,2-b]pyrrole-5-carboxylic acid 48 (4.9 mg,
30%). LC/MS m/e 251.9 (M-H). Purity by HPLC: 97.9% (UV); 100%
(ELSD). .sup.1H NMR (400 MHz, CD.sub.3OD) .delta. (ppm): 8.40 (s,
1H), 7.76 (s, 1H), 7.58-7.62 (m, 2H), 7.34-7.39 (m, 2H), 7.31 (d,
J=16.40 Hz, 1H), 7.22-7.27 (m, 1H), 7.12 (d, J=16.40 Hz, 1H), 6.76
(s, 1H).
Example 2
D-Amino Acid Oxidase Inhibition
2.1. D-Amino Acid Oxidase Enzyme Assay
[0164] DAAO enzyme activity was measured using the substrate
D-serine at its Michaelis-Menton K.sub.m of 5 mM. The rate of
oxidation is measured as a rate of production of hydrogen peroxide,
which was detected using the enzyme horseradish peroxidase (Sigma
cat. No. P-8375). This coupled reaction uses the enzyme substrate
Amplex Red (Molecular Probes), which is converted to the
fluorescent reaction product, resorufin (excitation 530-560 nm;
emission .about.590 nm). Although DAAO has a higher pH optimum, all
reagents were prepared in 50 mM sodium phosphate buffer at pH 7.4
and inhibition curves were generated at this pH.
[0165] The final concentrations of components in 200 .mu.l total
volume per well (black clear-bottom 96-well plate, Costar)
were:
[0166] (a) Horseradish peroxidase: 4 Units per ml
[0167] (b) D-serine: 5 mM
[0168] (c) Test Compound: 100-0.0064 uM for IC50s
[0169] (d) Amplex Red reagent: 50 uM
[0170] (e) DMSO: 1.6%
[0171] The reactions were initiated by addition of DAAO enzyme
while the fluorescence was monitored. H.sub.2O.sub.2 was added at
16 uM final concentration to a control well on each plate to test
for compound interference with a coupled enzyme. Inhibition curves
were generated in the presence of varying concentrations of the
inhibitor and IC.sub.50 values were calculated for each
inhibitor.
2.2. Results of DAAO Inhibition Assay
[0172] IC.sub.50 values were determined for selected compounds,
which are summarized in Table 2 below.
TABLE-US-00002 TABLE 2 Human and Porcine DAAO Inhibition
[IC.sub.50] Compound Human DAAO No. Compound Name (.mu.M) 11
4H-furo[3,2-b]pyrrole-5-carboxylic acid (+++) 17
3-Phenethyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid (++) 24
2-Benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid (+) 26
3-Benzyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid (+) 32
3-vinyl-4H-furo[3,2-b]pyrrole-5-carboxylic acid (+++) 46
(Z)-3-(prop-1-enyl)-4H-furo[3,2-b]pyrrole-5-carboxylic acid (+) 48
(E)-3-styryl-4H-furo[3,2-b]pyrrole-5-carboxylic acid (+) IC.sub.50
.ltoreq. 100 nM = (+++); IC.sub.50 .ltoreq. 1 .mu.M = (++);
IC.sub.50 .ltoreq. 100 .mu.M = (+)
Example 3
Chung Model Data for Compound 11
3.1. Methods
[0173] Adult male Sprague-Dawley rats, weighing 200-230 g at the
time of surgery, were used. They were housed in groups of 4 in an
air-conditioned room on a 12 h light/dark cycle. Food and water
were available ad libitum. The animals were allowed to acclimatize
to the experimental environment for three days by leaving them on a
lifted metal mesh for at least 40 min. The baseline paw withdrawal
threshold (PWT) was examined using a series of graduated von Frey
hairs for 3 consecutive days before surgery and re-assessed on the
7th day after surgery and on the 11.sup.th to 14.sup.th day before
drug dosing. The rat Chung model was prepared as described by Kim
and Chung (1992). The rat was anaesthetized with 5% isoflurane
mixed with oxygen (2 L per min) followed by an i.p. injection of
sodium pentobarbitone at 50 mg/kg. The back was shaved and
sterilized with 75% ethanol. The animal was placed in a prone
position and a para-medial incision was made on the skin covering
L4-6 level. The L5 spinal nerve was carefully isolated and tightly
ligated with 6/0 silk suture. The wound was then closed in layers
after a complete hemostasis. A single dose of antibiotics (Amoxipen
15 mg/rat, ip) was routinely given for prevention of infection
after surgery. The animals were placed in a temperature controlled
recovery chamber until fully awake before being returned to the
home cage. The animals were placed in individual Perspex boxes on a
raised metal mesh for at least 40 min before the test. Starting
with the filament of lowest force, each filament was applied
perpendicularly to the centre of the ventral surface of the paw
until slightly bent for 6 seconds. If the animal withdrew or lifted
the paw upon stimulation, then a hair with force immediately lower
than that tested was used. If no response was observed, then a hair
with force immediately higher was tested. The lowest amount of
force required to induce reliable responses (positive in 3 out of 5
trials) was recorded as the value of PWT. Only those animals with
significant allodynia (PWT.ltoreq.3.5 g) were selected for drug
dosing experiments. The rats in a neuropathic pain state were
randomly divided into experimental groups: Vehicle group and 1
group had 8 rats and the gabapentin group had 9 rats. The drug test
was carried out 12 to 14 days after surgery. Isotonic 50 mM
phosphate buffer (PB), dosed orally at 3 mL/kg, served as the
vehicle control. Gabapentin was dissolved in normal saline and
given orally at 100 mg/kg. 1 was dissolved in PB to 10 mg/mL and
given orally at 30 mg/kg. The PWT was assessed at 1, 3, 6 and 24 h
following drug or vehicle administration. The animals were returned
to their home cage for a break (about 30 min) between two
neighboring testing time points. One-way analysis of variance
(ANOVA) (SPSS software) was used for statistical analysis to
compare different groups on the same time points. Paired Student-t
test was used to compare different time points in the same group.
The significance level was set at P<0.05.
3.2. Results for 4H-furo[3,2-b]pyrrole-5-carboxylic acid (11)
[0174] In rats that were dosed orally with vehicle, there were no
significant changes in PWT from the baseline value over the 24-hour
observation period. Gabapentin, as a positive control, orally dosed
at 100 mg/kg, significantly increased the PWT, with effects
commencing the first hour after oral dosing and reaching a peak 3
hours after dosing. The effect of gabapentin gradually declined
from 6 hours onwards. Compound 11, at an oral dose of 10 mg/kg,
also significantly elevated the PWT. Similar to gabapentin, the
increase in PWT was first observed 1 hour after dosing. The effect
reached a peak at 6 hours after dosing.
Example 4
Contextual Fear Conditioning Data for Compounds 11 and 1
4.1. Methods
[0175] Young-adult C57BL/6 male mice were used. Mice were received
at 6-7 weeks of age. Upon arrival, mice were assigned unique
identification numbers (tail marked) and were group housed in
polycarbonate cages with filter tops. All mice were acclimated to
the colony room for at least four weeks prior to testing and were
subsequently tested at an average age of 10-12 weeks of age. During
the period of acclimation, mice were examined on a regular basis,
handled, and weighed to assure adequate health and suitability.
Mice were maintained on a 12/12 light/dark cycle with the light on
at 6:00 a.m. The experiments were always conducted during the light
phase of the cycle. The day before the initiation of the
experiment, mice were housed single in individual cages and
maintained so till the end of the experiment. Animals were randomly
assigned across treatment groups. With the exception of testing
times, the mice had ad lib access to food and water. Rolipram (0.1
mg/kg) was dissolved in 1% DMSO i.p. 20 min prior to training at a
dose volume of 8 ml/kg. To assess contextual conditioning, we use a
standardized contextual fear conditioning task originally developed
for evaluation of memory in CREB mutant mice (Bourtchouladze, R. et
al.; Cell 1994, 79, 59-68). Specifically, on the training day, the
mouse is placed into the conditioning chamber for 2 minutes before
the onset of the unconditioned stimulus (US), a 0.75 mA foot shock
of 2 seconds duration. The US is repeated two times with a 1 min
inter-trial interval between shocks. Training is performed using an
automated software package. After the last training trial, a mouse
is left in the conditioning chamber for another 30 sec and then
placed back in its home cage. Contextual memory is tested 24 hours
after training. The mouse is placed into the same training chamber
and conditioning is assessed by scoring freezing behavior. Freezing
is defined as the complete lack of movement in intervals of 5
seconds (Kim, J. J.; Rison, R. A.; Fanselow, M. S. Behavioral
Neuroscience, 1993, 107, 1093-1098; Phillips, R. G.; LeDoux, J. E.
Behavioral Neuroscience, 1992, 106, 274-285; Bourtchouladze, R.;
Frenguelli, B.; Blendy, J.; Cioffi, D.; Schutz, G.; Silva, A. J.
Cell, 1994, 79, 59-68; 1998; Bourtchouladze, R.; Abel, T.; Berman,
N.; Gordon, R.; Lapidus, K.; Kandel, E. R. Learning & Memory,
1998, 5, 365-374; Abel, T.; Nguyen, P. V.; Barad, M.; Deuel, T. A.
S.; Kandel, E. R.; Bourtchouladze, R. Cell, 1997, 88, 615-626;
Kogan, J. H.; Frankland, P. W.; Blendy, J. A.; Coblentz, J.;
Marowitz, Z.; Schutz, G.; Silva, A. J. Current Biology, 1997, 7,
1-11). Total testing time lasted 3 minutes. After each experimental
subject, the experimental apparatus is thoroughly cleaned with 75%
ethanol, water, dried, and ventilated for a few minutes. To
evaluate the effects of compounds on contextual memory, we injected
mice with a compound or vehicle 2 hours before training and trained
them with 2 training trials. In parallel, a separate group of mice
was injected with a reference compound, Rolipram or vehicle alone,
20 minutes before training. Mice were tested in the same context 24
hours after training.
4.2. Results
[0176] Compound 11 was dissolved in vehicle A and administered P.O.
2 hrs prior to training at a dose volume of 10 ml/kg. 10 mg/kg of
11-injected mice froze significantly more than vehicle injected
mice (69.7%+/-3.0% and 33.3%+/-5.1% for a compound- and
vehicle-injected, respectively; p<0.001; n=10 per dose).
Similarly, Rolipram injected mice froze significantly more than
their corresponding vehicle-injected mice (44.4%+/-4.4% vs.
27.2%+/-3.6% for Rolipram and vehicle, respectively, p<0.05).
Importantly, there was no effect of drug-compound injections on
immediate freezing responses measured 30 sec after training.
[0177] H-thieno[3,2-b]pyrrole-5-carboxylic acid (1) was active at
10 mg/kg P.O.
[0178] All publications and patent documents cited in this
application are incorporated by reference in their entirety for all
purposes to the same extent as if each individual publication or
patent document were so individually denoted. By their citation of
various references in this document, Applicants do not admit any
particular reference is "prior art" to their invention.
* * * * *