U.S. patent application number 10/756290 was filed with the patent office on 2004-07-29 for cubane derivatives as metabotropic glutamate receptor antagonists and process for their preparation.
This patent application is currently assigned to Prescient NeuroPharma Inc.. Invention is credited to Curry, Kenneth, Pajouhesh, Hassan.
Application Number | 20040147482 10/756290 |
Document ID | / |
Family ID | 4162343 |
Filed Date | 2004-07-29 |
United States Patent
Application |
20040147482 |
Kind Code |
A1 |
Pajouhesh, Hassan ; et
al. |
July 29, 2004 |
Cubane derivatives as metabotropic glutamate receptor antagonists
and process for their preparation
Abstract
Thee present invention relates to therapeutically active cubane
compounds, a method of preparing the same, and to pharmaceutical
compositions comprising the compounds. The novel compounds are
useful in creating diseases of the central nervous system related
to the metabotropic glutamate receptor system.
Inventors: |
Pajouhesh, Hassan;
(Vancouver, CA) ; Curry, Kenneth; (Vancouver,
CA) |
Correspondence
Address: |
Gary M. Nath, Esq.
NATH & ASSOCIATES PLLC
6th Floor
1030 15th Street, N.W.
Washington
DC
20005
US
|
Assignee: |
Prescient NeuroPharma Inc.
Vancouver
CA
|
Family ID: |
4162343 |
Appl. No.: |
10/756290 |
Filed: |
January 14, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10756290 |
Jan 14, 2004 |
|
|
|
09673473 |
Nov 29, 2000 |
|
|
|
09673473 |
Nov 29, 2000 |
|
|
|
PCT/CA99/00311 |
Apr 19, 1999 |
|
|
|
Current U.S.
Class: |
514/64 ; 514/114;
514/381; 514/553; 514/561; 548/240; 548/254; 562/104; 562/11;
562/498; 562/7 |
Current CPC
Class: |
C07C 229/28 20130101;
A61P 25/16 20180101; A61P 25/20 20180101; A61P 9/02 20180101; C07F
9/383 20130101; A61P 25/04 20180101; A61P 9/10 20180101; A61P 25/28
20180101; C07C 69/753 20130101; C07C 2603/90 20170501; A61P 25/06
20180101; A61P 25/18 20180101; A61P 1/08 20180101; A61P 25/00
20180101; C07C 2603/00 20170501; C07C 2603/86 20170501; A61P 27/02
20180101; C07C 255/28 20130101; A61P 21/02 20180101; C07D 233/86
20130101; A61P 25/14 20180101; A61P 25/22 20180101; A61P 25/30
20180101 |
Class at
Publication: |
514/064 ;
514/114; 514/381; 514/553; 514/561; 548/254; 548/240; 562/007;
562/011; 562/104; 562/498 |
International
Class: |
A61K 031/69; A61K
031/66; A61K 031/41; A61K 031/185; A61K 031/195 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 1998 |
CA |
2,235,119 |
Claims
We claim:
1. A compound of the formula: 14wherein: R1 can be an acidic group
selected from the group consisting of carboxyl, phosphono,
phosphino, sulfono, sulfino, borono, tetrazol, isoxazol,
--CH.sub.2-carboxyl, --CH.sub.2-phosphono, --CH.sub.2-phosphino,
--CH.sub.2-sulfono, --CH.sub.2-sulfino, --CH.sub.2-borono,
--CH.sub.2-tetrazol, and --CH.sub.2-isoxazol; R2 can be a basic
group selected from the group consisting of 1.degree. amino,
2.degree. amino, 3.degree. amino, quaternary ammonium salts,
aliphatic 1.degree. amino, aliphatic 2.degree. amino, aliphatic
3.degree. amino, aliphatic quaternary ammonium salts, aromatic
1.degree. amino, aromatic 2.degree. amino, aromatic 3.degree.
amino, aromatic quaternary ammonium salts, imidazol, guanidino,
boronoamino, allyl, urea, thiourea, R3 can be H, aliphatic,
aromatic or heterocyclic; R4 can be an acidic group selected from
the group consisting of carboxyl, phosphono, phosphino, sulfono,
sulfino, borono, tetrazol, isoxazol; and pharmaceutically
acceptable salts thereof.
2. A compound as claimed in claim 1, wherein R1 is COOH
3. A compound as claimed in claim 1, wherein R2 is COOH
4. A compound as claimed in claim 1, wherein R3 can be --H, or -Me;
or xanthyl or thioxanthyl and R4 is NH.sub.2
5. A process for the preparation of a compound of Formula I, or a
pharmaceutically acceptable metabolically-labile ester or amide
thereof, or a pharmaceutically acceptable salt thereof, which
comprises: (a) hydrolyzing a compound of formula: 15in which R1 is
defined as above, R5 represents a hydrogen atom or an acyl group
and R4 has the meaning defined above. Preferred values for R5 are
hydrogen and (2-6C), alkanoyl groups, such as acetyl; (b)
hydrolyzing a compound of formula: 16wherein R6 and R7 each
independently represent a hydrogen atom, a (2-6C) alkanoyl group, a
(1-4C) alkyl group, a (3-4C) alkenyl group or a phenyl (1-4C) alkyl
group in which the phenyl is unsubstituted or substituted by
halogen, (1-4C) alkyl or (1-4C) alkoxy, or a salt thereof; or (c)
deprotecting a compound of formula: 17in which R8 represents a
hydrogen atom or a carboxyl protecting group, or a salt thereof,
and R9 represents a hydrogen atom or a nitrogen protecting group;
whereafter, if necessary and/or desired. (i) resolving the compound
of Formula I; (ii) converting the compound of Formula I into a
non-toxic metabolically-labile ester or amide thereof; and/or;
(iii) converting the compound of Formula I or a non-toxic
metabolically-labile ester or amide thereof into a pharmaceutically
acceptable salt thereof.
6. A pharmaceutical formulation, which comprises a compound as
claimed in claim 1 and a pharmaceutically acceptable carrier,
diluent or excipient.
7. A method of modulating one or more metabotropic glutamate
receptor functions in a warm blooded mammal requiring such
treatment, which comprises administering an effective amount of a
compound as claimed in claim 1.
8. A compound of formula: 18in which R1, R4 and R5 have the
meanings as defined above.
9. A compound of formula: 19wherein R6 and R7 have meanings as
defined above.
10. A compound of formula: 20in which R8 and R9 have meanings as
defined above.
Description
FIELD OF THE INVENTION
[0001] This invention pertains to therapeutically active cubane
derivatives, a method for preparing the same, pharmaceutical
compositions comprising the compounds and a method of treating
diseases of the Central Nervous System (CNS) therewith.
BACKGROUND OF THE INVENTION
[0002] The acidic amino acid L-Glutamate is recognized as the major
excitatory neurotransmitter in the CNS. The receptors that respond
to L-Glutamate are called excitatory amino acid receptors. The
excitatory amino acid receptors are thus of great physiological
importance, playing a role in a variety of physiological processes
such as long-term potentiation (learning and memory), the
development of synaptic plasticity, motor control, respiratory and
cardiovascular regulation and sensory perception.
[0003] Excitatory amino acid receptors are classified into two
general types and both are activated by L-Glutamic acid and its
analogs. Receptors activated by L-Glutamic acid that are directly
coupled to the opening of cation channels in the cell membrane of
the neurons are termed "ionotropic." This type of receptor has been
subdivided into at least three subtypes, which are defined by the
depolarizing actions of the selective agonists N-Methyl-D-aspartate
(NOMA), .alpha.-Amino-3-hydroxy-5- -methyllsoxazole-4-propionic
acid (AMPA), and Kainic acid (KA).
[0004] The second general type of receptor is the G-protein or
second messenger-linked "metabotropic" excitatory amino acid
receptor. This second type is coupled to multiple second messenger
systems that lead to enhanced phosphoinositide hydrolysis,
activation of phospholipase D, increases or decreases in cAMP
formation, and changes in ion channel function (Schoepp and Conn,
Treads in Pharmacological Science, 14:13, 1993). Both types of
receptors appear not only to mediate normal synaptic transmission
along excitatory pathways but also to participate in the
modification of synaptic connections during development and
throughout life.
[0005] So far eight different clones of the G-protein-coupled
metabotropic glutamate receptors (mGluRs) have been identified
(Knopfel et al., 1995, J. Med. Chem., 38, 1417-1426). These
receptors function to modulate the presynaptic release of
L-Glutamate, and the postsynaptic sensitivity of the neuronal cell
to L-Glutamate excitation. Based on pharmacology, sequence homology
and the signal transduction pathway that they activate, the mGluRs
have been subclassified into three groups. The mGluR1 and mGluR5
receptors form group I. They are coupled to hydrolysis of
phosphatidylinositol (PI) and are selectively activated by
(RS)-3',5-dihydroxyphenylglycine (Brabet et al.,
Neuropharmacicology, 34, 895-903, 1995). Group II comprises
mGluR.sub.2 and mGluR.sub.3 receptors. They are negatively coupled
to adenylate cyclase and are selectively activated by
(2S,1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine (DCG-IV;
Hayashi et al., Nature, 366, 687-690, 1993). Finally, the
mGluR.sub.4, mGluR.sub.6, mGluR.sub.7 and mGluR.sub.8 receptors
belong to group III. They are also negatively coupled to adenylate
cyclase and are selectively activated by
(L)-2-amino-4-phosphonobutyric acid (L-AP4; Knopfel et al., 1995,
J. Med. Chem., 38, 1417-1426).
[0006] Agonists and antagonists of these receptors are believed
useful for the treatment of acute and chronic neurodegenerative
conditions, and as antipsychotic, anticonvulsant, analgesic,
anxiolytic, antidepressant, and anti-emetic agents. Antagonists and
agonists of neural receptors are classified as selective for a
particular receptor or receptor subtype, or as non-selective.
Antagonists may also be classified as competitive or
non-competitive. While competitive and non-competitive antagonists
act on the receptors in a different manner to produce similar
results, selectivity is based upon the observations that some
antagonists exhibit high levels of activity at a single receptor
type, and little or no activity at other receptors. In the case of
receptor-specific diseases and conditions, the selective agonists
and antagonists are of the most value.
[0007] Compounds such as L-Glutamic acid, Quisqualic acid and
Ibotenic acid are known to act as non-selective agonists on the
mGluRs, while selective ionotropic glutamate receptor agonists such
as NMDA, AMPA and Kainic acid have little effect on these
receptors. Recently a few compounds without activity at the
ionotropic glutamate receptors but with activity at the
metabotropic receptors have been identified. These include
trans-ACPD (trans (1S,3R-1-aminocyclopentane-1,3-dicarboxylic
acid), the partial agonist L-AP3 (L-2-amino-3-phosphonopropionic
acid; Palmer, E., Monaghan; D. T. and Cotman, C. W. Eur. J.
Pharmacol. 166, 585-587, 1989; Desai, M. A. and Conn, P. J.
Neuroscience Lett. 109, 157-162, 1990; Schoepp; D. D. et al., J.
Neurochemistry. 56, 1789-1796, 1991; Schoepp D. D. and Johnson B.
G. J. Neurochemistry 53., 1865-1613, 1989), L-AP4
(L-2-amino-4-phosphonobutyric acid) which is an agonist at the
mGluR.sub.4 receptor (Thomsen C. et al., Eur. J. Pharmacol. 227,
361-362, 1992) and some of the isomers of CCG
(2-(carboxycyclopropyl)glyc- ines) especially L-CCG-I and L-CCG-II
(Hayashi, Y. et al., Br. J. Pharmacol. 107, 539-543, 1992).
[0008] Very few selective antagonists at the mGluRs have been
reported. However some phenylglycine derivatives, S-4CPG
(S-4-carboxyphenylglycine)- , S-4C3HPG
(S-4-carboxy-3-hydroxyphenylglycine) and S-MCPG
(S-.alpha.-methyl-4-carboxyphenylglycine) have been reported to
antagonize trans-ACPD-stimulated phosphoinositide hydrolysis and
thus possibly act as antagonists at mGluR.sub.1 and mGluR.sub.5
subtypes (Thomsen, C. and Suzdak, P, Eur. J. Pharmacol. 245, 299,
1993).
[0009] Research directed towards mGluRs is beginning to show that
mGluRs may be implicated in a number of normal as well as
pathological mechanisms in the brain and spinal cord. For example,
activation of these receptors on neurons can: influence levels of
alertness, attention and cognition; protect nerve cells from
excitotoxic damage resulting from ischemia, hypoglycemia and
anoxia; modulate the level of neuronal excitation; influence
central mechanisms involved in controlling movement; reduce
sensitivity to pain; reduce levels of anxiety.
[0010] The use of compounds active at the mGluRs for the treatment
of epilepsy is corroborated by investigations of the influence of
trans-ACPD on the formation of convulsions (Sacaan and Schoepp,
Neuroscience Lett. 139, 77, 1992) and that phosphoinositide
hydrolysis mediated via mGluR is increased after kindling
experiments in rats (Akiyama et al. Brain Res. 569, 71, 1992).
Trans-ACPD has been shown to increase release of dopamine in the
rat brain, which indicates that compounds acting on the mGluRs
might be usable for the treatment of Parkinson's disease and
Huntington's Chorea (Sacaan et al., J. Neurochemistry 59, 245,
1992).
[0011] Trans-ACPD has also been shown to be a neuroprotective agent
in a medial cerebral artery occlusion (MCAO) model in mice
(Chiamulera et al. Eur. J. Pharmacol. 215, 353, 1992), and it has
been shown to inhibit NMDA-induced neurotoxicity in nerve cell
cultures (Koh et al., Proc. Natl. Acad. Sci. USA 88, 9431, 1991).
The mGluR-active compounds are also implicated in the treatment of
pain. This is proved by the fact that antagonists at the
metabotropic glutamate receptors antagonize sensory synaptic
response to noxious stimuli of thalamic neurons (Eaton, S. A. et
al., Eur. J. Neuroscience, 5, 186, 1993):
[0012] The use of compounds active at the mGluRs for treatment of
neurological diseases such as senile dementia have also been
indicated by the findings of Zheng and Gallagher (Neuron 9, 163,
1992) and Bashir et al. (Nature 363, 347, 1993) who demonstrated
that activation of mGluRs is necessary for the induction of
long-term potentiation (LTP) in nerve cells (septal nucleus,
hippocampus) and the finding that long-term depression is induced
after activation of metabotropic glutamate receptors in cerebellar
granule cells (Linden et al. Neuron 7, 81, 1991).
[0013] Thus compounds that demonstrate either activating or
inhibiting activity at mGluRs have therapeutic potential for the
treatment of neurological disorders. These compounds have
application as new drugs to treat both acute and chronic
neurological disorders, such as stroke and head injuries; epilepsy;
movement disorders associated with Parkinson's disease and
Huntington's chorea; pain: anxiety; AIDS dementia; and Alzheimer's
disease. Since the mGluRs can influence levels of alertness,
attention and cognition; protect nerve cells from excitotoxic
damage resulting from ischemia, hypoglycemia and anoxia; modulate
the level of neuronal excitation; influence central mechanisms
involved in controlling movement; reduce sensitivity to pain; and
reduce levels of anxiety, these compounds can also be used to
influence these situations and also find use in learning and memory
deficiencies such as senile dementia. mGluRs may also be involved
in addictive behavior, alcoholism, drug addiction, sensitization
and drug withdrawal (Science, 280:2045, 1998), so compounds acting
at mGluRs might also be used to treat these disorders.
[0014] The current pharmaceutical options for treating neurological
disorders tend to be very general and non-specific in their actions
in that, although they may reduce the clinical symptoms associated
with a specific neurological disorder, they may also negatively
impact normal function of the central nervous system of patients.
Thus new cellular targets and drugs that are more specific in their
actions require to be identified and developed and thus a need
remains for chemical compounds that demonstrate specific binding
characteristics towards mGluRs.
SUMMARY OF THE INVENTION
[0015] It is an object of this invention to provide novel compounds
that demonstrate activity at the various metabotropic glutamate
receptors (mGluRs). In particular, a compound of Formula I and
stereoisomers thereof: 1
[0016] wherein:
[0017] R1 can be an acidic group selected from the group consisting
of carboxyl, phosphono, phosphino, sulfono, sulfino, borono,
tetrazol, isoxazol, --CH.sub.2-carboxyl, --CH.sub.2-phosphono,
--CH.sub.2-phosphino, --CH.sub.2-sulfono, --CH.sub.2-sulfino,
--CH.sub.2-borono, --CH.sub.2-tetrazol, --CH.sub.2-isoxazol and
higher homologues thereof;
[0018] R2 can be a basic group selected from the group consisting
of 1.degree. amino, 2.degree. amino, 3.degree. amino, quaternary
ammonium salts, aliphatic 1.degree. amino, aliphatic 2.degree.
amino, aliphatic 3.degree. amino, aliphatic quaternary ammonium
salts, aromatic 1.degree. amino, aromatic 2.degree. amino, aromatic
3.degree. amino, aromatic quaternary ammonium salts, imidazol,
guanidino, boronoamino, allyl, urea, thiourea;
[0019] R3 can be H, aliphatic, aromatic or heterocyclic;
[0020] R4 can be an acidic group selected from the group consisting
of carboxyl, phosphono, phosphino, sulfono, sulfino, borono,
tetrazol, isoxazol;
[0021] and pharmaceutically acceptable salts thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The terms and abbreviations used in the instant examples
have their normal meanings unless otherwise designated. For example
".degree. C." refers to degrees Celsius; "N" refers to normal or
normality; "mmol" refers to millimole or millimoles; "g" refers to
gram or grams; "mL" means milliliter or milliliters; "M" refers to
molar or molarity; "MS" refers to mass spectrometry; "IR" refers to
infrared spectroscopy; and "NMR" refers to nuclear magnetic
resonance spectroscopy.
[0023] As would be understood by the skilled artisan throughout the
synthesis of the compounds of Formula 1, it may be necessary to
employ an amino-protecting group or a carboxy-protecting group in
order to reversibly preserve a reactively susceptible amino or
carboxy functionality while reacting other functional groups on the
compound.
[0024] Examples of such amino-protecting groups include formyl,
trityl, phthalimido, trichloroacetyl, chloroacetyl, bromoacetyl,
iodoacetyl, and urethane-type blocking groups such as
benzyloxycarbonyl, 4-phenylbenzyloxycarbonyl,
2-methylbenzyloxycarbonyl, 4-methoxybenzyloxycarbonyl,
4-fluorobenzyloxycarbonyl, 4-chlorobenzyloxycarbonyl,
3-chlorobenzyloxycarbonyl, 2-chlorobenzyloxycarbonyl,
2,4-dichlorobenzyloxycarbonyl, 4-bromobenzyloxycarbonyl,
3-bromobenzyloxycarbonyl, 4-nitrobenzyloxycarbonyl,
4-cyanobenzyloxycarbonyl, t-butoxycarbonyl,
2-(4-xenyl)-isopropoxycarbonyl, 1,1-diphenyleth-1-yloxycarbonyl,
1,1-diphenylprop-1-yloxycarbonyl, 2-phenylprop-2-yloxycarbonyl,
2-(p-toluyl)-prop-2-yloxycarbonyl, cyclopentanyloxy-carbonyl,
1-methylcyclopentanyloxycarbonyl, cyclohexanyloxycarbonyl,
1-methylcyclohexanyloxycarbonyl, 2-methylcyclohexanyloxycarbonyl,
2-(4-toluylsulfono)-ethoxycarbonyl,
2-(methylsulfono)ethoxycarbonyl,
2-(triphenylphosphino)-ethoxycarbonyl, fluorenylmethoxycarbonyl
("FMOC"), 2-(trimethylsilyl)ethoxycarbonyl, allyloxycarbonyl,
1-(trimethylsilylmethyl)prop-1-enyloxycarbonyl,
5-benzisoxalylmethoxycarb- onyl, 4-acetoxybenzyloxycarbonyl,
2,2,2-trichloroethoxycarbonyl, 2-ethynyl-2-propoxycarbonyl,
cyclopropylmethoxycarbonyl, 4-(decycloxy)benzyloxycarbonyl,
isobornyloxycarbonyl, 1-piperidyloxycarbonlyl and the like;
benzoylmethylsulfono group, 2-nitrophenylsulfenyl,
diphenylphosphine oxide and like amino-protecting groups. The
species of amino-protecting group employed is not critical so long
as the derivatized amino group is stable to the condition of
subsequent reaction(s) on other positions of the intermediate
molecule and can be selectively removed at the appropriate point
without disrupting the remainder of the molecule including any
other amino-protecting group(s). Preferred amino-protecting groups
are t-butoxycarbonyl (t-Boc), allyloxycarbonyl and
benzyloxycarbonyl (CbZ). Further examples of these groups are found
in E. Haslam in Protective Groups in Organic Synthesis; McOmie, J.
G. W., Ed. 1973, at Chapter 2; and Greene, T. W. and Wuts, P. G.
M., Protective Groups in Organic Synthesis, Second edition;
Wiley-Interscience: 1991; Chapter 7.
[0025] Examples of such carboxyl-protecting groups include methyl,
p-nitrobenzyl, p-methylbenzyl, p-methoxybenzyl,
3,4-dimethoxybenzyl, 2,4-dimethoxybenzyl, 2,4,6-trimethoxybenzyl,
2,4,6-trimethylbenzyl, pentamethylbenzyl, 3,4-methylenedioxybenzyl,
benzhydryl, 4,4'-dimethoxybenzhydryl,
2,2',4,4'-tetramethoxybenzhydryl, t-butyl, t-amyl, trityl,
4-methoxytrityl, 4,4'-dimethoxytrityl, 4,4',4"-trimethoxytrityl,
2-phenylprop-2-yl, trimethylsilyl, t-butyldimethylsilyl, phenacyl,
2,2,2-trichloroethyl, .beta.-(di(n-butyl)methylsilyl)ethyl,
p-toluenesulfonoethyl, 4-nitrobenzylsulfonoethyl, allyl, cinnamyl,
1-(trimethylsilylmethyl)prop-- 1-en-3-yl and like moieties.
Preferred carboxyl-protecting groups are allyl, benzyl and t-butyl.
Further examples of these groups are found in E. Haslam, supra, at
Chapter 5; and T. W. Greene and P. G. M. Wuts, supra, at Chapter
5.
[0026] The present invention provides a compound of the formula:
2
[0027] wherein:
[0028] R1 can be an acidic group selected from the group consisting
of carboxyl, phosphono, phosphino, sulfono, sulfino, borono,
tetrazol, isoxazol; --CH.sub.2-carboxyl, --CH.sub.2-phosphono,
--CH.sub.2-phosphino, --CH.sub.2-sulfono, --CH.sub.2-sulfino,
--CH.sub.2-borono, --CH.sub.2-tetrazol, --CH.sub.2-isoxazol and
higher analogues thereof,
[0029] R2 can be a basic group selected from the group consisting
of 1.degree. amino, 2.degree. amino, 3.degree. amino, quaternary
ammonium salts, aliphatic 1.degree. amino, aliphatic 2.degree.
amino, aliphatic 3.degree. amino, aliphatic quaternary ammonium
salts, aromatic 1.degree. amino, aromatic 2.degree. amino, aromatic
3.degree. amino, aromatic quaternary ammonium salts, imidazol,
guanidino, boronoamino, allyl, urea, thiourea;
[0030] R3 can be H, aliphatic, aromatic or heterocyclic;
[0031] R4 can be an acidic group selected from the group consisting
of carboxyl, phosphono, phosphino, sulfono, sulfino, borono,
tetrazol, isoxazol;
[0032] and pharmaceutically acceptable salts thereof.
[0033] In particular compounds wherein the compound of Formula I is
selected from the group consisting of: 3
[0034] wherein:
[0035] R1 is COOH
[0036] R2 is COOH
[0037] R3 can be H or methyl or xanthyl or thioxanthyl and
[0038] R4 is NH.sub.2
[0039] While all of the compounds of Formula I are believed to
demonstrate activity at the metabotropic glutamate receptors
(mGluRs), certain groups of Formula I compounds are more preferred
for such use.
[0040] As noted above, this invention includes the pharmaceutically
acceptable salts of the compounds defined by Formula I. A compound
of this invention can possess a sufficiently acidic, a sufficiently
basic, or both functional groups, and accordingly react with any of
a number of organic and inorganic bases, and inorganic and organic
acids, to form a pharmaceutically acceptable salt.
[0041] The term "pharmaceutically acceptable salt" as used herein,
refers to salts of the compounds of the above formula which are
substantially non-toxic to living organisms. Typical
pharmaceutically acceptable salts include those salts prepared by
reaction of the compounds of the present invention with a
pharmaceutically acceptable mineral or organic acid or an organic
or inorganic base. Such salts are known as acid addition and base
addition salts.
[0042] Acids commonly employed to form acid addition salts are
inorganic acids such as hydrochloric acid, hydrobromic acid,
hydriodic acid, sulfuric acid, phosphoric acid, and the like, and
organic acids such as p-toluenesulfonic acid, methanesulfonic acid,
oxalic acid, p-bromophenylsulfonic acid, carbonic acid, succinic
acid, citric acid, benzoic acid, acetic acid, and the like.
Examples of such pharmaceutically acceptable salts are the sulfate,
pyrosulfate, bisulfate, sulfite, bisulfite, phosphate,
monohydrogenphosphate, dihydrogenphosphate, metaphosphate,
pyrophosphate, bromide, iodide, acetate, propionate, decanoate,
caprylate, acrylate, formate, hydrochloride, dihydrochloride,
isobutyrate, caproate, heptanoate, propiolate, oxalate, malonate,
succinate, suberate, sebacate, fumarate, maleate,
butyne-1,4-dioate, hexyne-1,6-dioate, benzoate, chlorobenzoate,
methylbenzoate, hydroxybenzoate, methoxybenzoate, phthalate,
xylenesulfonate, phenylacetate, phenylpropionate, phenylbutyrate,
citrate, lactate, gamma-hydroxybutyrate, glycolate, tartrate,
methanesulfonate, propanesulfonate, naphthalene-1-sulfonate,
napththalene-2-sulfonate, mandelate and the like. Preferred
pharmaceutically acceptable acid addition salts are those formed
with mineral acids such as hydrochloric acid and hydrobromic acid,
and those formed with organic acids such as maleic acid and
methanesulfonic acid.
[0043] Salts of amine groups may also comprise quarternary ammonium
salts in which the amino nitrogen carries a suitable organic group
such as an alkyl, alkenyl, alkynyl, or aralkyl moiety.
[0044] Base addition salts include those derived from inorganic
bases, such as ammonium or alkali or alkaline earth metal
hydroxides, carbonates, bicarbonates, and the like. Such bases
useful in preparing the salts of this invention thus include sodium
hydroxide, potassium hydroxide, ammonium hydroxide, potassium
carbonate, sodium carbonate, sodium bicarbonate, potassium
bicarbonate, calcium hydroxide, calcium carbonate, and the like.
The potassium and sodium salt forms are particularly preferred.
[0045] It should be recognized that the particular counterion
forming a part of any salt of this invention is usually not of a
critical nature, so long as the salt as a whole is
pharmacologically acceptable and as long as the counterion does not
contribute undesired qualities to the salt as a whole. This
invention further encompasses the pharmaceutically acceptable
solvates of the compounds of Formula I. Many of the Formula I
compounds can combine with solvents such as water, methanol,
ethanol and acetonitrile to form pharmaceutically acceptable
solvates such as the corresponding hydrate, methanolate, ethanolate
and acetonitrilate.
[0046] The compounds of the present invention have multiple
asymmetric (chiral) centers. As a consequence of these chiral
centers, the compounds of the present invention occur as racemates,
mixtures of enantiomers and as individual enantiomers, as well as
diastereomers and mixtures of diastereomers. All asymmetric forms,
individual-isomers and combinations thereof, are within the scope
of the present invention.
[0047] The prefixes "R" and "S" are used herein as commonly used in
organic chemistry to denote the absolute configuration of a chiral
center, according to the Cahn-Ingold-Prelog system. The
stereochemical descriptor. R (rectus) refers to that configuration
of a chiral center with a clockwise relationship of groups tracing
the path from highest to second-lowest priorities when viewed from
the side opposite to that of the lowest priority group. The
stereochemical descriptor S (sinister) refers to that configuration
of a chiral center with a counterclockwise relationship of groups
tracing the path from highest to second-lowest priority when viewed
from the side opposite to the lowest priority croup. The priority
of groups is decided using sequence rules as described by Cahn et
al., Angew. Chem., 78, 413-447, 1966 and Prelog, V. and Helmchen,
G.; Angew Chem. Int. Ed. Erg., 21, 567-583, 1982).
[0048] In addition to the R,S system used to designate the absolute
configuration of a chiral center, the older D-L system is also used
in this document to denote relative configuration, especially with
reference to amino acids and amino acid derivatives. In this system
a Fischer projection of the compound is oriented so that carbon-1
of the parent chain is at the top. The prefix "D" is used to
represent the relative configuration of the isomer in which the
functional (determining) group is on the right side of the carbon
atom at the chiral center and "L", that of the isomer in which it
is on the left.
[0049] As would be expected, the stereochemistry of the Formula I
compounds is critical to their potency as agonists or antagonists.
The relative stereochemistry is established early during synthesis,
which avoids subsequent stereoisomer separation problems later in
the process. Further manipulation of the molecules then employs
stereospecific procedures so as to maintain the preferred
chirality. The preferred methods of this invention are the methods
employing those preferred compounds
[0050] Non-toxic metabolically-labile esters and amides of
compounds of Formula I are ester or amide derivatives of compounds
of Formula I that are hydrolyzed in vivo to afford said compounds
of Formula I and a pharmaceutically acceptable alcohol or amine.
Examples of metabolically-labile esters include esters formed with
(1-6C) alkanols in which the alkanol moiety may be optionally
substituted by a (1-8C) alkoxy group, for example methanol,
ethanol, propanol and methoxyethanol. Examples of
metabolically-labile amides include amides formed with amines such
as methylamine.
[0051] According to another aspect, the present invention provides
a process for the preparation of a compound of Formula I, or a
pharmaceutically acceptable metabolically-labile ester or amide
thereof, or a pharmaceutically acceptable salt thereof, which
comprises:
[0052] (a)-hydrolyzing a compound of formula: 4
[0053] in which R1 is defined as above, R5 represents a hydrogen
atom or an acyl group and R4 has the meaning-defined above.
Preferred values for R5 are hydrogen and (2-6C) alkanoyl groups,
such as acetyl.
[0054] (b) hydrolyzing a compound of formula: 5
[0055] in which R6 and R7 each independently represent a hydrogen
atom, a (2-6C) alkanoyl group, a (1-4C) alkyl group, a (3-4C)
alkenyl group or a phenyl (1-4C) alkyl group in which the phenyl is
unsubstituted or substituted by halogen, (1-4C) alkyl or (1-4C)
alkoxy, or a salt thereof: or:
[0056] (c) deprotecting a compound of formula: 6
[0057] in which R8 represents a hydrogen atom or a carboxyl
protecting group, or a salt thereof, and R9 represents a hydrogen
atom or a nitrogen protecting group; whereafter, if necessary
and/or desired:
[0058] (i) resolving the compound of Formula I;
[0059] (ii) converting the compound of Formula I into a non-toxic
metabolically-labile ester or amide thereof;
[0060] and/or;
[0061] (iii) converting the compound of Formula I or a non-toxic
metabolically-labile ester or amide thereof into a pharmaceutically
acceptable salt thereof.
[0062] The protection of carboxylic acid and amine groups is
Generally described in McOmie: Protecting Groups in Organic
Chemistry, Plenum Press, NY, 1973, and Greene and Wuts, Protecting
Groups in Organic Synthesis, 2nd. Ed., John Wiley & Sons, NY,
1991. Examples of carboxyl protecting groups include alkyl groups
such as methyl, ethyl, t-butyl and t-amyl; aralkyl groups such as
benzyl, 4-nitrobenzyl, 4-methoxybenzyl, 3,4-dimethoxybenzyl,
2,4-dimethoxybenzyl 2,4,6-trimethoxybenzyl, 2,4,6-trimethylbenzyl,
benzhydryl and trityl; silyl groups such as trimethylsilyl and
t-butyldimethylsilyl; and allyl groups such as allyl and
1-(trimethylsilylmethyl)prop-1-en-3-yl.
[0063] Examples of amine-protecting groups include acyl groups,
such as groups of formula R9 CO in which R9 represents (1-6C)
alkyl, (3-10C) cycloalkyl, phenyl(1-6C) alkyl, phenyl(1-6C) alkoxy,
or a (3-10C) cycloalkoxy, wherein a phenyl group may optionally be
substituted by one or two substituents independently selected from
amino, hydroxy, nitro, halogeno, (1-6C) alkyl, (1-6C) alkoxy,
carboxyl, (1-6C) alkoxycarbonyl, carbamoyl, (1-6C) alkanoylamino,
(1-6C) alkylsulphonylamino, phenylsulphonylamino,
toluenesulphonylamino, and (1-6C) fluoroalkyl.
[0064] The compounds of Formula II are conveniently hydrolyzed in
the presence of an acid, such as hydrochloric acid or sulfuric
acid, or a base, such as an alkali metal hydroxide, for example
sodium hydroxide. The hydrolysis is conveniently performed in an
aqueous solvent such as water and at a temperature in the range of
50 to 200.degree. C.
[0065] The compounds of Formula III are conveniently hydrolyzed in
the presence of a base, for example an alkali metal hydroxide such
as lithium, sodium or potassium hydroxide, or an alkaline earth
metal hydroxide such as barium hydroxide. Suitable reaction media
include water. The temperature is conveniently in the range of from
50 to 150.degree. C.
[0066] The compounds of Formula IV may be deprotected by a
conventional method. Thus, an alkyl carboxyl protecting group may
be removed by hydrolysis. The hydrolysis may conveniently be
performed by heating the compound of Formula V in the presence of
either a base, for example an alkali metal hydroxide such as
lithium, sodium or potassium hydroxide, or an alkaline metal
hydroxide, such as barium hydroxide, or an acid such as
hydrochloric acid. The hydrolysis is conveniently performed at a
temperature in the range from 10 to 300.degree. C. An aralkyl
carboxyl protecting croup may conveniently be removed by
hydrogenolysis. The hydrogenolysis may conveniently be effected by
reacting the compound of Formula V with hydrogen in the presence of
a Group VIII metal catalyst, for example a palladium catalyst such
as palladium on charcoal. Suitable solvents for the reaction
include alcohols-such as ethanol. The reaction is conveniently
performed at a temperature in the range from 0 to 100.degree. C. An
acyl, amine protecting group is also conveniently removed by
hydrolysis, for example as described for the removal of an alkyl
carboxyl protecting group.
[0067] The compounds of Formula II may be prepared by reacting a
compound of formula: 7
[0068] with an alkali metal cyanide, such as lithium, sodium or
potassium cyanide, and an ammonium halide, such as ammonium
chloride, conveniently in the presence of ultrasound. Thus, the
ammonium halide is mixed with chromatography grade alumina in the
presence of a suitable diluent such as acetonitrile. The mixture is
then irradiated with ultrasound, whereafter the compound of Formula
V is added, and the mixture is again irradiated. The alkali metal
cyanide is then added, followed by further irradiation with
ultrasound.
[0069] Individual isomers of compounds of Formula II may be made by
reacting a compound of the Formula V with the stereoisomers of the
chiral agent (S)- and (R)-phenylglycinol and a reactive cyanide
such as trimethylsilyl cyanide.
[0070] The compounds of Formula III may be prepared by reacting a
compound of Formula V with an alkali metal cyanide, such as
lithium, sodium or potassium cyanide, and ammonium carbonate or
ammonium carbamate. Convenient solvents include water, dilute
ammonium hydroxide, alcohols such as methanol, aqueous methanol and
aqueous ethanol. Conveniently the reaction is performed at a
temperature in the range of from 10 to 150.degree. C. If desired,
the compounds of Formula III may then be alkylated, for example
using an appropriate compound of formula R6 Cl and/or R7 Cl.
[0071] The compounds of Formula V can be prepared by reacting a
compound of formula: 8
[0072] with a chlorinating agent such as thionyl chloride or
phosphorous(V) chloride, followed by reaction with R4X wherein R4
has the meaning defined above and X is halogen or OH.
[0073] The compounds of Formula V can also be prepared by oxidizing
a compound of formula 9
[0074] under Swern conditions.
[0075] The compounds of Formula VI can be prepared from compounds
of formula: 10
[0076] by reduction.
[0077] If R1 is CO.sub.2Me, this compound can be bought
commercially. If R1 is another substituent, the compound of Formula
VIII can be made using standard procedures.
[0078] Many of the intermediates described herein, for example the
compounds of Formula II, III and IV are believed to be novel, and
are provided as further aspects of the invention.
[0079] The Formula I compounds of the present invention are
agonists or antagonists at certain metabotropic excitatory amino
acid receptors (mGluRs). Therefore, another aspect of the present
invention is a method of affecting mGluRs in mammals, which
comprises administering to a mammal requiring modulated excitatory
amino acid neurotransmission a pharmacologically-effective amount
of a compound of Formula I. The term "pharmacologically-effective
amount" is used to represent an amount of the compound of the
invention that is capable of affecting the mGluRs. By affecting, a
compound of the invention is acting as an agonist or antagonist.
When a compound of the invention acts as an agonist, the
interaction of the compound with the excitatory amino acid receptor
mimics the response of the interaction of this receptor with its
natural ligand (i.e. L-Glutamic acid). When a compound of the
invention acts as an antagonist, the interaction of the compound
with the excitatory amino acid receptor blocks the response of the
interaction of this receptor with its natural ligand (i.e.
L-Glutamic acid).
[0080] The particular dose of compound administered according to
this invention will, of course, be determined by the particular
circumstances surrounding the case, including the compound
administered, the route of administration, the particular condition
being treated, and similar considerations. The compounds can be
administered by a variety of routes including oral, rectal,
transdermal, subcutaneous, intravenous, intramuscular, or
intranasal routes. Alternatively, the compound may be administered
by continuous infusion. A typical daily dose will contain from
about 0.001 mg/kg to about 100 mg/kg of the active compound of this
invention. Preferably, daily doses will be about 0.05 mg/kg to
about 50 mg/kg, more preferably from about 0.1 mg/kg to about 20
mg/kg.
[0081] A variety of physiological functions have been shown to be
subject to influence by excessive or inappropriate stimulation of
excitatory amino acid transmission. The Formula I compounds of the
present invention are believed (through their interactions at the
mGluRs) to have the ability to treat a variety of neurological
disorders in mammals associated with this condition including acute
neurological disorders such as cerebral deficits subsequent to
cardiac bypass surgery and grafting, cerebral ischemia (e.g. stroke
and cardiac arrest), spinal cord trauma, head trauma, perinatal
hypoxia, and hypoglycemic neuronal damage. The Formula I compounds
are believed to have the ability to treat a variety of chronic
neurological disorders, such as Alzheimer's disease, Huntington's
Chorea, amyotrophic lateral sclerosis, AIDS-induced dementia,
ocular damage and retinopathy, cognitive disorders, and idiopathic
and drug-induced Parkinson's disease. The present invention also
provides methods for treating these disorders which comprises
administering to a patient in need thereof an effective amount of a
compound of Formula I.
[0082] The Formula I compounds of the present invention (through
their interactions at the mGluRs) are also believed to have the
ability to treat a variety of other neurological disorders in
mammals that are associated with glutamate dysfunction, including
muscular spasms, convulsions, migraine headaches, urinary
incontinence, psychosis, drug tolerance, withdrawal, and cessation
(i.e. opiates, benzodiazepines, nicotine, cocaine, or ethanol),
smoking cessation, anxiety and related disorders (e.g. panic
attack), emesis, brain edema, chronic pain, sleep disorders,
Tourette's syndrome, attention deficit disorder, and tardive
dyskinesia. Therefore, the present invention also provides methods
for treating these disorders which comprise administering to a
patient in need thereof an effective amount of the compound of
Formula I.
[0083] The Formula I compounds of the present invention (through
their interactions at the mGluRs) are also believed to have the
ability to treat a variety of psychiatric disorders, such as
schizophrenia, anxiety and related disorders (e.g. panic attack),
depression, bipolar disorders, psychosis, and obsessive compulsive
disorders. The present invention also provides methods for treating
these disorders which comprises administering to a patient in need
thereof an effective amount of a compound of Formula I.
[0084] The pharmacological properties of the compounds of the
invention can be illustrated by determining their effects in
various functional in vitro assays. The compounds of the invention
were studied in an in vitro assay that measured the inhibition of
PI hydrolysis or the formation of cyclic AMP in Chinese hamster
ovary cell lines expressing mGluR.sub.1a, mGluR.sub.2 and
mGluR.sub.4a cloned metabotropic glutamate receptors.
[0085] Principle
[0086] So far eight different clones of the G-protein-coupled
mGluRs have been identified (Knopfel et al. 1995, J. Med. Chem.,
38, 1417-1426). These receptors function to modulate the
presynaptic release of L-Glutamate, and the postsynaptic
sensitivity of the neuronal cell to L-Glutamate excitation. Based
on pharmacology, sequence homology and the signal transduction
pathway that they activate, the mGluRs have been subclassified into
three groups. The mGluR.sub.1 and mGluR.sub.5 receptors form group
1. They are coupled to hydrolysis of phosphatidylinositol (PI) and
are selectively activated by (RS)-3,5-dihydroxyphenylglycine
(Brabet et al., Neuropharmacology, 34, 895-903, 1995). Group II
comprises mGluR.sub.2 and mGluR.sub.3 receptors. They are
negatively coupled to adenylate cyclase and are selectively
activated by (2S, 1'R,2'R,3'R)-2-(2,3-dicarboxycyclopropyl)glycine
(DCG-IV; Hayashi et al., Nature, 366, 687-690, 1993). Finally, the
mGluR.sub.4, mGluR.sub.6, mGluR.sub.7 and mGluR.sub.8 receptors
belong to group III. They are also negatively coupled to adenylate
cyclase and are selectively activated by
(S)-2-amino-4-phosphonylbutyric acid (L-AP4, Knopfel et al., 1995,
J. Med. Chem., 38, 1417-1426).
[0087] Cell Culture
[0088] The Chinese hamster ovary cell lines expressing
mGluR.sub.1a, mGluR.sub.2 and mGluR.sub.4a receptors have been
described previously (Aramori and Nakanishi, Neuron 8, 757-765;
1992; Tanabe et al., Neuron 8, 169-179, 1992; Tanabe et al., J.
Neurosci. 13, 1372-1378). They were maintained at 37.degree. C. in
a humified 5% CO.sub.2 incubator in Dulbecco's Modified Eagle
Medium (DMEM) containing a reduced concentration of (S)-glutamine
(2 mM) and were supplemented with 1% proline, penicillin (100
U/ml), streptomycin (100 mg/ml) and 10% dialyzed fetal calf serum
(all GIBCO, Paisley). Two days before assay 1.8.times.10.sup.6
cells were divided into the wells of 24 well plates.
[0089] Second Messenger Assays
[0090] PI hydrolysis was measured as described previously (Hayashi
et al., Br. J. Pharmacol. 107, 539-543, 1992; Hayashi et al., J.
Neurosci. 14, 3370-3,77, 1994). Briefly, the cells were labeled
with [.sup.3H]inositol (2 .mu.Ci/ml) 24 h prior to the assay. For
agonist assays, the cells were incubated with ligand dissolved in
phosphate-buffered saline (PBS)-LiCl for 20 min, and agonist
activity was determined by measurement of the level of
.sup.3H-labeled mono-, bis- and tris-inositol phosphates by
ion-exchange chromatography. For antagonist assays, the cells were
preincubated with the ligand dissolved in PBS-LiCl for 20 min prior
to incubation with ligand and 10 .mu.M (L)-Glutamic acid for 20
min. The antagonist activity was then determined as the inhibitory
effect of the (L)-Glutamic acid-mediated response. The assay of
cyclic AMP formation was performed as described previously (Hayashi
et al., Br. J. Pharmacol. 107, 539-543, 1992; Hayashi et al., J.
Neurosci. 14, 3370-3377, 1994). Briefly, the cells were incubated
for 10 min in PBS containing the ligand and 10 .mu.M forskolin and
1 mM 3-Isobutyl-1-methyxanthine (IBMX; both Sigma, St. Louis, Mo.,
USA). The agonist activity was then determined as the inhibitory
effect of the forskolin-induced cyclic AMP formation. For
antagonist assay, the cells were preincubated with ligand dissolved
in PBS containing 1 mM IBMX for 20 min prior to a 10 min incubation
in PBS containing the ligand, 20 .mu.M (mGluR.sub.2) or 50 .mu.M
(mGluR.sub.4a), (L)-Glutamic acid, 10 .mu.M Forskolin and 1 mM
IBMX.
[0091] Results
[0092] Some of the compounds of the invention were tested for
antagonist activity against Chinese hamster ovary cell lines
expressing mGluR.sub.1a, mGluR.sub.2 and mGluR.sub.4a cloned mGluRs
at a concentration of 1 mM. When tested as antagonists of the
increase in PI hydrolysis evoked by 10 .mu.M (L)-Glutamic acid,
some compounds of the invention effectively blocked this increase
in PI hydrolysis by an action at the mGluR.sub.1a receptor. The
data for one of the compounds of the invention is shown in FIG. 1
below.
[0093] According to another aspect, the present invention provides
a method of modulating one or more metabotropic glutamate receptor
functions in a warm-blooded mammal which comprises administering an
effective amount of a compound of Formula I, or a non-toxic
metabolically-labile ester or amide thereof, or a pharmaceutically
acceptable salt thereof.
[0094] The compounds of the present invention are preferably
formulated prior to administration.
[0095] Therefore, another aspect of the present invention is a
pharmaceutical formulation comprising a compound of Formula I and a
pharmaceutically-acceptable carrier, diluent, or excipient. The
present pharmaceutical formulations are prepared by known
procedures using well-known and readily available ingredients. In
making the compositions of the present invention, the active
ingredient will usually be mixed with a carrier, or diluted by a
carrier, or enclosed within a carrier, and may be in the form of a
capsule, sachet, paper, or other container. When the carrier serves
as a diluent, it may be a solid, semi-solid, or liquid material
that acts as a vehicle, excipient, or medium for the active
ingredient.
[0096] The compounds of Formula I are usually administered in the
form of pharmaceutical compositions. These compounds can be
administered by a variety of routes including oral, rectal,
transdermal, subcutaneous, intravenous, intramuscular, and
intranasal. These compounds are effective as both injectable and
oral compositions. Such compositions are prepared in a manner well
known in the pharmaceutical art and comprise at least one active
compound.
[0097] The present invention also provides pharmaceutical
compositions containing compounds as disclosed in the claims in
combination with one or more pharmaceutically acceptable, inert or
physiologically active, diluent or adjuvant. The compounds of the
invention can be freeze-dried and, if desired, combined with other
pharmaceutically acceptable excipients to prepare formulations for
administration. These compositions may be presented in any form
appropriate for the administration route envisaged. The parenteral
and the intravenous route are the preferential routes for
administration.
[0098] Compounds of the general Formula I may be administered
orally, topically, parenterally, by inhalation or spray or rectally
in dosage unit formulations containing conventional non-toxic
pharmaceutically acceptable carriers, adjuvants and vehicles. The
term parenteral as used herein includes subcutaneous injections,
intravenous, intramuscular, intrasternal injection or infusion
techniques. In addition, there is provided a pharmaceutical
formulation comprising a compound of general Formula I and a
pharmaceutically acceptable carrier. One or more compounds of
general Formula I may be present in association with one or more
non-toxic pharmaceutically acceptable carriers and/or diluents
and/or adjuvants and if desired other active ingredients. The
pharmaceutical compositions containing compounds of general Formula
I may be in a form suitable for oral use, for example, as tablets,
troches, lozenges, aqueous or oily suspensions, dispersible powders
or granules, emulsions, hard or soft capsules, or syrups or
elixirs.,
[0099] Compositions intended for oral use may be prepared according
to any known to the art for the manufacture of pharmaceutical
compositions and such compositions may contain one or more agents
selected from the group consisting of sweetening agents, flavouring
agents, colouring agents and preserving agents in order to provide
pharmaceutically elegant and palatable preparations. Tablets
contain the active ingredient in admixture with non-toxic
pharmaceutically acceptable excipients that are suitable for the
manufacture of tablets. These excipients may be for example, inert
diluents, such as calcium carbonate, sodium carbonate, lactose,
calcium phosphate or sodium phosphate: granulating and
disintegrating agents for example, corn starch, or alginic acid:
binding agents, for example starch, gelatin or acacia, and
lubricating agents, for example magnesium stearate, stearic acid or
talc. The tablets may be uncoated or they may be coated by known
techniques to delay disintegration and absorption in the
gastrointestinal tract and thereby provide a sustained action over
a longer period. For example, a time delay material such as
glyceryl monostearate or glyceryl distearate may be employed.
[0100] Formulations for oral use may also be presented as hard
gelatin capsules wherein the active ingredient is mixed with an
inert solid diluent, for example, calcium carbonate, calcium
phosphate or kaolin, or as soft gelatin capsules wherein the active
ingredient is mixed with water or an oil medium, for example peanut
oil, liquid paraffin or olive oil.
[0101] Aqueous suspensions contain active materials in admixture
with excipients suitable for the manufacture of aqueous
suspensions. Such excipients are suspending agents, for example
sodium carboxylmethylcellulose, methyl cellulose,
hydropropylmethylcellulose, sodium alginate, polyvinylpyrrolidone,
gum tragacanth and gum acacia: dispersing or wetting agents may be
a naturally-occurring phosphatide, for example, lecithin, or
condensation products of an alkylene oxide with fatty acids, for
example polyoxyethylene stearate, or condensation products of
ethylene oxide with long chain aliphatic alcohols, for example
hepta-decaethyleneoxycetanol, or condensation products of ethylene
oxide with partial esters derived from fatty acids and a hexitol
such as polyoxyethylene sorbitol monooleate, or condensation
products of ethylene oxide with partial esters derived from fatty
acids and hexitol anhydrides, for example polyethylene sorbitan
monooleate. The aqueous suspensions may also contain one or more
preservatives, for example ethyl, or n-propyl-p-hydroxy benzoate,
one or more colouring agents, one or more flavouring agents or one
or more sweetening agents, such as sucrose or saccharin.
[0102] Oily suspensions may be formulated by suspending the active
ingredients in a vegetable oil, for example peanut oil, olive oil,
sesame oil or coconut oil, or in a mineral oil such as liquid
paraffin. The oily suspensions may contain a thickening agent, for
example beeswax, hard paraffin or cetyl alcohol. Sweetening agents
such as those set forth above, and flavouring agents may be added
to provide palatable oral preparations. These compositions may be
preserved by the addition of an antioxidant such as ascorbic
acid.
[0103] Dispersible powders and granules suitable for preparation of
an aqueous suspension by the addition of water provide the active
ingredient in admixture with a dispersing or wetting agent,
suspending agent and one or more preservatives. Suitable dispersing
or wetting agents and suspending agents are exemplified by those
already mentioned above. Additional excipients, for example
sweetening, flavouring and colouring agents, may also be
present.
[0104] Pharmaceutical compositions of the invention may also be in
the form of oil-in-water emulsions. The oil phase may be a
vegetable oil, for example olive oil or peanut oil, or a mineral
oil, for example liquid paraffin or mixtures of these. Suitable
emulsifying agents may be naturally-occurring gums, for example gum
acacia or gum tragacanth, naturally-occurring phosphatides, for
example soy bean, lecithin, and esters or partial esters derived
from fatty acids and hexitol, anhydrides, for example sorbitan
monooleate, and condensation products of the said partial esters
with ethylene oxide, for example polyoxyethylene sorbitan
monooleate. The emulsions may also contain sweetening and
flavouring agents.
[0105] Syrups and elixirs may be formulated with sweetening agents,
for example glycerol propylene glycol, sorbitol or sucrose. Such
formulations may also contain a demulcent, a preservative and
flavouring and colouring agents. The pharmaceutical compositions
may be in the form of a sterile injectable aqueous or oleaginous
suspension. This suspension may be formulated according to known
art using those suitable dispersing or wetting agents and
suspending agents that have been mentioned above. The sterile
injectable preparation may also be a sterile injectable solution or
a suspension in a non-toxic parentally acceptable diluent or
solvent, for example as a solution in 1,3-butanediol. Among the
acceptable vehicles and solvents that may be employed are water,
Ringer's solution and isotonic sodium chloride solution. In
addition, sterile, fixed oils are conventionally employed as a
solvent or suspending medium. For this Purpose any bland fixed oil
may be employed including synthetic mono- or diglycerides. In
addition, fatty acids such as oleic acid find use in the
preparation of injectables.
[0106] The compound(s) of the general Formula I may be
administered, together or separately in the form of suppositories
for rectal administration of the drug. These compositions can be
prepared by mixing the drug with a suitable non-irritating,
excipient which is solid at ordinary temperatures but liquid at the
rectal temperature and will therefore melt in the rectum to release
the drug. Such materials are cocoa butter and polyethylene
glycols.
[0107] Compound(s) of general Formula I may be administered,
together or separately, parenterally in sterile medium. The drug,
depending on the vehicle and concentration used, can either be
suspended or dissolved in the vehicle. Advantageously, adjuvants
such as local anaesthetics, preservatives and buffering agents can
be dissolved in the vehicle.
[0108] The dosage to be administered is not subject to defined
limits, but it will usually be an effective amount. It will usually
be the equivalent, on a molar basis of the pharmacologically active
free form produced from a dosage formulation upon the metabolic
release of the active free drug to achieve its desired
pharmacological and physiological effects. The compositions are
preferably formulated in a unit dosage form, each dosage containing
from about 0.05 to about 100 mg, more usually about 1.0 to about 30
mg, of the active ingredient. The term "unit dosage form"refers to
physically discrete units suitable as unitary dosages for human
subjects and other mammals, each unit containing a predetermined
quantity of active material calculated to produce the desired
therapeutic effect, in association with a suitable pharmaceutical
excipient.
[0109] The active compound is effective over a wide dosage range.
For examples, dosages per day normally fall within the range of
about 0.01 to about 30 mg/kg of body weight. A typical daily dose
will contain from about 0.01 mg/kg to about 100 mg/kg of the active
compound of this invention. Preferably, daily doses will be about
0.05 mg/kg to about 50 mg/kg, more preferably from about 0.1 mg/kg
to about 25 mg/kg. In the treatment of adult humans, the range of
about 0.1 to about 15 mg/kg/day, in single or divided dose, is
especially preferred. However, it will be understood that the
amount of the compound actually administered will be determined by
a physician, in the light of the relevant circumstances, including
the condition to be treated, the chosen route of administration,
the actual compound administered, the age, weight, and response of
the individual patient, and the severity of the patient's symptoms,
and therefore the above dosage ranges are not intended to limit the
scope of the invention in any way. In some instances dosage levels
below the lower limit of the aforesaid range may be more than
adequate, while in other cases still larger doses may be employed
without causing any harmful side effect, provided that such larger
doses are first divided into several smaller doses for
administration throughout the day.
[0110] The compositions are preferably formulated in a unit dosage
form, each dosage containing from about 5 mg to about 500 mg, more
preferably about 25 mg to about 300 mg of the active ingredient.
The term "unit dosage form" refers to a physically discrete unit
suitable as unitary dosages for human subjects and other mammals,
each unit containing a predetermined quantity of active material
calculated to produce the desired therapeutic effect, in
association with a suitable pharmaceutical carrier, diluent, or
excipient. The following formulation examples are illustrative only
and are not intended to limit the scope of the invention in any
way.
Formulation 1
[0111] Hard gelatin capsules are prepared using the following
ingredients:
1 Quantity (mg/capsule) Active Ingredient 250 Starch, dried 200
Magnesium stearate 10 Total 460 The above ingredients are mixed and
filled into hard gelatin capsules in 460 mg quantities.
Formulation 2
[0112] A tablet is prepared using the ingredients below:
2 Quantity (mg/tablet) Active Ingredient 250 Cellulose,
microcrystalline 400 Silicon dioxide, fumed 10 Stearic acid 5 Total
665 The components are blended and compressed to form tablets each
weighing 665 mg.
Formulation 3
[0113] An aerosol solution is prepared containing the following
components:
3 Weight % Active Ingredient 0.25 Ethanol 29.75 Propellant 22
(Chlorodifluoromethane) 70.00 Total 100 The active compound is
mixed with ethanol and the mixture added to a portion of the
Propellant 22, cooled to -30.degree. C. and transferred to a
filling device. The required amount is then fed to a stainless
steel container and diluted with the remainder of the propellant.
The valve units are then fitted to the container.
Formulation 4
[0114] Tablets each containing 60 mg of active ingredient are made
as follows:
4 Quantity (mg/tablet) Active Ingredient 60 Starch 45
Microcrystalline cellulose 35 Polyvinylpyrrolidone 4 Sodium
carboxymethyl starch 4.5 Magnesium stearate 0.5 Talc 1.0 Total 150
The active ingredient, starch, and cellulose are passed through a
No. 45 mesh U.S. sieve and mixed thoroughly. The solution of
polyvinylpyrrolidone is mixed with the resultant powders that are
then passed through a No. 14 mesh U.S. sieve. The granules so
produced are dried at 50.degree. C. and passed #through a No. 18
mesh U.S. sieve. The sodium carboxymethyl starch, magnesium
stearate, and talc, previously passed through a No. 60 mesh U.S.
sieve, are then added to the granules which, after mixing, are
compressed on a tablet machine to yield tablets each weighing 150
mg.
Formulation 5
[0115] Capsules each containing 80 mg medicament are made as
follows:
5 Quantity (mg/capsule) Active Ingredient 80 Starch 59
Microcrystalline cellulose 59 Magnesium stearate 2 Total 200 The
active ingredient, cellulose, starch, and magnesium stearate are
blended, passed through a No. 45 sieve, and filled into hard
gelatin capsules in 200 mg quantities.
Formulation 6
[0116] Suppositories each containing 225 mg of active ingredient
may be made as follows:
6 Quantity (mg/suppository) Active Ingredient 225 Saturated fatty
acid glycerides 2000 Total 2225 The active ingredient is passed
through a No. 60 mesh U.S. sieve and suspended in the saturated
fatty acid glycerides previously melted using the minimum heat
necessary. The mixture is then poured into a suppository mold of
nominal 2 g capacity and allowed to cool.
Formulation 7
[0117] Suspensions each containing 50 mg of medicament per 5 mL
dose are made as follows:
7 Active Ingredient 50 mg Sodium carboxylmethyl cellulose 50 mg
Syrup 1.25 mL Benzoic acid solution 0.10 mL Flavour q.v. Color q.v.
Purified water to total 5 mL The medicament is passed through a No.
45 mesh U.S. sieve and mixed with the sodium carboxymethyl
cellulose and syrup to form a smooth paste. The benzoic acid
solution, flavor and color are diluted with some of the water and
added, with stirring. Sufficient water is then added to produce the
required volume.
Formulation 8
[0118]
8 An intravenous formulation may be prepared as follows: Quantity
Active Ingredient 100 mg Mannitol 100 mg 5 N Sodium hydroxide 200
mL Purified water to total 5 mL
[0119] A topical formulation may be prepared as follows:
9 Quantity Active Ingredient 1-10 g Emulsifying Wax 30 g Liquid
Paraffin 20 g White soft paraffin to 100 g The white soft paraffin
is heated until molten. The liquid paraffin and emulsifying wax are
incorporated and stirred until dissolved. The active ingredient is
added and stirring is continued until dispersed. The mixture is
then cooled until solid.
Formulation 10
[0120] Sublingual or buccal tablets, each containing 10 mg of
active ingredient, may be prepared as follows:
10 Quantity (mg/tablet) Active Ingredient 10.0 Glycerol 210.5 Water
143.0 Sodium Citrate 4.5 Polyvinyl Alcohol 26.5
Polyvinylpyrrolidone 15.5 Total 410.0 The glycerol, water, sodium
citrate, polyvinyl alcohol, and polyvinylpyrrolidone are admixed
together by continuous stirring and maintaining the temperature at
about 90.degree. C. When the polymers have gone into solution, the
solution is cooled to about 50.degree.-55.degree. C. and the
medicament #is slowly admixed. The homogenous mixture is poured
into forms made of an inert material to produce a drug-containing
diffusion matrix having a thickness of about 2-4 mm. This diffusion
matrix is then cut to form individual tablets having the
appropriate size.
[0121] Another preferred formulation employed in the methods of the
present invention employs transdermal delivery devices ("patches").
Such transdermal patches may be used to provide continuous or
discontinuous infusion of the compounds of the present invention in
controlled amounts.
[0122] The construction and use of transdermal patches for the
delivery of pharmaceutical agents is well known in the art (see,
for example, U.S. Pat. No. 5,023,252, issued Jun. 11, 1991) herein
incorporated by reference. Such patches may be constructed for
continuous, pulsatile, or on demand delivery of pharmaceutical
agents.
[0123] Frequently, it will be desirable or necessary to introduce
the pharmaceutical composition to the brain, either directly or
indirectly. Direct techniques usually involve placement of a drug
delivery catheter into the host's ventricular system to bypass the
blood-brain barrier. One such implantable delivery system, used for
the transport of biological factors to specific anatomical regions
of the body, is described in U.S. Pat. No. 5,011,472 issued Apr.
30, 1991, which is herein incorporated by reference.
[0124] Indirect techniques, which are generally preferred, usually
involve formulating the compositions to provide for drug
latentiation by the conversion of hydrophilic drugs into
lipid-soluble drugs or prodrugs. Latentiation is generally achieved
through blocking of the hydroxy, carbonyl, sulfate, and primary
amine groups present on the drug to render the drug more lipid
soluble and amenable to transportation across the blood-brain
barrier. Alternatively, the delivery of hydrophilic drugs may be
enhanced by intra-arterial infusion of hypertonic solutions that
can transiently open the blood-brain barrier.
EXAMPLES
[0125] The following Examples illustrate the invention. The
following abbreviations are used in the Examples: EtOAc, ethyl
acetate; THF, tetrahydrofuran; EtOH, ethanol; TLC, thin layer
chromatography; GC, gas chromatography; HPLC, high pressure liquid
chromatography; m-CPBA, m-chloroperbenzoic acid; Et.sub.2O, diethyl
ether; DMSO, dimethyl sulfoxide; DBU,
18-diazabicyclo-[5.4.0]undec-7-ene, MTBE, methyl t-butyl ether;
FDMS, field desorption mass spectrometry and r.t., room
temperature.
Example 1
Synthesis of Cubanylglycinates IGT 1.0 Series
[0126] 11
[0127] Preparation 1: 4-methoxycarbonylcubane Carboxylic Acid
[0128] A solution of cubane dimethyl ester (6.0g, 27.24 mmol) in
182 mL of dry THF is stirred under N.sub.2 at room temperature. A
solution of methanolic NaOH (26.7 mmol, 10.7 mL 2.5 M) is added
dropwise from a pressure equalized addition funnel and the
resulting solution stirred at room temperature for 16 h. The
mixture is evaporated under reduced pressure at r.t., the residue
is taken up in 66 mL of water and extracted with 3.times.25 mL of
chloroform. The aqueous layer is acidified to pH 3 with
concentrated HCl and extracted with 3.times.30 mL of chloroform.
The combined organic layers were dried over magnesium sulphate,
filtered and evaporated to give (2) 182-183.degree. C.: .sup.1H NMR
(CDCl.sub.3) .delta. 3.72 (s, 3H), 4.27 (m, 6H).
[0129] Yield 5.1 g (91%)
[0130] Preparation 2: 4-methoxycarbonyl-1-(hydroxymethyl)
Cubane
[0131] The mono acid (2) (0.48 g) is dissolved in dry TIN (5 mL)
and cooled to -70.degree. C.; A solution of BH.sub.3 in THF is
added slowly with stirring. The reaction mixture is stirred at
-78.degree. C. for 4 hrs and allowed to come to room temperature.
Water (3 mL) is added and stirred for 30 min, potassium carbonate
(0.85 g) is added and the solution extracted with Et.sub.2O. The
organic phase is dried over magnesium sulfate and evaporated to
give the alcohol (3) 0.46 g (100%) m.p. 83-85.degree. C. .sup.1H
NMR (200 MHz, solvent) .delta.: 1.58 (s, 1H), 3.62 (s, 3H), 3.72
(s, 2H), 3.81 (m, 3H), 4.1 (m, 3H).
[0132] Preparation 3: 4-methoxycarbonyl-1-(formyl) Cubane
[0133] DMSO (0.7 mL, 9.68 mmol) is added to oxalyl chloride (0.42
mL, 4.84 mmol) in 12 mL of CH.sub.2Cl.sub.2 at -78.degree. C. The
alcohol (3) (0.46 g, 2.42 mmol) in 3 mL CH.sub.2Cl.sub.2 is added
and stirred at -78.degree. C. for 1.5 h. Triethylamine (2.0 mL,
14.4 mmol) is added and the mixture is allowed to come to 0.degree.
C. Saturated ammonium chloride solution is added and the phases
separated, the aqueous layer is extracted with CH.sub.2Cl.sub.2 and
the combined organic layers are dried (MgSO.sub.4), then evaporated
to give crude product which is purified by flash chromatography
(1:1 hexanes:diethlyl ether) to give 0.35 g (76%) of pure product
(4). .sup.1H NMR (200 MHz, solvent) .delta.: 3.7 (s, 3H), 4.2 (m,
3H), 4.32 (m, 3H), 9.72 (s, 1H).
[0134] Preparation 4:
4-methoxycarbony-1-[2'-hydroxy-1'-phenylethyl]methyl-
nitrilecubane
[0135] (R)-phenylglycinol (257 mg, 1.87 mmol) is added to a
solution of the aldehyde (4) (0.35 g, 1.84 mmol) in 14 mL of
methanol. The solution is cooled to 0.degree. C. and TMSCN (0.49
mL, 3.68 mmol) is added and the mixture stirred at 0.degree. C.
overnight. Evaporation of the solvent leaves a residue which is
purified by chromatography (diethyl ether:hexanes, 3:1) to give
0.48 g (77%) of pure product (5). .sup.1H NMR (CDCl.sub.3) .delta.:
2.23 (s, 1H), 2.6 (br, 1H), 3.5-3.75 (m, 2H), 3.7 (s, 3H), 3-0.9
(m, 3H), 4.11 (dd, 1H), 4.2 (m, 3H), 7.3 (s, 5H).
[0136] Preparation 5: 4-carbony-1-cubanylcglycine
[0137] Lead acetate (0.69 g, 1.57 mmol) is added to a stirred
solution of nitrile (5) (0.48 g, 1.42 mmol) in dry
methanol/dichloromethane 1:1 (12 mL). After 10 min 10 mL of water
is added and the suspension filtered through celite. The organic
layer is dried and evaporated to give the crude imine. The crude
imine is refluxed with 6N HCl (30 mL) for 6 hr. The solution is
evaporated to dryness and placed on anion exchange resin, eluting
with 1N acetic acid to yield the product (6). mp. 241.degree. C.
(dec.) .sup.1H NMR (D.sub.2O) .delta. 3.96 (s, 1H), 4.01 (m, 3H),
4.14 (m, 3H).
Example 2
[0138] 12
[0139] Preparation 1: 4-methoxycarbonylcubane Carboxylic Acid
[0140] A solution of cubane dimethyl ester (6.0 g, 27.24 mmol) in
182 mL of dry TH is stirred under N.sub.2 at r.t. a solution of
methanolic NaOH (26;7 mmol, 10.7 mL 2.5 M) is added dropwise from a
pressure equalized addition funnel and the resulting solution
stirred at r.t. for 16 h. The mixture is evaporated under reduced
pressure at r.t., the residue is taken up in 66 mL of water and
extracted with 3.times.25 mL of chloroform. The aqueous layer is
acidified to pH 3 with concentrated HCl and extracted with
3.times.30 mL of chloroform. The combined organic layers were dried
over magnesium sulphate, filtered and evaporated to give (2)
182-183.degree. C.: .sup.1H NMR (CDCl.sub.3) .delta. 3.72 (s, 3H),
4.27 (m, 6H).
[0141] Yield 5.1 g (91%).
[0142] Preparation 2: 4-methoxycarbonylcubane-1-carbonyl
Chloride
[0143] The monomethyl ester (2) (1.37 g, 6.65 mmol) is dissolved in
15 mL of thionyl chloride and gently refluxed overnight. The
thionyl chloride is evaporated off and the resultant residue
containing (3) was used immediately without further
purification.
[0144] Preparation 3: 4-methoxycarbonylcubane-1-methyl Ketone
[0145] A suspension of copper iodide (1.49 g, 7.83 mmol) in 30 mL
of dry THF is stirred at 0.degree. C. Methyl lithium (15.75 mmol,
11.2 mL of 1.4 M) was added and stirred at 0.degree. C. for 30 min,
then cooled to -78.degree. C. A solution of 1.6 g, 7.12 mmol of (3)
in 10 mL dry THF is added and the resultant mixture stirred for 1
h. at -78.degree. C. The mixture was quenched with saturated
ammonium chloride solution (15 mL) and extracted with 3.times.30 mL
of diethyl ether. The combined organic layers were dried over
magnesium sulphate, filtered and evaporated to give crude (4). The
product was purified by silica chromatography (hexanes-ethyl
acetate, 2:1) to give 1.0 g of product (yield 69%). m.p.
87-99.degree. C. .sup.1H NMR (CDCl.sub.3) .delta. 2.17 (s, 3H), 3.7
(s, 3H), 4.21 (m, 6H).
[0146] Preparation 4:
4-methoxycarbonylcubane-1-methyl-1-(5,5'-hydantoin)
[0147] A solution of the methyl ketone (4) (1.0 g 4.9 mmol) in 40
mL of ethanol and 5.8 mL of 1 N NaOH, is stirred at 70.degree. C.
for 4 h. The resulting solution is evaporated to dryness under
reduced pressure and redissolved in 1:1 ethanol: water (20 mL). To
this solution is added potassium cyanide (0.35 g, 5.4 mmol) and
ammonium carbonate (0.96 g 9.8 mmol) and the mixture heated in a
sealed tube at 85.degree. C. for 24 h. The reaction is cooled,
acidified with 6 N HCl and reduced in volume until a precipitate
forms. The precipitate is filtered and the filtrate evaporated to
dryness and extracted with ethyl acetate. The solvent is evaporated
and the product combined with the residue from above to give (5) as
a white solid. Yield 0.95 g (75%) m.p. 244-248.degree. C. NMR
.sup.1H (DMSO) .delta. 1.18 (s, 3H) 3.9 (ma, 3H), 4.0 (m, 3H), 8.1
(s, 12), 10.6 (s, 1H).
[0148] Preparation 5: 4-carboxycubane-1-methylglycine
[0149] The hydantoin (5) (0.95 g, 3.65 mmol) is dissolved in 30 mL
of 2 N NaOH and heated to 170.degree. C. in a sealed tube for 20 h.
The reaction is cooled and filtered to remove precipitate and the
filter cake washed with 3.times.10 mL of water. The combined
aqueous washings are evaporated to give crude (6) which is applied
to Spectrum 1.times.4 anion exchange resin, eluted with 0.5 N
acetic acid.
[0150] Isolation by evaporation and crystallization gives (6) as
colorless crystals. m.p. >250.degree. C. (decomp.). NMR .sup.1H
(D.sub.2O) .delta. 1.38 (s, 3H), 3.95 (s, 6H).
Example 3
[0151] 13
[0152] Preparation 1: 4-methoxycarbonylcubane-1-acetyl
Ethylcarboxylate.
[0153] n-butyl lithium (34.83 mmol, 23.5 mL of 1.5 M) is added
dropwise to a stirred solution of ethyl hydrogen malonate (2.32 g,
17.41 mmol) in 80 mL of dry THF under N.sub.2 at -78.degree. C. The
mixture was warmed to -30.degree. C. over 0.5 h and then re-cooled
to -78.degree. C. The acid chloride of cubane monomethyl ester from
example (2) above (2.35 g, 10.46 mmol) in 7 mL of THF is added
dropwise to the stirred solution. The reaction is warmed slowly to
r.t and stirred for a further 1 h. The solution is poured into 50
mL of 1 N HCl and extracted with 3.times.50 mL of diethyl ether.
The combined organic extracts are further extracted with 20 mL of
saturated sodium hydrogen carbonate and brine, dried over magnesium
sulphate, filtered and evaporated to give crude (2). The product is
purified by column chromatography on silica with hexanes:ethyl
acetate 2:1 to yield 2.5 g (86%) of (2). .sup.1H NMR (CDCl.sub.3)
.delta. 1.2 (t, 3H) 3.4 (s, 2H), 3.65 (s, 3H), 4.2 (m, 8H).
[0154] Preparation 2:
4-methoxycarbonylcubane-1-(thioxanthyl)-acetyl
Ethylcarboxylate.
[0155] cubane-.beta.-ketoester (2) (1.15 g, 4.16 mmol) and
thioxanthene-9-ol (0.88 g, 4.1 mmol) are dissolved in 18 mL of a
1:1 mixture of ethanol:acetic acid and stirred at r.t. for 3 days.
The resulting crystalline solid was filtered off to yield 1.52 g
(77%) of pure (3) m.p. 147-149.degree. C. .sup.1H NMR (CDCl.sub.3)
1.00 (t, 3H), 3.24 (s, 3H), 3.75 (m, 3H), 3.9 (q, 2H), 4.0 (m, 3H,
4.6 (d, 1H), 5.0 (d, 1H), 7.3. (m, 8H).
[0156] Preparation 3: 4-carboxycubane-1-methylthioxanthylketone
[0157] The thioxanthylcubane adduct (3) (1.69 g, 3.57 mmol) is
dissolved in ethanol 33 mL and 8.7 mL of 1 N NaOH and heated at
70.degree. C. for 4 h. The resulting solution is evaporated and
redissolved in 25 mL of water, acidified with 6 N HCl and extracted
with 3.times.50 mL of diethyl ether. The combined organic layers
are dried over magnesium sulphate, filtered and concentrated to
give a crude product containing (4). Chromatography on silica using
ethyl acetate gives 1.26 g (88%) of (4)
[0158] .sup.1H NMR (CDCl.sub.3) .delta. 2.8 (d, 2H), 3.8 (m, 3H),
4.0 (m, 3H), 4.7 (t, 1H), 7.3 (m, 8H), 9.5 (br, 1H).
[0159] Preparation 4:
4-carboxycubane-1-thioxanthyl-1-(5,5'-hydantoin)
[0160] The thioxanthyl cubane ketone (4) (1.24 g, 3.22 mmol) is
dissolved in 1:1 ethanol:water (20 mL). Potassium cyanide (0.522 g,
8.0 mmol) and ammonium carbonate (1.39 g, 14.4 mmol) are added and
the solution heated in a sealed tube at 85.degree. C. for 65 h. The
reaction is cooled and acidified with 2 N HCl and extracted with
3.times.40 mL of ethyl acetate. The organic layers are combined,
dried over magnesium sulphate, filtered and evaporated to give (5)
1.3 g (88%) as a crude product. This material was hydrolyzed in the
next step without purification.
[0161] .sup.1H NMR (CD.sub.3OD) .delta. 1.7 (m, 1H), 2.7 (m, 1H),
3.8 (m, 3H), 4.0 (m, 3H), 4.3 (m, 1H), 7.4 (m, 8H).
[0162] Preparation 5: 4-carboxycubane-1-thioxanthyl lglycine
[0163] The hydantoin adduct (5) (300 mg, 0.65 mmol) is taken up in
1 N NaOH (10 mL) and heated at 170.degree. C. for 20 h in a sealed
tube. The mixture is cooled and the pH adjusted with 6 N HCl to
between 7 and 8. The precipitate formed is filtered and washed with
water. The combined filtrate and washings are combined and
evaporated to dryness. The resulting residue is purified by column
chromatography and finally by reverse phase chromatography to yield
(6) as colorless crystals. 70 mg. .sup.1H NMR (CD.sub.3OD+D.sub.2O)
.delta. 2.3 (m, 2H) 3.9 (s, 6H), 4.4 (m, 1H), 7.4 (m, 8H).
* * * * *