U.S. patent application number 10/936062 was filed with the patent office on 2005-03-10 for process for the preparation of aniline-derived thyroid receptor ligands.
Invention is credited to Chidambaram, Ramakrishnan, Ghosh, Arun, Kant, Joydeep, Weaver, Raymond E., Yu, Jurong.
Application Number | 20050054873 10/936062 |
Document ID | / |
Family ID | 23315547 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050054873 |
Kind Code |
A1 |
Chidambaram, Ramakrishnan ;
et al. |
March 10, 2005 |
Process for the preparation of aniline-derived thyroid receptor
ligands
Abstract
Provided are processes for the synthesis of aniline derivatives,
specifically certain aniline derivatives which have activity as
thyroid receptor ligands.
Inventors: |
Chidambaram, Ramakrishnan;
(Pennington, NJ) ; Kant, Joydeep; (Cherry Hill,
NJ) ; Weaver, Raymond E.; (Hampton, NJ) ; Yu,
Jurong; (Dayton, NJ) ; Ghosh, Arun; (Madison,
CT) |
Correspondence
Address: |
STEPHEN B. DAVIS
BRISTOL-MYERS SQUIBB COMPANY
PATENT DEPARTMENT
P O BOX 4000
PRINCETON
NJ
08543-4000
US
|
Family ID: |
23315547 |
Appl. No.: |
10/936062 |
Filed: |
September 8, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10936062 |
Sep 8, 2004 |
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10273268 |
Oct 17, 2002 |
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6806381 |
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60336318 |
Nov 2, 2001 |
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Current U.S.
Class: |
560/41 ;
562/450 |
Current CPC
Class: |
C07C 201/12 20130101;
C07C 201/12 20130101; C07C 201/12 20130101; C07C 201/12 20130101;
C07C 45/00 20130101; C07C 205/43 20130101; C07C 201/12 20130101;
C07C 47/575 20130101; C07C 205/37 20130101; C07C 217/90 20130101;
C07C 205/38 20130101; C07C 205/12 20130101; C07C 233/25 20130101;
C07C 231/02 20130101; C07C 231/02 20130101; C07C 205/12 20130101;
C07C 213/02 20130101; C07C 213/02 20130101; C07C 205/43 20130101;
C07C 309/65 20130101; C07C 233/25 20130101; C07C 205/37 20130101;
C07C 309/24 20130101; C07C 45/00 20130101; C07C 205/38
20130101 |
Class at
Publication: |
560/041 ;
562/450 |
International
Class: |
C07C 233/73 |
Claims
1-27. (cancel)
28. A compound of formula IIA 20wherein R.sup.2 and R.sup.3
independently represent bromo, chloro, or methyl; R.sup.4
represents hydrogen or methyl; and L represents mesyl, tosyl,
p-nitrobenzenesulfonyl, trihaloacetate, or triflate.
29. The compound according to claim 28, selected from the group
consisting of trifluoro-methanesulfonic acid
2,6-dibromo-4-nitrophenyl ester, trifluoro-methanesulfonic acid
2,6-dibromo-3-methyl-4-nitrophenyl ester, trifluoro-methanesulfonic
acid 2,6-dichloro-4-nitrophenyl ester, and
trifluoro-methanesulfonic acid 2,6-dichloro-3-methyl-4-nitrophenyl
ester.
30. The compound according to claim 28, trifluoro-methanesulfonic
acid 2,6-dibromo-4-nitrophenyl ester.
31. A compound of formula IIIA 21wherein R.sup.2 and R.sup.3
independently represent bromo, chloro, or methyl; and R.sup.4
represents hydrogen or methyl.
32. The compound according to claim 31, selected from the group
consisting of l,3-dibromo-2-iodo-5-nitrobenzene,
1,3-dibromo-2-iodo-4-methyl-5-nitro- benzene,
1,3-dichloro-2-iodo-5-nitrobenzene, and 1,3-dichloro-2-iodo-4-met-
hyl-5-nitrobenzene.
33. The compound according to claim 31,
1,3-dibromo-2-iodo-5-nitrobenzene.
34. A process for the synthesis of a phenol of formula A 22wherein
G is a protecting group; and R.sup.1 represents halogen,
trifluoromethyl, an alkyl group of 1 to 6 carbons, or a cycloalkyl
group of 3 to 7 carbons; comprising the steps of: a) reacting an
aldehyde of formula A-I with MHSO.sub.3 to form a sulfonate of
formula A-II 23wherein M is a metal; and b) reacting the
sulfonate-of formula A-II with an oxidant, in the presence of a
proton source, to form the phenol of formula A[, above].
35. A compound selected from the group consisting of compounds of
formula A-I and formula A-II, 24wherein G represents a protecting
group; M represents a metal; and R.sup.1 represents halogen,
trifluoromethyl, an alkyl group of 1 to 6 carbons, or a cycloalkyl
group of 3 to 7 carbons.
36. The compound according to claim 35,
3-isopropyl-4-methoxybenzaldehyde.
37. The compound according to claim 35,
hydroxy-(3-isopropyl-4-methoxyphen- yl)methanesulfonic acid, sodium
salt.
38. A compound of formula A 25wherein G represents a protecting
group; and R.sup.1 represents halogen, trifluoromethyl, an alkyl
group of 1 to 6 carbons, or a cycloalkyl group of 3 to 7 carbons;
with the proviso that, when G is a methyl group, R.sup.1 is not a
member of the group consisting of bromo, chloro, iodo, t-butyl,
cyclohexyl, cyclopentyl, and isopropyl.
Description
BACKGROUND OF THE INVENTION
[0001] This application is a Divisional of co-pending U.S. patent
application Ser. No. 10/273,268, filed Oct. 17, 2002 that claim
priority from U.S. Provisional Application No. 60/336,318, filed
Nov. 2, 2001.
[0002] The present invention relates to processes for the synthesis
of organic molecules, specifically molecules that have activity as
thyroid receptor ligands.
[0003] While the essential role of thyroid hormones in regulating
metabolism in humans is well recognized, the discovery and
development of new specific drugs for improving the treatment of
hyperthyroidism and hypothyroidism has been slow. This has also
limited the development of thyroid agonists and antagonists for
treatment of other important clinical indications, such as
hypercholesterolemia, obesity and cardiac arrhythmias.
[0004] Thyroid hormones affect the metabolism of virtually every
cell of the body. At normal levels, these hormones maintain body
weight, the metabolic rate, body temperature, and mood, and
influence serum-low density lipoprotein (LDL) levels. Thus, in
hypothyroidism there is weight gain, high levels of LDL
cholesterol, and depression. In excess with hyperthyroidism, these
hormones lead to weight loss, hypermetabolism, lowering of serum
LDL levels, cardiac arrhythmias, heart failure, muscle weakness,
bone loss in postmenopausal women, and anxiety.
[0005] Thyroid hormones are currently used primarily as replacement
therapy for patients with hypothyroidism. Therapy with L-thyroxine
returns metabolic functions to normal and can easily be monitored
with routine serum measurements of levels of thyroid-stimulating
hormone (TSH), thyroxine (3,5,3',5'-tetraiodo-L-thyronine, or
T.sub.4) and triiodothyronine (3,5,3'-triiodo-L-thyronine, or
T.sub.3). However, replacement therapy, particularly in older
individuals, is limited by certain of the deleterious effects of
thyroid hormones.
[0006] In addition, some effects of thyroid hormones may be
therapeutically useful in non-thyroid disorders if adverse effects
can be minimized or eliminated. These potentially useful influences
include weight reduction, lowering of serum LDL levels,
amelioration of depression and stimulation of bone formation. Prior
attempts to utilize thyroid hormones pharmacologically to treat
these disorders have been limited by manifestations of
hyperthyroidism, and in particular by cardiovascular toxicity.
[0007] Development of specific and selective thyroid hormone
receptor agonists could lead to specific therapies for these common
disorders while avoiding the cardiovascular and other toxicities of
native thyroid hormones. Tissue-selective thyroid hormone agonists
may be obtained by selective tissue uptake or extrusion, topical or
local delivery, targeting to cells through other ligands attached
to the agonist and targeting receptor subtypes. Thyroid hormone
receptor agonists that interact selectively with the .beta.-form of
the thyroid hormone receptor offer an especially attractive method
for avoiding cardio-toxicity.
[0008] Thyroid hormone receptors (TRs) are, like other nuclear
receptors, single polypeptide chains. The various receptor forms
appear to be products of two different genes .alpha. and .beta..
Further isoform differences are due to the fact that differential
RNA processing results in at least two isoforms from each gene. The
TR.alpha..sub.1, TR.beta..sub.1 and TR.beta..sub.2 isoforms bind
thyroid hormone and act as ligand-regulated transcription factors.
In adults, the TR.beta..sub.1 isoform is the most prevalent form in
most tissues, especially in the liver and muscle. The
TR.alpha..sub.1 isoform is prevalent in the pituitary and other
parts of the central nervous system, does not bind thyroid
hormones, and acts in many contexts as a transcriptional repressor.
The TR.alpha..sub.1 isoform is also widely distributed, although
its levels are generally lower than those of the TR.beta..sub.1
isoform. This isoform may be especially important for development.
Whereas many mutations in the TR.beta. gene have been found and
lead to the syndrome of generalized resistance to thyroid hormone,
mutations leading to impaired TR.alpha. function have not been
found.
[0009] A growing body of data suggest that many or most effects of
thyroid hormones on the heart, and in particular on the heart rate
and rhythm, are mediated through the a-form of the TR.alpha..sub.1
isoform, whereas most actions of the hormone such as on the liver,
muscle and other tissues are mediated more through the .beta.-forms
of the receptor. Thus, a TR.beta.-selective agonist might not
elicit the cardiac rhythm and rate influences of the hormones but
would elicit many other actions of the hormones. It is believed
that the .alpha.-form of the receptor is the major drive to heart
rate for the following reasons:
[0010] 1. tachycardia is very common in the syndrome of generalized
resistance to thyroid hormone in which there are defective
TR.beta.-forms, and high circulating levels of T.sub.4 and
T.sub.3;
[0011] 2. there was a tachycardia in the only described patient
with a double deletion of the TR.beta. gene (Takeda et al., J.
Clin. Endrocrinol. & Metab. 1992, Vol. 74, p. 49);
[0012] 3. a double knockout TR.alpha. gene (but not .beta.-gene) in
the mouse has a slower pulse than control mice; and,
[0013] 4. western blot analysis of human myocardial TRs show
presence of the TR.alpha..sub.1, TR.alpha..sub.2 and TR.beta..sub.2
proteins, but not TR.beta..sub.1.
[0014] If these indications are correct, then a TR.beta.-selective
agonist could be used to mimic a number of thyroid hormone actions,
while having a lesser effect on the heart. Such a compound may be
used for: (1) replacement therapy in elderly subjects with
hypothyroidism who are at risk for cardiovascular complications;
(2) replacement therapy in elderly subjects with subclinical
hypothyroidism who are at risk for cardiovascular complications;
(3) obesity; (4) hypercholesterolemia due to elevations of plasma
LDL levels; (5) depression; and, (6) osteoporosis in combination
with a bone resorption inhibitor.
[0015] Thyroid receptor ligands of the formula I, below, have
previously been synthesized by several methods including the method
summarized in Scheme A. (See U.S. patent application Serial No.
09/761,050, filed Jan. 16, 2001.) The group G represents any group
appropriate for protecting a hydroxyl moiety. The group Z
represents a leaving group, such as a halogen. Examples of
appropriate protecting groups G can be found, for example, in T. W.
Greene & P. G. M. Wuts, "Protecting Groups in Organic
Synthesis", 3rd Edition, Wiley, 1999. 1
[0016] This route is not optimal, however, due to the exothermicity
of the formation of the iodonium triflate salt which is an
unisolated intermediate in the synthesis depicted in Scheme A. In
addition, the isolated, bis-phenyl iodonium salt is an intractable
gummy solid at room temperature, and the yield of the formation
reaction is unpredictable. Further, the coupling reaction to form
the mixed ether from the iodonium salt is not well adapted to
commercial practice, because it takes place over an extended period
of time, it requires unusual provisions to exclude light, and its
yield is also unpredictable.
[0017] Accordingly, there is a need for improved processes for the
preparation of thyroid receptor ligands, especially for processes
that improve upon the safety and economic feasibility of the
processes known in the art.
SUMMARY OF THE INVENTION
[0018] The present invention relates to the synthesis of compounds
that have activity as thyroid receptor ligands, specifically
compounds of formula I 2
[0019] wherein:
[0020] R.sup.1 represents halogen, trifluoromethyl, an alkyl group
of 1 to 6 carbons, or a cycloalkyl group of 3 to 7 carbons;
[0021] R.sup.2 and R.sup.3 are the same or different and represent
hydrogen, halogen, an alkyl group of 1 to 4 carbons, or a
cycloalkyl group of 3 to 6 carbons, at least one of R.sup.2 and
R.sup.3 being other than hydrogen;
[0022] R.sup.4 represents hydrogen or a lower alkyl group;
[0023] R.sup.5 represents a carboxylic acid or an alkyl ester
thereof; and
[0024] Y represents --(CH.sub.2).sub.n-- where n is an integer from
1 to 5, or a cis- or trans-ethylene group --CH.dbd.CH--;
[0025] and all stereoisomers thereof, prodrug esters thereof, and
pharmaceutically acceptable salts thereof.
[0026] Compounds of formula I may be synthesized by reacting a
compound of formula III with a phenol of formula A, wherein G is a
protecting group, in the presence of a base to produce a compound
of formula IV, wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are
as defined above; 3
[0027] deprotecting the compound of formula IV to form a compound
of formula V; 4
[0028] reducing the compound of formula V to produce a compound of
formula VI; 5
[0029] reacting the compound of formula VI with a compound of the
formula XC(O)YR.sup.5, wherein X represents OH or a halogen and
R.sup.5 is a carboxylic acid alkyl ester, in the presence of a
base, to produce a compound of formula I wherein R.sup.5 is a
carboxylic acid alkyl ester; and
[0030] optionally de-esterifying the compound of formula I wherein
R.sup.5 is a carboxylic acid alkyl ester to produce a compound of
formula I wherein R.sup.5 is a carboxylic acid.
[0031] Also provided by the present invention are compounds that
are novel starting materials of the above process having the
formulae IIA and IIIA 6
[0032] wherein
[0033] R.sup.2 and R.sup.3 independently represent bromo, chloro,
or methyl;
[0034] R.sup.4 represents hydrogen or methyl; and
[0035] L represents mesyl, tosyl, p-nitrobenzenesulfonyl,
trihaloacetate, or triflate.
[0036] The present invention also provides compounds of the
formulae A, A-I, and A-II 7
[0037] wherein M is a metal and G and R.sup.1 are as defined above.
In compounds of formula A, however, when G is a methyl group,
R.sup.1 is not a bromo, chloro, iodo, t-butyl, cyclohexyl,
cyclopentyl, or isopropyl group.
[0038] Also provided by the present invention is a process for
synthesizing a phenol of formula A, above, by reacting an aldehyde
of formula A-I, above, with M.sup.+HSO.sub.3.sup.- wherein M is a
metal to form a sulfonate of formula A-II, above. The sulfonate of
formula A-II is reacted with an oxidant in the presence of a proton
source to form the phenol of formula A.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a graph of the results of a temperature vs. time
study of the formation reaction of the iodonium triflate salt of
the comparative example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] The following definitions apply to the terms as used
throughout this specification, unless otherwise limited in specific
instances.
[0041] The term "thyroid receptor ligand" as used herein, is
intended to cover any moiety which binds to a thyroid receptor. The
ligand may act as an agonist, an antagonist, a partial agonist or a
partial antagonist. Another term for "thyroid receptor ligand" is
"thyromimetic".
[0042] Unless otherwise indicated, the term "lower alkyl", "alkyl"
or "alk" as employed herein alone or as part of another group
includes both straight and branched chain hydrocarbons, containing
1 to 12 carbons (in the case of alkyl or alk), in the normal chain,
preferably 1 to 4 carbons, such as methyl, ethyl, propyl,
isopropyl, butyl, t-butyl, or isobutyl, pentyl, hexyl, isohexyl,
heptyl, 4,4-dimethylpentyl, octyl, 2,2,4-trimethylpentyl, nonyl,
decyl, undecyl, dodecyl. Each alkyl group may be optionally
substituted with 1 to 4 substituents which may include alkyl,
alkenyl, alkynyl, aryl, cycloalkyl, halogen, heteroaryl, hydroxy,
cyano, nitro, amino and/or carboxyl or alkyl ester thereof.
[0043] The term "aryl" as employed herein alone or as part of
another group refers to monocyclic and bicyclic aromatic groups
containing 6 to 10 carbons in the ring portion (such as phenyl or
naphthyl including l-naphthyl and 2-naphthyl) and may be optionally
substituted through available carbon atoms with 1, 2, or 3 groups
selected from hydrogen, halo, alkyl, haloalkyl, alkoxy, haloalkoxy,
alkenyl, trifluoromethyl, trifluoromethoxy, alkynyl, hydroxy,
amino, nitro, cyano and/or carboxyl or an alkyl ester thereof.
[0044] The term "heteroaryl" or "heteroaromatic moiety" as used
herein alone or as a part of another group refers to a 5- or
6-membered aromatic ring which includes 1, 2, 3, or 4 heteroatoms,
one of which must be a nitrogen atom; the other heteroatoms when
present may be nitrogen, oxygen or sulfur, and such rings may be
fused to another aryl or heteroaryl ring. The heteroaryl groups may
include one or more N-oxides. The heteroaryl group may optionally
include 1 to 4 substituents such as aryl, alkyl, alkenyl, alkynyl,
cycloalkyl, hydroxy, cyano, nitro, amino and/or carboxyl, or an
alkyl ester thereof.
[0045] Unless otherwise indicated, the term "lower alkenyl" or
"alkenyl" as used herein by itself or as part of another group
refers to straight or branched chain radicals of 2 to 12 carbons,
preferably 2 to 5 carbons, in the normal chain, which include one
to six double bonds in the normal chain, such as vinyl, 2-propenyl,
3-butenyl, 2-butenyl, 4-pentenyl, 3-pentenyl, 2-hexenyl, 3-hexenyl,
2-heptenyl, 3-heptenyl, 4-heptenyl, 3-octenyl, 3-nonenyl,
4-decenyl, 3-undecenyl, 4-dodecenyl, and the like, which may be
substituted in the same manner as that described for alkyl
groups.
[0046] Unless otherwise indicated, the term "lower alkynyl" or
"alkynyl" as used herein by itself or as part of another group
refers to straight or branched chain radicals of 2 to 12 carbons,
preferably 2 to 8 carbons, in the normal chain; which include one
triple bond in the normal chain, such as 2-propynyl, 3-butynyl,
2-butynyl, 4-pentynyl, 3-pentynyl, 2-hexynyl, 3-hexynyl,
2-heptynyl, 3-heptynyl, 4-heptynyl, 3-octynyl, 3-nonynyl,
4-decynyl, 3-undecynyl, 4-dodecynyl and the like, which may be
substituted in the same manner as that described for alkyl
groups.
[0047] Unless otherwise indicated, the term "cycloalkyl" as
employed herein alone or as part of another group includes
saturated cyclic hydrocarbon groups or partially unsaturated
(containing 1 or 2 double bonds) cyclic hydrocarbon groups,
containing one ring and a total of 3 to 7 carbons, preferably 3 to
6 carbons, forming the ring, which includes cyclopropyl,
cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl and
cyclohexenyl, which may be substituted in the same manner as that
described for alkyl groups.
[0048] The term "halogen" or "halo" as used herein alone or as part
of another group refers to fluorine, chlorine, bromine, and iodine,
with chlorine or bromine being preferred.
[0049] The term "metal" as used herein refers to an element that
can exist as a positive ion in solution. Suitable metals include
alkali metals, transition metals, lanthanides, and actinides.
Alkali metals are preferred. Lithium, sodium, and potassium are the
most preferred metals.
[0050] As used herein, the term "about" means that amounts, sizes,
formulations, parameters, and other quantities and characteristics
are not and need not be exact, but may be approximate and/or larger
or smaller, as desired, reflecting tolerances, conversion factors,
rounding off, measurement error and the like, and other factors
known to those of skill in the art. In general, an amount, size,
formulation, parameter or other quantity or characteristic is
"about" or "approximate" whether or not expressly stated to be
such.
[0051] The divalent linking group represented by Y may be an
alkylene group --(CH.sub.2).sub.n-- that includes 1 to 5 carbons in
the normal chain, and may also include 1, 2, or 3 alkyl
substituents.
[0052] Examples of (CH.sub.2), groups include --CH.sub.2--,
--CH.sub.2CH.sub.2--, --CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2C(CH.sub.3).sub.2- CH.sub.2--,
--CH.sub.2CH.sub.2CH(CH.sub.2CH.sub.3)CH.sub.2--,
--CH.sub.2CH.sub.2CH(CH.sub.2CH.sub.3)CH.sub.2CH(CH.sub.3)--,
--C(CH.sub.3)(CH.sub.2CH.sub.3)CH.sub.2CH.sub.2--,
--CH(CH.sub.3)--, --CH(CH.sub.2CH.sub.3)--,
--CH(CH.sub.3)CH.sub.2CH(CH.sub.2CH.sub.3)CH.su- b.2--.
[0053] Alternatively, Y may represent a cis- or trans-alkylene
group --CH.dbd.CH-- which may be substituted as described
above.
[0054] The compounds of formula I may be present as salts, in
particular pharmaceutically acceptable salts. If the compounds of
formula I have, for example, at least one basic center, they can
form acid addition salts. These are formed, for example, with
strong inorganic acids, such as mineral acids, for example sulfuric
acid, phosphoric acid or a hydrohalic acid, with strong organic
carboxylic acids, such as alkanecarboxylic acids of 1 to 4 carbon
atoms which are unsubstituted or substituted, for example, by
halogen, for example acetic acid, such as saturated or unsaturated
dicarboxylic acids, for example oxalic, malonic, succinic, maleic,
fumaric, phthalic or terephthalic acid, such as hydroxycarboxylic
acids, for example ascorbic, glycolic, lactic, malic, tartaric or
citric acid, such as amino acids, (for example aspartic or glutamic
acid or lysine or arginine), or benzoic acid, or with organic
sulfonic acids, such as (C1-C4) alkyl or arylsulfonic acids which
are unsubstituted or substituted, for example by halogen, for
example methanesulfonic acid or p-toluenesulfonic acid.
[0055] Corresponding acid addition salts can also be formed having,
if desired, an additional basic center. The compounds of formula I
having at least one acid group (for example COOH) can also form
salts with bases. Suitable salts with bases are, for example, metal
salts, such as alkali metal or alkaline earth metal salts, for
example sodium, potassium or magnesium salts, or salts with ammonia
or an organic amine, such as morpholine, thiomorpholine,
piperidine, pyrrolidine, a mono-, di-, or tri-lower alkylamine, for
example ethyl, t-butyl, diethyl, diisopropyl, triethyl, tributyl or
dimethyl-propylamine, or a mono, di, or trihydroxy lower
alkylamine, for example mono, di or triethanolamine. Corresponding
internal salts may furthermore be formed. Salts which are
unsuitable for pharmaceutical uses but which can be employed, for
example, for the isolation or purification of free compounds of
formula I or their pharmaceutically acceptable salts, are also
included.
[0056] Preferred salts of the compounds of formula I which include
a basic group include monohydrochloride, hydrogensulfate,
methanesulfonate, phosphate or nitrate.
[0057] Preferred salts of the compounds of formula I which include
an acid group include sodium, potassium and magnesium salts and
pharmaceutically acceptable organic amines.
[0058] Preferred compounds of formula I are those wherein
[0059] Y represents --(CH.sub.2).sub.n-- where n is 1 or 2;
[0060] R.sup.1 represents halogen, trifluoromethyl, an alkyl group
of 1 to 6 carbons, or a cycloalkyl group of 3 to 7 carbons;
[0061] R.sup.2 and R.sup.3 independently represent bromo, chloro,
or methyl;
[0062] R.sup.4 represents hydrogen or methyl; and
[0063] R.sup.5 represents carboxyl.
[0064] More preferred compounds of formula I are those wherein
[0065] Y represents --(CH.sub.2).sub.n-- where n is 1;
[0066] R.sup.1 represents halogen, trifluoromethyl, an alkyl group
of 5 1 to 6 carbons, or a cycloalkyl group of 3 to 7 carbons, most
preferred being isopropyl;
[0067] R.sup.2 and R.sup.3 independently represent bromo or
chloro;
[0068] R.sup.4 represents hydrogen or methyl; and
[0069] R.sup.5 represents carboxyl.
[0070] Compounds of formula I that can be prepared by the methods
of the invention include the following: 8
[0071]
N-[3,5-dibromo-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-malonamic
acid; 9
[0072]
N-[3,5-dibromo-4-(4-hydroxy-3-isopropyl-phenoxy)-2-methyl-phenyl]-m-
alonamic acid; 10
[0073]
N-[3,5-dibromo-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-succinamic
acid; 11
[0074]
N-[3,5-dichloro-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-malonamic
acid; 12
[0075]
N-[3,5-dichloro-4-(4-hydroxy-3-isopropyl-phenoxy)-2-methyl-phenyl]--
malonamic acid; and 13
[0076]
N-[3,5-dichloro-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-succinami-
c acid, or alkyl esters thereof, such as the methyl or ethyl
ester.
[0077] The most preferred compounds of the invention are: 14
[0078]
N-[3,5-dibromo-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-malonamic
acid; and 15
[0079]
N-[3,5-dichloro-4-(4-hydroxy-3-isopropyl-phenoxy)-phenyl]-malonamic
acid, or alkyl esters thereof, such as the methyl or ethyl
ester.
[0080] Preferred compounds of formula IIA include
trifluoro-methanesulfoni- c acid 2,6-dibromo-4-nitrophenyl ester,
trifluoro-methanesulfonic acid 2,6-dibromo-3-methyl-4-nitrophenyl
ester, trifluoro-methanesulfonic acid 2,6-dichloro-4-nitrophenyl
ester, and trifluoro-methanesulfonic acid
2,6-dichloro-3-methyl-4-nitrophenyl ester.
[0081] A more preferred compound of formula IIA is
trifluoro-methanesulfon- ic acid 2,6-dibromo-4-nitrophenyl
ester.
[0082] Preferred compounds of formula IIIA include
1,3-dibromo-2-iodo-5-ni- trobenzene,
1,3-dibromo-2-iodo-4-methyl-5-nitrobenzene,
l,3-dichloro-2-iodo-5-nitrobenzene, and
1,3-dichloro-2-iodo-4-methyl-5-ni- trobenzene.
[0083] A more preferred compound of formula IIIA is
1,3-dibromo-2-iodo-5-nitrobenzene.
[0084] Preferred compounds of formulae A, A-I, and A-II for
practicing the present invention are those in which R.sup.1
represents halogen, trifluoromethyl, an alkyl group of 1 to 6
carbons, or a cycloalkyl group of 3 to 7 carbons.
[0085] More preferred compounds of formulae A, A-I, and A-II are
those in which R.sup.1 represents halogen, trifluoromethyl, an
alkyl group of 1 to 6 carbons, or a cycloalkyl group of 3 to 7
carbons, most preferred being isopropyl.
[0086] The most preferred compound of formula A-I is
3-isopropyl-4-methoxybenzaldehyde. The most preferred compound of
formula A-II is
hydroxy-(3-isopropyl-4-methoxyphenyl)methanesulfonic acid, sodium
salt. The most preferred phenol of formula A is
3-isopropyl-4-methoxyphen- ol.
[0087] All stereoisomers of the compounds of formula I are
contemplated, either in admixture or in pure or substantially pure
form. The compounds of formula I can have asymmetric centers at any
of the carbon atoms including any one of the R substituents.
Consequently, compounds of formula I can exist in enantiomeric or
diastereomeric forms or in mixtures thereof. The processes for
preparation can utilize racemates, enantiomers or diastereomers as
starting materials. When diastereomeric or enantiomeric products
are prepared, they can be separated by conventional methods, for
example, chromatographic or fractional crystallization.
[0088] The compounds of formula I may be prepared by the exemplary
processes described in the following reaction schemes. Exemplary
reagents and procedures for these reactions appear hereinafter and
in the working examples. Protection and deprotection in the Schemes
herein may be carried out by procedures generally known in the art
(see, for example, Greene & Wuts).
[0089] Scheme 1 sets forth an improved method of synthesizing
compounds of formula I. 1617
[0090] In scheme 1, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are as
defined above, M represents a metal, the group G represents any
group appropriate for protecting a hydroxyl moiety, and the group
--OL represents a leaving group. Examples of suitable protecting
groups G can be found in Green and Wuts, for example. Examples of
suitable leaving groups L can be found in Carey, F. A. and
Sundberg, R. J., Advanced Organic Chemistry (1977, Plenum Press,
New York), Part A, Section 5.6, for example.
[0091] Preferred protecting groups include, e.g., substituted or
unsubstituted alkyl, methoxymethyl (MOM), carboxybenzyl (CBz),
benzyloxymethyl (BOM), 2-(trimethylsilyl)ethoxymethyl (SEM), aryl
thiomethyl (MTM), tetrahydropyranyl, methyl 2-propenyl ether, ethyl
vinyl ether, triphenylmethyl (trityl) and other triarylmethyl
groups, esters, carbonates, phosphinates, sulfonates, and silyl
groups.
[0092] More preferred protecting groups are alkyl groups.
[0093] The most preferred protecting groups are alkyl groups
containing 1 to 6 carbons, especially methyl groups.
[0094] Preferred leaving groups include, e.g., tri-haloacetates and
sulfonate esters.
[0095] More preferred leaving groups are trihalo-methylsulfonate,
methylsulfonate (mesyl), p-nitrobenzenesulfonate,
p-toluenesulfonate (tosyl), and trihaloacetate groups.
[0096] The most preferred leaving groups are
trifluoromethylsulfonate (triflate) groups.
[0097] Phenols of formula A may be synthesized by methods known in
the art. See, for example, Blank, B., J. Med Chem., 1963, 6, 554,
and Bowman et al., J. Chem. Soc. C, 1966, 2274. Phenols of formula
A may also be synthesized by the novel method of the present
invention, wherein an aldehyde of formula A-I is reacted with about
2 to 4 equivalents of a sulfite reagent, such as an sodium sulfite
or an alkali hydrogen sulfite, at about 20.degree. to 30.degree. C.
to produce a sulfonate of formula A-II. Preferably, about 2.25 to
2.75 equivalents of sulfite reagent are used, the preferred sulfite
reagent being sodium sulfite.
[0098] The phenol of formula A is formed by reacting the sulfonate
of formula A-II with an oxidant, in the presence of a proton
source. Preferably, about 1 to 2 equivalents of protons and about 3
to 5 equivalents of oxidant are used.
[0099] Suitable oxidants for use in the synthesis of Phenol A
include, e.g., peroxybenzoic acids, alkali metal
monoperoxophthalates, hydrogen peroxide optionally catalyzed by
Me-ReO.sub.3, oxygen in the presence of a copper species,
H.sub.3PO.sub.5, and oxone. More preferably, the oxidant is
hydrogen peroxide.
[0100] Preferably, the proton source is a protic acid. More
preferably, the proton source is p-toluenesulfonic acid.
[0101] Phenol B may be synthesized by well-known methods from
commercially available starting materials. See, for example, Yenes,
S. et al., Tetrahedron, 1999, 55, 14111; Bozell, J. et al., Tet.
Lett., 1998, 39, 2261; Fischer, A. et al., Tet. Lett., 1988, 29,
1869; Rodygin, M. et al., Zh. Org. Khim., 1992, 28, 1926; Xu, F. et
al., Shanghai Keji Daxue Xuebao, 1989, 12, 72; Clewly, R. et al.,
Can. J. Chem., 1989, 67, 1472; Kajigaeshi, S. et al., Bull. Chem.
Soc. Japan, 1987, 60, 4187; Kajigaeshi S. et al., Chem. Lett.,
1987, 4, 627; Lemaire, M. et a.1, Tetrahedron, 1987, 43, 835;
Fujita, S. et al., J P 03291241, 1991; Clewly, R. et al.,
Tetrahedron, 1989, 45, 1299; Kajigaeshi, S. et al., Chem. Express,
1990, 5, 141; Kakinami, T. et al., Bull. Chem. Soc. Japan, 1989,
62, 3373; Kajigaeshi, S. et al., Technol. Rep. Yamaguchi Univ.,
1987, 4, 65; Gaude D. et al., Can. J. Chem., 1989, 67, 104;
Kajigaeshi, S. et al., Chem. Lett., 1987, 2109. Certain Phenol B
compounds are also commercially available from the Aldrich Company,
for example.
[0102] Compounds of formula III are synthesized from compounds of
formula II by iodination. Iodination reagents include, e.g., alkali
metal iodides and tetraalkylammonium iodides. Preferred iodination
reagents include, e.g., sodium iodide and potassium iodide.
Preferably, the iodination agent is present in about 1-fold to
10-fold excess. Preferably, the iodination is carried out at 800 to
110.degree. C. Preferably, the solvent is acetone, methyl ethyl
ketone (MEK), methyl isobutyl ketone (MIBK), toluene,
hexamethylphosphorustriamide (HMPA), dimethyl formamide (DMF), or a
higher-boiling acetate. More preferably, the iodination is carried
out by reacting the compound of formula II with 3- to 5-fold excess
NaI or KI in DMF, MEK or MIBK at a temperature of about 75.degree.
to 100.degree. C.
[0103] The coupling reaction to form the mixed ether of formula IV
from the compound of formula III and phenol A is conducted in the
presence of a base. Preferred bases include, e.g., alkyl lithiums,
lithium diisopropylamine, Grignard reagents, alkali metal hydrides,
alkali metal carbonates, alkali metal hydroxides, and alkali metal
alkoxides. Preferred solvents include THF, 1,2-dimethoxyethane,
1,1-dimethoxyethane, dimethyl sulfoxide (DMSO), and toluene.
Preferably, about 1.1 to 1.5 equivalents of base are used.
Preferably, the reaction temperature is between about -78.degree.
and 30.degree. C. More preferably, the coupling reaction is
performed in toluene/DMF or toluene/THF or DMF at room temperature
using potassium hexamethyldisilazide (KHMDS), potassium t-butoxide,
potassium t-pentoxide, LiHMDS, or NaHMDS as the base.
[0104] The deprotection of the protected hydroxyl group of compound
IV may be carried out at reaction temperatures below room
temperature. Preferred deprotecting agents include, e.g.,
trialkylsilyl halides, mercaptans, boron halides, magnesium
halides, aluminum halides, hydrogen over palladium catalyst, or
iron halides. Preferably, the reaction temperature is maintained
between about 0.degree. to 15.degree. C. Preferably, the
deprotection reaction is quenched with at least about 4 molar
equivalents of methanol. More preferably, the deprotecting agent is
a trialkylsilyl halide or BBr.sub.3.
[0105] Reducing agents and conditions suitable for use in reducing
the formula V compound include, e.g., elemental metals such as Fe
and Na; hydrogen catalyzed by nickel, palladium or platinum; alkali
metal borohydrides; magnesium-mediated reductions; iron carbonyls;
iron sulfate mediated reductions; iron and HCl; sodium hydrogen
sulfite; sodium dithionite; tin and tin halide mediated reductions;
and alkali metal sulfides and polysulfides. Preferred reducing
agents include, e.g., sodium hydrogen sulfite, sodium dithionite,
or iron and HCl. Preferably, about 4 to 6 equivalents of reducing
agent are used. Preferably, the reaction temperature is maintained
between about 25.degree. to 50.degree. C. More preferably, the
reducing agent is sodium dithionite, and the reaction is carried
out over about 1 h in THF/H.sub.2O at about 50.degree. C.
[0106] Formula VI compounds may be converted into formula I
compounds wherein R.sup.5 is an alkyl ester group by reaction with
a compound of formula XC(O)YR.sup.5, wherein X and Y are as defined
above, under basic conditions. Preferred bases are alkali and
alkaline earth metal hydroxides and alkoxides, alkyl amines, and
substituted alkyl amines. Preferred compounds of formula
XC(O)YR.sup.5 are alkyl and malonyl halides. Preferably, the
reaction temperature is maintained between about 0.degree. and
5.degree. C. Preferably, about 1 equivalent or a slight excess of
base is used. Preferably, about 50% to 100% excess of the compound
of formula XC(O)YR.sup.5 is used. More preferably, XC(O)YR.sup.5 is
ethyl or methyl malonyl chloride and the reaction is carried out at
a temperature around 0.degree. C. under basic conditions, using
NaOH in t-butyl methyl ether (TBME).
[0107] In the above Scheme 1, the deprotection of the phenol
hydroxyl group of compound IV to form the compound of formula V is
depicted as being performed before the reduction of the nitro group
to form the compound of formula VI. The order in which these two
reactions are performed may be reversed, however. When the order is
thus reversed, a compound of formula VA is formed by the reduction.
18
[0108] The compound of formula VA is readily deprotected to form
the compound of formula VI. It is preferred, however, to carry out
the deprotection before the reduction.
[0109] Compounds of formula I wherein R.sup.5 is an alkyl ester may
be de-esterified by hydrolysis under acidic or basic conditions to
form compounds of formula I wherein R.sup.5 is a carboxylic acid.
Examples of suitable de-esterifying agents include, e.g., enzymes;
hydrogen over catalytic palladium; lithium and ammonia; zinc;
alkali metal hydroxides and alkoxides; alkaline earth metal
hydroxides and alkoxides; sodium sulfide; KSCN; thioethers in
combination with Lewis acids; anions of alkyl thiols or selenols;
trialkyl silyl halides; zinc dichloride; mercury (II) acetate; and
strong protic acids.
[0110] Preferred hydrolysis reagents and conditions include, e.g.,
an alkali metal hydroxide in the presence of an ether such as
tetrahydrofuran or tert-butyl methyl ether. Most preferably, the
hydrolysis is carried out in situ by the addition of approximately
1.5 to 2 molar equivalents of NaOH to the reaction mixture at a
temperature around 0.degree. C. after the reaction of compound VI
with XC(O)YR.sup.5 wherein X and Y are as previously defined and
R.sup.5 is an alkyl ester group is observed to be essentially
complete.
[0111] The compounds made by the processes of the invention are
agonists that are preferably selective for the thyroid hormone
receptor-beta, and as such are useful in the treatment of obesity,
hypercholesterolemia and atherosclerosis by lowering of serum LDL
levels, alone or optionally in combination with a lipid modulating
drug such as an HMG CoA reductase inhibitor, fibrate, MTP
inhibitor, squalene synthetase inhibitor and/or other hypolipidemic
agent and/or optionally in combination with an antidiabetic agent;
useful in the amelioration of depression, alone or optionally in
combination with an antidepressant such as fluoxetine and
desipramine; and useful in the stimulation of bone formation to
treat osteoporosis, alone or optionally in combination with any
known bone resorption inhibitor such as alendronate sodium.
[0112] In addition, the compounds of the invention may be useful as
replacement therapy in elderly patients with hypothyroidism or
subclinical hypothyroidism who are at risk for cardiovascular
complications, in the treatment of the elderly to provide a sense
of well-being, and in the treatment of non-toxic goiter; in the
management of papillary or follicular thyroid cancer (alone or with
T4); in the treatment of skin disorders such as psoriasis; and in
the treatment of glaucoma, cardiovascular disease such as in the
prevention or treatment of atherosclerosis, and congestive heart
failure.
[0113] The compounds made by the processes of the invention may be
employed alone or in combination with an appetite suppressant such
as sibutramine, and/or in combination with anti-obesity agents such
as orlistat, and/or in combination with a .beta.3 agonist, for
treating obesity.
[0114] The compounds made by the processes of the invention may
also be used to treat skin disorders or diseases involving dermal
atrophy such as glucocorticoid induced dermal atrophy, including
restoration of dermal atrophy induced by topical glucocorticoids,
the prevention of dermal atrophy induced by topical glucocorticoids
(such as the simultaneous treatment with topical glucocorticoid or
a pharmacological product including both glucocorticoid and a
compound of the invention), the restoration/prevention of dermal
atrophy induced by systemic treatment with glucocorticoids,
restoration/prevention of atrophy in the respiratory system induced
by local treatment with glucocorticoids, UV-induced dermal atrophy,
or dermal atrophy induced by aging (wrinkles, etc.), wound healing,
keloids, stria, cellulite, roughened skin, actinic skin damage,
lichen planus, ichthyosis, acne, psoriasis, Dernier's disease,
eczema, atopic dermatitis, chloracne, pityriasis and skin
scarring.
[0115] In treating skin disorders or diseases as described above,
the compounds made by the processes of the invention may be used
alone or optionally in combination with a retinoid such as
tretinoin or a vitamin D analog, employing amounts as disclosed in
the PDR.
[0116] The hypolipidemic agent which may be optionally employed in
combination with the compounds of formula I may include
thiazolidinediones, MTP inhibitors, HMG CoA reductase inhibitors,
squalene synthetase inhibitors, 5 fibric acid derivatives, ACAT
inhibitors, cholesterol absorption inhibitors, ileal Na.sup.+/bile
acid cotransporter inhibitors, bile acid sequestrants, and/or
nicotinic acid and derivatives thereof.
[0117] MTP inhibitors employed herein include MTP inhibitors
disclosed in U.S. Pat. No. 5,595,872, U.S. Pat. No. 5,739,135, U.S.
Pat. No. 5,712,279, U.S. Pat. No. 5,760,246, U.S. Pat. No.
5,827,875, U.S. Pat. No. 5,885,983 and U.S. Pat. No. 5,962,440.
Preferred are each of the preferred MTP inhibitors disclosed in
each of the above patents and applications.
[0118] Most preferred MTP inhibitors to be employed with the
compounds made by the processes of the present invention include
preferred MTP inhibitors as set out in U.S. Pat. Nos. 5,739,135 and
5,712,279, and U.S. Pat. No. 5,760,246.
[0119] The most preferred MTP inhibitor is
9-[4-[4-[[2-(2,2,2-Trifluoroeth-
oxy)benzoyl]amino]-1-piperidinyl)butyl]-N-(2,2,2-trifluoroethyl)-9H-fluore-
ne-9-carboxamide, formula VII. 19
[0120] The hypolipidemic agent may be an HMG CoA reductase
inhibitor which includes, but is not limited to, mevastatin and
related compounds as disclosed in U.S. Pat. No. 3,983,140,
lovastatin (mevinolin) and related compounds as disclosed in U.S.
Pat. No. 4,231,938, pravastatin and related compounds such as
disclosed in U.S. Pat. No. 4,346,227, simvastatin and related
compounds as disclosed in U.S. Pat. Nos. 4,448,784 and 4,450,171.
Other HMG CoA reductase inhibitors which may be employed herein
include, but are not limited to, fluvastatin, disclosed in U.S.
Pat. No. 5,354,772, cerivastatin disclosed in U.S. Pat. Nos.
5,006,530 and 5,177,080, atorvastatin disclosed in U.S. Pat. Nos.
4,681,893, 5,273,995, 5,385,929 and 5,686,104, pyrazole analogs of
mevalonolactone derivatives as disclosed in U.S. Pat. No.
4,613,610, indene analogs of mevalonolactone derivatives as
disclosed in PCT application WO 86/03488,
6-[2-(substituted-pyrrol-1-yl)-alkyl)pyran-2-one- s and derivatives
thereof as disclosed in U.S. Pat. No. 4,647,576, Searle's SC-45355
(a 3-substituted pentanedioic acid derivative) dichloroacetate,
imidazole analogs of mevalonolactone as disclosed in PCT
application WO 86/07054, 3-carboxy-2-hydroxy-propane-phosphonic
acid derivatives as disclosed in French Patent No. 2,596,393,
2,3-disubstituted pyrrole, furan and thiophene derivatives as
disclosed in European Patent Application No. 0221025, naphthyl
analogs of mevalonolactone as disclosed in U.S. Pat. No. 4,686,237,
octahydronaphthalenes such as disclosed in U.S. Pat. No. 4,499,289,
keto analogs of mevinolin (lovastatin) as disclosed in European
Patent Application No. 0,142,146 A2, as well as other known HMG CoA
reductase inhibitors.
[0121] In addition, phosphinic acid compounds useful in inhibiting
HMG CoA reductase suitable for use with compounds of formula I are
disclosed in GB 2205837.
[0122] The squalene synthetase inhibitors suitable for use with
compounds of formula I include, but are not limited to,
.alpha.-phosphonosulfonates disclosed in U.S. Pat. No. 5,712,396,
those disclosed by Biller et al., J. Med. Chem., 1988, Vol. 31, No.
10, pp 1869-1871, including isoprenoid
(phosphinylmethyl)phosphonates as well as other squalene synthetase
inhibitors as disclosed in U.S. Pat. Nos. 4,871,721 and 4,924 024
and in Biller et al., Current Pharmaceutical Design, 2, 1-40
(1996).
[0123] In addition, other squalene synthetase inhibitors suitable
for use with compounds of formula I include the terpenoid
pyrophosphates disclosed by P. Ortiz de Montellano et al., J. Med.
Chem., 1977, 20, 243-249, the farnesyl diphosphate analog A and
presqualene pyrophosphate (PSQ-PP) analogs as disclosed by Corey
and Volante, J. Am. Chem. Soc., 1976, 98, 1291-1293,
phosphinylphosphonates reported by McClard, R. W. et al,
J.Am.Chem.Soc., 1987, 109, 5544 and cyclopropanes reported by
Capson, T. L., PhD dissertation, June, 1987, Dept. Med. Chem. Univ.
of Utah, Abstract, Table of Contents, pp 16, 17, 40-43, 48-51,
Summary.
[0124] Other hypolipidemic agents suitable for use with compounds
of formula I include, but are not limited to, fibric acid
derivatives, such as fenofibrate, gemfibrozil, clofibrate,
bezafibrate, ciprofibrate, clinofibrate and the like, probucol, and
related compounds as disclosed in U.S. Pat. No. 3,674,836, probucol
and gemfibrozil being preferred, bile acid sequestrants such as
cholestyramine, colestipal and DEAE-Sephadex (Secholexk,
Policexide, as well as lipostabil (Rhone-Poulenc), Eisai E-5050 (an
N-substituted ethanolamine derivative), imanixil (HOE-402),
tetrahydrolipstatin (THL), istigmastanylphosphorylcho- line (SPC,
Roche), aminocyclodextrin (Tanabe Seiyoku), Ajinomoto AJ-814
(azulene derivative), melinamide (Sumitomo), Sandoz 58-035,
American Cyanamid CL-277,082 and CL-283,546 (disubstituted urea
derivatives), nicotinic acid, acipimox, acifran, neomycin,
p-aminosalicylic acid, aspirin, poly(diallylmethylamine)
derivatives such as disclosed in U.S. Pat. No. 4,759,923,
quaternary amine poly(diallyldimethylammonium chloride) and ionenes
such as disclosed in U.S. Pat. No. 4,027,009, and other known serum
cholesterol lowering agents.
[0125] The other hypolipidemic agent may be an ACAT inhibitor such
as disclosed in Drugs of the Future 24, 9-15 (1999), (Avasimibe);
Nicolosi et al., Atherosclerosis (Shannon, Ireland) 1998, 137(1),
77-85; Ghiselli, Giancarlo, Cardiovasc. Drug Rev. 1998, 16(1),
16-30; Smith, C., et al., Bioorg. Med. Chem. Lett. 1996, 6(1),
47-50; Krause et al., Editor(s): Ruffolo et al., Inflammation:
Mediators Pathways 1995, 173-98, Publisher: CRC Press, Boca Raton,
Fla.; Sliskovic et al., Curr. Med. Chem. 1994, 1(3), 204-25; Stout
et al., Chemtracts: Org. Chem. 1995, 8(6), 359-62.
[0126] The hypolipidemic agent may be a cholesterol absorption
inhibitor preferably Schering-Plough's SCH48461 as well as those
disclosed in Atherosclerosis 115, 45-63 (1995) and J. Med. Chem.
41, 973 (1998).
[0127] The hypolipidemic agent may be an ileal Na.sup.+/bile acid
cotransporter inhibitor such as disclosed in Drugs of the Future,
24, 425-430 (1999). Preferred hypolipidemic agents are pravastatin,
lovastatin, simvastatin, atorvastatin, fluvastatin
andcerivastatin.
[0128] The amounts and dosages employed will be as indicated in the
Physician's Desk Reference (PDR) and/or in the patents set out
above.
[0129] The compounds of formula I will be employed in a weight
ratio to the hypolypidemic agent, the antidepressant, and/or bone
resorption inhibitor and/or appetite suppressant (where present),
within the range from about 500:1 to about 0.005:1, preferably from
about 300:1 to about 0.01:1.
[0130] The antidiabetic agent which may be optionally employed in
combination with compounds of formula I may include biguanides,
sulfonyl ureas, glucosidase inhibitors, thiazolidinediones and/or
aP2 inhibitors and/or PPAR .alpha. agonists, PPAR .gamma. agonists
or PPAR .alpha./.gamma. dual agonists, and/or SGLT2 inhibitors, or
meglitinide.
[0131] The antidiabetic agent may be an oral antihyperglycemic
agent, preferably a biguanide such as metformin or phenformin or
salts thereof.
[0132] Where the antidiabetic agent is a biguanide, the compounds
of formula I will be employed in a weight ratio to biguanide within
the range from about 0.01:1 to about 100:1, preferably from about
0.5:1 to about 2:1.
[0133] The antidiabetic agent may also preferably be a sulfonylurea
such as glyburide (also known as glibenclamide), glimepiride
(disclosed in U.S. Pat. No. 4,379,785), glipizide, gliclazide or
chlorpropamide, other known sulfonylureas or other
antihyperglycemic agents which act on the ATP-dependent channel of
the .beta.-cells, with glyburide and glipizide being preferred.
[0134] The compounds of formula I will be employed in a weight
ratio to the sulfonyl urea in the range from about 0.01:1 to about
100:1, preferably from about 0.2:1 to about 10:1.
[0135] The oral antidiabetic agent may also be a glucosidase
inhibitor such as acarbose (disclosed in U.S. Pat. No. 4,904,769)
or miglitol (disclosed in U.S. Pat. No. 4,639,436), which may be
administered in a separate oral dosage form.
[0136] The compounds of formula I will be employed in a weight
ratio to the glucosidase inhibitor within the range from about
0.01:1 to about 100:1, preferably from about 0.5:1 to about
50:1.
[0137] The compounds of formula I may be employed in combination
with a thiazolidinedione oral anti-diabetic agent or other insulin
sensitizers (which has an insulin sensitivity effect in NIDDM
patients) such as troglitazone (Warner-Lambert's Rezulin.TM.,
disclosed in U.S. Pat. No. 4,572,912), rosiglitazone (SKB),
pioglitazone (Takeda), Mitsubishi's MCC-555 (disclosed in U.S. Pat.
No. 5,594,016), Glaxo-Welcome's GI-262570, englitazone (CP-68722,
Pfizer), or darglitazone (CP-86325, Pfizer).
[0138] The compounds of formula I will be employed in a weight
ratio to the thiazolidinedione in an amount within the range from
about 0.01:1 to about 100:1, preferably from about 0.5:1 to about
5:1.
[0139] The sulfonylurea and thiazolidinedione in amounts of less
than about 150 mg oral antidiabetic agent may be incorporated in a
single tablet with the compounds of structure I.
[0140] The compounds of formula I may also be employed in
combination with a non-oral antihyperglycemic agent such as insulin
or with glucagon-like peptide-1 (GLP-1) such as GLP-1(1-36) amide,
GLP-1(7-36) amide, GLP-1(7-37) (as disclosed in U.S. Pat. No.
5,614,492 to Habener, the disclosure of which is incorporated
herein by reference), which may be administered via injection,
intranasal, or by transdermal or buccal devices.
[0141] Where present, metformin, the sulfonylureas, such as
glyburide, glimepiride, glipyride, glipizide, chlorpropamide and
gliclazide and the glucosidase inhibitors acarbose or miglitol or
insulin may be employed in formulations as described above and in
amounts and dosing as indicated in the Physician's Desk Reference
(PDR).
[0142] Where present, metformin or salt thereof may be employed in
amounts within the range from about 500 to about 2000 mg per day
which may be administered in single or divided doses one to four
times daily.
[0143] Where present, the thiazolidinedione anti-diabetic agent may
be employed in amounts within the range from about 0.01 to about
2000 mg/day, which may be administered in single or divided doses
one to four times per day.
[0144] Where present insulin may be employed in formulations,
amounts and dosing as indicated by the Physician's Desk Reference
(PDR).
[0145] Where present GLP-1 peptides may be administered in oral
buccal formulations, by nasal administration or parenterally as
described in U.S. Pat. No. 5,346,701 (TheraTech), U.S. Pat. No.
5,614,492 and 5,631,224.
[0146] The antidiabetic agent may also be a PPAR .alpha./.beta.
dual agonist such as disclosed by Murakami et al., "A Novel Insulin
Sensitizer Acts As a Coligand for Peroxisome
Proliferation-Activated Receptor Alpha (PPAR alpha) and PPAR gamma.
Effect on PPAR alpha Activation on Abnormal Lipid Metabolism in
Liver of Zucker Fatty Rats", Diabetes 47, 1841-1847 (1998).
[0147] The antidiabetic agent may be an aP2 inhibitor such as
disclosed in U.S. application Ser. No. 09/391,053, filed Sep. 7,
1999, and U.S. provisional application No. 60/127,745, filed Apr.
5, 1999, employing dosages as set out herein.
[0148] The antidiabetic agent may be an SGLT2 inhibitor such as
disclosed in U.S. provisional application 60/158,773, filed Oct.
12, 1999.
[0149] The compounds of formula I will be employed in a weight
ratio to the PPAR .alpha. agonist, PPAR .gamma. agonist, PPAR
.alpha./.gamma. dual agonists, SGLT2 inhibitor and/or aP2 inhibitor
within the range from about 0.01:1 to about 100:1, preferably from
about 0.5:1 to about 5:1.
[0150] The dose administered must be carefully adjusted according
to age, weight and condition of the patient, as well as the route
of administration, dosage form and regimen and the desired
result.
[0151] The dosages and formulations for the hypolipidemic agent and
antidiabetic agent will be as disclosed in the various patents and
applications discussed above and in the Physicians' Desk
Reference.
[0152] The dosages and formulations for the other hypolipidemic
agent, antidepressant, bone resorption inhibitor, appetite
suppressant and anti-obesity agent to be employed, where
applicable, will be as set out in the latest edition of the
Physicians' Desk Reference.
[0153] For oral administration, a satisfactory result may be
obtained employing the MTP inhibitor in an amount within the range
of from about 0.01 mg/kg to about 100 mg/kg and preferably from
about 0.1 mg/kg to about 75 mg/kg, one to four times daily.
[0154] A preferred oral dosage form, such as tablets or capsules,
will contain the MTP inhibitor in an amount of from about 1 to
about 500 mg, preferably from about 2 to about 400 mg, and more
preferably from about 5 to about 250 mg, one to four times
daily.
[0155] For parenteral administration, the MTP inhibitor will be
employed in an amount within the range of from about 0.005 mg/kg to
about 10 mg/kg and preferably from about 0.005 mg/kg to about 8
mg/kg, one to four times daily.
[0156] For oral administration, a satisfactory result may be
obtained employing an HMG CoA reductase inhibitor, for example,
pravastatin, lovastatin, simvastatin, atorvastatin, fluvastatin or
cerivastatin in dosages employed as indicated in the Physician's
Desk Reference, such as in an amount within the range of from about
1 to 2000 mg, and preferably from about 4 to about 200 mg.
[0157] The squalene synthetase inhibitor may be employed in dosages
in an amount within the range of from about 10 mg to about 2000 mg
and preferably from about 25 mg to about 200 mg.
[0158] A preferred oral dosage form, such as tablets or capsules,
will contain the HMG CoA reductase inhibitor in an amount from
about 0.1 to about 100 mg, preferably from about 5 to about 80 mg,
and more preferably from about 10 to about 40 mg.
[0159] A preferred oral dosage form, such as tablets or capsules
will contain the squalene synthetase inhibitor in an amount of from
about 10 to about 500 mg, preferably from about 25 to about 200
mg.
[0160] The compounds of formula I and the hypolipidemic agent,
antidepressant or bone resorption inhibitor may be employed
together in the same oral dosage form or in separate oral dosage
forms taken at the same time.
[0161] The compositions described above may be administered in the
dosage forms as described above in single or divided doses of one
to four times daily. It may be advisable to start a patient on a
low dose combination and work up gradually to a high dose
combination.
[0162] The preferred hypolipidemic agent is pravastatin,
simvastatin, lovastatin, atorvastatin, fluvastatin or
cerivastatin.
[0163] The compounds of formula I can be administered orally or
parenterally such as subcutaneously or intravenously, as well as by
nasal application, rectally or sublingually to various mammalian
species known to be subject to such maladies, e.g., humans, cats,
dogs and the like in an effective amount within the dosage range of
about 0.1 to about 100 mg/kg, preferably about 0.2 to about 50
mg/kg and more preferably about 0.5 to about 25 mg/kg (or from
about 1 to about 2500 mg, preferably from about 5 to about 2000 mg)
on a regimen in single or 2 to 4 divided daily doses.
[0164] The active substance can be utilized in a composition such
as tablet, capsule, ointment, hydrophilic ointment, cream, lotion,
solution or suspension or in other type carrier materials such as
transdermal devices, iontophoretic devices, rectal suppositories,
inhalant devices and the like. The composition or carrier will
contain about 5 to about 500 mg per unit of dosage of a compound of
formula I. The active substances may be compounded in a
conventional matter with a physiologically acceptable vehicle or
carrier, excipient, binder, preservative, stabilizer, or flavor, as
called for by accepted pharmaceutical practice.
[0165] The following examples are provided to describe the
invention in further detail. These examples are intended to
illustrate and not to limit the invention. All temperatures are
given in centigrade degrees (.degree. C.) unless otherwise
noted.
EXAMPLE 1
[0166] Preparation of 1-isopropyl-2-methoxybenzene
[0167] A 22 L three-necked round bottom flask equipped with
mechanical stirring was charged with KOH (1154 g, 20.56 moles),
tetrabutylammonium hydrogen sulfate (140 g, 0.411 mole), and
deionized water (5.6 L). The mixture was cooled to a temperature of
approximately 20.degree. C. to 25.degree. C. Methylene chloride
(5.6 L) was added to the flask, then 2-isopropylphenol (590 g, 4.33
moles). The mixture was stirred for 0.5 h before iodomethane (741
g, 5.22 moles) was added. The stirring was continued at room
temperature until the reaction was observed to be complete by HPLC,
typically after approximately 5 h. Stirring was discontinued and
the reaction mixture was allowed to settle into aqueous and organic
layers, which were then separated. Triethylamine (185 mL, 1.33
moles) was added to the organic phase with stirring for at least 15
min. Solvent was then removed by vacuum distillation to afford a
white solid. Cyclohexane (41) was added to the white solid, which
was filtered and washed with further cyclohexane to remove the
reaction product as a solvate. The cyclohexane solution was washed
with aqueous HCl (2N), then half-saturated aqueous NaCl, and
finally saturated aqueous NaCl. The cyclohexane was removed by
vacuum distillation to afford 1-isopropyl-2-methoxybenzene as a
light yellow oil of medium viscosity (612 g, 94% yield).
EXAMPLE 2
[0168] Preparation of 3-isopropyl-4-methoxybenzaldehyde
[0169] A 5 L three-necked round bottom flask was equipped with
mechanical agitation and provided with an inert gas blanket. The
flask was charged with 1-isopropyl-2-methoxybenzene (859 g, 5.85
moles) and dimethylformamide (1584 mL, 20.46 moles), and the
mixture was heated to 80.degree. C. Phosphorus oxychloride (2690 g,
17.54 moles) was added to the reaction mixture over approximately 3
h while maintaining the temperature of the reaction mixture between
80.degree. C. and 90.degree. C. The addition of POCl.sub.3 caused
an immediate color change with continuous darkening over the course
of the reaction. The reaction mixture was maintained at 80.degree.
C. for approximately 16 h, then checked by HPLC for presence of
unreacted starting materials. The reaction mixture was quenched by
slow addition over approximately 2 h to icewater (8 kg total, 5 kg
ice); alternatively the reaction mixture was added over
approximately 3 h to deionized water (10 L) in a jacketed 30 L
reactor whose cooling bath was maintained between 0.degree. and
5.degree. C. Ethyl acetate (12 L) was added to the quenched
reaction with stirring. After settling, the layers were separated,
and the aqueous layer was washed with additional ethyl acetate (4
L). The combined organic layers were washed with saturated aqueous
sodium bicarbonate solution (4 L) and saturated aqueous sodium
chloride (4 L). The ethyl acetate was removed by vacuum
distillation to yield 3-isopropyl-4-methoxybenzaldehyde (881 g,
86.5%).
EXAMPLE 3
Preparation of
hydroxy-(3-isopropyl-4-methoxy-phenyl)methanesulfonic acid, sodium
salt
[0170] A 22 L three-necked round bottom flask equipped with
mechanical agitation was charged with
3-isopropyl-4-methoxybenzaldehyde (880 g, 4.94 moles), THF (4650
mL), and cyclohexane (3740 mL) at room temperature. To this mixture
was added, with stirring, an aqueous solution of sodium bisulfite
(1310 g, 12.56 moles, in 4360 mL of deionized water). The reaction
mixture was stirred overnight at room temperature. The reaction
product was removed by filtration, washed liberally with
cyclohexane:THF (3:1) and dried overnight by evaporation under air
flow at room temperature to yield
hydroxy-(3-isopropyl-4-methoxyphenyl)methanesulfonic acid as the
sodium salt (1302 g, 93.4%).
EXAMPLE 4
[0171] Preparation of 3-isopropyl-4-methoxyphenol
[0172] A 22 L three-necked round bottom flask equipped with
mechanical agitation was charged with
hydroxy-(3-isopropyl-4-methoxyphenyl)methanesu- lfonic acid, sodium
salt (1300 g, 4.61 moles), p-toluenesulfonic acid monohydrate (908
g, 4.77 moles), and methanol (10.4 L), and the mixture was cooled
to 0.degree. to 5.degree. C. Hydrogen peroxide (30% aqueous, 1.625
L, 16.12 moles) was added slowly to the reaction mixture over about
2 h. The reaction mixture was stirred overnight and allowed to
return to room temperature. The completeness of the reaction was
assayed by HPLC; if the reaction was incomplete, further hydrogen
peroxide was added to the reaction mixture. The reaction mixture
was cooled once more to 0.degree. to 5.degree. C. and then quenched
by addition of an aqueous slurry of sodium dithionite (1860 g,
10.68 moles, stirred 1 h at room temperature in 6.5 L deionized
water). After stirring at least 0.5 h, the reaction mixture was
filtered, and the white solids were washed with ethyl acetate (8
L). The ethyl acetate and the aqueous filtrate were combined,
agitated, and allowed to separate. Cyclohexane was added if
necessary to facilitate separation. The organic phase was washed
with sodium bicarbonate (4 L, 10% aqueous solution), then with
saturated aqueous sodium chloride solution (4 L). The solvent was
removed by vacuum distillation to afford
3-isopropyl-4-methoxyphenol (510 g, 66.7%).
EXAMPLE 5
Preparation of Trifluoromethanesulfonic acid
2,6-dibromo-4-nitrophenyl ester
[0173] A 12 L jacketed vessel equipped with a mechanical stirrer
and nitrogen inlet adapter was charged with dichloromethane (3.2 L)
and 2,5-dibromo-4-nitrophenol (800 g, 2.69 moles). The reaction
mixture was cooled to 0C and sparged with nitrogen gas. Pyridine
(0.436 L, 3.23 moles) was introduced via addition funnel while the
temperature of the reaction mixture was maintained below 8.degree.
C. The reaction mixture was stirred at 0.degree. C. for 5 min, then
a solution of triflic anhydride (0.544 L, 3.23 moles) in
dichloromethane (0.400 L) was added via addition funnel while
maintaining the reaction temperature below 10.degree. C. The
reaction mixture was warmed to room temperature, stirred 30 min,
and monitored periodically by HPLC. After the reaction had run to
completion, aqueous hydrochloric acid (1N, 1.6 L) was added to the
reaction mixture dropwise with stirring. The reaction temperature
was maintained below 35.degree. C. during the addition of the acid.
The reaction mixture was allowed to settle into layers, and the
organic phase was separated and washed first with saturated aqueous
sodium bicarbonate (0.8 L), then with saturated aqueous sodium
chloride (0.8 L). The organic phase was concentrated by rotary
evaporation under vacuum at 40.degree. C., then dried overnight
under vacuum to yield trifluoromethane sulfonic acid
2,6-dibromo-4-nitrophenyl ester (1140 g, 99.1%).
EXAMPLE 6
Preparation of 1,3-dibromo-2-iodo-5-nitrobenzene
[0174] Dimethylformamide (4 L) and trifluoromethane sulfonic acid
2,6-dibromo-4-nitrophenyl ester (1135 g, 2.65 moles) were charged
into a 22 L jacketed vessel equipped with a mechanical stirrer, a
condenser, and a nitrogen purge. Sodium iodide (1595 g, 10.64
moles) was added to the reaction mixture in portions while
maintaining the reaction temperature below 25.degree. C. The
reaction mixture was then heated to 100.degree. C. and monitored
for completion by HPLC. Upon completion, the reaction mixture was
cooled to 0.degree. C. Water (4 L) was added while maintaining the
temperature below 14.degree. C. The reaction mixture was stirred
for 30 min, then filtered and washed with water (1.5 L). The
resultant solid product was dried overnight by evaporation under
air flow at room temperature to yield
1,3-dibromo-2-iodo-5-nitrobenzene (892.7 g, 82.9%). The product may
optionally be purified further by recrystallization from
ethanol.
EXAMPLE 7
Preparation of
4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole
[0175] A 22 L jacketed vessel equipped with mechanical stirring and
a nitrogen inlet adapter was charged with dimethylformamide (4 L)
and 3-isopropyl-4-methoxyphenol (462.8 g, 2.59 moles). The solution
was cooled to 0C, and KHMDS (5.50 L of 0.5M toluene solution, 2.25
moles) was added over 1.5 h while maintaining the temperature of
the mixture below 2.degree. C. The reaction mixture was stirred for
30 min at 2.degree. C., then 1,3-dibromo-2-iodo-5-nitro-benzene
(798.6 g, 1.96 moles) was added in portions, still maintaining
temperature of the mixture below 2.degree. C. After the addition
was complete, the reaction mixture was allowed to stir at room
temperature for 2 h or until the reaction was complete as assayed
by HPLC. The reaction mixture was cooled once more to 2.degree. C.
and ethyl acetate (4.5 L) was added, followed by slow addition of
saturated aqueous sodium bicarbonate (6 L) while maintaining the
temperature of the reaction mixture below 28.degree. C. The organic
layer was washed with saturated aqueous sodium chloride solution,
then concentrated by rotary evaporation. The black, oily residue
was taken up in acetone (3.87 L). Water (0.77 L) was added to the
solution over 30 min with heating to 42.degree. C. The solution was
seeded with crystals of the product, cooled to 0.degree. C., and
stirred for 15 min. The resulting crystals of
4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole (665 g, 76.1%)
were recovered by filtration and dried for 48 h by evaporation
under air flow at room temperature.
EXAMPLE 7A
Preparation of
4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole
[0176] 3-Isopropyl-4-methoxyphenol (197.2 g, 1.19 moles) was
dissolved in dimethylformamide (4 L). The mixture was stirred while
the reaction vessel was cooled in an icewater bath. Sodium
hydroxide (1.278 L of 1.0M aqueous solution, 1.278 moles) was added
while maintaining the temperature of the reaction mixture below
35.degree. C. 1,3-Dibromo-2-iodo-5-nitrobenzene (400.0 g, 0.983
moles) dissolved in dimethylformamide (portion of 4 L) was added to
the reaction mixture over approximately 45 min. The reaction
mixture was stirred at 20.degree. to 25.degree. C. for 24 h.
Deionized water (2 L) was added over 2 h and the reaction mixture
was cooled to 5.degree. C. The resulting crystals of
4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole (405.4 g, 92.6%)
were recovered by filtration and dried for 48 h by evaporation
under air flow at room temperature.
EXAMPLE 8
Preparation of 4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylphenol
[0177] A 12 L three-necked round bottom flask equipped with a
mechanical stirrer, an addition funnel, and a temperature probe was
charged with 4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole
(752.1 g, 1.69 moles), which was dissolved by stirring in
dichloromethane (2 L) at room temperature. The mixture was cooled
to 8.7.degree. C. in an ice-water bath. A solution of boron
tribromide (2.050 L, 1M in CH.sub.2Cl.sub.2, 2.05 moles) was added
over 30 min. An increase of approximately 10.degree. C. in the
temperature of the reaction mixture was observed. The ice-water
bath was removed and the reaction mixture was allowed to stir at
room temperature until the reaction was complete, as assayed by
HPLC. The reaction mixture was cooled once more in an ice-water
bath, then quenched by slow addition of methanol (850 mL), during
which the temperature of the reaction mixture was maintained below
18.degree. C. Saturated aqueous sodium bicarbonate solution was
added until the pH of the reaction mixture was 6 or 7. The aqueous
phase was separated and washed with aliquots of ethyl acetate
(2.times.1 L). The organic layers were combined and the solvent
removed under a vacuum at room temperature to yield crude
4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylphenol (796 g, 110%).
EXAMPLE 9
Preparation of 4-(4-amino-2,6-dibromophenoxy)-2-isopropylphenol
[0178] 4-(2,6-Dibromo-4-nitrophenoxy)-2-isopropylphenol (795 g,
1.84 moles) was divided into three roughly equal portions. Each
portion was dissolved in THF (2.6 L) and charged into a 12 L
three-necked round bottom flask equipped with a mechanical stirrer,
addition funnel, and temperature probe. The solutions were heated
to 33.degree. C. Sodium dithionite (482 g, 2.4 moles) dissolved in
deionized water (2.6 L) was added to each flask. The reaction
temperature was held at 50.degree. C. until each reaction was
complete as assayed by HPLC. Hydrochloric acid (6N aqueous) was
added dropwise to the heated reaction mixtures until their pH was
about 3, and heating was continued for 45 min. The reaction
mixtures were cooled to room temperature and their pH was adjusted
to 6.6 by addition of saturated aqueous sodium bicarbonate
solution. Ethyl acetate (2.5 L) was added to each flask with
stirring for 2 min. Each reaction mixture was separated, and each
organic layer was washed once with half-saturated aqueous sodium
chloride solution, then once with saturated aqueous sodium chloride
solution. The solvents were removed by rotary evaporation and the
solids were dried overnight in a vacuum oven at 40.degree. C. to
yield crude 4-(4-amino-2,6-dibromophenoxy)-2-isopropy- lphenol (657
g, 96.9%). The crude 4-(4-amino-2,6-dibromophenoxy)-2-isoprop-
ylphenol was purified by recrystallization from isopropanol upon
addition of 2.5 volumes of deionized water (90% recovery).
EXAMPLE 10
Preparation of
N-[3,5-dibromo-4-(4-hydroxy-3-isopropylphenoxy)phenyl]malon- amic
acid
[0179] A slurry of 4-(4-amino-2,6-dibromophenoxy)-2-isopropylphenol
(160 g, 0.401 mole) in t-butyl methyl ether (TBME, 1.07 L) was
prepared in a 3 L, three-necked round bottom flask equipped with a
mechanical stirrer, a thermocouple probe and an addition funnel.
The mixture was cooled to 2.degree. C. using a dry ice-acetone
bath. A solution of sodium hydroxide (0.76M, 0.53 L, 0.401 mole)
was added over 20 min while keeping the internal temperature of the
reaction mixture below 2.degree. C. Ethyl malonyl chloride (78.2
mL, 0.614 mole) was added via addition funnel to the biphasic
mixture over 10 min while still maintaining the internal
temperature below 2.degree. C. The cooling bath was removed and the
mixture was stirred for 40 min at room temperature. Fifteen minutes
after the addition of malonyl chloride was completed, the reaction
temperature was 5.degree. C. and HPLC analysis of the reaction
mixture failed to detect any remaining starting material. The
reaction mixture was once more cooled to 2.degree. C. using a dry
ice-acetone bath, and a solution of sodium hydroxide (10.0 M, 176
mL, 1.76 moles) was added over 10 min. The internal temperature of
the reaction mixture was maintained below 2.degree. C. After the
addition was complete, the cooling bath was removed and the mixture
was stirred at room temperature. Two hours after the addition of
NaOH was complete, the reaction temperature was 19.degree. C. and
none of the intermediate ethyl ester was detected by HPLC analysis.
The organic layer was separated and extracted with water (150 mL).
Any remaining traces of organic solvent were removed from the
combined aqueous layers by distillation under reduced pressure. The
aqueous solution was cooled in a dry ice-acetone bath to an
internal temperature of 1.degree. C. and acidified with HCl (10%
aqueous, 1.25 L). The internal temperature of the mixture was
maintained below 2.degree. C. throughout the addition. The
resultant precipitated solid was collected by filtration and washed
twice with water. The solid was dried to constant weight in a
vacuum oven at 40.degree. C. to provide crude
N-[3,5-dibromo-4-(4-hydroxy-3-isopropylphenoxy)phenyl]malonamic
acid as a beige solid (219.5 g, 113%). The crude product was
recrystallized with 90% recovery from methanol upon addition of
water and cooling to 0.degree. C.
COMPARATIVE EXAMPLE
[0180] Acetic anhydride (9.9 g, 97.5 mmoles) was charged to a
three-necked round bottom flask equipped with magnetic stirring, a
nitrogen-inlet adapter, and an addition funnel. The acetic
anhydride was cooled to a temperature of 200 to 25.degree. C. by
immersing the flask in a dry ice-ethanol bath. Fuming nitric acid
(6 g, 94.9 mmoles) was added dropwise to the acetic anhydride while
maintaining the internal temperature of the mixture. Iodine (1 g,
3.94 mmoles) was added in one portion, followed by the addition of
trifluoroacetic anhydride (5.4 g, 47.3 mmoles). The reaction
mixture, which contained the unisolated intermediate iodonium salt
(CF.sub.3CO.sub.2).sub.3I, was warmed to room temperature.
[0181] An aliquot of the reaction mixture (9 mL) in a Reactive
System Screening Tool (RSST) was placed inside a bomb. The bomb was
pressurized with nitrogen (300 psig at 15.degree. C.) and heated at
the rate of 1 C.degree./min. The 10 mL glass cell of the RSST did
not break; however, some of the reaction mixture erupted into the
bomb, and the remainder of the aliquot changed color from red to
dark purple-black.
[0182] FIG. 1 is a graph of the resulting temperature vs. time
measurements. It is apparent that an exothermic reaction began
almost immediately with the commencement of heating. Similar
results were obtained in differential scanning calorimetry (DSC)
experiments. The data in FIG. 1, and the accompanying observations,
illustrate that the thermal decomposition of the unisolated
iodonium salt (CF.sub.3CO.sub.2)3I is so highly exothermic as to
render (CF.sub.3CO.sub.2)3I hazardous as an intermediate in large
scale preparations.
[0183] 2-Isopropylphenol was reacted with methyl iodide in the
presence of potassium carbonate to yield
1-isopropyl-2-methoxybenzene, which in turn was reacted with the
solution of unisolated intermediate (CF.sub.3CO.sub.2).sub.3I
described above to form the bis-[3-isopropyl-4-methoxyphenyl]
iodonium salt in 40-70% yield. The
bis-[3-isopropyl-4-methoxyphenyl] iodonium salt precipitated as a
gummy solid, making purification impracticable and contributing to
the unpredictability of the yield.
[0184] The bis-[3-isopropyl-4-methoxyphenyl] iodonium salt was
reacted with 2,6-dibromo-4-nitrophenol in the presence of elemental
copper and triethylamine, over the course of 4 to 5 days in the
dark, to form 4-(4-nitro-2,6-dibromophenoxy)-2-isopropylphenol in
50 to 80% yield. The extended time required for the ether
formation, its unpredictable yield, and the unusual necessity to
exclude light are inefficiencies that also militate against
commercial practice of this synthetic route.
[0185] The entire disclosures of the patents and other publications
cited above are incorporated herein by reference. While certain
preferred embodiments of the present invention have been described
and specifically exemplified above, it is not intended that the
invention be limited to such embodiments. Various modifications may
be made to the invention without departing from the scope and
spirit thereof as set forth in the following claims.
* * * * *