CZ20004725A3 - 4-benzylpiperidine alkyl sulfoxide heterocycles and their use as subtype-selective NMDA receptor antagonists - Google Patents

Abstract

The novel 4-benzylpiperidine alkylsulfoxide heterocycles and their use as selective NMDA receptor antagonists, particularly for the treatment of Parkinson's disease, most preferably in combination with L-DOPA.

Description

Technical field

The invention relates to 4-benzylpiperidine alkylsulfoxide heterocycles. The compounds of the invention are selectively active as antagonists of N-methyl-D-aspartate (NMDA) receptor subtypes. The invention also relates to the use of 4-benzylpiperidine alkylsulfoxide heterocycles as neuroprotective agents for the treatment of such conditions as, for example, strokes, cerebral ischemia, central nervous system trauma, macular and other retinal degenerative diseases, hypoglycemia, anxiety, psychoses, asthma, glaucoma, CMV retinitis, urinary incontinence, tinnitus, hearing loss caused by aminoglycoside antibiotics, convulsions, headache, chronic depression, opiate tolerance or withdrawal, or neurodegenerative diseases such as lathyrism, Alzheimer's disease, Parkinson's and Huntington's disease. A particularly preferred use of the compositions of the invention is the treatment of Parkinson's disease.

BACKGROUND OF THE INVENTION

4-Benzylpiperidine analogs which are useful as subtype selective NMDA receptor antagonists are described in PCT International Application No. WO 97/23216. However, piperidine analogs that contain a sulfofoxide functionality are not disclosed.

Benzylpiperidine derivatives are also described in US Patent No. 5,698,553 and have the formula:

B • 99 · · ······ · · · · ·

9 9 ··· 98 9

999 9999 99 99 99 999 where

R ¹ is H, halogen or nitro,

R ² is benzyl that is unsubstituted or substituted on the aromatic moiety at the 2-, 3- or 4-position of the piperidine ring, with the proviso that R ² is not 4benzyl, i.e. R ² is not 4-position of the piperidine ring, if X is -CO-, Y and Z are CH ₂ and R ¹ is H,

R ³ is H or A,

X is -O-, -S-, -NH-, -CO- or -SO ₂ -,

Y is -CH ₂ -, -O-, -S- -NH- or alternatively -CO- if X is -CO- and Z is -NHor -NA-,

Z is -CH ₂ -, -C (A) ₂ -, -CH ₂ CH ₂ -, -CH = CH-, -CO-, -NH-, -NA-, -O-, -S- or a bond, wherein XY or YZ is not -O-O-, -SS-, -NH-O-, -Ο-NH-, -NH-NH-, -O-S- or -S-O-,

A is alkyl of 1 to 6 carbon atoms,

B is O or both H and OH, i.

together with the carbon atom to which they are attached, form -CH (OH) Hal is F, Cl, Br or I and n is 0, 1 or 2 and salts thereof.

The compounds are said to be useful for the treatment of cerebrovascular disease, epilepsy, schizophrenia, Alzheimer's disease, Parkinson's or Huntington's disease, cerebral ischemia or heart attack. However, subtype selectivity is not indicated and again, piperidine analogs having a sulfoxide functionality are not disclosed.

Excitatory amino acid receptor antagonists that block NMDA receptors are expected to be useful in the treatment of diseases. NMDA receptors are primarily involved in the phenomenon of excitotoxicity, which may be a determining factor causing some neurological diseases. Diseases known to be due to NMDA receptor blockade include acute cerebral ischemia (e.g., stroke or brain trauma), muscle spasm, seizure disorders, neuropathic pain and anxiety, and may be a major factor in causing chronic neurodegenerative diseases such as Parkinson's Disease [T. Klockgether, L. Turski, Ann. Neurol. 34 585-593 (1993)], Human Immunodeficiency Virus (HIV) Neurological Changes, Amyotrophic Lateral Sclerosis · · · ··· ··· (ALS), Alzheimer's disease [PT] Francis, N.R. Sims, A.W. Proder, D.M. Bowen,

J. Neurochem: 60 (5), 1589-1604 (1993)] and Huntington's Disease. [See. Lipton, S. 16 (12), 527-532 (1993); S.A. Lipton, P.A. Rosenberg, New Eng. J. Med. 330 (9): 613-622 (1994); and C.F.Bigge, Biochem. Pharmacol. 45, 1547-1561 (1993) and references cited herein]. NMDA receptor antagonists can also be used to prevent tolerance to opiate analgesia or to help control the regression of drug addiction symptoms (Eur. Pat. Appl. 488.959A).

By initial cloning of the first NMDA receptor subunit, NMDAR1 (NR1) in the Nakanis laboratory in 1991, an initial investigation of the molecular structure of the NMDA receptor was performed [Nature 354, 31-37 (1991)]. There are several structurally related subunits (NMDAR2A to NMDAR2D) that bind to NR 1. in a heteromeric arrangement to form a functional ion channel complex of the receptor [Annu. Roar. Neurosci. 17, 31-108 (1994)]. Molecular heterogeneity of NMDA receptors suggests possible future agents with selective pharmacology towards subunits.

Many properties of native NMDA receptors are evident in the recombinant homomeric NR1 receptors expressed in Xenopus oocytes. These properties are altered by NR2 subunits. Recombinant NMDA receptors expressed by Xenopus oocytes were studied using voltage clamp according to developmental data and local expression of mRNAs encoding NMDA receptor subunits. Electrophysiological measurements were used to characterize the effects of compounds on NMDA receptors expressed in Xenopus oocytes. Compounds were tested on four combinations of cloned rat NMDA receptor subunits, corresponding to the three putative NMDA receptor subunits [Moriyoshi et al., Nature 1991, 354, 31-37; Monyer et al., Science 1992, 256, 1217-1221; Kutsuwada et al., Nature 1992, 358, 36-41; Sugihara et al., Biochem Biophys. Res. Commun. 1992, 185, 826-832]

Novel 4-benzylpiperidines having increased subtype selectivity will be highly desirable, particularly for the treatment of Parkinson's disease.

SUMMARY OF THE INVENTION

The present invention relates to novel 4-benzylpiperidine alkylsulfoxide heterocycles of formula (I)

or stereoisomers or pharmaceutically acceptable salts thereof, wherein R and R 'are independently selected from hydrogen, hydroxy, alkyl, halogen, nitro, cyano, carboxaldehyde, aldehyde, lower alkoxycarbonylmethyl, hydroxy lower alkyl, aminocarbonylmethyl, hydrazinocarbonylmethyl, acetamido, aryl, aralkyl, amino, halogenated alkyl, lower alkylamino or lower alkoxy;

R and R 'are independently selected from hydrogen, hydroxy, alkyl, halogen, amino, halogenated alkyl, lower alkylamino or lower alkoxy;

X is hydrogen or hydroxy;

Z is -CH 2 or -C (O) -;

n is 2 to 4; and

Y is O, NH or S.

The compounds of the invention include stereoisomers such as enantiomers as well as racemic mixtures. A particularly preferred enantiomer of the present invention is (+) 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} benzoxazol-2-one.

Examples of pharmaceutically acceptable addition salts include inorganic and organic acid addition salts, for example, hydrochloride, hydrobromide, phosphate, sulfate, citrate, lactate, tartrate, malate, fumarate, mandelate, oxalate, and actetate.

Halogen is fluorine, chlorine, bromine or iodine; a preferred group is fluorine, chlorine and bromine.

Alkyl represents a straight or branched chain of one to six carbon atoms or a cyclic alkyl of three to seven carbon atoms including, but not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.

Aryl represents a monocyclic or bicyclic carbocyclic aromatic ring system which may be substituted or unsubstituted, for example, but not limited to, phenyl, naphthyl and the like.

Aralkyl represents any of the alkyl groups defined herein, substituted with any aryl group defined herein.

Halogenated alkyl represents any alkyl group as defined herein, substituted with one or more halogen groups as defined herein.

Lower alkylamine represents any alkyl group as defined herein, substituted with an amino group.

Lower alkoxy represents an alkoxy group containing an alkyl group as defined herein.

The invention also relates to a pharmaceutical composition comprising a compound of the invention in an effective amount for the treatment of chronic neurodegenerative diseases or cerebrovascular diseases responsive to selective blockade of subunits

NMDA receptor subtypes and a pharmaceutically acceptable carrier. Examples of responsive diseases include cerebral ischemia caused by stroke, stroke, hypoglycaemia, heart attack and postoperative conditions; anxiety, psychosis and schizophrenia; glaucoma; CMV retinitis; antibiotic-induced hearing loss; asthma; urinary incontinence; opioid tolerance or withdrawal; and chronic neurodegenerative diseases such as Huntington's disease, ALS, Parkinsonism, and Aizheimer's disease. The pharmaceutical composition of the invention may act as an analgesic or be adapted to treat epilepsy or migraine headaches. The pharmaceutical composition of the invention may also be used for the treatment of otological diseases, including, for example, tinnitus, aminoglycoside antibiotic-induced hearing loss and sound-induced hearing loss. Eye diseases such as glaucoma, CMV retinitis, age-related macular degradation (AMD) and other retinal degenerative diseases can also be treated with the composition of the invention.

A particularly preferred composition of the invention comprises a compound of the invention in combination with dopamine agonists or prodrugs, for example L-DOPA and a pharmaceutically acceptable carrier. 4-Benzylpiperidine alkylsulfoxide heterocycles and LDOPA are present in an amount effective to treat Parkinson's disease. The composition of the invention may also contain other agents used to treat Parkinson's such as pergolide, bromocryptine, pramipexole (mirapas), depreryl, amorphine and the like.

The invention further relates to a method of treating diseases which are susceptible to selective blocking of N-methyl-D-aspartate receptor subtypes in animals suffering from these diseases, which comprises administration in a unit dosage form of at least one compound of the invention. A particularly preferred embodiment includes a method of treating Parkinson's disease with both a 4-benzylpiperidine alkylsulfoxide heterocycle and L-DOPA.

The novel 4-benzylpiperidine alkylsulfoxide heterocycles of the invention are represented by the general formula I. Preferably, Z is -CH ₂ -, R is hydrogen and R 'is hydrogen.

More preferably, X is hydrogen and R is selected from the group consisting of hydrogen, fluoro, chloro, bromo and alkyl. More preferably, n is 2 and Y is 0. The compounds of the invention are selective NMDA

more preferably, the NR1A / 2B selective subtypes.

Examples of compounds of the invention include:

6- {2- [4- (4-chloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (4-Methyl-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one;

6- {2- [4- (4-Methoxy-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (3,4-dichloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (2-Fluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- [2- (4-benzy-4-hydroxypiperidin-1-yl) ethanesulfinyl] -3H-benzoxazol-2-one;

6- {2- [4- (4-Fluorobenzyl) -4-hydroxypiperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one;

6- [2- (4-Benzoyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one;

6- {2- [4- (2,3-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (2,4-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (4-Trifluoromethylbenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (2,6-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

6- {2- [4- (2,4-dichloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one;

N- (4- {1- [2- (2-oxo-2,3-dihydrobenzoxazole-6-sulfinyl) ethyl] piperidin-4-ylmethyl} phenyl) acetamide;

6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -5-chloro-3H-benzoxazol-2-one; 5-chloro-6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; (+) - 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; (-) - 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; and pharmaceutically acceptable salts thereof.

The compounds of the invention can be used in the treatment or prevention of neuronal loss, neurodegenerative diseases and chronic pain. They can also be used as antispasmodic as well as for the treatment of epilepsy and psychosis. The therapeutic and side effects of the subtype of selective NMDA receptor subtype antagonists may differ significantly from many of the subtype of non-selective NMDA receptor inhibitors. The subtypes of selective analogs of the present invention are expected to

• ·· • Φ · • • • • * Φ · ♦ · ΦΦ · · • φ Φ Φ Φ φ Φ Φ • « • • • Φ • · • · • Φ ♦ ·· ··· • ΦΦ • · φ Φ φφφ

exhibit little or no undesirable side effects due to non-specific binding to other receptors, more specifically PCP and glutamate binding sites associated with the NMDA receptor. In addition, selectivity to different NMDA receptor subtypes reduces side effects, such as sedative effects, that are common to all subtypes of non-selective NMDA receptor antagonists. The compounds of the invention are effective in treating or preventing the adverse consequences of excitatory amino acid hyperactivity, for example, those involved in the NMDA receptor system, by preventing ligand-closed cation channels prior to opening and allowing subsequent Ca ⁺⁺ flow to neurons, which occurs during ischemia.

Neurodegenerative diseases that can be treated with the compounds of the invention include those selected from the group consisting of Alzheimer's disease, amyotropic lateral sclerosis, Huntington's disease, Parkinson's disease, and Down's syndrome. The treatment of Parkinson's disease in combination therapy with L-DOPA is particularly preferred.

The compounds of the invention have particular utility in the treatment or prevention of neuronal loss associated with strokes that cause dementia. After a patient has been diagnosed with a stroke, the compounds of the invention may be administered to suppress immediate ischemia and to prevent further neuronal damage that may occur after repeated strokes.

The compounds of the invention have particular utility in the treatment or prevention of adverse neurological postoperative sequelae. For example, cardiac bypass surgery requires the use of cardiac and pulmonary devices that deliver air bubbles to the circulatory system that can settle in the brain. The presence of these air bubbles removes oxygen from the neural tissue, causing oxygen deficiency in the tissue and ischemia. Prior to or post-operative administration of the compounds of the invention, they act therapeutically or prevent possible ischemia. In a preferred embodiment, the compounds of the invention are administered to patients prior to cardiopulmonary bypass surgery or carotid endarterectomy.

The compounds of the invention may also find use in the treatment or prevention of chronic pain. This chronic pain may be the result of surgery, trauma, 9

9 9 «99 9 999

9 9 9 9 9

9,999,999 9

999 9999 99 99 99 999 headache, arthritis, end-stage cancer pain or degenerative diseases. The compounds of the invention may also find use in the treatment or prevention of apparent pain following necessary amputation. In addition to pain relief, the compounds of the invention are also expected to induce anesthesia, general or local anesthesia, for example during surgery.

Selective NMDA receptor subtype antagonists and modulators can be tested for in vivo anticonvulsant activity following intraperitoneal or intravenous injection using a series of anticonvulsant tests in mice (audiogenic seizure model in DBA-2 mice, pentylentetrazole-induced seizures in mice, maximum seizure-induced seizure test (MES) ) or NMDA-induced death). The compounds may also be tested in drug discrimination assays to test for the resolution of PCP from saline. It is believed that most of the compounds of the invention will not be generalized to PCP at any dose. These results are believed to confirm the assumption that the selective NMDA receptor subtype antagonists of the invention do not exhibit similar behavioral side effects as PCP (PCP-like) common to NMDA channel blockers such as MK-801 and PCP, or competitive NMDA antagonists, for example CGS 19755.

Selective NMDA receptor subtype antagonists are also believed to exhibit potent activity in vivo following intraperitoneal or intravenous injection, provided that these compounds can cross the blood / brain barrier.

Elevated glutamate levels are associated with glaucoma. In addition, it has been found that treatment of glaucoma, more specifically, retinal ganglion cell protection, can be achieved by administering to a patient a compound capable of reducing glutamate-induced external toxicity at a concentration effective to reduce excitotoxicity. See WO94 / 13275. Compounds of the invention that are believed to cross the blood / retina barrier are also expected to be useful in the treatment of glaucoma. Preferably, the invention is directed to the treatment of patients with primary open-angle glaucoma, chronic closed-angle glaucoma, pseudo doexfoliation or other types of glaucoma or ocular hypertension. Preferably, the compound is administered on a long-term basis (for example at least six months and preferably at least one year), with respect to changes in pressure of flflflflflflflflflfl.

Wflfl flflflfl flflfl inside the patient's eye during the time of administration. The compounds of the invention may also be useful in the treatment of CMV retinitis, particularly in combination with antiviral agents.

CMV affects the ganglion cell layer, which may result in higher levels of glutamate. Thus, NMDA receptor antagonists can block retinitis by blocking the toxic effects of high levels of glutamate. The compounds of the invention may also be useful in the treatment of other ocular diseases, such as AMD and other retinal degenerative diseases.

Aminoglycoside antibiotics have been used successfully in the treatment of serious gram-negative bacterial infections. However, prolonged treatment with these antibiotics results in disruption of the sensory cells of the inner ear and consequently permanent hearing loss. In a recent study by Basile et al. (Nature Medicine, 2: 1338-1344, 1996), aminoglycosides have been found to increase glutamate excitotoxicity similar to polyamine-like induced by their interaction with the NMDA receptor. Thus, compounds of the invention with NMDA receptor antagonist activity are useful in preventing hearing loss caused by aminoglycoside antibiotics through antagonistic interaction with the receptor. The compounds of the invention may also be useful in the treatment of other otological diseases such as tinnitus and noise-induced hearing loss.

The compounds of the invention are useful in the treatment of headaches, especially headaches in migraine. During a migraine attack, a sensory disorder with exceptional changes in brain blood flow manifests itself in the development of characteristic migraine auras. Since this exceptional phenomenon has been repeated in animal experiments with extended cerebral palsy (CSD), Leao, A.A.P.J., Neurophysiol. 7: 359-390 (1944), CSD is believed to have an important effect on the pathophysiology of migraine with aura (Tepley et al., Biomagnetism, eds. S. Williamson, L. Kaufamann, pp. 327-330, Plenum Press, New York (1990) )). CSD is associated with the spread (2 to 6 mm / s) of transient changes in electrical activity associated with impaired ionic homeostasis in the brain, outflow of excitatory amino acids from neurons, and increased energy metabolism (Lauritzen, M., Acta Neurol. Scand. 76 (Suppl. 113): 4-40 (1987)).

CSD infiltration in a variety of animals, including humans, has been shown to involve glutamate release and may trigger NMDA (Curtis et al., Nature).

191: 1010-1011 (1961); and Lauritzen et al., Brain. Res. 475: 317-327 (1988)).

φφ ····φφφ φφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφφ φφφφφφφφφφφφφφφφφ

The subtype selective NMDA antagonists are therapeutically useful in migraine headaches because they are thought to have low side effects, the ability to cross the blood brain barrier and their overall bioavailability.

Bladder activity is controlled by parasympathetic preganglionic neurons in the sacral spinal cord (DeGroat et al., J. Auton. Nerv. Sys. 3: 135-160 (1981)). In humans, the highest density of NMDA receptors in the spinal cord has been found to be in the sacral portion, including those areas that are reported to contain parasympathetic preganglionic bladder neurons (Shaw et al., Brain Research 539: 164-168 (1991)). Because NMDA receptors are naturally excitable, pharmacological blockade of these receptors decreases bladder activity. The non-competitive NMDA receptor antagonist MK801 has been found to increase urinary frequency in rats (Vera and Nadelhaft, Neuroscience Letters 134: 135-138 (1991)). In addition, competitive NMDA receptor antagonists also cause dose-dependent inhibition of bladder and urinary sphincter activity (U.S. Patent 5,192,751). It is therefore expected that subtype selective NMDA receptor antagonists will be effective in treating urinary incontinence through their effect on receptor channel activity.

The non-competitive NMDA receptor antagonist MK801 has been shown to be effective in various animal models of anxiety states that are very similar to human anxiety states (Clineschmidt, B.V. et al., Drug Dev. Res. 2: 147-163 (1982)). In addition, NMDA receptor glycine site antagonists have been shown to be effective in the startle assay (Anthony, EW, Eur. J. Pharmacol. 250: 317-324 (1993)), as well as in some other animal models of anxiety (Winslow, J. & J. Pharmacol., 190: 11-22 (1990), Dunn, R. et al., Eur. J. Pharmaeol. 214: 207-214 (1992); and Kehne, JH et al., Eur. J. Pharmacol. 193: 282-292 (1981)). Glycine site antagonists, (+) HA-966 and 5,7-dichtorkinurenic acid have been found to selectively antagonize d-amphetamine-induced stimulation when injected into rat kernel but not into the striatum (Hutson, PH et al. , Br J Pharmacol 103: 2037-2044 (1991)). Interestingly, (+) HA-966 was also found to block PCP and MK801-induced excited behavior. (Bristow, L. J. et al. Br. J. Pharmacol. 108: 1156-1163 (1993)). These findings demonstrate the possible use of NMDA receptor channel modulators, but not channel blockers, as atypical neuroleptics.

·· 4444 · · • 4 4 4 4 4 4 4 4 4 ·· 4 4 4 4 4 4 4 ··· 4444 44 44 ♦ * 44

It has been found that the rat model of Parkinson's disease -MPP 'or methamphetamine-induced dopaminergic neuron disorder can be inhibited by NMDA receptor antagonists (Rojas et al., Drug Dev. Res.29: 222-226 (1993); and Sonsalla et al., Science 243: 398-400 (1989)). In addition, NMDA receptor antagonists demonstrate inhibition of haloperidolam-induced catalepsy (Schmidt, WJ et al., Amino Acids 1: 225-237 (1991)), an increase in activity in rodents with depleted monoamines (Carlsson et al., Trends Neurosci. 13: 272- 276 (1990)) and an increase in the y-axis rotation after a substantial one-sided lesion of substantia nigra in rats (Snell, LD, et al., J. Pharmacol. Exp. Ther. 235: 50-57 (1985)). These are also experimental animal models of Parkinson's disease. The antiparkinsonian agents amantadine and memantine exhibit similar plasma activity in animals in antiparkinsonian studies, leading to NMDA receptor antagonism (Danysz, W. et al., J. Neural Trans. 7: 155-166 (1994)). Thus, it is possible that these antiparkinsonian agents act therapeutically due to NMDA receptor antagonism. Thus, the level of NMDA receptor activity may be important in regulating the extrapyramidal function associated with the manifestation of parkinsonian symptoms.

It is well known to use opiates, such as morphine, which are used in medicine to alleviate pain. (The term opioid as used herein means any form or derivative of opium, especially the alkaloids in which they are naturally present, of which about twenty, for example morphine, noscapine, codeine, papaverine and thebaine, and derivatives thereof). Unfortunately, with prolonged use, the body develops opioid tolerance, and over a longer period the patient must take higher doses. Tolerance occurs following acute and chronic administration of morphine (Kornetski et al., Science 162: 1011-1012 (1968); Way et al., J. Pharmacol. Exp. Ther. 167: 1-8 (1969); Huidobro et al. , J. Pharmacol. Exp Ther. 198: 318-329 (1976); Lutfy et al., J. Pharmacol. Exp Ther. 256: 575-580 (1991)). This can in itself be at the expense of the patient's health. In addition, there may be a moment when the tolerance is substantially maximum and the drug no longer acts to ease the pain. Administration of high doses of morphine may also result in respiratory depression leading to respiratory arrest in the patient. Efforts to develop alternative analgesic drugs without tolerance, or as adjunctive therapy to block tolerance without affecting analgesic effects, is an active field of research.

Recent studies suggest a regulatory role for the NMDA receptor in morphine tolerance.

«W 000 0

0 0 0 0 0 0 0 0 0 0

0 0 0 0 • 0 0 0

00 000 (Trujillo et al., Science 251: 85-87 (1991); Mareka et al., Brain Res. 547: 77-81 (1991); Tiseo et al., J. Pharmacol.; Exp Ther. 264: 1090 -1096 (1993); Lutfy et al., Brain Res. 616: 83-88 (1993); Herman et al., Neuropsychopharmacology 12: 269-294 (1995)). It has also been reported that NMDA receptor antagonists are useful in inhibiting opioid tolerance and some symptoms after opioid regression. Thus, the invention is also directed to the administration of the compounds described herein for inhibiting opioid tolerance and suppressing symptoms after opioid withdrawal by blocking the glycine coagon site associated with the NMDA receptor.

It has been suggested that peripheral NMDA receptor activity may be an important mechanism of airway inflammation and hyperactivity in bronchial asthma. Said, S.J., Trends in Pharmacpol. Sci., 20: 132-34 (1999). It has been reported that this may explain the observation that acute asthma attacks may be due to glutamate-containing food and the ability of ketamine to relax smooth airway muscles due to the ability of ketamine to block the NMDA receptor. Thus, the compounds of the invention may be useful in the treatment of asthma.

Thus, the invention results in compounds having a high affinity for a particular NMDA receptor subtype and a low affinity for other sites, such as dopamine and other catecholamine receptors. The compounds of the invention with high binding affinity to a particular NMDA subunit exhibit an IC 50 of about 100 µΜ or less, preferably 10 µΜ or less, in the NMDA subunit binding assay. Most preferably, the compounds of the invention exhibit an IC 50 for a selective subunit of about 1.0 µΜ or less.

A composition within the scope of the present invention includes a composition wherein the compounds of the invention are contained in an amount effective to achieve the desired effect. Since the dosages are individual, the determination of optimal ranges of effective amounts of each component will be determined by one skilled in the art. The compound may generally be administered to a mammal, including a human, orally at a dosage of 0.0025 to 50mg / kg, or an equivalent amount of a pharmaceutically acceptable salt thereof, daily depending on the weight of the mammal being treated for anxiety, such as generalized anxiety disease, phobia, obsessive compulsion. disease, panic disease and post-traumatic stress diseases. Preferably, about 0.01 to 10 mg / kg is orally administered to treat or prevent.

0000 000 • 0000 0000 0, _Α 0 0 0 * 00 00 0 14 * Diseases such as schizophrenia or other psychoses. For intramuscular injection, the dose is generally about one-half of the oral dose. For example, an intramuscular dose of about 0.0025 to 15 mg / kg, and preferably about 0.01 to 10 mg / kg, is suitable for treating or preventing anxiety.

In a method of treating or preventing neuronal loss in ischemia, brain trauma or spinal cord trauma, hypoxia, hypoglycemia and postoperative conditions, treating or preventing glaucoma or urinary incontinence, as well as treating Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease and Down's syndrome, or in a method of treating diseases with pathophysiology including excitatory amino acid hyperactivity or NMDA receptor ion channel neurotoxicity, the pharmaceutical compositions of the invention may comprise compounds of the invention at a unit dose level of from about 0.01 to about 50 mg / kg body weight, or an equivalent amount of a pharmaceutically acceptable salt thereof, either as an intravenous injection, intravenous infusion, or in a dosage regimen of 1 to 4 times daily. In the treatment of chronic headache in migraine, in the treatment or prevention of asthma, in the induction of anesthesia, in the treatment or prevention of convulsions such as seizures caused by epilepsy, in the treatment of depression, in the treatment or prevention of opiate tolerance or according to the invention to be administered in a unit dose of from about 0.01 to about 50 mg / kg of body weight or an equivalent amount of a pharmaceutically acceptable salt thereof 1x to 4x daily. Obviously, the precise treatment depends on the prior condition of the animal, for example the human being treated. The exact dose of the drug can only be determined by one skilled in the art without undue experimentation.

A unit oral dose may contain from about 0.01 to about 50 mg of the compound, preferably from about 0.1 to 10 mg of the compound. The unit dose may be administered one or more times per day in one or more tablets each containing from about 0.01 to about 10, typically 0.25 to 50 mg, of the compound or solvates thereof.

In addition to administering the compound in the form of a raw chemical, the compounds of the invention may be administered as part of a pharmaceutical composition comprising suitable pharmaceutically acceptable carriers comprising excipients and excipients which are: ftft; ftft; ftt; ftt; ftt; Ft ft ft ft ft ft ft ft ft

facilitate processing of the compounds into forms that can be used pharmaceutically. Preferably, especially forms which can be administered orally and which can be used in a preferred mode of administration, such as tablets, dragees and capsules, and also forms that can be used rectally, such as suppositories, as well as suitable solutions for injection. or orally, comprise from about 0.01 to 99 percent, preferably from about 0.25 to 75 percent, of the active compound (s), together with a carrier.

Also included within the scope of the invention are non-toxic pharmaceutically acceptable salts of the compounds of the invention. Acid addition salts are prepared by mixing a solution of a particular selective NMDA receptor subtype antagonist of the invention with a solution of a pharmaceutically acceptable non-toxic acid such as hydrochloric acid, fumaric acid, maleic acid, succinic acid, acetic acid, citric acid, tartaric acid, carbonic acid, phosphoric acid, oxalic acid and the like.

The pharmaceutical compositions of the invention may be administered to any animal that may recognize the beneficial effects of the compounds of the invention. Most of these animals are mammals, for example humans, although the invention is not limited thereto.

The pharmaceutical compositions of the invention may be administered by any means to achieve their effect. For example, administration may be by the parenteral, subcutaneous, intravenous, intramuscular, intraperitoneal, transdermal or buccal route. Alternatively or conventionally, the oral route may be used. The dose to be administered depends on the age of the patient, the weight of the patient, the type of possible further treatment, the frequency of treatment and the type of effect desired.

The pharmaceutical forms according to the invention are prepared in a known manner, for example by conventional mixing, granulating, dragee-forming, dissolving or lyophilizing processes. Pharmaceutical forms for oral use can thus be prepared by combining the active ingredients with solid carriers, optionally grinding the resulting mixture and forming granules therefrom, and, if desired or necessary, upon addition of suitable additives, tablets or dragees are obtained.

Suitable excipients are, in particular, fillers, for example, carbohydrates, for example, 9, 9, 9, 90, 90 and 90. Lactose or sucrose, mannitol or sorbitol, cellulosic forms and / or calcium phosphates, for example calcium phosphate or dibasic calcium phosphate, the same as binders such as starch paste using, for example, corn starch, wheat starch, rice starch, tomato starch, gelatin, tragacanth, methylcellulose, hydroxypropylmethylcellulose, sodium carboxymethylcellulose and / or polyvinylpyrrolidone. If desired, disintegrating agents such as the above-mentioned starches as well as carboxymethyl starch, cross-linked polyvinylpyrrolidone, agar, or an alginic acid or a salt thereof, for example sodium alginate, may be added. Excipients include, but are not limited to, flowability agents and lubricants, for example, silica, talc, stearic acid or salts thereof, for example, magnesium or calcium stearate, and / or polyethylene glycol. In the dragee, a suitable coating substance, which is optionally resistant to gastric fluid, is used. For example, concentrated carbohydrate solutions may be used, which may optionally include gum arabic, talc, polyvinylpyrrolidone, polyethylene glycol and / or titanium dioxide, lacquer solutions, and suitable organic solvents, or solvent mixtures. Solutions of suitable forms of cellulose, for example acetylcellulose phthalate or hydroxypropylmethylcellulose phthalate, are used to form a suitable gastric fluid-resistant coating layer. Dyes or pigments may be added to the tablets or dragee coatings, for example, to distinguish or characterize combinations of active compound doses.

Other pharmaceutical forms which can be used orally include flexible capsules made of gelatin, as well as soft, sealed capsules made of gelatin and a plasticizer, for example glycerol and sorbitol. The flexible capsules may contain the active compounds in the form of granules, which may be mixed with fillers, for example lactose, binders, for example starch, and / or lubricants, for example talc or magnesium stearate, and optionally stabilizers. In soft capsules, the active compounds are preferably dissolved or suspended in suitable liquids, for example, fatty oils or liquid paraffin. In addition, stabilizers may be added.

Suitable pharmaceutical forms that can be used rectally include, for example, suppositories that consist of a combination of one or more active compounds and a suppository base. Suitable bases for suppositories are, for example, natural or synthetic triglycerides or paraffin hydrocarbons. It is also possible to use gelatin rectal capsules which consist of a combination of the active compounds with a carrier base. Possible carrier bases include, for example, liquid triglycerides, polyethylene glycols, or paraffin hydrocarbons.

• · · · · · · · · · · · · · · ·

Suitable forms for parenteral administration include aqueous solutions of the active compounds in water-soluble form, for example, water-soluble salts and alkaline solutions. In addition, suspensions of the active compounds may be employed as the appropriate oily suspensions in injectable form. Suitable lipophilic solvents or carriers include fatty oils such as sesame oil or synthetic fatty acid esters such as ethyl oleate or triglycerides or polyethylene glycol-400 (the compounds are soluble in PEG-400). Aqueous injection suspensions may contain substances which increase the viscosity of the suspension, including, for example, sodium carboxymethylcellulose, sorbitol, and / or dextran. The suspension may also optionally contain stabilizers.

In vitro characterization of NMDA subunit binding sites is difficult due to the lack of selective drug ligands. Thus, the compounds of the invention may be used to characterize and distribute NMDA subunits. Particularly preferred subtype selective NMDA receptor antagonists of the invention used for this purpose are isotopically labeled derivatives, for example where one or more atoms are replaced by ³ H, ¹¹ C, ¹⁴ C, ¹⁵ N or ¹⁸ F.

The following examples are illustrative of certain preferred embodiments only and are not intended to limit the scope of the present invention in any way.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

6- [2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl] -3H-benzoxazol-2-one

Step A: Preparation of 4- (4-fluorobenzyl) -1-piperidinethanthiol

A mixture of 4- (4-fluorobenzyl) piperidine (5.9 g, 30.5 mmol) and ethyl 2-mercaptoethyl carbonate (4.8 g, 32 mmol) was refluxed in toluene (250 mL) for 18 h under nitrogen. The toluene was removed in vacuo and the resulting oil was used in the next step without further purification.

Step B: Preparation of 5- [2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfanyl] -2-nitroanisole

A mixture of 4- (4-fluorobenzyl) -1-piperidinethanethiol (7.7 g, 30.4 mmol), 5-bromo-2-nitroanisole (7 g, 30.4 mmol) and K 2 CO 3 (4.8 g, 35 mmol) in of acetonitrile (250 mL) was refluxed for 18 hours under nitrogen. After cooling, the salts were removed by filtration and the filtrate was concentrated to an oil. The compound was purified by chromatography to give 6 g of an oil.

Step C: Preparation of 5- [2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfanyl] -2-nitrophenol

5- [2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfonyl] -2-nitroanisole (6 g) was heated under reflux in 48% hydrobromic acid (100 mL) for 2.5 h. The residue was partitioned between 2N Na ₂ CO 3 (200 mL) and chloroform (200 mL). The organic layer was dried (MgSO 4) and concentrated to a solid. Trituration in ethyl ether gave 4.3 g of 5- [2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfanyl] -2-nitrophenol, mp 130-133 ° C.

Step D: Preparation of 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfanyl} -3H-benzoxazol-2-one

5- [2- [4- (4-Fluorobenzyl) piperidin-1-yl) ethanesulfanyl] -2-nitrophenol (0.62 g, 1.59 mmol) was dissolved in a 50:50 mixture of tetrahydrofuran and methanol (100 mL) . After addition of Raney nickel (0.5 g), the reaction mixture was hydrogenated (0.35 MPa) for 2 hours. The catalyst was removed by filtration and the solvents were removed by distillation to give the aminophenol which was used immediately. The aminophenol (1.59 mmol) was treated with 1,1'-carbonyldiimidazole (0.5 g, 3 mmol) in tetrahydrofuran (100 mL) and stirred at ambient temperature for 18 hours. Removal of the solvent and purification of the residue by silica gel chromatography eluting with 5% 1N methanolic ammonia in chloroform gave the crude product. Triturace

in ethyl ether gave 0.42 g of 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfanyl} -3H-benzoxazol-2-one, m.p. Mp 177-179 ° C.

Step E: Preparation of 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

A solution of 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfanyl} -3H-benzoxazol-2-one (1.80 g, 4.55 mmol) in glacial acetic acid (120 mL) was added. This was treated with 30% hydrogen peroxide (1 mL, 9 mmol) and stirred at ambient temperature for 18 hours. After finding no peroxide, the reaction mixture was concentrated in vacuo and the residue neutralized with aqueous ammonia. The resulting solid was collected by filtration, dried and chromatographed on silica gel eluting with 20% 2N methanolic ammonia in chloroform. The homogeneous fractions were combined, concentrated to a solid and triturated in ethyl ether to give 1.25 g of 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one, m.p. Mp 202-204 ° C.

Example 2

6- {2- [4- (4-Chloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to Example 1, except that 4- (4-chlorobenzyl) piperidine was used as the starting material. (m.p. 213-214 ° C)

Example 3

6- {2- [4- (4-Methylbenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to that of Example

1, except that 4- (4-methylbenzyl) piperidine is used as the starting material.

(m.p. 177-179 ° C)

Example 4 • ·

6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to Example 1, except that 4-benzyl-piperidine was used as the starting material. (m.p. 176 through

178 ° C)

Example 5

6- {2- [4- (4-Methoxybenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to Example 1, except that 4- (4-methoxybenzyl) piperidine was used as the starting material (m.p. 169-170 ° C).

Example 6

6- {2- [4- (3,4-Dichlorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to Example 1, except that 4- (3,4-dichlorobenzyl) piperidine was used as the starting material (m.p. 189-191 ° C).

Example 7

6- {2- [4- (2-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4- (2-fluorobenzyl) piperidine was used as the starting material. (m.p.

179-181 ° C)

Example 8

• · · ·

6- [2- (4-Benzyl-4-hydroxypiperidin-1-yl) ethanesulfinyl] -3H-benzoxazol-2-one

• Φ

The title compound was prepared in an analogous manner to Example 1 except that 4-benzyl-4-hydroxypiperidine was used as the starting material. (mp 138-140 ° C).

Example 9

6- {2- [4- (4-Fluorobenzyl) -4-hydroxypiperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4- (fluorobenzyl) -4-hydroxypiperidine was used as the starting material. (m.p. 153-155 ° C)

Example 10

6- [2- (4-Benzoyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4-benzoyl-piperidine was used as the starting material. (mp 68-72 ° C)

Example 11

6- {2- [4- (2,3-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1, except that 4- (2,3-difluorobenzyl) piperidine was used as the starting material. (mp 183-190 ° C)

Example 12

6- {2- [4- (2,4-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4- (2,4-difluorobenzyl) piperidine was used as the starting material (m.p. 166-168 ° C).

Example 13,

6- {2- [4- (4-Trifluoromethyl-benzyl) -piperidin-1-yl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1, except that 4- (4-trifluoromethylbenzyl) piperidine was used as the starting material (m.p. 165-166 ° C).

Example 14

6- {2- [4- (2,6-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4- (2,6-difluorobenzyl) piperidine (m.p. 187-189 ° C) was used as the starting material.

Example 15

6- {2- [4- (2,4-Dichloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared in an analogous manner to Example 1 except that 4- (2,4-dichlorobenzyl) piperidine was used as the starting material (m.p. 146-148 ° C).

Example 16

N- [4- {1- [2- (2-oxo-2,3-dihydrobenzoxazole-6-sulfinyl) ethyl] piperidin-4-ylmethyl} phenyl) acetamide

The title compound was prepared in an analogous manner to Example 1 except that N - ({piperidin-4-ylmethyl} -phenyl) -acetamide was used as the starting material (m.p. 104-105 ° C).

Example 17,

6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -5-chloro-3H-benzoxazol-2-one

Step A: Preparation of 5-chloro-6-chlorosulfonyl-3H-benzoxazol-2-one

5-Chloro-3H-benzoxazol-2-one (10.0 g, 59 mmol) was added portionwise at -20 ° C to chlorosulfonic acid (30 mL). The mixture was stirred at room temperature for

2.5 hours and then at 70 ° C for 1.5 hours. The cooled reaction mixture was poured slowly into a mixture of ice and water (300 mL) and stirred for 1 hour. The precipitate was collected and washed with water. The dry precipitate was stirred in chloroform (500 mL) for 3 hours at room temperature, filtered and dried to give a pale orange solid.

Step B: Preparation of 5-chloro-6-sulfanyl-3H-benzoxazol-2-one

Zinc powder (14.4 g, 0.22 mol) was added to a solution of mercuric chloride (2.86 g, 10.6 mmol) in water (42 mL) and concentrated hydrochloric acid (1.7 mL). The mixture was stirred for 15 minutes and the supernatant was discarded. The residue was washed with water (2 x 15 mL), ethanol (2 x 15 mL) and diethyl ether (2 x 15 mL). To the residue was added 5-chloro-6-chlorosulfonyl-3H-benzoxazol-2-one (12.3 g, 46 mmol) and ethanol (70 mL) and the mixture was placed in an ice bath. Concentrated hydrochloric acid (36 ml) was added from a separatory funnel over 15 minutes and the resulting mixture was heated under reflux for 18 hours. The cooled reaction mixture was poured into ice-water (300 mL) and stirred for 20 minutes. The precipitate was collected to give 9.5 g of a white powder.

Step C: Preparation of 5-chloro- {6-chloroethanesulfanyl} -3H-benzoxazol-2-one Flflflfl Fl 4 9 4 9 4 4 4 9 ··· »« fl · ····· ·· ·· · 9

1,8-Diazabicyclo [5.4.0] undec-7-ene (7.2 mL, 48 mmol) was added at 0 ° C with stirring to 5-chloro-6-sulfanyl-3H-benzoxazol-2-one (9.5 g, 47 mmol) and 1-bromo-2-chloroethane (17.3 mL, 0.21 mol) in acetonitrile (80 mL). The resulting solution was stirred at room temperature overnight. The reaction mixture was poured into ice / water (200 mL) and the precipitate was collected. The precipitate was dissolved in ethyl acetate (350 mL), dried over magnesium sulfate, filtered and evaporated to give 6.0 g of an off-white solid.

Step D: Preparation of 5-chloro- {6-chloroethanesulfinyl} -3H-benzoxazol-2-one

Sodium periodate (2.49 g, 11.7 mmol) was added at 0 ° C with stirring to 5-chloro (6-chloroethanesulfanyl) -3H-benzoxazol-2-one (3.08 g, 11.7 mmol) ) in methanol (300 mL) and water (80 mL). The resulting mixture was stirred at room temperature for 1 hour and additional sodium periodate (2.49 g, 11.7 mmol) was added at 0 ° C and stirring was continued at room temperature for 3 days. Water (500 mL) was added and the mixture was extracted with chloroform (3 x 300 mL). The extracts were dried over magnesium sulfate, filtered and evaporated to give 3.1 g of a brown solid.

Step E: Preparation of 6- [2- (4-benzylpiperidin-1-yl) ethanesulfinyl] -5-chloro-3H-benzoxazol-2-one

4-Benzylpiperidine (0.2 mL, 1.2 mmol) in acetonitrile (5 mL) was treated with 5-chloro- {6-chloroethanesulfinyl} -3H-benzoxazol-2-one (300 mg, 1.1 mmol), 2N NaOH ( 0.5 ml) and water (0.5 ml). The mixture was stirred at 60 ° C under argon for 30 minutes. Additional 2N NaOH (0.5 mL) was added and the mixture was stirred at 60 ° C for a further 2 hours. The mixture was cooled to room temperature and the pH adjusted to 6. The precipitate was filtered off and dried to give 0.26 g of a powder. The powder was recrystallized from hot EtOAc (30 mL) and methanol (20 mL) to give 0.14 g of 6- [2- (4-benzylpiperidin-1-yl) ethanesulfinyl] -5-chloro-3H-benzoxazol-2-one as white powder (mp 190-192 ° C)

Example 18

5-Chloro-6- {2- [4- (4-fluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one

9 9 9 9 9 • 9 9 9

The title compound was prepared using a procedure analogous to that of Example 17, except that 4- (4-fluorobenzyl) piperidine (m.p. 199-200 ° C) was used as the starting material.

Example 19 (+) - 6- {2- [4- (4-Fluorobenzyl) piperidin-1-ylethanesulfinyl} -3H-benzoxazol-2-one

6-Chloroethanesulfinyl-3H-benzoxazol-2-one was prepared using a procedure analogous to that of Example 17, steps A-D, except that 3H-benzoxazol-2-one was used as the starting material.

The enantiomers of 6-chlorosulfinyl-3H-benzoxazol-2-one are separated by liquid chromatography on a 20 x 250 mm chirobiotic-T column, eluting with ethanol 2 ml / min. The faster eluting enantiomer was coupled with 4- (4-fluorobenzyl) piperidine using a procedure analogous to Example 17, step E yielding the title compound (mp 150-155 ° C) [α] 2 D = + 124 ° (C = 0.002, 1% CF ₃ CO ₂ H in MeOH)

Example 20 (-) - 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one

The title compound was prepared using a procedure analogous to that of Example 19, except that a slowly eluting enantiomer (mp 150-155 ° C) was obtained [α] ^D 20 = -146 ° (C = 0.002, 1%) CF ₃ CO ₂ H in MeOH)

The compounds of the present invention were tested by electrophysiological assays on NMDA receptor subunits and were found to be subtype selective NMDA antagonists.

9 ΦΦ Φ ΦΦ · 9 · · · · · · φ · φ

Electrophysiological assays on NMDA receptor subunits.

RNA preparation. CDNA clones encoding NR1A, NR2A, NR2B, NR2C and NR2D rat receptor subtypes were used (see Moriyoshi et al. Nature (Lond.) 354: 31-37 (1991); Kutsuwada et al., Nature (Lond.) 358: 36-41 (1992) Monyer et al., Science (Washington, DC) 256: 1217-1221 (1992); lkeda et al. FEBS Lett. 313: 34-38 (1992); Ishii et al., J. Biol. Chem., 268: 2836-2843 (1993) for details of these clones or their murine homologues). Clones were transformed into the appropriate host bacteria and plasmid preparations were prepared by conventional DNA purification techniques. A sample of each clone was linearized by restriction enzyme digestion and cRNA was synthesized using T3 RNA polymerase. cRNA was diluted to 400 ng / μΙ and stored in 1 μΐ aliquots at -80 ° C until injection.

Xenopus oocyte expression system.

Adult female Xenopus laevis were anesthetized (20-40 minutes) using 0.15% 3-aminobenzoic acid ethyl ester (MS-222) and 2-4 ovarian vesicles were surgically removed. Oocytes in the IV-VI stage of maturation were dissected from the ovary (Dumont, JN, J. Momhol. 136: 153-180 (1972)), still wrapped in ovarian tissue. Follicle-coated oocytes were microinjected with 1: 1 cRNA: NR1A + NR2A, 2B or 2C; injection of 1 to 10 ng of RNA encodes each receptor subunit. NR1A coding cRNA was injected alone at about 20 ng. Oocytes were stored in Barth's medium containing (in mM): NaCl, 88; KCl, 1; CaCl ₂ , 0.41; Ca (NO ₃ ) ₂ , 0.33; MgSO ₄ , 0.82; NaHCO3, 2.4; HEPES 5, pH 7.4, with 0.11 mg / ml gentamicin sulfate. While oocytes have so far been enveloped in surrounding ovarian tissues, 0.1% bovine serum was added to Barth's medium. The oocytes were cleared of follicle after 1-2 days followed by injection of collagenase treatment (0.5 mg / ml Sigma type I for 0.5-1 hour) (Miledi and Woodward, J. Physiol. (Lond.) 416 : 601-621 (1989)) and subsequently stored in serum-free medium.

Electrical measurements were made using a conventional two electrode volt terminal

4444 44 4,444 • 4 · 4 4 4 4 • 4,444 444

444 4444 44 44 44 444 (Dagan TEV200) within 3 to 21 days after injection. (Woodward et al., Mol. Pharmacol. 41: 89-103 (1992)). The oocytes were placed in a 0.1 ml measuring chamber, washed continuously (5-15 ml min) with a Ringers solution containing (in mM): NaCl, 115; KCl, 2; BaCl 2, 1.8; HEPES, 5; pH 7.4. Drugs were administered by bath wash. By using oocytes expressing different combinations of NMDA receptor subunits, existing NMDA were activated by concomitant administration of glutamate (100 μΜ) and glycine (1-100 μΜ). The inhibitory potency of the new antagonists was measured by response elicited by constant concentrations of glutamate and glycine, by measuring the decrease in induction with increasing concentrations of the antagonist.

Concentration inhibition curves were generated using Equation 1.

I / I control “1 / (1 + ([antagonist] / 10 ' ^pic5 °) ⁿ ) equation 1 where Icontroia is induced only by agonists alone, plC50 = -log IC50, IC50 is the concentration of antagonist which causes half maximal inhibition and slope factor (De Lean et al. Am. J. Physiol. 235: E97-102 (1978)). Analysis of incomplete curves was unreliable and IC50 values were calculated by simple regression of the linear portion of the curves. (Original source: Microcal Software).

The results of the electrophysiological tests are shown in Table 1.

Rat test using 6-OHDA

Rats in which lesions were caused using 6-hydroxydopamine were used in the assay (see Ungerstedt, U .; Arbuthnott, GW, Quantitative recording of rotational behavior in rats after 6-hydroxy-dopamine lesions of the nigrostriatal dopamine system. Brain Res. 1971, 24 ( 3), 485-93). Adult male SpragueDawley rats were anesthetized with chloral hydrate and unilateral lesions of the nigrostriatal dopamine system were completed by infusion of 8 µg dopamine HBr (6-OHDA) into the right part of the forebrain. Previously, rats were pre-treated intraperitoneally (IP) with 25 mg / kg of desipramine HCl for 30 minutes to protect norandrenergic neurons and pargylin, at 25 mg / kg of IP to enhance the effect of 6-OHDA.

··· ·

9 9 99 9 · 9 99

9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

Q Q * · ·······

99 ··· ·· »· · · · + 99

At least 3 weeks after surgery, the rotational movement of rats induced by amorphine HCl at 50 pg / kg was examined subcutaneously. In the present experiment, only those rats that demonstrated more than 100 controversial revolutions / hour in response to amorphine were used. Rotational behavior was measured using an automatic measurement system (Rotorat Rotational Activity System, MED Associates, Georgia, VT). Anti-parkinsonian activity was evaluated as the ability of the compounds of the invention to enhance the contraversive rotation induced by LDOPA methyl ester, 10 mg / kg SC over a 6 hour period. Experiments were performed using a cross-paradigm where each rat received either vehicle and L-DOPA or test compound and L-DOPA in random order. Rats were tested at 7 daily intervals. In experiments in which the compound was tested orally, the rats were foodless for 16 hours. Statistical analyzes between treatment groups were performed using the paired p-test. The results are shown in Table 1 as the minimum effective dose (MED) of the compound required to induce a statistically significant increase in the number of contraversive rotations compared to rats receiving only L-DOPA.

Table 1

0000 00

0000 000 000 0000 00 00 00 000

Example NRIA / 2A IC ₅₀ M NR1A / 2B IC 50 NR1A / 2C IC 50 OHDA test in rats MED mg / kg po 1 105 0.03 190 1 2 > 300 0.02 200 3 3 100 ALIGN! 0.03 3 4 > 300 0.03 > 300 3 5 55 0.10 150 > 10 6 70 0.10 80 > 10 7 55 0.09 60 10 8 40 1.10 230 - 9 50 0.90 200 > 10 10 70 0.34 140 - 11 40 0.05 140 10 12 30 0.01 130 10 13 35 0.04 150 10 14 55 0.04 160 > 10 15 Dec 90 0.04 150 10 16 > 300 10 > 300 - 17 40 0.16 > 300 > 10 18 35 0.11 > 300 > 10 19 Dec - 0.03 - 1 20 May - 0.03 - 10

Other variations and modifications of the present invention will be apparent to those skilled in the art. The invention is not limited to these variations except as indicated in the following claims.

Claims (28)

A compound of formula I or a stereoisomer or pharmaceutically acceptable salt thereof, wherein R and R 'are independently selected from hydrogen, hydroxy, alkyl, halogen, nitro, cyano, carboxaldehyde, aldehyde, lower alkoxycarbonylmethyl, hydroxy lower alkyl, aminocarbonylmethyl, hydrazinocarbonylmethyl, acetamido, aryl, aralkyl, amino, halogenated alkyl, lower alkylamino or lower alkoxy; R and R 'are independently selected from the group consisting of hydrogen, hydroxy, alkyl, halogen, amino, halogenated alkyl, lower alkylamino or lower alkoxy; X is hydrogen or hydroxy; Z is -CH ₂ or-C (O) -; n is 2 to 4; and Y is O, NH or S. A compound according to claim 1, wherein Z is -CH ₂ -, R is hydrogen and R 'is hydrogen. 4 4 4 5 6 7 8 9 0 0 9 9 9 9 9 9 0 • 99 9999 90 99 90 909 The compound of claim 2, wherein R 1 is hydrogen and X is hydrogen. The compound of claim 3, wherein R is selected from the group consisting of hydrogen, chloro, bromo and alkyl. The compound of claim 4, wherein n is 2. The compound of claim 5, wherein Y is O. The compound of claim 1, wherein said compound is selected from the group consisting of 6- {2- [4- (4-chloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (4-Methyl-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one; 6- {2- [4- (4-Methoxy-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (3,4-dichloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (2-Fluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- [2- (4-benzy-4-hydroxypiperidin-1-yl) ethanesulfinyl] -3H-benzoxazol-2-one; 6- {2- [4- (4-Fluoro-benzyl) -4-hydroxypiperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- [2- (4-Benzoyl-piperidin-1-yl) -ethanesulfinyl] -3H-benzoxazol-2-one; 6- {2- [4- (2,3-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (2,4-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (4-Trifluoromethylbenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (2,6-Difluoro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; 6- {2- [4- (2,4-dichloro-benzyl) -piperidin-1-yl] -ethanesulfinyl} -3H-benzoxazol-2-one; N- (4- {1- [2- (2-oxo-2,3-dihydrobenzoxazole-6-sulfinyl) ethyl] piperidin-4-ylmethyl} phenyl) acetamide; 6- [2- (4-Benzyl-piperidin-1-yl) -ethanesulfinyl] -5-chloro-3H-benzoxazol-2-one; 5-chloro-6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; (+) - 6- {2- [4- (4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one; • 00 00 ·· · · 0 • · · · 0 0 0 00 0 0 0 0 00 00 00 00 00 0 00 00 00 00 00 ethanesulfinyl} -3H-benzoxazol-2-one; and pharmaceutically acceptable salts thereof. The compound of claim 1, wherein said compound is 6- [2 - [- (4-Fluorobenzyl) piperidin-1-yl] -ethanesulfinyl] -3H-benzoxazol-2-one or a pharmaceutically acceptable salt thereof. An enantiomer of 6- [2- [4- (4-fluorobenzyl) piperidin-1-yl] -ethanesulfinyl] -3H-benzoxazol-2-one or a pharmaceutically acceptable salt thereof, wherein said enantiomer is present in at least 50% enantiomeric excess over the other enantiomers. The enantiomer of claim 9, wherein said enantiomer is (+) - 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one. A pharmaceutical composition comprising a pharmaceutically acceptable carrier or diluent and a therapeutically effective amount of at least one compound of claims 1 to 10. Pharmaceutical composition according to claim 11, characterized in that said composition is useful for the treatment of diseases sensitive to selective blockade of Nmethyl-D-aspartate receoptor subtypes selected from the group consisting of stroke, cerebral ischemia, central nervous system diseases, trauma , hypoglycaemia, neurodegenerative diseases, anxiety conditions, migraine headache, seizures, tinnitus, aminoglycoside antibiotic hearing loss, macular or retinal degeneration, psychosis, glaucoma, asthma, CMV retinitis, opioid tolerance or withdrawal, chronic pain or urinary incontinence. 13. The pharmaceutical composition of claim 12 wherein said neurodegenerative disease is Parkinson's disease. 14. The pharmaceutical composition of claim 13, further comprising a dopamine agonist or precursor thereof in an amount effective to treat Parkinson's disease. Ftft ftft ftft ftft ftft ftft ftft ftft ftft ftft ftftft 15. A pharmaceutical composition according to claim 14, wherein said dopamine agonist is L-DOPA. A pharmaceutical composition comprising (+) - 6- (2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one or a pharmaceutically acceptable salt thereof; substantially free of (-) - 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one and a pharmaceutically acceptable carrier or diluent. The pharmaceutical composition of claim 16, further comprising L-DOPA. 18. A method of treating diseases susceptible to selective blockade of N-methyl-D-aspartate receptor subtypes in animals suffering from these diseases, comprising administering to said animal in unit dosage form at least one compound represented by the general formula or a stereoisomer or pharmaceutically acceptable salt thereof. wherein R and R 'are independently selected from hydrogen, hydroxy, alkyl, halogen, nitro, cyano, carboxaldehyde, aldehyde, lower alkoxycarbonylmethyl, hydroxy lower alkyl, aminocarbonylmethyl, hydrazinocarbonylmethyl, and acetamido , aralkyl, amino, halogenated alkyl, lower alkylamino or lower alkoxy; • 9 Φ φφφφ φ »·· <· R and R 'are independently selected from the group consisting of hydrogen, hydroxy, alkyl, halogen, amino, halogenated alkyl, lower alkylamino or lower alkoxy; X is hydrogen or hydroxy; Z is -CH ₂ or-C (O) -; n is 2 to 4; and Y is O, NH or S. 19. The method according to claim 18, characterized mares s c s t in that Z is -CH ₂ -, R is hydrogen and R 'is hydrogen. 20. The method of claim 18 wherein said disease is selected from the group consisting of stroke, cerebral ischemia, central nervous system diseases, trauma, hypoglycemia, neurodegenerative diseases, anxiety conditions, migraine headache, convulsions, tinnitus, loss hearing loss caused by aminoglycoside antibiotics, macular or retinal degeneration, psychosis, glaucoma, asthma, CMV retinitis, opioid tolerance or withdrawal, chronic pain or urinary incontinence. 21. The method of claim 18, wherein said disease is Parkinson's disease. 22. The method of claim 18 wherein said disease is chronic pain. 23. The method of claim 18 wherein said disease is depression. 24. The method of claim 18, wherein said disease is a convulsion. • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · φ φφ φ 25. The method of claim 21, further comprising administering to said animal suffering from Parkinson's disease in a unit dosage form of a dopamine agonist. 26. The method of claim 25, wherein said dopamine agonist is L-DOPA. 27. A method for treating diseases susceptible to selective blockade of N-methyl-D-aspartic receptor subtypes in animals suffering from these diseases, which is administered in unit dosage form of (+) - 6- {2- [4- ( 4-Fluorobenzyl) piperidin-1-yl] ethanesulfinyl} -3H-benzoxazol-2-one or a pharmaceutically acceptable salt thereof, substantially free of (-) - 6- {2- [4- (4-fluorobenzyl) piperidin-1-yl] ethanesulfinyl } -3H-Benzoxazol-2-one. 28. The method of claim 27, wherein the method further comprises administering to said animal L-DOPA in unit dosage form.