GB2288800A - Pyrazolo-quinoline derivatives as NMDA and AMPA antagonists - Google Patents

Abstract

A class of 3,5-dihydro-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione derivatives, substituted in the 2-position by an optionally substituted phenyl moiety, (formula IA; R<1> - R<6> are H or organic residues as defined in claim 1) are selective non-competitive antagonists of NMDA receptors and/or are antagonists of AMPA receptors, and are therefore of utility in the treatment and/or prevention of a wide range of conditions (including neurodegenerative disorders, convulsions or schizophrenia) which require the administration of an NMDA and/or AMPA antagonist. <IMAGE>

Description

PYRAZOLO-QUINOLINE DERIVATIVES This invention relates to a class of 3,5-dihydro-lH- pyrazolo[3,4-c]quinoline- 1,4(2H)-dione derivatives which are substituted in the 2-position by an optionally substituted phenyl moiety. These compounds are selective non-competitive antagonists of N-methyl-Daspartate (NMDA) receptors. More particularly, the class of compounds provided by the present invention are ligands for the strychnineinsensitive glycine modulatory site of the NMDA receptor and are therefore useful in the treatment and/or prevention of neurodegenerative disorders arising as a consequence of such pathological conditions as stroke, hypoglycaemia, cerebral palsy, transient cerebral ischaemic attack, cerebral ischaemia during cardiac pulmonary surgery or cardiac arrest, perinatal asphyxia, epilepsy, Huntington's chorea, Alzheimer's disease, Amyotrophic Lateral Sclerosis, Parkinson's disease, Olivo-ponto-cerebellar atrophy, anoxia such as from drowning, spinal cord and head injury, and poisoning by exogenous and endogenous NMDA receptor agonists and neurotoxins, including environmental neurotoxins.

By virtue of their NMDA receptor antagonist properties, the compounds according to the present invention are also useful as anticonvulsant and antiemetic agents, as well as being of value in the prevention or reduction of dependence on dependence-inducing agents such as narcotics.

NMDA receptor antagonists have recently been shown to possess analgesic (see, for example, Dickenson and Aydar, Neuroscience Lett., 1991, 121, 263; Murray et al Pain, 1991, 44, 179; and Woolf and Thompson, Pain, 1991, 44, 293), antidepressant (see, for example, Trullas and Skolnick, Eur. J. Pharmacol., 1990, 185, 1) and anxiolytic (see, for example, Rehne et al., Eur. J. Pharmacol., 1991, 193, 283) effects, and the compounds of the present invention may accordingly be useful in the management of pain, depression and anxiety.

The association of NMDA receptor antagonists with regulation of the nigrostriatal dopaminergic system has recently been reported (see, for example, Werling et al., J. Pharmacol. Exo. Ther., 1990, 255, 40; Graham et al., Life Sciences, 1990, 47, PL-41; and Turski et al., Nature (London), 1991, 349, 414). This suggests that the compounds of the present invention may thus be of assistance in the prevention and/or treatment of disorders of the dopaminergic system such as schizophrenia and Parkinson's disease.

It has also been reported recently (see Lauritzen et al., Journal of Cerebral Blood Flow and Metabolism, 1991, vol. 11, suppl. 2, Abstract XV-4) that NMDA receptor antagonists block cortical spreading depression (CSD), which may thus be of clinical importance since CSD is a possible mechanism of migraine. The class of substituted 2-amino-4phosphonomethylalk-3-ene carboxylic acids and esters described in EP-A0420806, which are stated to be selective NMDA antagonists, are alleged thereby to be of potential utility in the treatment of inter alia migraine.

Excitatory amino acid receptor antagonists, including inter alia antagonists of NMDA receptors, are alleged in EP-A-0432994 to be of use in suppressing emesis.

Recent reports in the literature have also suggested a link between the neurotoxicity of certain viruses and the deleterious effects of these viruses on an organism caused by the potentiation of neurotransmission via excitatory amino acid receptors. By virtue of their activity as antagonists of NMDA receptors, therefore, the compounds of the present invention may be effective in controlling the manifestations of neuroviral diseases such as measles, rabies, tetanus (cf. Bagetta et al Br.

J. Pharmacol., 1990, 101, 776) and AIDS (cf. Lipton et al., Societv for Neuroscience Abstracts, 1990, 1G, 128.11).

NMDA antagonists have, moreover, been shown to have an effect on the neuroendocrine system (see, for example, van den Pol et al Science, 1990, 250, 1276; and Urbanski, Endocrinology, 1990, 127, 2223), and the compounds of this invention may therefore also be effective in the control of seasonal breeding in mammals.

In addition, certain compounds of the invention are antagonists of 2 -amino-3 -hydroxy- 5 -methyl-4-isoxazolepropionic acid (AMPA) receptors, also known as quisqualate receptors. An excitatory amino acid projection from the prefrontal cortex to the nucleus accumbens (a particular region of the forebrain possessing dopamine-sensitive neurones) is well known to exist (see, for example, J. Neurochem., 1985, 45 477). It is also well known that dopaminergic transmission in the striatum is modulated by glutamate (see, for example, Neurochem. Int., 1983, 5, 479), as also is the hyperactivity associated with presynaptic stimulation of the dopamine system by AMPA in the nucleus accumbens (cf. Life Sci., 1981, 28, 1597). Compounds which are antagonists of AMPA receptors are therefore of value as neuroleptic agents.

The preparation of the specific compound 3,5-dihydro-2 phenyl- 1H-pyrazolo[3,4-c]quinoline- 1,4(2H)-dione is described both in Helv. Chim. Acta, 1928, 11, 242; and in Ind. J. Chem., 1992, 31B, 316. In neither of these publications, however, is any pharmaceutical utility ascribed to this compound. Moreover, in neither of these publications is there any suggestion that the compounds described therein would be of assistance in solving the problem of providing an effective agent for the treatment and/or prevention of conditions requiring the administration of an antagonist of NMDA and/or AMPA receptors.

The present invention accordingly provides a pharmaceutical composition comprising a compound of formula IA or a pharmaceutically acceptable salt thereof or a prodrug thereof:

wherein R1 and R2 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRn, -SORa, -SO2Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; or R1 and R2 together represent the residue of a carbocyclic or heterocyclic ring; R3, R4, R5 and R6 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -SORa, -SO2Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -C02Ra or -CONRaRb; and Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group; in association with one or more pharmaceutically acceptable carriers and/or excipients.

The invention also provides a compound of formula IA as defined above or a pharmaceutically acceptable salt thereof or a prodrug thereof for use in therapy.

The term "hydrocarbon" as used herein includes straightchained, branched and cyclic groups containing up to 18 carbon atoms, suitably up to 15 carbon atoms, and conveniently up to 12 carbon atoms.

Suitable hydrocarbon groups include Cl.6 alkyl, C2-6 alkenyl, C2.6 alkynyl, C3-7 cycloalkyl, C3.7 cyclo alkyl(C i.e) alkyl, aryl, aryl(C i.e) alkyl, aryl(C2.6)alkenyl and aryl(C2.6)alkynyl.

The expression "a heterocyclic group" as used herein includes cyclic groups containing up to 18 carbon atoms and at least one heteroatom preferably selected from oxygen, nitrogen and sulphur. The heterocyclic group suitably contains up to 15 carbon atoms and conveniently up to 12 carbon atoms, and is preferably linked through carbon. Examples of suitable heterocyclic groups include C3.7 heterocycloalkyl, C3.7 heterocyclo alkyl(C 1.6) alkyl, heteroaryl and heteroaryl(C1-6)alkyl groups.

Suitable alkyl groups include straight-chained and branched alkyl groups containing from 1 to 6 carbon atoms. Typical examples include methyl and ethyl groups, and straight-chained or branched propyl and butyl groups. Particular alkyl groups are methyl, ethyl, n-propyl, isopropyl and t-butyl.

Suitable alkenyl groups include straight-chained and branched alkenyl groups containing from 2 to 6 carbon atoms. Typical examples include vinyl and allyl groups.

Suitable alkynyl groups include straight-chained and branched alkynyl groups containing from 2 to 6 carbon atoms. Typical examples include ethynyl and propargyl groups.

Suitable cycloalkyl groups include groups containing from 3 to 7 carbon atoms. Particular cycloalkyl groups are cyclopropyl and cyclohexyl.

Suitable aryl groups include phenyl and naphthyl groups.

A particular aryl(Ci.e)alkyl group is benzyl.

A particular aryl(C2-6)alkenyl group is phenylethenyl.

A particular aryl(C2.6)alkynyl group is phenylethynyl.

Suitable heterocycloalkyl groups include piperidyl, piperazinyl and morpholinyl groups.

A particular heterocycloalkyl(Cl.6)alkyl group is morpholinylethyl.

Suitable heteroaryl groups include pyridyl, quinolyl, isoquinolyl, pyridazinyl, pyrimidinyl, pyrazinyl, pyrrolyl, indolyl, pyranyl, furyl, benzofuryl, thienyl, benzthienyl, imidazolyl, oxadiazolyl and thiadiazolyl groups. Particular heteroaryl groups are pyridyl, pyrrolyl, indolyl, furyl, benzofuryl, thienyl, benzthienyl and oxadiazolyl.

Particular heteroaryl(Cl.6)alkyl groups include pyridylmethyl, pyrrolylmethyl, indolylmethyl, furylmethyl and thienylmethyl.

Where Rl and R2 together represent the residue of a carbocyclic or heterocyclic ring, the ring may be saturated or unsaturated.

The ring may suitably be a 4- to 9-membered ring, but will preferably be a 5- or 6-membered ring. Where R' and R2 together represent the residue of a heterocyclic ring, this ring may contain up to four heteroatoms selected from oxygen, nitrogen and sulphur. Suitable carbocyclic rings of which Rl and R2 together represent the residue include cyclohexane, cyclohexene, cyclohexadiene and benzene rings. Suitable heterocyclic rings of which R' and R2 together represent the residue include dioxolane, dioxane, pyridine, furan, thiophene, pyrrole, thiazole and thiadiazole rings.

The hydrocarbon and heterocyclic groups, as well as the carbocyclic or heterocyclic ring completed by R1 and R2, may in turn be optionally substituted by one or more groups selected from C1.6 alkyl, adamantyl, phenyl, halogen, C i.e haloalkyl, morpholinyl(C i.e)alkyl, trifluoromethyl, hydroxy, C1-6 alkoxy, C1-6 alkoxy(C1-6)alkyl, C1-6 alkoxy(Ci-e)alkoxy, aryloxy, keto, C1.3 alkylenedioxy, nitro, cyano, carboxy, C2.e alkoxycarbonyl, C.e alkoxycarbonyl(Ci.6)alkyl, C2-6 alkylcarbonyloxy, arylcarbonyloxy, C2.6 alkylcarbonyl, arylcarb onyl, C1-6 alkylthio, C1.6 alkylsulphinyl, Cl.6 alkylsulphonyl, amino, mono- or di(C1-6)alkylamino, C2.6 alkylcarbonylamino and C2.6 alkoxycarbonylamino.

The term "halogen" as used herein includes fluorine, chlorine, bromine and iodine, especially chlorine.

Suitable values for the substituents R1 and R2 include C1-6 alkyl, aryl, aryl(C1-6)alkyl, aryl(C2.6)alkenyl, aryl(C2.6)alkynyl, heteroaryl(C1-6)alkyl, C1-6 alkoxy, C2-6 alkenyloxy, aryloxy, aryl(C1-6)alkoxy, heteroaryloxy, arylthio, arylsulphonyl, arylamino, aryl(C i.e)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarbonyl or heteroarylcarbonyl, any of which groups may be optionally substituted; and hydrogen, halogen, trifluoromethyl or nitro. Examples of optional substituents on the groups Rl and/or R2 include C1-6 alkyl, morpholinyl(Ci.e)alkyl, hydroxy, Cl.6 alkoxy, Ci.e alkoxy(Ci.e)alkyl, C1-6 alkoxy(C i.e) alkoxy, C i.e alkylthio and di(C i.e)alkylamino.

Particular values for the substituents R1 and R2 include hydrogen, methyl, phenyl, benzyl, methoxymethyl-benzyl, morpholinylethyl-benzyl, hydroxybenzyl, methoxybenzyl, methoxymethoxy-benzyl, methylthio-benzyl, phenylethenyl, phenylethynyl, thienylmethyl, pyrrolylmethyl, indolylmethyl, fluoro, chloro, bromo, iodo, trifluoromethyl, nitro, methoxy, ethoxy, allyloxy, methyl-allyloxy, phenoxy, methyl-phenoxy, methoxy-phenoxy, dimethylamino-phenoxy, benzyloxy, furyloxy, thienyloxy, pyridyloxy, phenylthio, phenylsulphonyl, phenylamino, benzylamino, dimethylamino, phenylcarbonylamino, phenylcarbonyl, furylcarb onyl and thienylcarb onyl.

Suitably, one or both of R1 and R2 represent hydrogen.

Where Rl and R2 together represent the residue of a carbocyclic or heterocyclic ring, this may be, in particular, a dioxolane or optionally substituted benzene ring.

The benzo moiety of the fused tricyclic ring system shown in formula IA above may be substituted or unsubstituted. Particular substituents include halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, C1-6 alkyl, C2-6 alkenyl, C1.6 alkoxy, C1.6 alkylthio and C2-7 alkoxycarbonyl. Suitably R6 is hydrogen and R3, R4 and R5 independently represent hydrogen, halogen, cyano, trifluoromethyl, nitro, Ci.e alkyl or C2.e alkenyl, at least one of R3, R4 and R5 desirably being other than hydrogen. Preferably, R4 and R6 each represents hydrogen and R3 and R" independently represent hydrogen, cyano, trifluoromethyl, nitro, methyl, ethyl, vinyl or halogen, especially chlorine or iodine. In a particular embodiment, R5 represents hydrogen, cyano, trifluoromethyl, nitro or halogen, especially chlorine; and R3 is hydrogen or ethyl.

Particular pharmaceutical compositions according to the invention contain, as the active ingredient, at least one of the following compounds: 3,5-dihydro-2-phenyl- 1H-pyrazolo[3,4-c] quinoline- 1,4(2H)-dione; and pharmaceutically acceptable salts thereof and pro drugs thereof.

Certain compounds falling within the definition of formula IA above are novel. Accordingly, in a still further aspect the present invention provides a compound of formula IB or a salt or prodrug thereof:

wherein Ril and Rl2 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -SORn, -SO2Ra, -SO2NRaRb, -NRaRs, -NRnCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; or R11 and R2 together represent the residue of a carbocyclic or heterocyclic ring; Rl3, R14, R15 and Rie independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRB, -SORa, -SO2Ra, -SO2NRaRb, -NRBRb, -NRaCORb, -NRaCO2Rb, -CORB, -CO2Ra or -CONRaRb; and Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group; provided that R, R12, R13, R14 R15 and R16 are not all simultaneously hydrogen.

Subject to the above proviso, the substituents Rii to Rie in the compounds of formula IB correspond to the substituents R' to R6 respectively as defined with reference to the compounds of formula IA.

For use in medicine, the salts of the compounds of formula IB will be pharmaceutically acceptable salts. Other salts may, however, be useful in the preparation of the compounds according to the invention or of their pharmaceutically acceptable salts.

Suitable pharmaceutically acceptable salts of the compounds of formulae IA and IB above include alkali metal salts, e.g. lithium, sodium or potassium salts; alkaline earth metal salts, e.g. calcium or magnesium salts; and salts formed with suitable organic ligands, e.g. quaternary ammonium salts. Where appropriate, acid addition salts may, for example, be formed by mixing a solution of the compound according to the invention with a solution of a pharmaceutically acceptable acid such as hydrochloric acid, sulphuric acid, fumaric acid, maleic acid, succinic acid, acetic acid, citric acid, tartaric acid, carbonic acid or phosphoric acid.

The present invention includes within its scope prodrugs of the compounds of formulae IA and IB above. In general, such prodrugs will be functional derivatives of the compounds of formulae IA and IB which are readily convertible in vivo into the required compound.

Conventional procedures for the selection and preparation of suitable prodrug derivatives are described, for example, in "Design of Prodrugs", ed. H. Bundgaard, Elsevier, 1985.

Where the compounds according to the invention have at least one asymmetric centre, they may accordingly exist as enantiomers.

Where the compounds according to the invention possess two or more asymmetric centres, they may additionally exist as diastereoisomers. It is to be understood that all such isomers and mixtures thereof are encompassed within the scope of the present invention.

One sub-class of compounds according to the invention is represented by the compounds of formula IIA and salts and pro drugs thereof:

wherein R2i and R22 independently represent C1-6 alkyl, C2.e alkenyl, C2-6 alkynyl, aryl, aryl(Cl.6)alkyl, aryl(C2.6)alkenyl, aryl(C2.6)alkynyl, heteroaryl(C1-6)alkyl, C1-6 alkoxy, C2-6 alkenyloxy, aryloxy, aryl(C1-6)alkoxy, heteroaryloxy, C1-6 alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarbonyl, heteroarylcarbonyl or C2.7 alkoxycarbonyl, any of which groups may be optionally substituted; or hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; or R21 and R22 together represent the residue of a carbocyclic or heterocyclic ring; R23 and R24 independently represent hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, C1-6 alkyl, C2.6 alkenyl, C1-6 alkoxy, Ci.e alkylthio or C2.7 alkoxycarbonyl; and R25 represents halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, Ci.e alkyl, C2-6 alkenyl, Ci.e alkoxy, C1-6 alkylthio or C2.7 alkoxycarbonyl.

Examples of optional substituents on the groups R21 and/or R22 include Ci.e alkyl, morpholinyl(C1-6)alkyl, hydroxy, Ci.e alkoxy, Ci.e alkoxy(Ci.e)alkyl, Ci.e alkoxy(Ci.e)alkoxy, Ci.6 alkylthio and di(C1-6)alkylamino.

Particular values of R21 and/or R22 with respect to formula IIA include hydrogen, methyl, phenyl, benzyl, methoxymethyl-benzyl, morpholinylethyl-benzyl, hydroxybenzyl, methoxybenzyl, methoxymethoxy-benzyl, methylthio-b enzyl, phenylethenyl, phenylethynyl, thienylmethyl, pyrrolylmethyl, indolylmethyl, fluoro, chloro, bromo, iodo, trifluoromethyl, nitro, methoxy, ethoxy, allyloxy, methyl-allyloxy, phenoxy, methyl-phenoxy, methoxy-phenoxy, dimethylamino-phenoxy, benzyloxy, furyloxy, thienyloxy, pyridyloxy, phenylthio, phenylsulphonyl, phenylamino, benzylamino, dimethylamino, phenylcarbonylamino, phenylcarb onyl, furylcarbonyl and thienylcarbonyl.

Suitably, at least one of R2l and R22 represents hydrogen. In a particular embodiment, one of R21 and R22 is hydrogen and the other is hydrogen, chloro, methoxy or phenoxy.

Suitably, R23 represents hydrogen, nitro, methyl, ethyl, vinyl or halogen, especially chlorine or iodine. Preferably, R23 is hydrogen, ethyl, chlorine or iodine.

Suitably, R24 represents hydrogen or chlorine, preferably hydrogen.

Suitably, R25 represents cyano, trifluoromethyl, nitro, methyl or halogen, preferably chlorine.

Another sub-class of compounds according to the invention is represented by the compounds of formula IIB and salts and prodrugs thereof:

wherein R31 represents Ci.e alkyl, C.e alkenyl, C2-6 alkynyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6alkynyl, heteroaryl(C1-6)alkyl, C1-6 alkoxy, C2-6 alkenyloxy, aryloxy, aryl(Ci.e)alkoxy, heteroaryloxy, Ci.e alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylaminbo, arylcarb onylamino, arylcarb onyl, heteroarylcarbonyl or C2.7 alkoxycarbonyl, any of which groups may be optionally substituted; or hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; and R32 represents C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkylnyl, heteroaryl(C1-6)alkyl, Ci-6 alkoxy, C2.6 alkenyloxy, aryloxy, aryl(Ci.e)alkoxy, heteroaryloxy, Ci.6 alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarb onyl, hetero arylcarb onyl or C2.7 alkoxycarbonyl, any of which groups may be optionally substituted; or halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; or R3l and R32 together represent the residue of a carbocyclic or heterocyclic ring; and R33, R34 and R95 independently represent hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, C1-6 alkyl, C.e alkenyl, C1-6 alkoxy, Ci.e alkylthio or C2.7 alkoxycarbonyl.

Examples of optional substituents on the groups R3l and/or R32 include C1-6 alkyl, morpholinyl(C1-6)alkyl, hydroxy, Ci.e alkoxy, Ci.e alkoxy(C1-6)alkyl, C1-6alkoxy(C1-6)alkoxy, C1-6 alkylthio and di(Cl.6)alkylamino.

Particular values of R31 and/or R82 with respect to formula IIB include methyl, phenyl, benzyl, methoxymethyl-benzyl, morpholinylethylbenzyl, hydroxyb enzyl, methoxybenzyl, methoxymethoxy-benzyl, methylthio-benzyl, phenylethenyl, phenylethynyl, thienylmethyl, pyrrolylmethyl, indolylmethyl, fluoro, chloro, bromo, iodo, trifluoromethyl, nitro, methoxy, ethoxy, allyloxy, methyl-allyloxy, phenoxy, methylphenoxy, methoxy-phenoxy, dimethylamino-phenoxy, benzyloxy, furyloxy, thienyloxy, pyridyloxy, phenylthio, phenylsulphonyl, phenylamino, benzylamino, dimethylamino, phenylcarb onylamino, phenylcarbonyl, furylcarbonyl and thienylcarbonyl. In addition, R3l may represent hydrogen.

Suitably, R3l is hydrogen. In a particular embodiment, R31 is hydrogen and R32 is chloro, methoxy or phenoxy.

Suitably, R33 represents hydrogen, nitro, methyl, ethyl, vinyl or halogen, especially chlorine or iodine. Preferably, R33 is hydrogen, ethyl, chlorine or iodine.

Suitably, R34 represents hydrogen or chlorine, preferably hydrogen.

Suitably, R35 represents hydrogen, cyano, trifluoromethyl, nitro, methyl or halogen, preferably hydrogen or chlorine.

Specific compounds within the scope of the present invention include: 7-chloro-3,5-dihydro-2-phenyl- 1H-pyrazolo [3,4-c] quinoline- 1,4(2H)-dione; 2-(2-chlorophenyl)-3,5-dihydro- lH-pyrazolo[3,4-c] quinoline- 1,4(2H)-dione; 2-(3-chlorophenyl)-3,5-dihydro- 1H-pyrazolo[3,4-c]quinoline- 1,4(2H)-dione; 2-(4-chlorophenyl)-3,5-dihydro- lH-pyrazolo[3,4-c] quinoline- 1,4(2H)-dione; 3,5-dihydro-2-(4-methoxyphenyl)- 1H-pyrazolo[3,4-c] quinoline-1,4(2H)- dione; 7-chloro-3, 5-dihydro-2-(4-methoxyphenyl)- lH-pyrazolo[3,4-c] quinoline1,4(2H)-dione; and salts and prodrugs thereof.

The pharmaceutical compositions according to the invention are preferably in unit dosage forms such as tablets, pills, capsules, powders, granules, sterile parenteral solutions or suspensions, metered aerosol or liquid sprays, drops, ampoules, auto-injector devices or suppositories; for oral, parenteral, intranasal, sublingual or rectal administration, or for administration by inhalation or insufflation.

Alternatively, the compositions may be presented in a form suitable for once-weekly or once-monthly administration; for example, an insoluble salt of the active compound, such as the decanoate salt, may be adapted to provide a depot preparation for intramuscular injection. For preparing solid compositions such as tablets, the principal active ingredient is mixed with a pharmaceutical carrier, e.g. conventional tableting ingredients such as corn starch, lactose, sucrose, sorbitol, talc, stearic acid, magnesium stearate, dicalcium phosphate or gums, and other pharmaceutical diluents, e.g. water, to form a solid preformulation composition containing a homogeneous mixture of a compound of the present invention, or a pharmaceutically acceptable salt thereof. When referring to these preformulation compositions as homogeneous, it is meant that the active ingredient is dispersed evenly throughout the composition so that the composition may be readily subdivided into equally effective unit dosage forms such as tablets, pills and capsules.

This solid preformulation composition is then subdivided into unit dosage forms of the type described above containing from 0.1 to about 500 mg of the active ingredient of the present invention. The tablets or pills of the novel composition can be coated or otherwise compounded to provide a dosage form affording the advantage of prolonged action. For example, the tablet or pill can comprise an inner dosage and an outer dosage component, the latter being in the form of an envelope over the former.

The two components can be separated by an enteric layer which serves to resist disintegration in the stomach and permits the inner component to pass intact into the duodenum or to be delayed in release. A variety of materials can be used for such enteric layers or coatings, such materials including a number of polymeric acids and mixtures of polymeric acids with such materials as shellac, cetyl alcohol and cellulose acetate.

The liquid forms in which the novel compositions of the present invention may be incorporated for administration orally or by injection include aqueous solutions, suitably flavoured syrups, aqueous or oil suspensions, and flavoured emulsions with edible oils such as cottonseed oil, sesame oil, coconut oil or peanut oil, as well as elixirs and similar pharmaceutical vehicles. Suitable dispersing or suspending agents for aqueous suspensions include synthetic and natural gums such as tragacanth, acacia, alginate, dextran, sodium carboxymethylcellulose, methylcellulose, p olyvinyl-pyrrolidone or gelatin.

In the treatment of neurodegeneration, a suitable dosage level is about 0.01 to 250 mg/kgper day, preferably about 0.05 to 100 mg/kg per day, and especially about 0.05 to 5 mg/kg per day. The compounds may be administered on a regimen of 1 to 4 times per day. In a particular embodiment, the compounds may be conveniently administered by intravenous infusion.

The compounds of formula IA above, including the novel compounds according to the present invention, may be prepared by a process which comprises reacting a compound of formula III with a compound of formula IV:

wherein R1, R2, R3, R4, R5 and Re are as defined above, and R represents C1.4 alkyl; in the presence of an acid.

Suitable values for the substituent R include methyl and ethyl, especially ethyl.

The reaction is conveniently effected by heating compounds III and IV together at reflux in acetic acid, which also acts as the solvent.

The starting materials of formula III may conveniently be prepared from a substituted oxindole derivative by a method analogous to that described in Justus Liebigs Ann. Chem., 1924, 436, 113. A general procedure for preparing substituted oxindoles is described in Svnthesis, 1993, 51.

Where they are not commercially available, the reagents of formula IV may suitably be prepared by standard methods well known from the art.

It will be appreciated that any compound of formula IA initially obtained from the above process may, where appropriate, subsequently be elaborated into a further desired compound of formula IA using techniques known from the art.

Where the above-described process for the preparation of compounds of use in the invention gives rise to mixtures of stereoisomers, these isomers may be separated by conventional techniques such as preparative chromatography. The compounds may be prepared in racemic form, or individual enantiomers may be prepared either by enantiospecific synthesis or by resolution. The compounds may, for example, be resolved into their component enantiomers by standard techniques such as preparative HPLC, or the formation of diastereomeric pairs by salt formation with an optically active acid, such as (-)-di-p-toluoyl-d-tartaric acid and/or (+)-di-p-toluoyl-l-tartaric acid, followed by fractional crystallization and regeneration of the free base. The compounds may also be resolved by formation of diastereomeric esters or amides, followed by chromatographic separation and removal of the chiral auxiliary.

During any of the above synthetic sequences it may be necessary and/or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in Protective Grounds in Organic Chemistrv, ed. J.F.W. McOmie, Plenum Press, 1973; and T.W. Greene & P.G.M. Wuts, Protective Groups in Organic Svnthesis, John Wiley & Sons, 1991. The protecting groups may be removed at a convenient subsequent stage using methods known from the art.

The following Examples illustrate the preparation of compounds of use in the invention.

The compounds useful in this invention potently and selectively block responses to NMDA and/or AMPA in a brain slice from rat cortex, and inhibit the binding of agonists and antagonists to the strychnine-insensitive site present on the NMDA receptor and/or AMPA binding to rat forebrain membranes.

Cortical Slice Studies The effects of compounds of use in the invention on responses to NMDA and AMPA can be assessed using the rat cortical slice as described by Wong et al., Proc. Natl. Acad. Sci. USA, 1986, 83, 7104. The apparent equilibrium constant (Kb) iS calculated from the righthand shift in the NMDA or AMPA concentration-response curves produced by the compound under test. The compounds of the accompanying Examples were tested and were found to possess Kb values in response to NMDA of below 150 ,eM in each case.

Binding Studies The ability of test compounds to displace 3H-L-689,560 (trans-2-carboxy-5, 7-dichloro-4-phenyl-aminocarbonylamino- 1,2,3,4- tetrahydroquinoline) binding to the strychnine-insensitive site present on the NMDA receptor of rat forebrain membranes can be determined by the method of Grimwood et al., Proceedings of The British Pharmacological Societv, July 1991, Abstract C78. The concentration of the compounds of the accompanying Examples required to displace 50% of the specific binding (IC50) iS below 50 RM in each case.

EXAMPLE 1 3,5-dihydro-2-phenyl-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione Ethyl oxindole-3-glyoxylate (220 mg) in glacial acetic acid (2 ml) was heated under reflux for 10 minutes with phenylhydrazine (0.1 ml). The reaction was cooled and the resulting precipitate filtered and crystallised from methanol to give the title compound, mp > 260"C; 1H nmr (250MHz, de-DMSO) 6 11.86 (1H, broad s), 8.25 (1H, broad d), 7.86 (2H, d, J=8Hz), 7.56 (2H, t, J=8Hz) and 7.22-7.42 (4H, m).

The following examples were prepared by the method of Example 1 using the appropriately substituted phenylhydrazine and oxindole reagents.

EXAMPLE 2 7-Chloro-3,5-dihydro-2-phenyl-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione lH nmr (250MHz, d6-DMSO) 7.30 (1H, dd, J=3Hz and 12.2Hz), 7.37-7.43 (2H, m), 7.56 (2H, t, J=8Hz), 7.84 (2H, d, J=8Hz) and 8.20 (1H, d, J=8Hz).

EXAMPLE 3 3,5-Dihydro-2-(2-chlorophenyl)-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione 1H nmr (250MHz, d6-DMSO) 7.29-7.41 (3H, m), 7.52-7.77 (4H, m) and 8.16 (1H, bs).

EXAMPLE 4 3,5-Dihydor-2-(3-chlorophenyl)-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione lH nmr (360MHz, d6-DMSO) 7.20-7.44 (4H, m), 7.58 (1H, t, J=8Hz), 7.86 (1H, d, J=8Hz), 8.02 (1H, s) and 8.37 (1H, d, J=8Hz).

EXAMPLE 5 3,5-Dihydro-2-(4-chlorophenyl)-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione 1H nmr (250MHz, dG-DMSO) 7.20-7.38 (3H, m), 7.62 (2H, d, J=12.6Hz), 7.91 (2H, d, J=12.6Hz) and 8.25 (1H, d, J=10.9Hz).

EXAMPLE 6 3.5-Dihydro-2-(4-methoxyphenyl)-1H-pyrazolo[3,4-c]quinoline-1,4(2H0dione 1H nmr (250MHz, d6-DMSO) 6 8.21 (1H, broad s,), 7.73 (2H, d, J=9Hz), 7.31-7.35 (2H, m), 7.12-7.25 (1H, m), 7.11 (2H, d, J=9Hz), 3.82 (3H, s); MS (ES+) 308 [M+H]+.

EXAMPLE 7 7-Chloro-3,5-dihydro-2-(4-methoxyphenyl)-1H-pyrazolo[3,4-c]quinoline1,4(2H)-dione 1H nmr (250MHz, de-DMSO) 6 11.46 (1H, broad s), 7.85 (1H, d, J=8.4Hz), 7.40 (2H, d, J=9.0Hz), 7.07 (1H, d, J=2Hz), 6.98 (1H, dd, J=2Hz and 8.4Hz), 6.81 (2H, d, J=9.0Hz), 3.52 (3H, s); MS (ES+) 342/344 [M+H]+.

Claims (21)

CLAIMS:

1. A pharmaceutical composition comprising a compound of formula IA or a pharmaceutically acceptable salt thereof or a pro drug thereof:

wherein R1 and R2 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -SORa, -S02Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; or R1 and R2 together represent the residue of a carbocyclic or heterocyclic ring; R3, R4, R5 and R6 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -SORa, -SO2Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; and Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group; in association with one or more pharmaceutically acceptable carriers and/or excipients.

2. A composition as claimed in claim 1 containing, as the active ingredient, at least one of the following compounds: 3,5-dihydro-2-phenyl- lH-pyrazolo[3,4-c]quinoline- 1,4(2H)-dione; and pharmaceutically acceptable salts thereof and prodrugs thereof.

3. The use of a compound of formula IA as defined in claim 1, or a pharmaceutically acceptable salt thereof or a prodrug thereof, for the manufacture of a medicament for the treatment and/or prevention of conditions which require the administration of a selective noncompetitive antagonist of NMDA receptors.

4. The use of a compound of formula IA as defined in claim 1, or a pharmaceutically acceptable salt thereof or a prodrug thereof, for the manufacture of a medicament for the treatment and/or prevention of conditions which require the administration of an antagonist of AMPA receptors.

5. A compound of formula IB or a salt or prodrug thereof:

wherein Ril and R12 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -SORa, -SO2Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; or R11 and R12 together represent the residue of a carbocyclic or heterocyclic ring; Rl3, R14, R15 and R16 independently represent hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRA, -SORa, -S02Ra, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -CORa, -CO2Ra or -CONRaRb; and Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group; provided that R11, R12, R13, R14, R15 and R16 are not all simultaneously hydrogen.

6. A compound as claimed in claim 5 represented by formula IIA and salts and pro drugs thereof:

wherein R21 and R22 independently represent C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl(C1-6)alkyl, C1.6 alkoxy, C2.6 alkenyloxy, aryloxy, aryl(Cl.6)alkoxy, heteroaryloxy, Ci.e alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarbonyl, heteroarylcarbonyl or C2-7 alkoxycarbonyl, any of which groups may be optionally substituted; or hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; or R21 and R22 together represent the residue of a carbocyclic or heterocyclic ring; R23 and R24 independently represent hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, C1-6 alkyl, C2-6 alkenyl, Ci.e alkoxy, Ci.e alkylthio or C2.7 alkoxycarbonyl; and R25 represents halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, Ci.e alkyl, C.e alkenyl, Ci.e alkoxy, Cie alkylthio or C2.7 alkoxycarbonyl.

7. A compound as claimed in claim 6 wherein one of R21 and R22 is hydrogen and the other is hydrogen, chloro, methoxy or phenoxy.

8. A compound as claimed in claim 6 or claim 7 wherein R23 is hydrogen, ethyl, chloro or iodo.

9. A compound as claimed in any one of claims 6 to 8 wherein R24 is hydrogen or chloro.

10. A compound as claimed in any one of claims 6 to 9 wherein R25 represents cyano, trifluoromethyl, nitro, methyl or halogen.

11. A compound as claimed in claim 10 wherein R25 is chloro.

12. A compound as claimed in claim 5 represented by formula IIB and salts and prodrugs thereof:

wherein R31 represents Ci.e alkyl, C.e alkenyl, C2-6 alkynyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl(C1-6)alkyl, C1-6 alkoxy, C2.e alkenyloxy, aryloxy, aryl(Ci.e)alkoxy, heteroaryloxy, Ci.e alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarbonyl, heteroarylcarbonyl or C2.7 alkoxycarbonyl, any of which groups may be optionally substituted; or hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; and R32 represents C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, aryl, aryl(C1-6)alkyl, aryl(C2-6)alkenyl, aryl(C2-6)alkynyl, heteroaryl(C1-6)alkyl, C1-6 alkoxy, C2-6 alkenyloxy, aryloxy, aryl(C1-6)alkoxy, heteroaryloxy, C1-6 alkylthio, arylthio, arylsulphonyl, arylamino, aryl(C1-6)alkylamino, di(C1-6)alkylamino, arylcarbonylamino, arylcarbonyl, heteroarylcarbonyl or C2.7 alkoxycarbonyl, any of which groups may be optionally substituted; or halogen, cyano, trifluoromethyl, nitro, hydroxy, amino or carboxy; or R31 and R32 together represent the residue of a carbocyclic or heterocyclic ring; and R33, R34 and R35 independently represent hydrogen, halogen, cyano, trifluoromethyl, nitro, hydroxy, amino, carboxy, Ci.6 alkyl, C2-6 alkenyl, Ci.e alkoxy, C1-6 alkylthio or C2.7 alkoxycarbonyl.

13. A compound as claimed in claim 12 wherein R3l is hydrogen and R92 is chloro, methoxy or phenoxy.

14. A compound as claimed in claim 12 or claim 13 wherein R93 is hydrogen, ethyl, chloro or iodo.

15. A compound as claimed in any one of claims 12 to 14 wherein R34 is hydrogen or chloro.

16. A compound as claimed in any one of claims 12 to 15 wherein R35 represents hydrogen, cyano, trifluoromethyl, nitro, methyl or halogen.

17. A compound as claimed in claim 16 wherein R35 is hydrogen or chloro.

18. A compound as claimed in claim 5 selected from: 7-chloro-3 ,5-dihydro-2-phenyl- lH-pyrazolo[3,4-c]quinoline- 1,4(2H)-dione; 2-(2-chlorophenyl)-3,5-dihydro-1H-pyrazolo[3,4-c]quinoline-1,4(2H)-dione; 2-(3-chlorophenyl)-3,5-dihydor-1H-pyrazolo[3,4-c]quinoline-1,4(2H0-dione; 2-(4-chlorophenyl)-3,5-dihydro- 1H-pyrazolo [3,4-c] quinoline- 1 ,4(2H)-dione; 3,5-dihydro-2-(4-methoxyphenyl) - 1H-pyrazolo[3,4-c] quinoline- 1,4(2H)- dione; 7-chloro-3,5-dihydro-2-(4-methoxyphenyl)-1H-pyrazolo[3,4-c]quinoline1,4(2H)-dione; and salts and prodrugs thereof.

19. A pharmaceutical composition comprising a compound as claimed in any one of claims 5 to 18 in association with one or more pharmaceutically acceptable carriers and/or excipients.

20. The use of a compound as claimed in any one of claims 5 to 18 for the manufacture of a medicament for the treatment and/or prevention of conditions which require the administration of a selective non-competitive antagonist of NMDA receptors.

21. The use of a compound as claimed in any one of claims 5 to 18 for the manufacture of a medicament for the treatment and/or prevention of conditions which require the administration of an antagonist of AMPA receptors.