GB2324301A - Pharmaceutically-active Piperazinedione Compounds - Google Patents

Abstract

A piperazinedione of general formula (I): wherein R<SP>1</SP> is selected from: - hydrogen; and - a group of formula -COR<SP>3</SP> -(NH) t -COR<SP>3</SP> wherein t is 1 and a group of formula: wherein v is 0 and wherein n is 0 or 1 and m is 0, 1, 2, or 3, at least one of n and m being other than 0, and R<SP>4</SP> and R<SP>5</SP>, together with the nitrogen atom to which they are attached, form a heterocyclic group selected from (1) to (4): wherein R<SP>6</SP> and R<SP>7</SP>, which are the same or different, are H or C 1 -C 6 alkoxy, or R<SP>6</SP> and R<SP>7</SP> together form a methylenedioxy group; Y is O or -NR<SP>8</SP> wherein R<SP>8</SP> is C 1 -C 6 alkyl or a phenyl group optionally substituted by CF 3 ; and R<SP>2</SP> is hydrogen or a group of formula -COR<SP>3</SP> as defined above, provided that one or R<SP>1</SP> and R<SP>2</SP> is hydrogen and the other is not hydrogen; and the pharmaceutically acceptable salts thereof have activity as modulators of multi-drug resistance.

Description

PHARMACEUTICAL PIPERAZINE COMPOUNDS The present invention relates to compounds useful as modulators of multi-drug resistance (MDR), to their preparation and to pharmaceutical and veterinary compositions containing them.

The resistance of tumours to treatment with certain cytotoxic agents is an obstacle to the successful chemotherapeutic treatment of cancer patients. A tumour ma > acquire resistance to a cytotoxic agent used in a previous treatment. A tumour may also manifest intrinsic resistance, or cross-resistance, to a cytotoxic agent to which it has not previously been exposed, that agent being unrelated by structure or mechanism of action to any agent used in previous treatments of the tumour.

Analogously, certain pathogens may acquire resistance to pharmaceutical agents used in previous treatments of the diseases or disorders to which those pathogens give rise.

Pathogens may also manifest intrinsic resistance, or cross resistance, to pharmaceutical agents to which they have not previously been exposed. Examples of this effect include multi-drug resistant forms of malaria, tuberculosis, leishmaniasis and amoebic dysentery.

The above phenomena are referred to collectively as multi-drug resistance (MDR). As discussed more fully later on, a plasma membrane glycoprotein (P-gp) is implicated in the mechanism which underlies MDR. P-gp has drug binding properties. Certain agents which have the capacity to modulate MDR may therefore also be useful in facilitating the delivery of drugs across the blood-brain barrier and in treating AIDS and AIDS-related complex.

Disadvantages of drugs which have so far been used to modulate MDR, termed resistance modifying agents or Emus, are that they frequently possess a poor pharmacokinetic profile and/or are toxic at the concentrations required for M3R modulation.

It has now been found that a series of piperazinedione derivatives have activity as modulators of multi-drug resistance. The present invention therefore provides a piperazinedione derivative of formula (I):

wherein R1 is selected from: - hydrogen; - a group of formula -(NH)t-COR wherein t is O or 1 and R3 is selected from:

wherein v is 0 when t is 1 and v is 1 when t is 0; and wherein n is 0 or 1 and m is 0, 1, 2 or 3, at least one of n and m being other than 0, and either: (a) R5 is H or C1-C6 alkyl and R5 is C1-C6 alkyl optionally substituted by one or two phenyl groups, the phenyl group or groups being optionally substituted by one or two C1-C6 alkoxy groups; or (b) R4 and RS, together with the nitrogen atom to which they are attached, form a heterocyclic group selected from (1) to (4):

wherein R6 and R', which are the same or different, are H or C,-C, alkoxy or R6 and R7 form together a methylenedioxy group; Y is O or -NR8 wherein R8 is C1-C6 alkyl or a phenyl group optionally substituted by CF3; (li) NH-(CH2)p-Z (B) wherein p is 1 or 2 and Z is C2-C6 alkenyl or a phenyl group optionally substituted by C1-C6 alkoxy; and

wherein R9 is C1-C6 alkyl, pyrimidinyl or a phenyl group optionally substituted by Q-C6 alkoxy; and

wherein w is 1, 2 or 3 and L is a heterocyclic group of formula (1) as defined above; - a group of the formula (D):

wherein each of R10 and Rill, which may be the same or different, is C1-C6 alkyl; and - a group of formula (E):

wherein s is 0 or 1 and each r, which may be the same or different, is 1, 2 or 3 and L is a heterocyclic group of formula (1) as defined above; and R2 is hydrogen or a group of formula -COR3 as defined above provided that one of R1 and R2 is hydrogen and the other is not hydrogen; or a pharmaceutically acceptable salt thereof.

An alkyl group may be linear or branched. A C1-C6 alkyl group is typically a C1-C4 alkyl group, for example a methyl, ethyl, propyl, i-propyl, n-butyl, sec-butyl or tert-butyl group. A C1-C6 alkoxy group is typically a C1-C4 alkoxy group, for example a methoxy, ethoxy, propoxy, i-propoxy, nbutoxy, sec-butoxy or tert-butoxy group.

When R1 is a group of formula -(NH)t-CGR3, t may be 0 in which case the group has the formula -COR3. The integer v in formula (A) is then 1. When R3 is a group of formula (A), n is typically 1 and m is 0, 1, 2 or 3, or n is 0 and m is 2.

R4 and R5 may be as defined under (a), in which case R4 is preferably C1-C6 alkyl, for instance methyl. Rs is preferable C-C6 alkyl, for instance methyl or ethyl, either unsubstituted or substituted on the terminal carbon atom by one or two phenyl groups. These phenyl groups are in turn unsubstituted or substituted by one or two methoxy groups.

For ir.stance, RE may be a diphenylmethyl, 2-2-diphenylethyl or 3,4-dimethoxyphenethyl group. Alternatively, R4 and R5 may be as defined under (b). When R4 and RE together form the heterocyclic ring (1), R6 and R7 are typically the same, and are preferably hydrogen or methoxy, or together form a methylenedioxy group. When R4 and R5 together worm the heterocyclic ring (2), Y is O or -NR8 wherein R8 is preferably methyl, phenyl or 3-trifluoromethylphenyl.

When R3 is a group of formula (B), Z is preferably ethenyl, prop-1-enyl or prop-2-enyl, or a phenyl group substituted by one or two C1-C6 alkoxy groups, preferably methoxy groups. Preferably the phenyl ring is 3,4disubstituted by methoxy groups.

When R3 is a group of formula (C), R9 is preferably selected from methyl, ethyl, pyrimidinyl and phenyl, the phenyl being monosubstituted at position 2, 3 or 4 by C1-C6 alkoxy, for instance methoxy, and more preferably being a 4methoxyphenyl group.

When R1 is a group of formula (D) S1 and R11 are typically the same and are preferably both methyl. When R1 is a group of formula (E), s may be 0 in which case the group has the formula -(CH2)r-L. In formula (E) the substituents R6 and R7 in the heterocyclic ring are typically the same and are preferably both H or methoxy, or together form a methylenedioxy group.

In a first embodiment of formula (I) in which t = 1 and v = 0, R1 is hydrogen and R2 is a group of formula -COR as defined above in which R3 is a group of formula A.

In a second embodiment of formula (I) R2 is hydrogen anti R' is a group of formula -COR3 as defined above in which R3 is a group of formula (A), a group of formula (B) wherein Z is ethenyl or phenyl substituted by two C1-C6 alkoxy groups, or a group of formula (C) wherein R2 is methyl, pyrimidinyl or phenyl. Phenyl substituted by two C1-C6 alkoxy groups is preferably 3,4 -dimethoxyphenyl.

In formula (A) in the first and second embodiments described above it is preferred that n is 0 and m is 2, or n is 1 and m=0, 1 or 2, and either: (a) R4 is C1-C6 alkyl and R5 is C1-C6 alkyl substituted on the terminal C atom by 2 unsubstituted phenyl groups or by one phenyl group which is disubstituted by C1-C6 alkoxy groups; or (b) R4 and R5 form together with the nitrogen atom to which they are attached a heterocyclic group selected from groups of formulae (1) wherein R6 and R7 are both H or both C1-C6 alkoxy, or wherein R6 and R7 together form a methylenedioxy group; (2) wherein Y is O or -NR8 wherein Ra is methyl, phenyl or trifluoromethylphenyl; (3); and (4).

Preferably R4 is methyl and R5 is diphenylmethyl or 2 (3,4-dimethoxyphenyl)ethyl, or R4 and R5 together form instead heterocyclic ring (1) in which R6 and R' are both H or both OMe, or together form a methylenedioxy group.

Examples of preferred compounds of formula (I) are as follows: 1-(4-((3Z,6Z)-6-Benzylidene-l-methyl-2,5-dioxo-3- piperazinylidene)methylbenzoyl) -4- (2-pyrimidyl)piperazine (9022) 1-(4-((3Z,6Z)-6-Benzylidene-1-methyl-2,5-dioxo-3- piperazinylidene)methylbenzoyl)-4-methylpiperazine, hydrochloride (9052) 1-(4-((3Z,6Z)-6-Benzylidene-1-methyl-2,5-dioxo-3 piperazinylidene)methylbenzoyl) -4- (4- ethoxypenyl)piperazine, hydrochloride (9071) N-Allyl-4-((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioXo-3- piperazinylidene)methylbenzamide (9070) N-(2-Diphenylmethylmethylaminoethyl)-4-((3Z,6Z)-6benzylidene-l-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide, hydrochloride (9076) N-(2-(1,2,3,4-Tetrahydro-2-isoquinol)ethyl)-1-((3Z,6Z)-6- benzylidene-l-methyl-2,5-dioxo-3piperazinylidene) methylbenzamide, hydrochloride (9116) N-(3,4-Dimethoxyphenethyl)-4-((3Z,6Z)-6-benzylidene-1methyl-2,5-dioxo-3-piperazinylidene)methylbenzamide (9117) N-(4-(4-Phenyl-l-piperazinyl)methylphenyl)-4-((3Z,sZ)-6- benzylidene-1-methyl-2,5-dioxo-3 piperazinylidene)methylbenzamide, hydrochloride (9104) N-(2-(4-Methyl-1-piperazinyl)ethyl)-4-((3Z,6Z)-6- benzylidene-l-methyl-2,5-dioxo-3- piperazinylidene)methylbenzamide (9007) N-t2-Morpholinoethyl)-4-((3Z,6Z)-6-benzylidene-1-methy -2,5- dioxo-3-piperazinylidene) methylbenzamide, hydrochloride (9053) N-(4-Morpholinophenyl)-4-((3Z,6Z)-6-benzylidene-1-methyl- 2,5-dioxo-3-piperazinylidene)methylbenzamize, hydrochloride (9054) N-(4-(2-(1,2,3,4-Tetrahydro- -carbolin-2-yl)ethyl)phenyl)-4 ((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3- piperazinylidene)methylbenzamide (9080) N-(4-(1,2,3,4-Tetrahydro- -carbolin-2-yl)methylphenyl)-4 ((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide (9096) N-(4-(2-(4-Phenyl-1-piperazinyl)ethyl)phenyl)-4-((3Z,6Z)-6benzylidene-1-methyl-2,5-dioxo-3 piperazinylidene)methylbenzamide (9103) N-(4-(2-(1,2,3,4-Tetrahydro-2-isoquinolyl)ethyl)phenyl)-4 ((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide (9065) N-(4-(2-(4-(3-Trifluoromethylphenyl)-1 piperazinyl)ethyl)phenyl)-4-((3Z,6Z)-6-benzylidene-1-methyl- 2,5-dioxo-3-piperazinylidene)methylbenzamide(9049) N- (4-(2-(4-(4-Chl orophenyl)-4- hydroxypiperidino)ethyl)phenyl) -4- ( (3Z,6Z) -6-benzylidene-l- methyl-2,5-dioxo-3-piperazinylidene)methylbenzamide (9079) N-(4-(2-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2- isO7uinolyl)ethyl)phenyl)-4-((3Z,6Z)-6-benzylidene-1-methyl- 2,5-dioxo-3-piperazinylidene)methylbenzamide (9006) N-(2-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2-isoquinolyl)ethyl) 4-((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide (9008) N-(4-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2isoquinolyl)methylphenyl)-4-((3Z,6Z)-6-benzylidene-1-methyl2,5-dioxo-3-piperazinylidene)methylbenzamide, hydrochloride (9064) (3Z,6Z)-6-Benzylidene-3-(4-(3-dimethylamino-2hydroxypropoxy)benzylidene)-1-methyl-2,5-piperazinedione (9023) (3Z,6Z)-6-Benzylidene-3-(4-(2-(6,7-dimethoxy-1,2,3,4 tetrahydro-2-isoquinolyl)ethyl)benzylidene)-l-methyl-2,5- piperazinedione (9115) N-(4-(2 -(6,7-Dimethoxy-1,2,3,4-tetrahydro-2isoquinolyl)ethyl)phenyl)-3-((3Z,6Z)-6-benzylidene-1-methyl 2, 5-dioxo-3-piperazinylidene)methylbenzamide, hydrochloride (9051) N-(4-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2 isoquinolyl)methylphenyl)-3-((3Z,6Z)-6-benzylidene-1-methyl 2,5-dioxo-3-piperazinylidene)methylbenzamide (9128) -(2-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2 3-((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide (9136) N-(2-(3,4-Dimethoxyphenethyl)methylamino)ethyl)-3-((3Z,6Z) 6-benzylidene-l-methyl-2,5-dioxo-3- piperazinylidene)methylbenzamide (9137) N-(4-(2-(3,4-Dimethoxyphenethyl)methylamino)ethyl)phenyl)-3 ((3Z,6Z)-6-benzylidene-1-methyl-2,5-dioxo-3- piperazinylidene)methylbenzamide (9138) N-(4-(2-( < -Phenyl-1-piperazinyl)ethyl)phenyl)-3-((3Z,6Z)-5- benzylidene-1-methyl-2,5-dioxo-3 pierazinylidene)methylbenzamide (9083) N-(4-(3-(6,7-Dimethoxy-1,2,3,4-tetrahydro-2 isoquinolyl)propyl)phenyl)-3-((3Z,6Z)-6-benzylidene-1- methyl-2,5-dioxo-3-piperazinylidene)methylbenz mide, hydrochloride (9161) N-(2-(2,2-Diphenylethyl)methylaminoethyl)-3-((3Z,6Z)-6 benzyiidene-l-methyl-2,5-dioxo-3- piperazinylidene) methylbenzamide (9163) (3Z,6Z)-6-Benzylidene-3-(4-(4-(2-(6,7-dimethoxy-1,2,3,4 te.rahydro-2-isoqtlinolyl)ethyl)benzyloxy)benzylidene)-l- methyl-2, 5-piperazinedione (9176) (3Z,6Z)-6-Benzylidene-3-(3-(4-(2-(6,7dimethoxy-1,2,3,4- tetrahydro-2-isoquinolyl)ethyl)benzyloxy)benzylidene)-1 rnethyl-2,5-piperazinedione (9177) N-(4-((3Z,6Z)-6-Benzylidene-1-methyl-2,5-dioxo-3- piperazinylidene)methylphenyl)-4-(2-(6,7-dimethoxy-1,2,3,4tetrahydro-2-isoquinolyl)ethyl)benzamide (9190) 1-(4-((3Z,5Z)-6-Benzylidene-l-methyl-2,5-dioxo-3- piperazinylidene)methylbenzoyl)-4-(6,7-dimethOxy-1,2,3,4- tetrahydroisoquinolyl)methylpiperidine (9200) Compounds of formula (I) are produced by a process which comprises treating 1-acetyl-3-benzylidene-4-methyl- 2,5-piperazinedione, which has the formula (II):

with an aldehyde of the following formula (III):

wherein R1 and R2 are as defined for formula (I) , in an organic solvent in the presence of a base; and, if desired, converting the resulting compound into a pharmaceutically acceptable salt thereof.

Suitable bases include caesium carbonate, sodium carbonate, potassium carbonate, sodium hydride, potassium tbutoxide and triethylamine.

Suitable organic solvents include dimethylformamide (DMF), tetrahydrofuran (THF) and in the case of potassium tbutoxide, t-butanol and mixtures thereof.

When DMF is used as solvent the temperature is lyrically between 0 C and reflux temperature, for example from 80'C to 95 C when caesium carbonate is used as base.

When sodium hydride or potassium t-butoxide is used as the base the reaction mixture is typically warmed from 0CC to room temperature or to 40 C.

The duration of the reaction may be from 1 to t hours, for example from 2 to 3 hours.

The compound of formula (II) may be prepared'as described in Reference Example 1 which follows. Compounds of formula (III) may be prepared from commercially available starting materials by conventional methods, the particular starting material and method employed depending upon the identity of the aldehyde. For instance, an aldehyde of formula (III) wherein one of R1 and R2 is hydrogen and the other is a group of formula -COR3 as defined above may be prepared by a process which comprises treating a compound cf formula (IV):

wherein one or R11 and R21 is hydrogen and the other is -COOH, -COX wherein X is a halogen, or -CO(OCOR') wherein R' is C1 C6 alkyl, with an amine of formula H-R3 wherein R3 is as defined above, in an inert organic solvent; the reaction being performed in the presence of a coupling agent when R11 or R21 is -COOH.

Suitable coupling agents for use when R11 or R12 is -COOtI include 1,3-dicyclohexylcarbodiimide, 1-cyclohexyl-3- (2- morpholinoethyl) carbodiimide metho-p-toluenesulphonate and 2-chloro-1-methylpyridinium iodide.

When R1 or R21 is a group -COX or -CO(OCOR') as defined above, the reaction is optionally conducted in the presence of a base, for instance a tertiary amine such as Et3N, or pyridine. The solvent is then suitably dichloromethane.

The activated compounds of formula (IV) wherein R11 or R2 is -COX or -CO(OCOR') may be prepared from the correspondingly compound of formula (IV) wherein R1' or R2;, respectively, is the carboxy group -COOH by conventional methods which are routine in organic synthesis.

For instance, compounds wherein R11 or R21 is -COX may be prepared by treating the carboxy compound with a halogenating agent, for example a chlorinating agent such as SOC12, PCl3 oxa lyl chloride or PC15.

Compounds wherein R1 or R21 is -CO(OCOR') may be prepared by treating the carboxy compound with a C,-Ce alkyl haloformate in the presence of a tertiary amine, for instance EtOCOCl or iBuOCOCl in the presence of Et3N. In this case it is generally convenient to treat the resulting mixture directly with the amine H-R3.

When R3 is a group of formula (A) as defined above in which n is 1 and v is 1, the amine H-R3 may be prepared by reducing the corresponding nitro compound of formula (v):

wherein m, R4 and R5 are as defined above for formula (A).

The reduction may suitably be performed using iron powder and concentrated hydrochloric acid in methanol, typically under reflux. Alternatively, the reduction may be performed using hydrogen over a palladium on carbon catalyst.

A compound of formula '(V) may be prepared by treating a compound of the following formula (VI):

wherein m is as defined in formula (V) and X is a halogen, with an amine of formula (VII):

wherein R4 and Rs are as defined above for formula (A), in an organic solvent in the presence of base. The organic solvent is typically DMF or acetonitrile, and the base is typically K2CO3. The temperature is typically from room temperature to 1000C, for instance from 60 C to 80 C. The duration of the reaction is usually from 1 to 30 hours, for instance 2 to 24 hours, typically from about 8 hours to about 12 hours.

When R3 is a group of formula (A) as defined above in which n is 0 and v is 1, the amine H-R3 may be prepared by reducing the corresponding nitrile of formula (VIII):

wherein m is 1, 2 or 3 and 4 and R5 are as defined above for formula (A). The reduction may suitably be performed with LiA'H4 in ethylene glycol dimethyl ether, at a temperature between OOC and 400C, typically warming from 0 C to room temperature, for instance from 0 C to 200C. Other amines H-R; may be prepared by analogous methods using known starting materials, or are commercially available products.

A nitrile of formula (VIII) may be prepared by treating a compound of formula (VII) as defined above with a compound of formula (X):

wherein X is a halogen and m is as defined for formula (VIII), in an organic solvent in the presence of a base.

The solvent is suitably acetonitrile. The base may be, for example, K2CO3. The reaction is typically carried out at the reflux temperature of the solvent for a period of from 1 hour to 30 hours, for instance from 1 hour to 20 hours.

An aldehyde of formula (III) wherein R1 is a group of formula (D) may be prepared by treating the compound of formula (XI):

with an amine of formula H - N(R10) (R11) wherein R10 and R1- are as defined for formula (D), in a suitable solvent. Such solvents include aqueous THF. The compound of formula (XI) may in turn be prepared by treatment of 4hydroxybenzaldehyde with 1.5N sodium hydroxide followed by epichlorohydrin. This reaction is typically performed at about 500C for about 5 hours.

The aldehyde of formula (III) wherein R1 is a group of formula (E) in which r is 2 (compound 5.1) may be prepared as described in Reference Example 5 which follows.

Corresponding aldehydes in which r in formula (E) is 1 or 3 may be prepared by an analogous process, replacing the 4-(2 oromoethyl)benzoic acid used as starting material by t- bromomethylbenzoic acid or 4-(3-bromopropyl)benzoic acid, respe~,ively.

An aldehyde of formula (III) may also be prepared by treating the corresponding nitrile of formula (XII)

with formic acid and Raney nickel, for instance as described in Reference Example 7 which follows.

Compounds of formula (I) may be converted into pharmaceutically acceptable salts, and salts may be converted into the free compound, by conventional methods.

Suitable salts include salts with pharmaceutically acceptable inorganic or organic acids. Examples Ci inorganic acids include hydrochloric acid, sulphuric acid and orthophosphoric acid. Examples of organic acids include t-toluenesulphonic acid, methanesulphonic acid, mucic acid and succinic acid.

Cancer cells which exhibit multi-drug resistance, referred to as MDR cells, display a reduction in intracellular drug accumulation compared with the corresponding drug-sensitive cells. Studies using in vitro derived MDR cell lines have shown that MDR is often associated with increased expression of a plasma membrane glycoprotein (P-gp) which has drug binding properties. P-gp is thought to function as an efflux pump for many hydrophobic compounds, and transfection studies using cloned P-gp have shown that its overexpression can confer the MDR phenotype on cells: see, for example, Ann. Rev. Biochem 58 137-171 (1989).

A major function of P-gp in normal tissues is to export intracellular toxins from the cell. There is evidence to suggest that overexpression of P-gp may play a clinical role in multi-drug resistance. Increased levels of P-gp mRNA or protein have been detected in many forms of human cancers leukaemias, lymphomas, sarcomas and carcinomas. Indeed, in some cases P-gp levels have been found to be increased in tumour biopsies obtained after relapse from chemotherapy.

Inhibition of P-gp function in P-gp mediated MDR has been shown to lead to a net accumulation of anti-cancer agent in the cells. For example, Verapamil a known calcium channel blocker was shown to sensitise MDR cells to Vinca alkaloids in vitro and in vivo: Cancer Res., 41, 1967-1972 (1981). The proposed mechanism of action involves competition with the anti-cancer agent for binding to the P- gp. A range of structurally unrelated resistance-modifying agents acting by this mechanism have been described such as tamoxifen (Nolvadex:ICI) and related compounds, and cyclosporin A and derivatives.

Compounds of formula I and their pharmaceutically acceptable salts (hereinafter referred to as the present compounds") have been found in biological tests to have activity in modulating multi-drug resistance. The results are set out in Example 3 which follows. The present compounds may therefore be used as multi-drug resistance modifying agents, also termed resistance-modifying agents, or RMAs. The present compounds can modulate, e.g. reduce, or eliminate multi-drug resistance.

The present compounds can therefore be used in a method of potentiating the cytotoxicity of an agent which is cytotoxic to a tumour cell. Such a method comprises, for instance, administering one of the present compounds to the tumour cell whilst the tumour cell is exposed to the cytotoxic agent in question. The therapeutic effect of a chemotherapeutic, or antineoplastic, agent may thus be enhanced. The multi-drug resistance of a tumour cell to a cytotoxic agent during chemotherapy may be reduced or eliminated.

The present compounds can also be used in a method of treating a disease in which the pathogen concerned exhibits multi-drug resistance, for instance multi-drug resistant forms of malaria (Plasmodium falciparum), tuberculosis, leishmaniasis and amoebic dysentery. Such a method comprises, for instance, administering one of the present compounds with (separately, simultaneously or sequentially) the drug to which the pathogen concerned exhibits multi-drug resistance. The therapeutic effect of the drug may thus be enhanced.

A human or animal patient harbouring a tumour may be treated for resistance to a chemotherapeutic agent by a method comprising the administration thereto of one of the present compounds. The present compound is administered in an amount effective to potentate the cytotoxicity of the said chemotherapeutic agent. Examples of chemotherapeutic or antineoplastic agents which are preferred in the context of the present invention include Vinca alkaloids such as vincristine and vinblastine; anthracycline antibiotics such as daunorubicin and doxorubicin; mitoxantrone; actinomycin D; taxanes e.g. taxol; epipodophyllotoxins e.g. etopoposide and plicamycin.

In addition, a human or animal patient suffering from a disease in which the responsible pathogen exhibits multidrug resistance may be treated for resistance to a therapeutic agent by a method comprising the administration thereto of one of the present compounds.

Examples of such disease include multi-drug resistant forms of malaria (Plasmodium falcitarum), tuberculosis, leishmaniasis and amoebic dysentery.

MDR modulators also have utility in the delivery of drugs across the blood-brain barrier, and in the treatment cf AIDS and AIDS-related complex. The present compounds can therefore be used in a method of facilitating-the delivery of drugs across the blood brain barrier, and in the treatment of AIDS or AIDS-related complex. A human or animal patient in need of such treatment may be treated by a method comprising the administration thereto of one of the present compounds.

The present compounds can be administered in a variety of dosage forms, for example orally such as in the form of tablets, capsules, sugar- or film-coated tablets, liquid solutions or suspensions or parenterally, for example intramuscularly, intravenously or subcutaneously. The present compounds may therefore be given by injection or infusion.

The dosage depends on a variety of factors including the age, weight and condition of the patient and the route of administration. Typically, however, the dosage adopted for each route of administration when a compound of the invention is administered alone to adult humans is 0.001 to 50 mg/kg, most commonly in the range of 0.01 to 5 mg/kg, bcdy weight. Such a dosage may be given, for example, from 1 te 5 times daily by bolus infusion, infusion over several hours and/or repeated administration.

A piperazinedione derivative of formula (I) or a pharmaceutically acceptable salt thereof is formulated for use as a pharmaceutical or veterinary composition also comprising a pharmaceutically or veterinarily acceptable carrier or diluent. The compositions are typically prepared following conventional methods and are administered in a pharmaceutically or veterinarily suitable form. An agent for use as a modulator of multi-drug resistance comprising any one of the present compounds is therefore provided.

For example, the solid oral forms may contain, together with the active compound, diluents such as lactose, dextrose, saccharose, cellulose, corn starch or potato starch; lubricants such as silica, talc, stearic acid, magnesium or calcium stearate and/or polyethylene glycols; binding agents such as starches, arabic gums, gelatin, methylcellulose, carboxymethylcellulose, or polyvinyl pyrrolidone; disintegrating agents such as starch, alginic acid, alginates or sodium starch glycolate; effervescing mixtures; dyestuffs, sweeteners; wetting agents such as lecithin, polysorbates, lauryl sulphates. Such preparations may be manufactured in known manners, for example by means of mixing, granulating, tabletting, sugar coating, or film-coating processes.

Liquid dispersions for oral administration may be syrups, emulsions and suspensions. The syrups may contain as carrier, for example, saccharose or saccharose with glycerol and/or mannitol and/or sorbitol. In particular, a syrup for diabetic patients can contain as carriers only products, for example sorbitol, which do not metabolise to glucose or which only metabolise a very small amount to glucose. The suspensions and the emulsions may contain as carrier, for example, a natural gum, agar, sodium alginate, pectin, methylcellulose, carboxymethy1cellulos or polyvinyl alcohol.

Suspensions or solutions for intramuscular injections may contain, together with the active compound, a pharmaceutically acceptable carrier such as sterile water, olive oil, ethyl oleate, glycols such as propylene glycol, and, if desired, a suitable amount of lidocaine hydrochloride. Some of the present compounds are insoluble in water. Such compounds may be encapsulated within liposomes.

The invention will be further illustrated in the Examples which follow.

Reference Example 1: 1-acetyl-3-benzylidene-4-methyl 2,5-piDerazinedione 1,4-Diacetyl-2,5-piperazinedione (described by Marcuccio and Elix in Aust. J. Chem, 1984, 37, 1791) (25.0g, 126 mmol) was treated at 1300C in DMF (200ml) with triethylamine (17.6ml, 126 mmol) and benzaldehyde (13.0 ml, 126 mmcl). After 4 hours the mixture was cooled to room temperature and poured into EtOAc (1000 ml) and washed 3 times with brine. Any solid formed at this stage was filtered off. The filtrate was dried (MgS04) and the solvent removed in vacuo. The residue was recrystallised from EtOAc:Hexane to give 11.78g (38k) of 1-acetyl-3-benzylidene2,5-piperazinedione.

The latter compound was treated with NaA and MeI in DMF: THF (1:5) at a temperature of 0 C and allowed to warm to room temperature to give the title compound in 57% yield.

Reference Example 2: Preparation of amines H-R3 via substituted nitrobenzene

4-Bromoethyl nitrobenzene (2a) was treated with 1phenylpiperazine (2b) in the presence of K2CO3 in DMF at 800C for 8 hours. Compound 2c was obtained in 58% yield. 2c was then reduced by treatment with iron powder and concentrated HCl in MeOH under reflux for 3 hours. The desired amine 2.1 was obtained in 40% yield.

Following an analogous synthetic route, but using where necessary 4-bromomethylnitrobenzene or 4-(3bromopropyl)nitrobenzene in place of 4-(2 bromoethyl)nitrobenzene (2a), and replacing 4phenylpiperazine (2b) by the appropriate compound of formula (VII) , further amines H-R3 were prepared as shown in Table 1.

The conditions employed at each stage in the preparation of these further amines were as described above for amine 2.1, except for amine 2.9 where the reduction step was conducted using hydrogen at 50 p.s.i. over palladium on carbon, in ethanol. This reduction was performed for 2.5 hours at room temperature. In the case of amine 2.4, reduction of the nitro group was accompanied by hydrogenolysis of the 4 cklorsphenyl group to give the amine 2.4.

TABLE 1

o (VI) Compound Amine Vii H-R3 o (N0) wherein m Is: 2 OMo (2.2) > X{\ z (2.3) 2 IiNIci (2A) 2 H2N (2.S) TABLE 1 continued

Reference Example 3: Preparation of amines H-R3 via substituted nitrile

6,7-Dimethoxy-1,2,3,4-tetrahydroisoquinoline hydrochloride (3a) was treated with chloroacetonitrile in tne presence of K2CO3 in acetonitrile under reflux for 24 hours. Compound 3b was obtained in 92% yield. 3b was then treated with LiAlH4 in ethylene glycol dimethyl ether at room temperature overnight. The temperature was then raised to 4C-C and the reaction continued for 30 minutes. The desired amine 3.1 was obtained in 98% yield.

Following an analogous synthetic route, but modifying the conditions of the first step where necessary and replacing compound 3a by the appropriate compound of formula Vi2, the further amines H-R3 listed in Table 2 were prepared: TABLE 2

Compound of Conditions of Amine H-R3 (No) formula VII first step A K2CO3, A HN NMe ClCH2CN, CH3CN N~N N NMe reflux 20h , m/ (3.2) Me K2 CO3 Me H- N/ Ph C1CH2 CN, N CH\ CH3CN reflux, H2N CH Ph Ph 24h (3.3) K2C03 ClCH2CN, CH3CN HN reflux 24h H2N (3-4) K2 CO3 fOMB K2C03 OMe HCIHNw&num;OMe CH3CN reflux 24h (35) OMe OM KC2jC & H32,CN &verbar;t ClCH2CN H2N N 4 oMe MeNH M'1)OM. DMe CH3CN . reflux 4h (36) Reference ExamPle 4: Preparation of further amines H-R3 1 (3,4-Dimethoxyphenethyl)methylamine

2-(3,4-Dimethoxyphenyl)ethylamine (4a) was treated with MeOCOCl in the presence of triethylamine in CH2C12 at -78 C and allowed to warm to 0 C overnight. Compound 4b was obtained in 9% yield. 4b was treated with LiAlH4 in THF at a temperature of 0 C and allowed to warm to room temperature overnight. Compound 4.1, which is the starting amine used to prepare compound 2.9 in Reference Example 2, was obtained in 91% yield.

2. H2N-(CH2)2-NMe-CH2CHPh2 2,2-Diphenylethylamine was treated with (CF2CO)2O in EtO at OOC for 1 hour. The resulting compound (Ph)2-CH-CH2-NHCOCF3, obtained in quantitative yield, was treated with KH in THF at OOC followed by MeI and 18-crown-6 at room temperature for 24 hours to give (Ph)2-CH-CH2-NMeCOCS3 in 91k yield. The latter compound was treated with 2M NaOH in methanol under reflux for 2 hours to give (Ph)2-CH-CH2N in 81% yield, which in turn was treated with chioroacetonitrile in the presence of K2CO3 in acetonitrile under reflux for 24 hours to give (Ph)2-CH-CH2-NMe-CH2CN in 83% yield. Reduction of this compound with LiAlH4 in ethylene glycol dimethyl ether at room temperature for 2 hours gave the title amine, which is compound 4.2, in 90% yield.

3. Amine 4.3

Compound 4c was treated with 6,7-dimethoxy-1,2,3,4tetrahydroisoquinoline in CH2C12 at OOC in the presence of 2chloro-l-methylpyridinium iodide and triethylamine. The solution was allowed to warm to room temperature overnight.

Compound 4d, which was obtained in 93% yield, was treated with trifluoroacetic acid in dichioromethane at room temperature for 30 minutes. Compound 4e was obtained in 10% yield after trituration with acetone. Compound 4e was treated with LiAlH4 in THF at 10 C and left overnight to warm to room temperature. Compound 4.3 was obtained in 75% yield.

Reference Example 5: Preparation of aldehyde 5.1

Compound 5a was treated with excess CH2N2 in THF at 0 C for 7 hours. 5b was obtained in 98% yield. Compound 5b was then treated with 6,7-dimethoxy-1,2,3,4- tetrahydroisoquinoline hydrochloride in DMF in the presence of K2CO3 at room temperature for 5 days to give 5c in 56% yield. Compound Sc was reduced by treatment with LiAlH4 in TMP at room temperature for 1 hour toXgive Sd (80W yield), which in turn was treated with pyridinium chlorochromate (PCC) buffered with NaOAc in CH2Cl2 at room temperature for 16 hours. Compound 5.1 was obtained in 25% yield.

Reference ExamPle 6: Preparation of aldehydes of formula (III) Method 1 The aldehydes of formula IIIa listed in Table 3 below were prepared by treating 3-formylbenzoic acid with the appropriate amine H-R3 (a compound prepared in one of Reference Examples 2 and 3) in CH2Cl2 in the presence of 2 c:loro-1-methylpyridinium iodide at 0CC. The reaction was allowed to warm to room temperature overnight.

TABLE 3: Aldehydes of formula IIIa

Aldehyde No. R3 Corresponding amine H-R3 6.1 2.2 6.2 In 2.1 t\J . ~~ ~iH 5 - NH - 7 2.7 -NH 6.4 2.9 OM.

6.5 3.5 --Nn?/ 6. 6 Me 3.6 ~NHNOMI Me 4. 2 6.29 NIPh -NH Ph Method 2 The aldehydes of formula Ilib listed in Table 4 below were prepared by treating 4-formylbenzoyl chloride with the appropriate amine H-R in CH2Cl2 in the presence of triethylamine at 0 C. In the case of aldehyde 6.32, 4 carboxybenzaldehyde was used in place of 4-formylbenzoyl chloride and 2-chloro-1-pyridinium iodide was additionally present in the reaction mixture. The reaction was allowed to warm to room temperature overnight. Each amine was either a compound prepared in one of reference Examples 2 and 3, or a commercially available product.

TABLE 4: Aldehvdes of formula IIIb

Aldehyde No. R3 Corresponding amine H-R3 6.7 2.2 NHM 6.8 3.2 . B , N NMe NHN NMe 6.9 3.1 OMe -NH 6.10 N Commercial Am , product -N N N 6.11 CF, Commercial In - product NHNN\/ 6.12 1 Commercial -N NMe product

6.13 Commercial product -NH O 6.14 Am /~~\ Commercial -NH < N O product i 6.15 - CH2 OMe 2.7 N OMe OMe -NH 6.16 2.3 -NH 6.17 Commercial --NHH-CH2CH=CH2 product 6.18 Am fiD Commercial OMe N--OMe product 6.19 3.3 -NH-CH2CH2-N-CHPh2 Me 6.20 - NH/\ < e or 2.4 6.21 NX 2.5 NH v H 6 22 - NHm H 2.8 6 23 2 1 (\C/C-N NPh N H 6.24 Am 2.6 NNPh -NH

6.25 f 3.4 --NH/N, 6.26 /m Commercial 6.26 N NPh product -NH 6.27 2.10 6.32 N < ( 4.3 Method 3 3y treating the compound of formula (XI) defined above in T.--:F with aqueous HNMe2 at room temperature for about 2 hours, the following aldehyde of formula (III) was produced in 91% yield:

Method 4 Compound Sd, described in Reference Example 5, was treated with 4-hydroxybenzaldehyde in TKF at OOC in the presence of triphenylphosphine and dimethyl azidocarboxylate to give the following aldehyde of formula (III) in 40% yield:

The above process was repeated, but using 3 hydroxybenzaldehyde in place of 4-hydroxybenzaldehyde. The following aldehyde of formula (III) was produced in 50% yield:

Reference Example 7: Preparation of aldehyde 7.1

7a was treated with an excess of SOCl2 and a catalytic amount oS DMF in toluene under reflux for 4 hours. The resulting compound 7b was treated with 4-aminobenzonitrile in CH2C12 in the presence of triethylamine at 0 C. The reaction mixture was warmed to room temperature overnight. Flash chromatography tl:l hexane:ethyl acetate) gave 7c in 39 yield, which was treated with 6,7-dimethoxy-1,2,3,4- tetrahydroisoquinoline in the presence of K2COl in acetonitrile under reflux for 18 hours. Flash chromatography (10% methanol in ethyl acetate) gave 7d in 25% yield. 7d was treated with formic acid and a 50% slurry in water of Raney nickel under reflux for 2 hours. The aldehyde 7.1 was obtained in 71% yield.

Example 1: Preparation of compounds of formula (I) By treating l-acetyl-3-benzylidene-4-methyl-2,5- piperazinedione, as described in Reference Example 1, with an aldehyde prepared in one of Reference Examples 5, 6 or 7 in DMF in the presence of Cs2CO, at a temperature of between 80 and 90"C, the compounds of formula I listed in Table 5 were prepared: TABLE 5

Aldehyde N Compound of formula I 6.7 6.8 6.9 9008 6.10 9022 6.28 9023 6.11 9049 6.1 9051 6.12 9052 6.13 9053 6.14 9054 6.15 9064 6.16 9065 6.17 9070 6.18 9071 6.19 9076 6.20 9079 6.21 9080 6.2 9083 6.22 9096 6.23 9103 6.24 9104 5.1 9115 6.25 9116 6.26 9117 6.3 9128 6.5 9136 6.6 9137 6.4 9138 6.27 9161

6.29 9163 6.30 9176 6.31 9177 7.1 9190 6.32 X 9200 Compounds 9052, 9071, 9076, 9116, 9104, 9053, 9054, 9064 and 9051 were converted in a final step to their hydrochloride salts, by bubbling gaseous HCl through a solution of each compound in THF. (For these compounds the hydrochloride salt rather than the free base was used in the biological testing described in Example 3).

Example 2: Pharmaceutical Composition Tablets, each weighing 0.15 g and containing 25 mg of a corr.pound o the invention can be manufactured as follows: Cotosition for 10,000 tablets compound of the invention (250 g) lactose (800 g) corn starch (415 g) talc powder (30 g) magnesium stearate (5 g) The compound of the invention, lactose and half of the corn starch are mixed. The mixture is then forced through a sieve 0.5 mm mesh size. Corn starch (10 g) is suspended in warm water (90 ml). The resulting paste is used to granulate the powder. The granulate is dried and broken up nr.o sall fragments on a sieve of 1.4 mm mesh size. The remaining quantity of starch, talc and magnesium stearate is added, carefully mixed and processed into tablets.

Example 3: Testinq of compounds (I) as modulators of MDR Materials and Methods The EMT6 mouse mammary carcinoma cell line and the MDR resistant subline AR 1.0 were cultured in RPMI 1640 medium containing 10% foetal calf serum and 2mM glutamine at 370C in 5k CO2. Cells were passaged between 1 in 200 and 1 in 2000 in the case of the parental cell line and between 1 in 20 and 1 in 200 in the case of the MDR resistant subline, after trypsinisation (0.25% trypsin, 0.2gll, EDTA) 1. Druq accumulation assay AR 1.0 cells were seeded into 96 well opaque culture plates (Canberra Packard) . The assay medium contained a mixture of tritiated Daunorubicin (DNR), a cytotoxic agent, and unlabelled DNR (0.3 Ci/ml; 2 M). Compounds of formula I were serially diluted in assay medium over a range of concentrations from 5 nM to 100 sM. The cells were incubated at 37 C for 1 hr before washing and determination of cell associated radioactivity. Results were expressed as k maximum accumulation where 100% accumulation is that observed in the presence of the known RMA verapamil at 100M. Where possible an IC, was determined The results are set out in the following Table 6. TABLE 6

Compound No. IC50 ( M) Max Accumulation Accumulation 9006 0.4 9007 30% 9008 3.0 9022 7.0 9023 30% 9049 20% 9051 0.15 9052 100 9053 50 9054 32% 9064 0.3 9065 6 9070 5 9071 6 9076 44% 9079 80 9080 18% 9083 2 9096 20% 9103 20% 9104 5 9115 9116 9117 9128 3.

9136 0.9 9137 2 9138 0.8 9161 20%

9163 2.0 9176 1.000 9177 1.750 9190 0.350 9200 1.700 2. Potentiation of Doxorubicin toxicitv Compounds of formula (I) were examined for their ability to potentiate the toxicity of doxorubicin in AR 1.0 cells. In initial proliferation assays compounds were titrated against a fixed concentration of doxorubicin (0.86 m) which alone is non-toxic to PR 1.0 cells. After a four day incubation with doxorubicin proliferation was measured using the colorimetric sulphorhodamine B assay (Skehan et G1; J.Natl. Cancer Inst. 82 pp 1107-1112 (1990)). The results are shown in Table 7.

Compounds which were shown to be able to sensitise AR 1.0 cells to 0.86 M doxorubicin without high innate toxicity were selected for further study. Cells were cultured for four days with a titration of doxorubicin (0.01 nm - 50 M) in the presence of a fixed concentration of each compound. Proliferation was quantified as described by Skehan et al loc cit. The IC50 (concentration required to reduce proliferation to 50% of the untreated controls) for doxorubicin alone and with each compound were derived ad used to calculate the potentiation index (PI): IC50 for Doxorubicin alone PI= IC50 for Doxorubicin plus RMA The results are shown in Table 8: TABLE 7

Compound No. Compound toxicity Toxicity with (IC50 UM) cytotoxic agent (IC50 M) 9006 2 0.04 9008 10 2 0 9022 35 0.8 9023 10 5.0 9049 2 0.2 9051 2 0.01 9053 40 4 0 9054 50 30 9064 2 0.01 9065 2 0.2 9070 40 4.0 9071 6 0.2 9079 2 1.7 9083 3 0.1 9104 40 0.05 9115 60 2.0 9116 8 1 9117 8 3 9128 10 2 9136 13 2 9137 12 4.5 9138 8 1.0 9163 10 0.5 9176 10. 0.2 9177 15 0.5 9190 15 0.05 9200 13 0.8 TABLE B

Potentiation Indices Compound No. Potentiation index (RMA at 1 HM) 9006 H 1000 9022 5 9049 15 9051 2000 9064 750 9065 15 9071 4 9079 3 9104 17 9136 25 9138 333 9163 6.7 9176 300.0 9177 75.0 9190 75.0 (measured at 0.3 M) 10.0 (measured at 0.1 M) 3.3 (measured at 0.03 M) 1.4 (measured at 0.01 M) Example 4: Characterisation of the cresent compounds The compounds and salts prepared in the preceding Examples were characterised by mass spectroscopic, microanalytical and proton nmr techniques. The results are set out in Tables 9 and 10: TABLE 9

No. Mol. Formula Mass spec data H nmr data Microanalysis mass mode solvent/ # Calc Found (intensity) field 9023 C24H27N3O4 422(100) ESI CDCl3/ 2.35 (6H,s), 2.41 C 68.39 68.09 68.26 400MHz (1H,dd), 2.57 (1H,dd) 2.99 (3H,s), 4.02 H 6.46 6.44 6 42 (2H,m), 4.08 (1H,m) 7.00-7.03 (3H,m), 7.28- N 9.97 9.81 9.81 7.42 (8H,m), 7.95 (1H,b) 9052 C25H26N4O3 HCl 431(100), FAB+ d6-DMSO/ 2.75 (3H,s), 2.88 C 64.3 64.3 331(50) 300MHz (3H,s), 3.10-3.30 (4H,bs), 3.35 (4H,bs), H 5.85 5.80 6.85 (1H,s), 7.12 (1H,s), 7.32-7.40 N 12.0 11.6 (5H,m), 7.48 (2H.d).

7.65 (2H,d). 10.30 (1H,bs) 9054 C30H28N4O4 HCl 509(40). CI d6-DMSO/ 2.96 (3H,s) 3.40 C 66.1 66.0 508(45). 300MHz (4H,bs), 3.99 (4H,bs), 331(35). 6.98 (1H,s), 7.20 H 5.35 5.30 178(100) (1H,s), 7.43-7.56 (7H,m), 7.82 (2H,d), N 10.3 10 3 7.89 (2H,d), 8.12 (2H,d) 10.43 (1H,s).

10.83 (1H.s) TABLE 10

No. Mol. Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9006 C39H38N2O5 643(100) ESI d6-DMSO/400MHz 2.87 (3H.s). 2 89-3.23 (8H.m) 3.73 (2x3H.s). 4.20-4.54 (2H,m). 6.78 (1H.s) 6.82 (1H.s). 6.88 (1H,s), 7.09 (1H.s).

7.20-8.07 (13H,m), 10.30 (1H.s) 10 62 (1H,s), 11.01 (1H,bs) 9007 C2@H31N5O3 474(100) ESI CDCl3/400MHz 2.35 (3H.s). 2.49-2.73 (10H.m). 3.02 (3H.s). 3.59 (2H.m). 7.07 (1H,s). 7.28-7 44 (6H.m). 7.50 (2H.d). 7.86 (2H.d) 9008 C33H34N4O5 567(100) ESI CDCl3/400MHz 2.76-2.90 (6H.m), 3.02 (3H.s) 3.61-3.70 (4H.m). 3.85 (2x3H.s).6.55 (1H.s). 6 64 (1H,s), 6.94 (1H.bs), 7.07 (1H,s), 7.277.43 (6H,m), 7.47 (2H,d), 7.85 (2H.d) 9022 C28H26N6O3 495 (20). ESI CDCl3/400MHz 3.02 (3H,s), 3.35-4.07 (8H,m), 6.56 (1H.t).

331 (100) 7.08 (1H,s), 7.29-7.43 (6H,m), 7.50 (2H.d) 7.55 (2H.d), 8.83 (2H.d) 9049 C39H36F3N5O3 680(100) ESI CDCl3/400MHz 2.64-2.75 (6H.m). 2.87 (2H.m). 3.04 (3H.s).

3.23-3.31 (4H,m), 7.04-7.10 (3H,m). 7 12 (1H,s) 7.23-7.42 (9H,m), 7.55 (2H,d), 7.59 (2H,d), 7.78 (1H,s), 7.96 (2H.d) 9051 C39H38N4O5 HCl 643(22). 348(30). CI d6-DMSO/400MHz 2.86 (3H,s), 2.92-3.18 (6H,m), 3.36-3.48 (2H,m), 3,73 (2x3H,s), 4.22-4.55 (2H,m).

6.78 (1H,s), 6.82 (1H,s), 6.89 (1H,s), 7 09 (1H,s), 7.28-8.14 (13H,m) 10.29 (1H,s) 10.69 (2H.bs)

No. Mol. Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9053 C26H28N4O4 HCl 461(100). 331(10) FAB+ d6-DMSO/ 2.82 (3H.s). 3.05-3.20 (2H.bs), 3.45-3.62 300MHz (2H.bs). 3.68-3.78 (4H.bs). 3.80-3.90 (2H.bs). 3.90-4.00 (2H.bs). 6.82 (1H.s).

7 07 (1H.s). 7.33-7.48 (5H.m). 7.66 (2H.d) 7.96 (2H.d). 8.80-9.05 (1H.bs) 10.15 (1H.s). 10.95-11.15 (1H.bs) 9064 C38H36N4O5.NCl 629(100) ESI d6-DMSO/ 2.87 (3H.s). 2.90-3.40 (4H,m). 3.70 400MHz (2x3H.s). 4.10-4.52 (4H.m). 6.80 (2x1H.s).

6.89 (1H.s). 7 11 (1H.s). 7.30-7.45 (5H.m).

7.59 (2H.d). 7.73 (2H.d). 7.91 (2H.d) 8 02 (2H.d). 1046 (1H.s). 10.64 (2H.bs) 9065 C37N34N4O3 582(10). 449(30). CI CDCl3/400MHz 2.65-3.10 (11H.m). 3.74 (2H.s). 6.95-8.10 331(100) (21H.m) 9070 C23H21N3O3 388(100) CI

No. Mol. Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9079 C39H38N4O4 627(5). 156(36) CI d6-DMSO/400MHz 1.62 (2H.m). 1.88-2.04 (2H.m). 2.40-2.82 85(100) (8H.m). 2.89 (3H.s). 4.77 (1H.s). 6.87 (1H.s). 7.09 (1H.s). 7.17-7.80 (17H.m) 8.02 (2H.d). 10.19 (1H.s) 9080 C39H35N5O3 622(100) ESI d6-DMSO/400MHz 2.64-2.90 (8H.m). 2.86 (3H.s). 3 68 (2H.s) 6 88 (1H.s). 6.90-7 04 (2H.m). 7.10 (1H s) 7.22-7.48 (9H.m). 7 72 (4H.m) 8.00 (2H d) 10.19 (1H.s). 10.67 (1H.s) 9096 C38H33N5O3 608(15). 291(100) CI d6-DMSO/400MHz 2 74 (3H.s). 2.70 (2H.m). 2.80 (2H.m) 3.58 (2H.s). 3 70 (2H.s) 6.88 (1H.s). 6.90-7.05 (2H.m). 7 10 (1H.s). 7 20-7.50 (9H.m) 7.65-7.80 (4H.m). 8.00 (2H.d) 10 27 (1H.s). 10 62 (1H.s) 9103 C38H37N5O3 612(87). 175(100) CI d6-DMSO/400MHz 2.5-2.6 (6H.m). 2.75 (2H.m). 2.85 (3H.s).

3 11 (4H.m). 6.75 (1H.t). 6 88 (1H.s). 6 90 (2H.d). 7.1 (1H.s). 7.2 (3Hm). 7.28-7.49 (7H.m), 7.75 (3H,m), 8.1 (2H.d). 10.15 (1H,s), 10.6 (1H,bs) 9104 C37H35N5O.HCl 598(100) CI d6-DMSO/400MHz 2.5 (4H.m). 2.85 (3H,s). 3.11 (4H,m), 3.5 (2H,s), 6.75 (1H,t), 6.88 (1H,s). 6.90 (2H.d). 7.1 (1H,s). 7.2 (3H.m), 7.28-7.49 (7H,m), 7.75 (3H,m). 8.1 (2H.d) 9116 C31H30N4O3 HCl 507(100) CI CDCl3/300MHz 2.90 (3H,s), 3.0-4.8 (10H,m), 6.86 (1H,s), 7.11 (1H.s). 7.15-7.50 (9H,m). 7.68 (2H,d) 7.96 (2H.d), 8.77 (1H.bs). 10.34 (1H.bs).

10.42 (1H,b)

No. Mol Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9117 C30H29N3O5 529(5). 512(100). CI CDCl3/300MHz 2.93 (2H.t). 3.05 (3H.s). 3.76 (2H.q). 3.90 275(10). 118(20) (3H.s). 3.92 (3H.s). 6.20 (1H. bt). 6 816.90 (3H.m). 7.08 (1H.s). 7 30-7.47 (6H m) 7.51 (2H.d). 7.81 (2H.d). 8 04 (1H.bs) 9115 C32H33N3O4 524(95). 190(100) CI d6-DMSO/400MHz 2 63-2.72 (4H.m). 2.7 (3H.s). 2 84 (4H.bs).

3.52 (2H.s). 3.69 (6H.s). 6.61 (1H.s) 6.65 (1H.s). 6.8 (1H.s). 6.98 (1H.s). 7 07 (1H.s). 7 28-7.51 (9H.m) 9161 C40H40N4O5 657(7) CI CDCl3/400MHz 1.92 (2H.m). 2.47-2.85 (8H.m). 2.99 (3H.s) 3.57 (2H.s). 3.85 (2x3H.s). 6.52 (1H.s) 6.59 (1H.s), 7.10 (1H.s). 7.15-7.60 (13H.m). 7 85 (1H.m). 7.98 (1H.s). 8 08 (1H.s) 9083 C38H37N5O3 612(100) ESI CDCl3/400MHz 2.62-2.72 (6H.m). 2.82-2.89 (2H.m). 2.99 (3H.s) 3.25 (4H.m) 6.88 (1H.t). 6 96 (2H.d). 7.09 (1H.s). 7.20-7.29 (6H.m) 7.32-7.42 (4H.m). 7.53-7.61 (4H.m). 7.85 (1H.m). 7 97 (1H.s). 8 05 (1H.s) 8 53 (1H.bs) 9128 C38H36O5N4 629(100) ESI CDCl3/400MHz 2.74 (m.2H). 2.83 (m.2H). 3.01 (s.3H). 3 55 (s.2H). 3.69 (s2H). 3.82 (s.3H). 3 85 (s.3H), 7.49 (s.1H), 6.58 (s.1H). 7.09 (s.1H). 7.25-7.44 (10H.m). 7 58 7.64 (4H.m). 7.92 (1H.s). 7.96 (1H.s) 9136 C33H34N4O5 567(100) CI CDCl3/400MHz 2.75-2.90 (6H.m), 3.00 (3H.s). 3.60-3.72 (4H,m), 3.84 (6H,s), 6.54 (1H,s), 6.60 (1H,s), 7.03-7.11 (2H.m). 7.24-7 78 (10H,m). 7 84 (1H.s)

No. Mol. Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9137 C38H36N4O5 569(95). 357(100) CI CDCl3/400MHz 2.38 (3H.s). 2 62-2 80 (6H.m) 3 2 (3H.s).

3 46-3.54 (2H.m). 3 75 (3H.s). 3.81 (3H.s) 6.60-6.85 (5H.m). 7 6 (1H.s) 7 25-7 55 (9H.m) 7.79 (1H.s) 9138 C39H40N4O5 645(71). 106(100) CI CDCl3/400MHz 2 38 (3H.s). 2 60-2 82 (8H.m) 2 96 (3H.s) 3.85 (2x3H.s). 6.68-6.82 (3H.m). 7.04-7 60 (14H.m). 7 81 (1H.d). 7.97 (1H.s). 8.07 (1H.s) 9155 C37H36N4O5S 649(100) ESI CDCl3/400MHz 2.72-2.93 (8H.m). 3 19 (3H.s). 3 65 (2H.s) 3 85 (2x3H.s). 6.54 (1H.s). 6 60 (1H.s).

7.04 (1H.m). 7.08-7 10 (2H.m). 7.22 7 29 (3H.m). 7.45 (1H.m). 7.52-7.60 (4H.m) 7.81 (1H.m). 7.95 (2H.s) 8.38 (1H.s) 9163 C3@H36N4O3 585(100) ESI CDCl3/400MHz 2 36 (3H.s). 2 65 (2H.t). 2 95-3 10 (5H.m) 3 45 (2H.d). 4 20 (1H.t). 6 38 (1H.brs) 7 05-8.20 (22H.m) 9176 CDCl3/400MHz 2 70-2.98 (8H.m). 3.00 (3H.s). 3.65 (2H s) 3.82 (2x3H.s). 5.09 (2H.s). 6.53 (1H.s).

6 61 (1H.s). 7.00-7 10 (4H.m). 7.21-7 58 (7H.m). 7.82 (2H.d) 7.91 (1H.br s) 9177 CDCl3/400MHz 2 62-2.89 (8H.m). 2.91 (3H.s). 3.57 (2H.s) 3.76 (2x3H.s). 4.97 (2H.s). 6.45 (1H.s).

6.51 (1H.s). 6.82-6.95 (3H.m). 7 12-7 38 (12H.m). 8.05 (1H.br s) 9190 C39H38H4O3 643(3) CI CDCl3/400MHz 2.70-304 (11H.m). 3.65 (2H.s). 3.85 (2x3H.s). 6.53 (1H.s). 6.60 (1H.s). 7.03 (1H.s). 7.15-7 50 (11H.m). 7 68-7.92 (5H.m)

No. Mol. Formula Mass spec data H nmr data mass (intensity) mode solvent/field # 9200 C37H40N4O5 620(32) EI CDCl3/400MHz 1.05-2.00 (9H.m). 2 35-2.45 (2H.d). 2.622.84 (4H.m). 3.2 (3H.s). 3.55 (2H.s). 3.84 (2x3H.s). 6 52 (1H.s). 6.60 (1H.s) 7 06 (1H.s). 7.20-7 55 (11H.m)

Claims (10)

1. CLAIMS 1. A piperazinedione of general formula (I):

   wherein R1 is selected from: - hydrogen; and - a group of formula -(NH)t-CoR3 wherein t is 1 and R3 is a group of formula:

   wherein v is 0 and wherein n is O or 1 and m is O, 1, 2 or 3, at least one of n and m being other than, and R4 and R5, together with the nitrogen atom to which they are attached, form a heterocyclic group selected from (1) to (4):

   wherein R6 and R7, which are the same or different, are H or C1-C6 alkoxy, or R6 and R7 together form a methylenedioxy group; Y is O or -NR8 wherein R8 is C1-C6 alkyl or a phenyl group optionally substituted by CF3; and R2 is hydrogen or a group of formula -COR3 as defined above, provided that one of R1 and R2 is hydrogen and the other is not hydrogen; or a pharmaceutically acceptable salt thereof.
2. 2. A compound according to claim 1 wherein, in formula (A), n is 0 and m is 2, or n is 1 and m is O, 1, 2, 3, or n is 1 and m is 0, and R4 and R5 form together with the nitrogen atom to which they are attached a heterocyclic group selected from groups of formula (1) wherein R6 and R7 are both H or both Cl-C6 alkoxy, or together form a methylenedioxy group; formula (2) wherein Y is O or -NR8 wherein Ra is methyl, phenyl or trifluoromethylphenyl; formula (3); and formula (4).
3. 3. A compound selected from: N-(2-(l/2/3/4-Tetrahydro-2-isoquinloyl)ethyl)-4-((3z/6z)-6 benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylbenzamide, hydrochloride (9116); N-(4-((3Z,6Z)-6-Benzylidene-1-methyl-2,5-dioxo-3piperazinylidene)methylphenyl)-4-(2-(6,7-dimethoxy-1,2,3,4tetrahydro-2-isoquinolyl)ethyl)benzamide (9190)
4. 4. A pharmaceutical or veterinary composition which comprises a pharmaceutically or veterinarily acceptable carrier or diluent and, as an active principal, a compound as claimed in any one of the preceding claims.
5. 5. A process for producing a compound as defined in claim 1, which process comprises treating l-acetyl-3benzylidene-4-methyl-2,5-piperazinedione with an aldehyde of formula (III):

   wherein R1 and R2 are as defined in claim 1, in an organic solvent in the presence of a base; and, if desired, converting the resulting compound into a pharmaceutically acceptable salt thereof.
6. 6. A compound as defined in any one of claims 1 to 3 for use as a modulator of multi-drug resistance.
7. 7. Use of a compound as defined in any one of claims 1 to 3 in the manufacture of a medicament for use as a modulator of multi-drug resistance.
8. 8. A compound as defined in claim 1 and specifically hereinbefore mentioned.
9. 9. A process as defined in claim 5 and substantially as hereinbefore described in Example 1.
10. 10. A compound when produced by a process as defined in claim 5 or 9.