N-aroyl piperazine derivatives as orexin receptor antagonists

A compound of formula (I):

• wherein:
• Y represents NR2;
• m represents 1, 2, or 3;
• p represents 0 or 1;
• X is O, S, C═O, SO2, or —CH═CH—;
• Ar1 is aryl, or a mono or bicyclic heteroaryl group containing up to 4 heteroatoms selected from N, O and S;
• any of which may be optionally substituted;
• Ar2 represents phenyl or a 5- or 6-membered heterocyclyl group containing 1 to 3 heteroatoms selected from N, O and S, wherein the phenyl or heterocyclyl group is substituted by R1 and further optional substituents;
• or Ar2 represents an optionally substituted bicyclic aromatic or bicyclic heteroaromatic group containing 1 to 4 heteroatoms selected from N, O and S;
• R1 represents optionally substituted (C1-4)alkoxy, halo, optionally substituted (C1-6)alkyl, optionally substituted phenyl, or an optionally substituted 5- or 6-membered heterocyclic ring containing 1 to 4 heteroatoms selected from N, O and S;
• R2 represents hydrogen, optionally substituted (C1-4)alkyl, optionally substituted (C1-6)alkanoyl, optionally substituted (C1-6)alkanoxycarbonyl or optionally substituted (C1-6)alkylaryloxycarbonyl;
• wherein the optional substituents for the groups Ar1, Ar2 and R1 are selected from the group consisting of halogen, hydroxy, oxo, cyano, nitro, (C1-4)alkyl, (C1-4)alkoxy, halo(C1-4)alkyl, halo(C1-4)alkoxy, aryl(C1-4)alkoxy, (C1-4)alkylthio, hydroxy(C1-4)alkyl, (C1-4)alkoxy(C1-4)alkyl, (C3-6)cycloalkyl(C1-4)alkoxy, (C1-4)alkanoyl, (C1-4)alkoxycarbonyl, (C1-4)alkylsulfonyl, (C1-4)alkylsulfonyloxy, (C1-4)alkylsulfonyl(C1-4)alkyl, arylsulfonyl, arylsulfonyloxy, arylsulfonyl(C1-4)alkyl, (C1-4)alkylsulfonamido, (C1-4)alkylamido, (C1-4)alkylsulfonamido(C1-4)alkyl, (C1-4)alkylamido(C1-4)alkyl, arylsulfonamido, arylcarboxamido, arylsulfonamido(C1-4)alkyl, arylcarboxamido(C1-4)alkyl, aroyl, aroyl(C1-4)alkyl, aryl(C1-4)alkanoyl, (C1-4)acyl, aryl, aryl(C1-4)alkyl, (C1-4)alkylamino(C1-4)alkyl, and
• R3 R4N—, R3OCO(CH2)r, R3CON(R4)(CH2)r, R3R4NCO(CH2)r, R3R4NSO2(CH2)r and R3SO2NR4(CH2)r wherein each of R3 and R4 independently represents a hydrogen atom or a (C1-4)alkyl group or where appropriate R3R4 forms part of a (C3-6)azacyloalkane or (C3-6)(2-oxo)azacycloalkane ring and r represents zero or an integer from 1 to 4, and
• R3R4N(CH2)n— and R3R4N(CH2)nO—, wherein n represents an integer from 1 to 4, wherein R3 with at least one CH2 of the (CH2)n portion of the group form a (C3-6)azacycloalkane and R4 represents hydrogen, a (C1-4)alkyl group or with the nitrogen to which it is attached forms a second (C3-6)azacycloalkane fused to the first (C3-6)azacycloalkane;
• or a pharmaceutically acceptable salt thereof.