Azaindole derivatives and their use as therapeutic agents

A compound of the formula (I):

• wherein:
• Het represents a heterocyclic residue selected from:
• where the dotted line in (b) represents an optional double bond;
• A completes a fused pyridine ring;
• B completes a fused benzene or pyridine ring;
• X represents an oxygen atom, a sulfur atom, two hydrogen atoms, ═NH or ═N(C1-6alkyl);
• Y is a straight or branched C1-4alkylene chain optionally substituted by halogen, oxo or hydroxy;
• or Y represents a straight or branched C2-4alkenylene or C2-4alkynylene chain;
• Z represents CR5R6 so as to complete a piperidine ring;
• R1a and R1b each independently represent hydrogen, C1-6alkyl, C2-6alkenyl, C1-6alkoxy, fluoroC1-6alkyl, fluoroC1-6alkoxy, halogen, cyano, NRaRb, SRa, SORa, SO2Ra, OSO2Ra, NRaCORb, CORa, CO2Ra or CONRaRb;
• R2 represents hydrogen, C1-6alkyl, fluoroC1-6alkyl, (CH2)mCORa, (CH2)pCO2Ra, (CH2)pOH, (CH2)mCONRaRb, (CH2)mphenyl or SO2C1-6alkyl;
• R3 represents phenyl, biphenyl, naphthyl or heteroaryl, wherein said phenyl, biphenyl, naphthyl or heteroaryl group may be optionally substituted by one, two or three groups independently selected from halogen, C1-6alkyl, C1-6alkoxy, fluoroC1-6alkyl, fluoroC1-6alkoxy, NO2, cyano, SRa, SORa, SO2Ra, CORa, CO2Ra, CONRaRb, C2-6alkenyl, C2-6alkynyl, C1-4alkoxyC1-4alkyl or —O(CH2)1-2O—;
• R4 represents hydrogen, methyl, carbonyl, benzyl, or a methylene bridge across the 2,5-positions on the piperadine ring;
• R5 and R6 each independently represent hydrogen, halogen, C1-6alkyl, C3-7cycloalkyl, C3-7cycloalkylC1-4alkyl, C2-6alkenyl, cyano, naphthyl, fluorenyl, (CH2)mphenyl, (CH2)mheteroaryl, CH(phenyl)2, CH(C1-6alkyl)(phenyl), C(C1-6alkyl)(phenyl)2, CO(phenyl), C(OH)(phenyl)2, C2-4alkenyl(phenyl), (CH2)mNRcRd, (CH2)pCONRcRd, (CH2)pNRaCORb, (CH2)mCORc, (CH2)mCO2Rc or (CH2)mOH wherein said phenyl, naphthyl, fluorenyl or heteroaryl groups may be optionally substituted by one, two or three groups independently selected from halogen, C1-6alkyl, C1-6alkoxy, fluoroC1-6alkyl, fluoroC1-6alkoxy, NO2, cyano, SRa, SORa, SO2Ra, CORa, CO2Ra, CONRaRb, C2-6alkenyl, C2-6alkynyl, C1-4alkoxyC1-4alkyl or —O(CH2)1-2O—;
• or R5 and R6 together are linked so as to form a 5- or 6-membered ring optionally substituted by ═O, ═S or a C1-4alkyl or hydroxy group, and optionally containing a double bond, which ring may optionally contain in the ring one or two heteroatoms selected from O and S, or groups selected from NRc, SO or SO2, and to which ring there is either fused or attached a benzene or thiophene ring, which benzene or thiophene ring is optionally substituted by 1, 2 or 3 substituents selected from C1-6alkyl, C3-7cycloalkyl, C3-7cycloalkylC1-4alkyl, phenylC1-4alkyl, trifluoromethyl, cyano, ORa, SRa, SORa, SO2Ra, NRaRb, NRaCORb, NRaCO2Rb, NRaSO2Rb, CORa, CO2Ra or CONRaRb, wherein the phenyl moiety of a phenylC1-4alkyl group may be substituted by C1-6alkyl, C1-6alkoxy, halogen or trifluoromethyl;
• Ra and Rb each independently represents hydrogen, C1-4alkyl, fluoroC1-4alkyl or phenyl;
• or the group —NRaRb may form a 5- or 6-membered ring optionally substituted by ═O, ═S or a C1-4alkyl or hydroxy group, and optionally containing a double bond, which ring may optionally contain in the ring one or two heteroatoms selected from O and S, or groups selected from NRc, SO or SO2;
• Rc and Rd each independently represents hydrogen, C1-4alkyl, fluoroC1-4alkyl, C2-4alkenyl, CORa, SO2Ra, phenyl or benzyl or Rc and Rd, together with the nitrogen atom to which they are attached, form a heteroaliphatic ring of 4 to 7 atoms, to which ring there may optionally be fused a benzene ring;
• m is zero or an integer from 1 to 4;
• p is an integer from 1 to 4;
• or a pharmaceutically acceptable salt thereof.