Abstract: Compound of formula (I) wherein: A is a bicyclic heteroaryl, optionally substituted with one or more substituents; B is linker group connecting group A to group D and comprising a 3 or 4 atom linker where each atom is independently selected from carbon, oxygen, nitrogen and sulphur and is optionally subsituted with one or more C1-6 alkyl groups or two of such adjacent alkyl substituents may form a ring; C is aryl or a mono or bicyclic heteroaryl, each of which can be optionally substituted; D is an aryl or heteroaryl, both of which are optionally substituted R1 is hydrogen, C1-5 alkyl, C1-3 alkanoyl or C1-3 alkoxycarbonyl; R2 to R5 are each independently selected from hydrogen, C1-6 alkyl, aryl and heteroaryl containing up to 2 heteroatoms chosen from oxygen, sulphur and nitrogen, the aryl and heteroaryl optionally substituted with C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C1-4 alkoxy, C1-4 alkanoyl, C1-6 alkylamino, C1-4alkylC1-6alkyoxyl, C1-6alkylaminoC1-6alkyl, nitro, cyano, halogeno, trifl