Imidazopyridine, pyrimidines and triazines for ponteciar cognition as ligands subclass alpha 5 receptor GABA-A.

A pharmaceutical composition comprising a compound of formula I or a pharmaceutically acceptable salt thereof: wherein: X represents N and Y represents N or CH; R1 represents hydrogen, hydrocarbon, a heterocyclic group, halogen, cyano, trifluoromethyl, nitro, -ORa, -SRa, -Sora, -SO 2 R, -SO2NRaRb, -NRaRb, -NRaCORb, -NRaCO2Rb, -COR, -CO 2 R, -CONR or -CRa = Norb; Ra and Rb independently represent hydrogen, hydrocarbon or a heterocyclic group; V and W are independently selected from H, halogen, C1-6 alkyl, OH and C1-6alkoxy; Z represents H, halogen, CN, NO2, CFA, OCF3, CF2H, SCF3, R2, OR3, SR3, (CH2) pN (R3) 2, O (CH2) pN (R3) 2, SO2R2, SO2N (R3) 2 , COR4, CO2R3, CON (R3) 2, NHCOR4, NR '(CH2) nheteroarilo or O (CH2) nheteroarilo wherein the heteroaryl is optionally substituted by one, two or three groups selected from C1-6 alkyl, benzyl, (CH2) pN (R3) 2, halogen and CF3, R '' is C1-6 alkyl, n is 1 or 2 and p is 0, 1 or 2; with the proviso that at least one of V, W and Z is other than H; R2 represents C1-6 alkyl, C3-6 cycloalkyl, (3-6C) C1-4 alkyl, C2-6 alkenyl or C2-6 alkynyl, any of which may bear a substituent selected from halogen, CN, NO2, CF3, OCF3, CF2H, SCF3, OH, C1-4alkoxy, C1-4alkoxycarbonyl, amino, C1-4 alkylamino, or di (C1-4alkyl) amino; R3 represents H or R2; or two R3 groups attached to the same nitrogen atom can complete a non-aromatic heterocyclic 5-7 membered ring; and R4 represents R3 or heteroaryl; in a pharmaceutically acceptable carrier.