| abstract |
A compound of the ** formula ** or a pharmaceutically acceptable salt thereof in which Ra is a group of the ** formula ** where P1 is phenyl, naphthyl or a benzo-condensed aromatic or aromatic ring containing 1 to 3 selected heteroatoms of oxygen, nitrogen and sulfur; R1 is halogen, C1-6 alkyl, C3-6 cycloalkyl, CO- C1-6 alkyl, C1-6 alkoxy, hydroxy, hydroxy C1-6 alkyl, nitro, CF3, cyano, SR6, SOR6, SO2R6, SO2NR6R7, CO2R6 , CONR6R7, OCONR6R7, NR6R7, NR6CO2R7, NR6CONR7R8, CR6 = NOR7 where R6, R7 and R8 are independently hydrogen or C1-6 alkyl; a is 0, 1, 2 or 3. |