. "A is OH, halo, C1 -C8 alkoxy, C1 -C9 alkanoyloxy, oxo, or oximino optionally substituted by a C1 -C8 alkyl, alkenyl, alkynyl, aryl, trialkylsilyl, aralkyl, C1 -C9 alkanoyl group or other group capable of being hydrolysed in vivo to the oxime, or hydrazono optionally substituted by at least one C1 -C8 alkyl, alkenyl, alkynyl, aryl, trialkylsilyl, aralkyl, C1 -C9 alkoxycarbonyl, carbamoyl, thiocarba" . . . .