. "R3 is a C1-6 alkyl, or C2-6 alkenyl, or cycloalkyl, or (CH2)k aryl group (k=1-4), preferably k=1, and each said group may be optionally substituted by up to four substituents in any position independently selected from CF3, CCl3, Me, NO2, OH, OMe, OEt, CONR5 R6, NR5 R6, OCF3, SMe, COOR7, SO2 NR5 R6, SO3 R7, COMe, COEt, CO-lower alkyl, SCF3 CN, C2-6 alkenyl, H, halogens, C1-4 alkoxy, C3-6 cycloalky" . . . .