. " alkyl containing 1 to 6 carbon atoms; R5 =R3 ; R7 is R1 other than H or the radical R6 COO--; R6 represents benzyl or a straight-chain or branched chain lower alkyl containing 1 to 6 carbon atoms; Y and Y1 independently represent chlorine or bromine; n is 1 to 4 inclusive; R2 represents hydrogen or a straight-chain or branched lower alkyl containing 1 to 6 carbon atoms or a phenyl group which is" . . .