Of the compounds represented by the general formula (1), the compounds (1a) wherein R1 is hydrogen atom or a lower alkyl group, and R5 is a halogen atom may be produced, for example, by Procedure 1 represented by the reaction scheme as described below: ##STR4## [wherein R1a represents a lower alkyl group; R10 represents a lower alkyl group; L1 represents a halogen atom; R5a represents a halogen at