(6) an intermediate represented by the following formula V for synthesizing the amide derivative of formula I: ##STR5## where in the formula V, when R9 is a hydrogen atom, R10 represents an alkanoyl group having 1 to 8 carbon atoms of a carbon chain that may have a branched chain, a haloalkanoyl group having 1 to 8 carbon atoms of a carbon chain that may have a branched chain, a phenylalkanoyl gro