To obtain the subject new compound producible on an industrial scale simply and in high yield, suitable for providing 2-chloro-5-methylpyridine as an intermediate for an insecticide in high yield.

This compound is shown by formula I [R1 is a (substituted) alkyl, a group of the formula C(alkyl)2-alkenyl, an alkynyl, a cycloalkyl(alkyl), an aralkyl or a heteroalkyl] such as cis-N-benzyl-N-propenyl-acetamide. The compound of formula I is obtained by isomerizing a compound of formula II with a strong base such as an alkali metal hydroxide or an alkali metal alcoholate, for example, in the presence of a diluent such as tert-butyl ether, acetonitrile or formamide.