To obtain a new compound for providing a 3-(2-chloro-2- fluorovinyl)-2,2-dimethylcyclopropanecarboxylic acid ester derivative by reacting the compound with a base.

This compound is shown by formula I (R is a lower alkyl or H) such as methyl 4,6-dibromo-6-chloro-6-fluoro-3,3-dimethylhexanoate. The compound of formula I is obtained by reacting a carboxylic acid derivative of formula II (e.g. methyl 3,3-dimethyl-4-pentenoate) with dibromochlorofluoromethane in the presence of at least one or more sulfur- containing compounds selected from the group consisting of a dithionite, hydroxymethylsulfinate and thioureadioxide.