In a method [B], a sulfoxide shown by the general formula [22] is dissolved in ethers such as ethyl ether, isopropyl ether, tetra hydrofuran and 1,2-dimethyl ether or a mixed solvent consisting of the ethers and halogenated hydrocarbons such as methylene chloride, methylene bromide, 1,2-dichloroethane and chloroform or aromatic hydrocarbons such as benzene, toluene and xylene, and Grignard reagent