2-Bis (methylthio) methylenebenzothiophen-3 (2H)-one, which was prepared by the reaction of benzothiophen-3 (2H)-one with carbon disulfide in the presence of sodium hydroxide in dimethyl sulfoxide, reacted with nucleophilic reagents such as amines or active methylenes to give the corresponding the replacement products of one or two methylthio groups in good yields.