Proton abstraction from 3-trimethylsilylmethylthio-1-propene by butyllithium followed by treatment with iodomethane provided 1-methylthio-4-trimethylsilyl-1-butene. Meanwhile, 1-trimethylsilylmethylthio-2-butene afforded 3-methyl-4-methylthio-1-trimethylsilyl-1-butene upon successive treatment with butyllithium and iodomethane.