Synthesis and Reactions of a Stable Precursor to Dienes Containing Both Silicon and Sulfur Substituents

3-(Phenylthio)-4-(trimethylsilyl)-3-sulfolene (2) was readily prepared by chlorosulphenylation-dehydrochlorination of 3-(trimethylsilyl)-3-sulfolene (4b) . Treatment of 2 with n-butyllithium at ?105 °C followed by an alkylating agent gave only C5 alkylation products 6 demonstrating the stronger carbanion stabilizing ability of phenylthio group than that of trimethylsilyl group. 2-(Phenylthio)-3(trimethylsilyl)-1,3-butadiene (3a) was readily prepared by thermal extrusion of sulfur dioxide from 2 . Selective oxidation of 3a with MCPBA gave the sulfinyl (3b) and sulfonyl (3c) derivatives. The Diels-Alder reactions of 3a-c were studied, and the regiocontrolling power of the substituents follows the order PhS >PhSO ～ PhSO₂ >Me₃Si.