Configuration‐Dependent Ring Opening of Silyloxiranes: Synthesis of Functionalized Alkenes or Tetrahydrofurans

Abstract cis ‐ and trans ‐Silyloxiranes with a potential tosylate or bromide leaving group in the β position are available by the diastereospecific reduction of the corresponding alkynes with DIBAL‐H and hydrosilylation with silanes, respectively. In the reaction with the anion of a silylthioacetal, the outcome of the reaction is configuration dependent: the cis ‐oxiranes add nucleophilic methanthiolate and give a cis ‐vinyl sulfide unit in a Peterson olefination. In contrast, the trans ‐oxiranes lead to functionalized tetrahydrofurans with silyl(methylthio) substitution on the ring and in the exocyclic α position. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)