1,3-Difunctionalization of Propargyl Silanes with Concomitant 1,2-Silyl Shift: Synthesis of Allyl Functionalized Vinyl Silanes

Terminal alkynes with a silyl groupat the propargylicpositionupon activation with electrophiles such as N-bromosuccinimideundergo (E)-selective 1,2-silyl group migration.Subsequently, an allyl cation is formed that is intercepted by anexternal nucleophile. This approach provides allyl ethers and esterswith stereochemically defined vinyl halide and silane handles forfurther functionalization. The scope of propargyl silanes and electrophile-nucleophilepairs are investigated, and various trisubstituted olefins are preparedin up to 78% yield. The obtained products have been demonstrated toserve as building blocks for transition-metal-catalyzed cross-couplingsof vinyl halides, silicon-halogen exchange, and allyl acetate functionalizationreactions.