Highly Selective Copper-Catalyzed Ring Expansion of Vinyl Thiiranes:  Application to Synthesis of Biotin and the Heterocyclic Core of Plavix

We report herein a new, highly selective, mild copper-catalyzed vinyl thiirane ring-expansion protocol for the formation of 2,5-dihydrothiophenes. Preliminary substrate scope and applications of this new synthetic disconnection to the formal racemic total synthesis of biotin and the synthesis of the antiplatelet blockbuster pharmaceutical agent Plavix are described.