The epoxidation of olefins via [beta]-bromoalkoxydimethylsulfonium ions ; total syntheses of (±)-dichroanone, (±)-dichroanal B, (±)-taiwaniaquinone H, and (±)-taiwaniaquinol D with formal syntheses of (±)-taiwaniaquinol B and (±)-taiwaniaquinone D

Abstract

Part I: A new method for the epoxidation of olefins is described. Reacting an olefin with NBS in the presence of DMSO forms a β-bromoalkoxydimethylsulfonium ion which collapses to an epoxide upon deprotonation. This method is general for a wide range of olefins, and optimized conditions for several of these classes are presented. Part II: The history and syntheses of the taiwaniaquinoids are described. The strategies surrounding the syntheses of the title compounds are rigorously detailed. The contributions to this field are highlighted by the nucleophilic aromatic substitution-based synthesis of (±)-dichroanal B.