Chiral Sulfide/Phosphoric Acid Cocatalyzed Enantioselective Intermolecular Oxysulfenylation of Alkenes with Phenol and Alcohol O-Nucleophiles

Abstract

Enantioselective intermolecular three-component oxysulfenylations of alkenes with phenols and alcohols as O-nucleophiles were achieved using chiral BINAM-derived sulfide/phosphoric acid as the cocatalyst. Notably, chiral BINAM-derived sulfide/phosphoric acid co-catalysis was first explored to successfully catalyze highly enantioselective transformation. A variety of sulfur-containing benzylic aryl ethers and benzylic alkyl ethers, which contained two contiguous chiral stereocenters, were obtained readily in moderate to excellent yields with high to excellent enantioselectivities. This protocol featured a broad substrate scope with excellent functional group tolerance and high chemo-, regio-, and enantioselectivity. Computational studies were performed to explain the origin of the high selectivity. Additionally, the calculation results indicated that the supposed commonly racemization “olefin-to-olefin” transfer process of thiiranium ion did not occur in this system.