Chiral Lewis base/Lewis acid/Brønsted acid cooperative catalysis enabled regio- and enantioselective electrophilic sulfenylation/semipinacol rearrangement of allenols

Abstract

A chiral sulfide/B(C₆F₅)₃/phosphoric acid co-catalyzed highly regio- and enantioselective tandem electrophilic sulfenylation/semipinacol rearrangement of allenols is developed for the first time. A variety of chiral organosulfur compounds bearing all-carbon quaternary stereocenters are efficiently synthesized via this cooperative catalysis. The products enable the facile synthesis of trisubstituted alkenes and thioester compounds through a one-step derivatization process. Mechanistic experiments demonstrate that B(C₆F₅)₃ and phosphoric acid cooperate to form a Lewis acid-assisted Brønsted acid (LBA) system, which significantly enhances catalytic reactivity. Density functional theory (DFT) calculations indicate that π⋯π and C–H⋯π interactions play a crucial role in determining the observed enantioselectivity.