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.