Catalytic Enantioselective Multicomponent Reactions of Sulfoxonium Ylides Enabled by a Formal Rearrangement—A Versatile Entry to Enantioenriched α-Sulfanyl Carbonyl Compounds

Sulfur ylides have emerged as versatile carbenoids for catalytic enantioselective X–H insertion reactions (X = C, N, O, and S), while offering a better safety profile compared to traditional diazo-based metal carbene precursors. However, the realization of valuable multicomponent reactions (MCRs) with sulfur ylides has been so far out of reach. Here, we report the enantioselective MCR of sulfoxonium ylides, aldehydes, and thiols catalyzed by a chiral phosphoric acid. Departing from carbenoid reactivity, the reaction pathway entails two sequential but nonoverlapping catalytic cycles, where the assembly of the components is followed by a delayed stereodetermining rearrangement across the central C─C bond of the molecule. The organocatalytic MCR delivers β-hydroxy-α-sulfanyl carbonyl products as single anti-diastereoisomers and generally in high yields and enantioselectivities. These products cannot be readily accessed by other catalytic means and are synthetic linchpins to a variety of α-sulfanyl carbonyl compounds via stereospecific substitutions of their hydroxy group.