Photoenzymatic Hydrosulfonylation for the Stereoselective Synthesis of Chiral Sulfones

Chiral sulfones are recurrent motifs in pharmaceuticals and bioactive molecules. Although chemical methods have been developed to afford α- or β- chiral sulfones, these protocols rely heavily on the pre-synthesis of structurally complicated starting materials and chiral metal complexes. Herein, we described a photoenzymatic approach for the radical-mediated stereoselective hydrosulfonylation. Engineered variants of ene reductases provide efficient biocatalysts for this transformation, enabling to achieve a series of β-chiral sulfonyl compounds with high yields (up to 92%) and excellent e.r. values (up to 99:1).

Hydrosulfonylation of Alkenes with Sulfonyl Chlorides under Visible Light Activation

Sulfonyl chlorides are inexpensive reactants extensively explored for functionalization, but never considered for radical hydrosulfonylation of alkenes. Herein, we report that tris(trimethylsilyl)silane is an ideal hydrogen atom donor enabling highly effective photoredox-catalyzed hydrosulfonylation of electron-deficient alkenes with sulfonyl chlorides. To increase the generality of this transformation, polarity-reversal catalysis (PRC) was successfully implemented for alkenes bearing alkyl substituents. This late-stage functionalization method tolerates a remarkably wide range of functional groups, is operationally simple, scalable, and allows access to building blocks which are important for medicinal chemistry and drug discovery.