Enantioselective Four-Component Arylsulfonylcyanation of Vinylarenes via the Insertion of SO₂ Enabled by SOgen as SO₂ Surrogate

Abstract

A copper-catalyzed four-component enantioselective arylsulfonylcyanation of vinylarenes has been developed that enables easy access to a variety of chiral β-sulfonyl nitriles with up to 95% yield and 96% ee. The reaction utilizes a bench-stable SO2 surrogate (SOgen), takes place under mild reaction conditions, and exhibits good substrate scope and functional group compatibility. Control experiments show that the use of SOgen as SO2 surrogate is key to achieving excellent reactivities and enantioselectivities. Preliminary mechanistic data indicates that this enantioselective vinylarene 1,2-difunctionalization reaction likely proceeds by a radical pathway. The reaction exemplifies a rare case of enantioselective catalysis involving gaseous SO2.