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

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.