Visible-light-driven graphitic carbon nitride-catalyzed ATRA of alkynes: highly regio- and stereoselective synthesis of (E)-β-functionalized vinylsulfones

Heterogeneous photocatalysis has emerged as a powerful and sustainable technique in organic synthesis; however, the application of graphitic carbon nitride (g-C3N4) as a heterogeneous photocatalyst for organic transformations is still in its infancy. The development of novel organic transformations catalyzed by g-C3N4 is actively being pursued by chemists but it remains challenging. Herein, we describe a visible-light-driven g-C3N4-catalyzed atom transfer radical addition (ATRA) of alkynes to synthesize valuable (E)-beta-thio/seleno vinylsulfones. This approach features heterogeneous photocatalysis, excellent regio- and stereoselectivities, 100% atom economy, a metal- and additive-free nature, and broad substrate scope covering (hetero)aryl and alkyl alkynes, especially the industrial feedstock propyne. Furthermore, this method can be applied to the late-stage functionalization of complex molecules. Notably, g-C3N4 can be recovered and reused in five runs without loss of catalytic activity. Mechanistic studies demonstrate that the reaction occurs via an energy transfer process rather than single electron transfer.