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

Abstract

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)-β-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.