Photoinduced Copper-Catalyzed Site-Selective C(sp 2 )-C(sp) Cross-Coupling via Aryl Sulfonium Salts.

The classical Sonogashira reaction of aryl electrophiles in the presence of Pd catalysts has been well established as a potent method for arylalkyne synthesis. However, the site-selective C(sp ² )-C(sp) cross-coupling strategy using a non-noble-metal catalyst is rare. An efficient alternative approach for the synthesis of arylalkynes via a Cu-catalyzed Sonogashira-type reaction promoted by visible light is described. This method enables site-selective alkynylation from aryl sulfonium salts derived from diverse arenes to a set of arylalkynes with high selectivity and high functional-group compatibility. Moreover, rapid alkynylation of drug molecules is demonstrated.