N -Halosuccinimide-Controlled Divergent Thiocyanation of Alkynes under Visible Light

A visible-light-mediated, N-halosuccinimide (NXS)-controlled strategy for divergent thiocyanation of alkynes is reported. NIS and NBS promote halothiocyanation via photoactive SCN–/NXS electron donor–acceptor complexes, placing the halogen at the aryl-substituted vinylic carbon with regioselectivity complementary to previous methods, whereas NCS promotes N-thiocyanatosuccinimide formation, enabling dithiocyanation. This protocol accommodates a range of alkynes, providing functionalized vinyl thiocyanates in moderate to good yields with predominant E selectivity through two distinct mechanistic pathways.