Rhodium-Catalyzed Transannulation of 1,2,3-Thiazoles with Alkynes for the Direct Synthesis of Thiochromenones

Comprehensive Summary A rhodium-catalyzed denitrogenative carbonylation of 1,2,3-thiadiazole with alkynes to construct (benzo)thiochromenones is developed. Both terminal and internal alkynes were compatible in this [3+2+1] cycloaddition, affording a broad range of poly-substituted thiochromenones. Unsymmetrical alkyne substrates exhibited good regioselectivity. It is noteworthy that the present strategy could be used to construct both monocyclic and benzo-thiochromenones, and it is a novel example of denitrogenative transannulation with CO insertion.