Visible-Light-Induced [2 + 2] Cyclization of Alkynes with Bromodifluoroacetylsilanes: Facile Access to gem-Difluorocyclobutenones

Herein, we report a simple and efficient method for the synthesis of gem-difluorocyclobutenones from alkynes and bromodifluoroacetylsilanes, proceeding via a formal cyclization with in situ generated difluoroketene under visible-light-induced conditions. The reaction conditions are mild and exhibit a broad substrate scope, including both aromatic and aliphatic alkynes. Additionally, the reaction demonstrates good functional group tolerance, facile scalability, and the potential for diverse downstream transformations. Mechanistic studies suggest that bromodifluoroacetylsilanes act as photochemical precursors to difluoroketene.