Electrochemical Entry to Alkynylphosphonates via Copper Redox Catalysis Enabled C–P Coupling

Abstract In this letter, we report the Csp–P coupling between terminal acetylenes and dialkylphosphites under electroredox copper catalysis to prepare alkynylphosphonates. The reaction works via electrochemical generation of cuprous acetylide, a requisite intermediate for oxidative addition/reductive elimination steps to deliver the product. Few intrinsic features of this chemistry are good synthetic yields, applicability to electron-rich/-poor alkynes together with the use of a base additive in controlling the product selectivity. Deuterium replacement experiments suggest that the yield variation is pronounced in phosphites than alkynes. Assessing the reactivity of electronically distinct alkynes via competitive reactions revealed that the product ratio is somewhat more favored in electron-rich alkynes.