One-Pot Benzo[b]phosphole Synthesis through Sequential Alkyne Arylmagnesiation, Electrophilic Trapping, and Intramolecular Phospha-Friedel–Crafts Cyclization

A one-pot multicomponent synthesis of a benzo­[b]­phosphole derivative has been achieved by a sequence of transition-metal-catalyzed arylmagnesiation of an internal alkyne, electrophilic trapping of the resulting alkenylmagnesium species with a dichloroorganophosphine, and an intramolecular phospha-Friedel–Crafts reaction. With appropriate arylmagnesiation and P–C bond formation conditions, the present method allows for the modular and expedient preparation of benzophospholes bearing a variety of substituents on the phosphorus atom, the C2 and C3 atoms, and the “benzo” moiety.