Photoredox-catalyzed decarboxylative alkylation/cyclization of alkynylphosphine oxides: a metal- and oxidant-free method for accessing benzo[b]phosphole oxides.

By photoredox-catalysis, alkylation/aryl C-H cyclization of readily available alkynylphosphine oxides towards benzo[b]phospholes has been realized under metal- and oxidant-free conditions at room temperature. This reaction readily incorporates various functionalized alkyl groups into the benzo[b]phosphole skeletons, representing a mild and versatile tool for the preparation of valuable phosphole compounds.