Direct air-induced arylphosphinoyl radicals for the synthesis of benzo[b]phosphole oxides

Benzo[b]phosphole oxides are valuable and significant organic functional molecules. Therefore, extensive efforts have been dedicated to the development of an environmentally friendly and convenient synthetic strategy for benzo[b]phosphole oxides. However, several critical issues still persist in the currently available protocols. In this study, we present a direct air-oxidized strategy enabling the transformation of arylphosphine oxides into phosphinoyl radicals, which were further utilized in the synthesis of benzo[b]phosphole oxides by combining with various alkynes. In addition, the results of DFT calculations show that phosphinoyl radical formation could involve an O-2-mediated O-H bond homolysis instead of the commonly recognized P-H bond homolysis mechanism.

Automated summary

A direct air-oxidized strategy for the synthesis of benzo[b]phosphole oxides was developed in this study. Arylphosphine oxides were transformed into phosphinoyl radicals, which were further combined with various alkynes to achieve the desired products. DFT calculations revealed the mechanism of phosphinoyl radical formation.