A mild and transition-metal-free three-component annulation was performed to obtain benzoxaphosphole 1-oxides using in situ formed arynes. We employed readily available substrates, 2-(trimethylsilyl)aryl triflates, phosphites, and ketones, as the three components; substrates with various functional groups, including the non-activated ketones, could be tolerated. The mechanistic study revealed that the pentavalent phosphorus intermediate might be produced through a three-component annulation and then converted to benzoxaphosphole 1-oxides, the desired compound, by hydrolysis in an aqueous workup step. Furthermore, we investigated the potential applications of this reaction by derivatizing the produced benzoxaphosphole 1-oxides. Our results improved the approaches to preparing organophosphorus compounds used in pharmaceuticals, materials, and natural products.
