A metal-free radical cascade reaction of phosphine oxides with 2-aryloxy phenylacetylenes to synthesize diphosphonyl xanthene derivatives

Abstract

A radical cascade reaction of 2-aryloxy phenylacetylenes with phosphine oxides promoted by K₂S₂O₈ was developed, which provided diphosphonyl xanthenes as products. This reaction proceeds under transition metal-free and mild conditions with simple operation and good yields. The mechanistic study indicated that phosphine oxide was induced into a phosphonyl radical, and then the following double radical addition/cyclization with 2-aryloxy phenylacetylenes generated bisphosphonyl xanthenes.