Bromide-Catalyzed Radical Cyclization of Biarylboronic Acids and Se/Te Powder

Herein, a metal-free and versatile strategy was successfully reported for the divergent synthesis of various functionalized dibenzo[<i>b</i>,<i>d</i>]selenophenes, dibenzo[<i>b</i>,<i>d</i>]tellurophenes, and phenoxaselenines in moderate to excellent yields in one-pot. This method utilized commercially available, cheap, and sustainable ammonium bromide as the catalyst to promote the radical cyclization of biarylboronic acids with elemental Se/Te. Comparatively, this method was highlighted by its readily available starting material, broad substrate scope, simple catalytic system, easy operation, good safety, being strongly oxidant-free, and easily scalable. The preliminary mechanistic experiments suggested that this transformation could possibly proceed via a radical pathway.