Copper-Catalyzed Radical Sulfonylative Cyclization of o-Vinylanilides with Sulfonyl Chlorides for the Synthesis of Sulfonylated 4H-Benzo[d][1,3]oxazines.

A copper-catalyzed sulfonylative cyclization of o-vinylanilides with sulfonyl chlorides has been developed, providing efficient access to sulfonylated 4H-benzo[d][1,3]oxazines under mild conditions. The transformation proceeds at room temperature and exhibits a broad substrate scope and functional-group compatibility, affording structurally diverse products in good to excellent yields. The method is amenable to the late-stage diversification of complex molecules. Preliminary mechanistic studies support a copper-mediated radical cyclization process.