A (Ru)-catalyzed ortho-CH sulphonamidation of benzo[b][1,4]oxazin-2-ones using sulfonyl azides enables access to diverse sulphonamides in excellent yields. The method features broad substrate scope, high regio- and chemoselectivity, and functional group tolerance, offering a streamlined route to functionalized heterocycles under mild conditions.

This study presents a novel ruthenium-catalyzed method for the regioselective ortho-sulphonamidation of benzo[b][1,4]oxazin-2-ones. Utilizing sulfonyl azides, which release benign nitrogen gas as a byproduct, this approach achieves high yields and excellent ortho-selectivity in CH functionalization. The protocol exhibits a broad substrate scope, good functional group tolerance, and operational simplicity. Optimization studies and control experiments support a plausible reaction mechanism involving a ruthenium-metallacycle intermediate. Gram-scale synthesis demonstrates the practicality and potential of the method to access biologically relevant molecules, significantly expanding CH functionalization in heterocyclic chemistry.