Synthesis of 3,4‐Functionalized Benzothiazines through C−H Activation

A method for the synthesis of a wide range of 1,2‐benzothiazines bearing pyridyl, amide, sulfonamide, alkenyl, as well as aryl groups in 3,4‐position has been developed using transition metal‐catalyzed C−H activation reactions of pyridylbenzothiazines with dioxazolones, tosyl azide, alkenes, alkynes, and diaryliodonium salts. The present reaction provides an efficient method for the synthesis of a variety of 3,4‐functionalized benzothiazines from readily available starting materials and benefits a broad substrate scope, high functional group tolerance, and good regioselectivity.