Synthesis of 1,2-Benzothiazines via C–H Activation/Cyclization in a Recyclable, Mild System

A mild and recyclable protocol to synthesize 1,2-benzothiazines by Rh(III)-catalyzed C–H activation/cyclization of NH-sulfoximines in ionic liquids with high yields is described. A broad substrate scope of NH-sulfoximines and coupling partners is applicable in this method without any base or acid additives. The catalytic system, namely, Cp*Rh(III)/AgSbF6/[BMIM][PF6], still maintained good catalytic activity even after 10 cycles.