Copper-catalyzed practical route for the synthesis of benzothiadiazine 1,1-dioxides has been developed. The method involves C–H functionalization of arylacetic acids to form aromatic aldehydes and their subsequent condensation with 2-aminobenzenesulfonamide. This functional group tolerant approach furnished benzothiadiazine 1,1-dioxide derivatives in good to excellent yields. Broad substrate scope, inexpensive catalyst and high product yields are notable features of this protocol. © 2019 Elsevier Ltd