1, 4-Benzothiazine derivatives have drawn much interest in the pharmacologic field due to their structural similarity with the phenothiazine system [1]. In particular the synthesis of the S- oxidized system, 4H-1, 4-benzothiazine-1, 1-dioxide, has been the object of several studies and patents for industrial and pharmacological applications [2-5]. The synthesis of such systems usually started from 2-aminobenzenethiols which were treated with β-diketones ...