A number of ring substituted 4H-1,4-benzothiazines 5a-5i have been prepared by the condensation and oxidative cyclization of substituted propane-1-phenyl-3-(3',4'-dioxymethylenephenyl)-1,3-dione 3a-3i with 2-amino benzenethiol 1 in DMSO. The structures of the newly synthesized compounds have been established by elemental, IR, H-1 NMR and mass spectral studies.