NEW SYNTHESIS OF 1,2,4-BENZOTHIADIAZINES AND A SELECTIVE PREPARATION OF ORTHO-AMINOBENZENESULPHONAMIDES

Reaction of a series of aniline derivatives with chlorosulphonyl isocyanate followed by cyclisation of the resulting chlorosulphonylureas with Lewis acids gives good yields of 2H-1,2,4-benzothiazidazin-3(4H)-one 1,1-dioxides. These, upon acid hydrolysis, yield the corresponding o-aminobenzenesulphonamides.