GB891471A - Benzothiadiazine compounds - Google Patents

Abstract

Benzothiadiazine-1 : 1-dioxides of the formula <FORM:0891471/IV (b)/1> or <FORM:0891471/IV (b)/2> wherein R DEG is an amino or nitro group and R1 is hydrogen or a C1-5 alkyl radical are prepared by (a) heating a chloronitroaniline (optionally bearing an alkyl substituent R1 on the amino group), e.g. a 3-chloro-4-nitro-aniline, with an aqueous solution of sodium sulphite, converting the resulting sodium nitroaniline sulphonate to the nitroaniline disulphonyl chloride by reaction with chlorosulphonic acid, reacting with ammonia to give the di-sulphonamide and cyclizing by reaction with formic acid or ethyl formate; (b) chlorosulphonating a chloro-nitro aniline, e.g. 4-chloro-3-nitro-aniline, with chlorosulphonic acid in the presence of an alkali-metal halide, e.g. sodium chloride, to give a corresponding aniline-o-sulphonyl chloride, heating with a C1-5 alkylamine, cyclizing the resulting aniline-o-sulphonamide by heating with ethyl orthoformate, reducing the nitro group of the resulting benzothiadiazine with simultaneous removal of the halogen atom, e.g. by catalytic hydrogenation, chlorosulphonating and reacting with ammonia to give a product having an amino and sulphamoyl substituent in the benzene ring; or (c) chlorosulphonating a chloro-nitro-aniline to give an o-sulphochloride, reacting with a C1-5 alkylamine, heating the resulting aniline-o-sulphonamide with an aqueous solution of sodium sulphite to give a sodium amino-(N-alkylsulphamoyl)-nitrobenzene sulphonate, heating with chlorosulphonic acid, treating the resulting sulphochloride with ammonia and cyclizing the N - alkylsulphamoyl - nitro - sulphamoylaniline obtained by heating with ethyl orthoformate, followed by reduction of the nitro group to an amino group, if desired. Specification 826,921 is referred to.