PROCEDIMIENTO PARA LA OBTENCIËN DE NUEVOS DERIVADOS DE PIRAZINA

摘要

The invention comprises 3-alkoxy-2-sulphapyrazines of the formula wherein R1 and/or R2 are H or alkyl (at least one being alkyl), R3 = H or Ac, R4 = -SO2-C6H4-NHAc, -SO2-C6H4-NH2 or -SO2-C6H4-NO2, Alk represents an alkyl radical of 1-4 carbon atoms and Ac represents an aliphatic monocarboxylic acyl radical of 1-4 carbon atoms; and the preparation of these compounds by treating the corresponding aminopyrazine with a p-acylaminobenzene-sulphonyl halide in the presence of a tertiary amine and if desired hydrolysing the resulting p-acylamino-derivative with alkali or acid; or by treating the aminopyrazine with a p-nitrobenzenesulphonyl halide and reducing the resulting nitrobenzenesulphonamido-pyrazine with hydrogen in the presence of a hydrogenation catalyst such as palladium/charcoal. Startinb materials. 5-Methyl- 3-chloro-2-aminopyrazine is made by treating 5-methyl-3-hydroxy-2-aminopyrazine with POCl3. 6-Methyl-3-chloro-2-aminopyrazine is made by converting 6-methyl-3-hydroxy- 2-carbamoylpyrazine into 6-methyl-3-hydroxy -2-aminopyrazine by Hoffmann reaction and chlorinating with POCl3. The 5-methyl-3-chloro-2-aminopyrazine may be converted into the 6-methyl-3-chloro-2-aminopyrazine and vice versa by treating successively with nitrous acid to give a 2-hydroxy-3-chloro-(5 or 6)-methyl-pyrazine, ammonia to give 2-hydroxy-3-amino-(5 or 6) methyl-pyrazine, and finally with POCl3.ALSO:Pharmaceutical preparations for treatment of bacterial infections comprise compounds of the formula wherein R1 and/or R2 are H or alkyl (at least one being alkyl), R3 = H or Ac, R4 = -SO2-C6H4-NHAc, -SO2-C6H4-NH2 or -SO2 -C6H4-NO2, Alk represents an alkyl radical of 1-4 carbon atoms and Ac represents an aliphatic monocarboxylic acyl radical of 1-4 carbon atoms, optionally admixed with other sulphonamides or antibiotics, and a carrier. The preparations may take the form of powders, tablets, pills or syrups and may be mixed with animal foods.