3-Amino-4H-pyrido[2,3-e]-1,2,4-thiadiazine 1,1-dioxide

The title compound, C6H6N4O2S, was prepared for structural comparison with diazoxide (7-chloro-3-methyl-4H-1,2,4-benzothiadiazine 1,1-dioxide) and other 3-alkylaminopyridothiadiazine 1,1-dioxides known to be potassium channel openers. Particular attention was paid to the tautomeric conformation adopted by the compound in the crystalline state, which is found to be the 4H-form.