Synthesis and reactivity of some amino‐substituted 1,2,5‐thiadiazole 1,1‐dioxides
The acid-catalyzed cyclizing addition of sulfamide to cyanogen yielded 3,4-diamino-1,2,5-thiadiazole 1,1-dioxide (2), from which through amino-exchange reactions, the substituted compounds 3, 4, and 5 could be derived. The unsubstituted amino groups of compounds 2 and 3 were easily hydrolyzed by basic treatment; the former afforded the 4-amino-3-oxothiadiazole 8 or the dipotassium salt 6 depending on the conditions, and the latter, 4-amino-3-oxo-1,2,5-thiadiazoles 1. Alternative syntheses of compounds 1a, b, and 8 by hydrogenolysis of the corresponding 2-benzyl derivatives are also reported.