1,2,4‐Triazoles. Improved synthesis of 5‐substituted 4‐amino‐3‐mer‐cato‐(4<i>H</i>)‐1,2,4‐triazoles and a facile route to 3,6‐disubstituted 1,2,4‐triazolo[3,4‐<i>b</i>][1,3,4]thiadiazoles

Abstract

Abstract The reaction of thiocarbohydrazide with carboxylic acids at the melting temperature allows an improved preparation of the S‐substituted 4‐amino‐3‐mercapto‐1,2,4‐triazole heterocycles. The crude 4‐amino‐5‐mercapto‐1,2,4‐triazoles react easily with carboxylic acids or carboxylic acid chlorides to afford the 1,2,4‐triazolo[3,4‐ fc ][1,3,4]thiadiazole ring system.