Synthesis of 1-substituted 3-amino-1H-1,2,4-triazoles from ethyl N-(5-phenyl-1,2,4-oxadiazol-3-yl)formimidate

A general and efficient method for the synthesis of 1-substituted 3-amino-1H-1,2,4-triazoles has been developed. The desired 3-amino-1H-1,2,4-triazoles (3) were prepared in good to excellent yields from ethyl N-(5-phenyl-1,2,4-oxadiazol-3-yl)formimidate (1a) and anilines or amines (2) via a one-pot process involving formimidamide formation followed by a thermal monocyclic rearrangement. The benzoyl protecting group could be readily removed by sulfuric acid promoted deprotection.