A Safe Synthesis of 1,5-Disubstituted 3-Amino-1H-1,2,4-triazoles from 1,3,4-Oxadiazolium Hexafluorophosphates

Abstract

Hexafluorophosphoric acid promotes 1,3,4-oxadiazolium hexafluorophosphate formation from N′-acyl-N-aroyl-N-arylhydrazides or N′-acyl-N-acyl-N-arylhydrazides under mild conditions. These 1,3,4-oxadiazolium hexafluorophosphates can be treated with cyanamide in propan-2-ol in the presence of triethylamine to generate 1,5-disubstituted 3-amino-1H-1,2,4-triazoles in good yields. This safe and scalable protocol displays a broad scope with respect to N-substitutions and N′-acyl protecting groups.

Key words

heterocycles - substituent effects - rearrangement - hydrazide - aminotriazole

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