EINHORN - BRUNNER Triazole synthesis

EINHORN - BRUNNER Triazole Synthesis Condensation of hydrazines with diacyclammes (imidea) to triazoies... 

Hydrazines condense with diacylamines to give 1,2,4-triazoles 2 (Einhorn-Brunner synthesis), e.g. ... 

This reaction was initially reported by Einhorn in 1905 and was extended by Brunner in 1914, therefore, it is known as the Einhorn-Brunner reaction. It is the synthesis of 1,2,4-triazoles by acid-catalyzed condensation between hydrazines (or semicarbazides) and diacylamines. It should be pointed out when two side chains in diacylamine are different, two isomeric triazoles will form. It was found that the substituent in the diacylamine derived from the stronger acid would appear in position 3 of the resulting triazole, indicating that the reaction is initiated by the attack of the free amino group of hydrazine on the more electrophilic carbonyl group of the stronger acid moiety. ... 

Einhorn-Brunner synthesis (1,2,4-triazole) Erlenmeyer synthesis (azlactone) 184 Eschenmoser sulfide contraction 28... 

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