Ring Transformation of Heterocycles Transformation of 4, 5-Dihydro-5, 5-Dimethyl-H-1, 2, 4-Triazoles Into 5-Methyl-H-1, 2, 4-Triazoles

Abstract

Reaction of 1-aryl-3-acetyl-4, 5-dihydro-5, 5-dimethyl-1H-1, 2, 4-triazoles (3) with acetyl chloride or acetic anhydride is found to give the ring transformation product 1-aryl-3-acetyl-5-methyl-1H-1, 2, 4-triazoles (4) instead of the expected N-acetyl derivative (5). This ring transformation is believed to start with N-acylation of the dihydrotriazole (3) to form the corresponding N-acetyl derivative (5), which extrudes the actone via a four-membered ring intermediate (6) and recyclizes to the aromatic triazole (4) suggesting the conversion sequence (3)→(5)→(6)→(4). It is Also found that. The triazoles 4 can be prepared directly via a one put reaction between nitrilimines and acetaldoximes.(Author) 8 refs., 4 Sches