A. S. Bunev, V. E. Statsyuk, G. Ostapenko
Oct 25, 2013
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Chemistry of Heterocyclic Compounds
Abstract
1,2,4-Triazoles are a class of compounds of practical and theoretical interest [1]. Despite the presence of numerous methods for the synthesis of the described heterocyclic system [2, 3], there is no information in the literature on the formation of 1,2,4-triazoles based on the condensation of N-formyl-1H-azolyl-1-carboxamidrazones. We have observed previously [4] that compounds 2a-c were formed in excellent yields in the reaction between hydrazide of formic acid with 1-cyanoazoles 1a-c [5] upon reflux in CH2Cl2. In the present work it is shown that compounds 2a-d underwent intramolecular cyclization with the formation of 3-azolylsubstituted derivatives of 1H-1,2,4-triazole 3a-d in good yields (69-78%) upon breaf reflux in DMF (about 1 h). Unfortunately the formation of compound 3e was not observed due to the instability of the obtained amidrazone 2e. Attempted cyclization of compound 2e under milder conditions (DMF, 100°C, 1 h) also led to resinification of the reaction mixture.