5,6-Dihydro-[1,2,4]triazolo[1,5-c]quinazolines. Message 1. Features of interactions between [2-(3-aryl-1H-1,2,4-triazole-5-yl)phenyl]amines, aliphatic and aromatic aldehydes

Reactions of [5+1]-cyclocondensation of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with aliphatic and aromatic aldehydes produce the corresponding 5-R-2-aryl-5,6-dihydro- or 5-R-2-aryl-[1,2,4]triazolo[1,5-с]quinazolines depending on the conditions. The optimal conditions of the reaction have been found, and factors contributing to oxidation of 5-R-2-aryl-5,6-dihydro-[1,2,4]triazolo[1,5-с]quinazolines have been determined. The alternative synthetic approaches for 5-R-2-aryl-[1,2,4]triazolo[1,5-с]quinazolines, namely oxidation of their reduced analogues and interaction of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with acylhalides of aliphatic or aromatic carboxylic acid have been proposed. Purity and the structure of the compounds synthesized have been confirmed by the complex of physicochemical methods, including LC-MS, 1H-, 13C NMR, mass-spectrometry and elemental analysis. The peculiarities and differences of 1H- and 13C-NMR spectral patterns of 5-R-2-aryl-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolines and their aromatic analogues have been described.