5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolines. Message 2. [5+1]-cyslocondensation of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with aliphatic and aromatic ketones

Abstract

The reactions of [5+1]-cyclocondensation of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines with aliphatic and aromatic ketones result in the corresponding 5-R-5-R1-2-aryl-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolines with good yields. Modifi cation of the synthetic protocol by variation of the solvent and duration of the reaction does not lead to the changes in target products yields. Conducting of the interaction between [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines and ketones in acetic acid leads to formation of the mixture the corresponding 2-aryl-5-R-5-R1-5,6-dihydro[1,2,4]triazolo[1,5-c]quinazolines and 5-methyl-2-aryl-[1,2,4]triazolo[1,5-c]quinazolin. The compounds mentioned above have been prepared using alternative synthetic approaches, namely via refl uxing of [2-(3-aryl-1H-1,2,4-triazol-5-yl)phenyl]amines in acetic acid. The formation of 5-methyl-2-aryl-[1,2,4]triazolo[1,5-c]quinazolines occurs as a competitive acylation followed by the condensation process. It can be explained by the low reactivity and spatial structure of the corresponding ketones. The purity and the structure of the compounds synthesized have been proven by the complex of physicochemical methods, including IR-, LC-MS, 1H-, 13C-NMR-spectrometry and elemental analysis. It has been found that the characteristic signal of sp3-carbon atom of position 5 for the compounds synthesized is observed at the 75.57-61.64 ppm.