Oxidative Aromatization of 4,7-dihydro-6-nitroazolo[1,5-a] Pyrimidines: Synthetic Possibilities and Limitations, Mechanism of Destruction, and the Theoretical and Experimental Substantiation

Abstract

The reaction tolerance of the multicomponent process between 3-aminoazoles, 1-morpholino2-nitroalkenes, and aldehydes was studied. The main patterns of this reaction have been established. Conditions for the oxidation of 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines were selected. Previous claims that the 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines could not be aromatised have now been refuted. Compounds with an electron-donor substituent at position seven undergo decomposition during oxidation. The phenomenon was explained based on experimental data, electro-chemical experiment, and quantum-chemical calculation. The mechanism of oxidative degradation has been proposed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.