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

Daniil N Lyapustin; Evgeny N Ulomsky; Ilya A Balyakin; Alexander V Shchepochkin; Vladimir L Rusinov; Oleg N Chupakhin

doi:10.3390/molecules26164719

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

Molecules. 2021 Aug 4;26(16):4719. doi: 10.3390/molecules26164719.

Authors

Daniil N Lyapustin¹, Evgeny N Ulomsky^{1

2}, Ilya A Balyakin^{3

4}, Alexander V Shchepochkin², Vladimir L Rusinov^{1

2}, Oleg N Chupakhin^{1

2}

Affiliations

¹ Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira St. 19, 620002 Ekaterinburg, Russia.
² Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, S. Kovalevskaya Str., 22, 620041 Ekaterinburg, Russia.
³ NANOTECH Centre, Ural Federal University, 620002 Ekaterinburg, Russia.
⁴ Institute of Metallurgy, Ural Branch of the Russian Academy of Sciences, 620016 Ekaterinburg, Russia.

Abstract

The reaction tolerance of the multicomponent process between 3-aminoazoles, 1-morpholino-2-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.

Keywords: azolo[1,5-a]pyrimidines; multicomponent reactions; nitro compounds; nitro-synthons; oxidation; oxidative destruction; synthesis of heterocycles.

Abstract

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