TY - JOUR

T1 - Triethylamine-Promoted Oxidative Cyclodimerization of 2H-Azirine-2-carboxylates to Pyrimidine-4,6-dicarboxylates: Experimental and DFT Study

AU - Zakharov, Timofei N.

AU - Sakharov, Pavel A.

AU - Novikov, Mikhail S.

AU - Khlebnikov, Alexander F.

AU - Rostovskii , Nikolai V.

N1 - : Zakharov, T.N.; Sakharov, P.A.; Novikov, M.S.; Khlebnikov, A.F.; Rostovskii, N.V. TriethylaminePromoted Oxidative Cyclodimerization of 2H-Azirine-2-carboxylates to Pyrimidine-4,6-dicarboxylates: Experimental and DFT Study. Molecules 2023, 28, 4315. https://doi.org/10.3390/molecules28114315

PY - 2023/5/24

Y1 - 2023/5/24

N2 - An unprecedented oxidative cyclodimerization reaction of 2H-azirine-2-carboxylates to pyrimidine-4,6-dicarboxylates under heating with triethylamine in air is described. In this reaction, one azirine molecule undergoes formal cleavage across the C-C bond and another across the C=N bond. According to the experimental study and DFT calculations, the key steps of the reaction mechanism include nucleophilic addition of N,N-diethylhydroxylamine to an azirine to form an (aminooxy)aziridine, generation of an azomethine ylide, and its 1,3-dipolar cycloaddition to the second azirine molecule. The crucial condition for the synthesis of pyrimidines is generation of N,N-diethylhydroxylamine in the reaction mixture in a very low concentration, which is ensured by the slow oxidation of triethylamine with air oxygen. Addition of a radical initiator accelerated the reaction and resulted in higher yields of the pyrimidines. Under these conditions, the scope of the pyrimidine formation was elucidated, and a series of pyrimidines was synthesized.

AB - An unprecedented oxidative cyclodimerization reaction of 2H-azirine-2-carboxylates to pyrimidine-4,6-dicarboxylates under heating with triethylamine in air is described. In this reaction, one azirine molecule undergoes formal cleavage across the C-C bond and another across the C=N bond. According to the experimental study and DFT calculations, the key steps of the reaction mechanism include nucleophilic addition of N,N-diethylhydroxylamine to an azirine to form an (aminooxy)aziridine, generation of an azomethine ylide, and its 1,3-dipolar cycloaddition to the second azirine molecule. The crucial condition for the synthesis of pyrimidines is generation of N,N-diethylhydroxylamine in the reaction mixture in a very low concentration, which is ensured by the slow oxidation of triethylamine with air oxygen. Addition of a radical initiator accelerated the reaction and resulted in higher yields of the pyrimidines. Under these conditions, the scope of the pyrimidine formation was elucidated, and a series of pyrimidines was synthesized.

KW - azirines

KW - pyrimidines

KW - aziridines

KW - azomethine ylides

KW - cycloaddition

KW - Cyclodimerization

KW - triethylamine

KW - hydroxylamines

KW - hippurates

KW - DFT calculations

M3 - Article

VL - 28

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 11

M1 - 4315

ER -