Triethylamine-Promoted Oxidative Cyclodimerization of 2H-Azirine-2-carboxylates to Pyrimidine-4,6-dicarboxylates: Experimental and DFT Study
作者:Timofei N. Zakharov、Pavel A. Sakharov、Mikhail S. Novikov、Alexander F. Khlebnikov、Nikolai V. Rostovskii
DOI:10.3390/molecules28114315
日期:——
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
描述了在空气中与三乙胺一起加热下,2H-azirine-2-carboxylates 到 pyrimidine-4,6-dicarboxylates 的前所未有的氧化环二聚反应。在此反应中,一个氮丙啶分子通过 CC 键进行正式切割,另一个通过 C=N 键进行正式切割。根据实验研究和DFT计算,该反应机理的关键步骤包括N,N-二乙基羟胺与氮杂环丙烷亲核加成形成(氨氧基)氮丙啶、偶氮亚胺叶立德的生成及其1,3-偶极环加成反应到第二个氮丙啶分子。嘧啶合成的关键条件是在反应混合物中以非常低的浓度生成 N,N-二乙基羟胺,这是通过三乙胺与空气氧气的缓慢氧化来确保的。添加自由基引发剂可加速反应并提高嘧啶的产率。在这些条件下,阐明了嘧啶形成的范围,并合成了一系列嘧啶。