Department of Basic Medicinal Sciences, Graduate School of Pharmaceutical Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
J Org Chem. 2023 Mar 3;88(5):3193-3207. doi: 10.1021/acs.joc.2c02971. Epub 2023 Feb 20.
To investigate the effect of N-substituents on their reactivity and selectivity of oxidopyridinium betaines, we performed density functional theory (DFT) calculations of model cycloadditions with -methylmaleimide and acenaphthylene. The theoretically expected results were compared with the experimental results. Subsequently, we demonstrated that 1-(2-pyrimidyl)-3-oxidopyridinium can be used for (5 + 2) cycloadditions with various electron-deficient alkenes, dimethyl acetylenedicarboxylate, acenaphthylene, and styrene. In addition, a DFT analysis of the cycloaddition of 1-(2-pyrimidyl)-3-oxidopyridinium with 6,6-dimethylpentafulvene suggested the possibility of pathway bifurcations involving a (5 + 4)/(5 + 6) ambimodal transition state, although only (5 + 6) cycloadducts were experimentally observed. A related (5 + 4) cycloaddition was observed in the reaction of 1-(2-pyrimidyl)-3-oxidopyridinium with 2,3-dimethylbut-1,3-diene.
为了研究 N-取代基对氧化吡啶𬭩内鎓盐反应性和选择性的影响，我们进行了 -甲基马来酰亚胺和苊模型环加成的密度泛函理论（DFT）计算。将理论上预期的结果与实验结果进行了比较。随后，我们证明了 1-(2-嘧啶基)-3-氧化吡啶𬭩可以用于与各种缺电子烯烃、二甲基丙炔二羧酸酯、苊和苯乙烯的（5 + 2）环加成。此外，对 1-(2-嘧啶基)-3-氧化吡啶𬭩与 6,6-二甲基五氟乙烯的环加成的 DFT 分析表明，可能存在涉及（5 + 4）/（5 + 6）双通道过渡态的分支途径，尽管仅观察到（5 + 6）环加成产物。在 1-(2-嘧啶基)-3-氧化吡啶𬭩与 2,3-二甲基-1,3-丁二烯的反应中观察到了相关的（5 + 4）环加成。
