5,10-CH^+-THF向邻苯二胺转移一碳单元反应的理论研究

Theoretical Study on One-carbon Unit Transfer from 5,10-CH^+-THF to 1,2-Diaminobenzene

叶酸辅酶在酶催化的一碳单元转移过程中具有重要的作用 ,已有大量的实验及实验模拟对其生物学功能进行了研究分析 .本文用 PM3半经验方法对 5 ,1 0 -CH+ -THF向邻苯二胺转移一碳单元的反应进行了理论研究 .结果表明 ,5 ,1 0 -CH+ -THF中的咪唑啉环有两种开环方式 ,从而使得该反应可以通过两种途径实现 ,每一种途径都经历了 6个反应步骤 ,其中包括限制速度的两次质子转移步骤 .优化计算了每个步骤所有可能的中间体和过渡态的结构和能量 ,并通过比较分析得到了各反应阶段的最优中间体和过渡态结构 .

Folic acid cofactor plays an important part in different enzymatic one carbon unit transfer reactions. Its functions have been imitated a lot experimentally by using simple chemical models. One carbon unit transfer reaction of imidazolinium with 1,2 diaminobenzene has been studied with PM3 semi empirical molecular orbital calculations in this paper. The results show that there are two ways to complete this reaction because the imidazolinium ring has two different breaking patterns. Both of these two ways have six steps, including two proton migrating steps that limit the reaction rate. The structures and energies of the intermediates and transition states have been calculated. All the intermediates and transition states have different conformations, and the reaction of classical conformations has been studied carefully.