C,N-二甲基硝酮与丙烯1,3-偶极环加成反应的理论研究

A theoretical study on the 1,3-dipolar cycloaddition reaction of C,N-dimethyl nitron with propylene

用abinitio方法在MP2 /6-31G水平上研究了C,N-二甲基硝酮与丙烯的 1, 3 -偶极环加成反应历程及区域选择性。在反应中,C,N-二甲基硝酮与丙烯从不同的方向相互接近首先形成 4种不同的氢键复合物,其相对能量分别为 0 27, 1 01, -18 98和-18 78kJ·mol-1。四种氢键复合物进一步反应生成四种不同产物,分别为endo-4,exo-4,endo-5,exo-5,四种反应途径的活化能分别为 67 09, 61 32, 60 00和 53 17kJ·mol-1。结果表明,决定该反应区域选择性的主要因素不是反应的活化能,而是氢键复合物间的能量差异。

The 1,3-dipolar cycloaddition reaction of C,N-dimethyl nitron with propylene has been calculated at the MP2/6-31G level using ab initio molecular orbital theory. Four H-bond complexes were produced first when C,N-dimethyl nitron was approaching to propylene, their relative energies are 0.27,1.01,-18.98 and (-18.78 kJ·mol^(-1)), respectively. These Four H-bond complexes lead to the formation of four transition states of endo-4, exo-4, endo-5 and exo-5. And the energy barriers of four reactions are 67.09, 61.32, 60.0 and 53.17kJ·mol^(-1), respectively. The calculated results show that the regioselectivity of this reaction doesn’t result from the energy barriers of relate reactions but the energy gap of the H-bond complexes.