A theoretical study of imine-ene reaction influencing factors

作者：Yang Qiwu; Liu Yan; Zhang Wenqin^*

来源：Organic and Biomolecular Chemistry, 2011, 9(18): 6343-6351.

DOI：10.1039/c1ob05493g

Potential energy surfaces of the imine-ene reaction between methanimine and propene have been calculated using restricted and unrestricted density functional theory at the B3LYP level. The results show that a concerted mechanism with an exo configuration for lone pair electrons transition structure is more favourable for the intermolecular bare imine-ene reaction. In addition, the C-C bond formation and the migration of the propene alpha-hydrogen occur simultaneously. The promoting effect of seventeen Lewis acids was also studied. When a Lewis acid is used as a promoter, the corresponding activation and reaction energies decline greatly compared to those of the bare imine-ene reaction. A good correlation (R-2 > 0.9) was found between the activation barriers and the polar character of the transition states. Lewis acids and electron-withdrawing substituents on methanimine were proven to facilitate the imine-ene reaction, whereas electron-donating groups, conjugated groups or a bulky group hinders the reaction. The steric factor is the most unfavourable. The reactivity indices defined by the conceptual density functional theory were also studied and there is a good correlation between the activation barrier and electrophilicity. Frontier molecular orbital theory gives a good explanation for the above results.

• 出版日期2011
• 单位天津大学