A computational study on the reaction mechanisms of N-formylation of amines under a Lewis acid catalysis

The mechanisms of the title reaction have been studied by density functional theory (DFT) and the second order Moller-Pleset (MP2) method. Two possible reaction channels including the non-catalyzed channel (channel 1) and the other catalyzed channel (promoted by Lewis acid ZnCl2, channel 2) are shown. The calculated results indicate that the catalyzed channel is more energy favorable than the non-catalyzed channel, and the energy barrier of channel 2 (31.62 kcal/mol at the B3LYP/6-31G(d,p) level and 30.32 kcal/mol at the MP2/6-311++G(2d,2p) level) is not a high energy barrier for the experimental condition (343 K), thus, we think the Lewis acid ZnCl2 would play an important role in making the title reaction easier to occur, which is in good agreement with the experimental results.