Substituent Effects on the Carboxylation Step of Allyllic Substrates: A Density Functional Theory Study

摘要

Ni(0/I) catalysed direct carboxylation of allyl alcohols represents an effective way to create β, γ-unsaturated carboxylic acids, with the carboxylation to be a crucial elementary step. Using density functional theory (DFT) calculations, we investigated how substituents affected the carboxylation process. The energy barrier of the carboxylation process is relatively low in the case of Ni(0), which can be efficiently lowered down by electron-donating group (at allyl-α-C). Other distal sites have less of an impact. The steric effect on this reaction is insignificant, although there is a certain threshold. Multiple linear regression was taken to fit the energy barrier of the carboxylation step using the NPA, Fukui function, and Wiberg bond index of the pre-intermediate The results showed that the energy barrier of the carboxylation step can be easily predicted by the property parameter of the pre-intermediate, eliminating the complex transition state calculation.