The role of benzoic acid in proline‐catalyzed asymmetric michael addition: A density functional theory study

Abstract

In asymmetric Michael addition between ketones and nitroolefins catalyzed by L-proline, we observed that it was benzoic acid or its derivatives rather than other proton acid that could accelerate the reaction greatly, and different benzoic acid derivatives brought different yields. To explain the experimental phenomena, a density functional theory study was performed to elucidate the mechanism of prolinecatalyzed asymmetric Michael addition with benzoic acid. The results of the theoretical calculation at the level of B3LYP/6-311þG(2df,p)//B3LYP/6-31G(d) demonstrated that benzoic acid played two major roles in the formation of nitroalkane: assisting proton transfer and activating the nitro group. In the stage of enamine formation from imine, the energy profiles of benzoic acid derivatives were also calculated to investigate the reasons why different benzoic acid derivatives caused different yields. The results demonstrated that the pK a value was the major factor for p-substituted benzoic acid derivatives to improve the yields, whereas for m/o-substituted benzoic acid derivatives, both pK a value and electronic and steric effects could significantly increase the yields. The calculated results would be very helpful for understanding the reaction mechanism of Michael addition and provide some insights into the selection of efficient additives for similar experiments.

Assessing the Accuracy of Density Functional Approximations for Predicting Hydrolysis Reaction Kinetics

“…This frequently involves performing calculations to predict the geometries and subsequently the energies of reactants, products, intermediates, and transition states (TSs) along the reaction pathway. In particular, density functional theory (DFT) is widely used for studies of small-molecule hydrolysis − due to its reasonably high accuracy and low cost compared to more advanced wave function methods. A particularly popular choice of density functional approximation (DFA) in such studies is B3LYP. − Beyond DFT, common methods employed in computational studies of hydrolysis reactions include Hartree–Fock (HF) ,,,, and second-order Møller–Plesset perturbation theory (MP2), − ,,,, with less frequent use of higher-order Møller–Plesset perturbation theory, ,, coupled-cluster, , and configuration-interaction methods. ,, …”

Assessing the Accuracy of Density Functional Approximations for Predicting Hydrolysis Reaction Kinetics

“…A particularly popular choice of DFA in such studies is B3LYP. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Beyond DFT, common methods employed in computational studies of hydrolysis reactions include Hartree-Fock (HF) 23,25,31,35,45 and second order Møller-Plesset perturbation theory (MP2), [23][24][25]30,32,47,48 with less frequent use of higher-order Møller-Plesset perturbation theory, 24,30,49 coupledcluster, 25,47 and configuration-interaction methods. 30,31,48 While numerous benchmark studies have been conducted to evaluate the performance of various exchange-correlation density functional approximations (DFAs) for the prediction of reaction thermochemistry, [50][51][52][53][54][55][56][57]…”

Theoretical investigation toward organophosphine‐catalyzed [3 + 3] annulation of Morita–Baylis–Hillman carbonates with azomethine imines: Mechanism, origin of stereoselectivity, and role of catalyst

“…Over the past several decades, DFT has been demonstrated to be a powerful method for studying the detailed reaction mechanisms and predicting the stereoselectivities as well as chemoselectivities in organic, biological, and transition‐metal‐catalyzed reactions . Phosphine‐catalyzed reactions have also attracted much attention from theoretical chemists because of their special reactivities and broad applications.…”