【摘 要】
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QM/MM hybrid molecular simulations of aliphatic Claisen rearrangement in several solvents have been conducted.By adopting a highly efficient sampling method
【机 构】
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College of Chemistry and Molecular Engineering,Peking University,Chengfu Road ＃202,Haidian District,
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QM/MM hybrid molecular simulations of aliphatic Claisen rearrangement in several solvents have been conducted.By adopting a highly efficient sampling method,SITS,an unreported but not unexpected result was observed that the reactant underwent a conformational pre-adjustment before it arrived at the transition state.According to this outcome in addition to the echo from the structure of natural enzyme,a two-step process of Claisen rearrangement has been proposed,which consists of the necessary trapping into a favorable compact conformation and the subsequent reorganization of chemical bonds and electrons.According to the post-simulation analysis,solvents with high CED were able to accommodate compact conformers better.Electrons were found to be partially polarized during the conformational transitions in solvents like water and ionic liquid.And different substituents would shift the conformational equilibrium.Besides,by virtue of the enhanced sampling of reactive trajectories(ESoRT),the rate constant of electron rearrangement of parent AVE in water has been statistically calculated,which was about hundreds of times faster than that in benzene or di-(n)butyl ether.This result was in line with the experimental measurement and provided more insight to the well-known but mysterious “in/on water” facilitation effect.
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