A joint experimental and theoretical study of kinetic and mechanism of rearrangement of allyl p-tolyl ether

Irani, Mehdi; Haqgu, M.; Talebi, A.; Gholami, Mohammad Reza

doi:10.1016/j.theochem.2008.09.030

Cited by 13 publications

(22 citation statements)

References 27 publications

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“…Notably, B3LYP/6-31G(d) calculations using the polarizable continuum model (PCM) failed to predict the correct order of reaction rates for the allyl p-tolyl ether rearrangement in solution. 81 Substituent effects on the Claisen rearrangement were also studied by the inclusion of R = Br, CH 3 , and OCH 3 groups in the allyl p-R-phenyl ether (Scheme 5(a)); the relative energies were in excellent agreement with experiment, e.g., the computed G ‡ values of 0.4, 0.0, and −1.1 kcal/mol compared with the reported values of 0.5, 0.0, and −0.9 kcal/mol for the Br, CH 3 , and OCH 3 reactions in water, 82 respectively. Calculation of a second Claisen rearrangement featuring allyl naphthyl ether (Scheme 5(b)) in five solvents: water, methanol, acetonitrile, DMF, and toluene, which were consistent with the qualitative representation of the rates and yields given by Sharpless and coworkers.…”

Section: Pericyclic Reactionsmentioning

confidence: 99%

Quantum and molecular mechanical Monte Carlo techniques for modeling condensed‐phase reactions

Acevedo

Jorgensen

2014

WIREs Comput Mol Sci

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A recent review (Acc. Chem. Res. 2010, 43:142–151) examined our use and development of a combined quantum and molecular mechanical (QM/MM) technique for modelling organic and enzymatic reactions. Advances included the PDDG/PM3 semiempirical QM (SQM) method, computation of multi-dimensional potentials of mean force (PMF), incorporation of on-the-fly QM in Monte Carlo simulations, and a polynomial quadrature method for rapidly treating proton-transfer reactions. The current article serves as a follow up on our progress. Highlights include new reactions, alternative SQM methods, a polarizable OPLS force field, and novel solvent environments, e.g., “on water” and room temperature ionic liquids. The methodology is strikingly accurate across a wide range of condensed-phase and antibody-catalyzed reactions including substitution, decarboxylation, elimination, isomerization, and pericyclic classes. Comparisons are made to systems treated with continuum-based solvents and ab initio or density functional theory (DFT) methods. Overall, the QM/MM methodology provides detailed characterization of reaction paths, proper configurational sampling, several advantages over implicit solvent models, and a reasonable computational cost.

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Section: Pericyclic Reactionsmentioning

confidence: 99%

Quantum and molecular mechanical Monte Carlo techniques for modeling condensed‐phase reactions

Acevedo

Jorgensen

2014

WIREs Comput Mol Sci

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“…A similar trend is observed for the PCM model (see the supplementary material) 116 and also observed previously for different reactions. 80,81 The above trend may be attributed to the inadequate description of solute-solvent specific interactions including hydrogen bonds. Another possible reason is that the apparent surface charge used in the continuum model is proportional to f(ε) = (ε − 1)/(ε + 1/2), which is a rather flat function for ε > 20.…”

Section: A Finkelstein Reactionmentioning

confidence: 99%

Variational calculation of quantum mechanical/molecular mechanical free energy with electronic polarization of solvent

Nakano

Yamamoto

2012

The Journal of Chemical Physics

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Quantum mechanical/molecular mechanical (QM/MM) free energy calculation presents a significant challenge due to an excessive number of QM calculations. A useful approach for reducing the computational cost is that based on the mean field approximation to the QM subsystem. Here, we describe such a mean-field QM/MM theory for electronically polarizable systems by starting from the Hartree product ansatz for the total system and invoking a variational principle of free energy. The MM part is then recast to a classical polarizable model by introducing the charge response kernel. Numerical test shows that the potential of mean force (PMF) thus obtained agrees quantitatively with that obtained from a direct QM/MM calculation, indicating the utility of self-consistent mean-field approximation. Next, we apply the obtained method to prototypical reactions in several qualitatively different solvents and make a systematic comparison of polarization effects. The results show that in aqueous solution the PMF does not depend very much on the water models employed, while in nonaqueous solutions the PMF is significantly affected by explicit polarization. For example, the free energy barrier for a phosphoryl dissociation reaction in acetone and cyclohexane is found to increase by more than 10 kcal/mol when switching the solvent model from an empirical to explicitly polarizable one. The reason for this is discussed based on the parametrization of empirical nonpolarizable models.

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“…Therefore, this SMD implicit solvent model failed to reproduce the experimentally observed changes in the rate of reaction in water and organic solvents. It is noteworthy that a report on the use of the B3LYP/PCM/6‐31G(d) method also failed to predict an accurate sequence of reaction rates of allyl p ‐tolyl ether rearrangement in solution …”

Section: Resultsmentioning

confidence: 99%

“…It is noteworthy that ar eport on the use of the B3LYP/PCM/6-31G(d) method also failed to predict an accurate sequence of reaction rates of allyl p-tolyl ether rearrangementins olution. [42] Turning our attention toward rationalizing the origin of the computed energy differences, we consider that the changes in hydrogen-bond interactions along the reaction path are expected to be vital to the reaction at the vacuum-water interface (an on-water environment) and are not reflected in the continuum treatment. Hence, QM/MM/MCc alculations were used as follow-up investigations to obtain an explicit representation of solvent molecules [under solution conditions:i n DMSO ando n-water ( Figure 1), for comparison].…”

Section: Solvent Effects Studiedbyd Ft Calculations With the Smd Modelmentioning

confidence: 99%

The Role of Water in the Catalyst‐Free Aldol Reaction of Water‐Insoluble N‐Methyl‐2,4‐thiazolidinedione with N‐Methylisatin from QM/MM Monte Carlo Simulations

Zhao

Zhang

et al. 2017

ChemPhysChem

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The role of water in the uncatalyzed aldol reaction of N-methyl-2,4-thiazolidinedione with N-methylisatin is investigated through Monte Carlo statistical mechanics simulations that utilize free energy perturbation theory and the mixed quantum mechanics and molecular mechanics (QM/MM) model with PDDG/PM3 for the QM method in "on-water" and DMSO environments. There are several conceivable orientations between thiazolidinedione and isatin in the process of C-C bond formation. However, the formation of the C-C bond takes place between the re face of isatin and the si face of (E)-enol of the thiazolidinedione to form the preferred anti-type product, which results from enhanced hydrogen-bonding interactions between water molecules and the oxygen atoms undergoing bond breakage and bond formation during the reaction. Novel insights into the effect of water on the aldol reaction are presented herein.

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A joint experimental and theoretical study of kinetic and mechanism of rearrangement of allyl p-tolyl ether

Cited by 13 publications

References 27 publications

Quantum and molecular mechanical Monte Carlo techniques for modeling condensed‐phase reactions

Quantum and molecular mechanical Monte Carlo techniques for modeling condensed‐phase reactions

Variational calculation of quantum mechanical/molecular mechanical free energy with electronic polarization of solvent

The Role of Water in the Catalyst‐Free Aldol Reaction of Water‐Insoluble N‐Methyl‐2,4‐thiazolidinedione with N‐Methylisatin from QM/MM Monte Carlo Simulations

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