A DFT study on the reaction mechanism of dimerization of methyl methacrylate catalyzed by N-heterocyclic carbene

Li, Yunxia; Zhu, Yanyan; Zhang, Wenjing; Wei, Donghui; Ran, Yingying; Zhao, Qilin; Tang, Mingsheng

doi:10.1039/c4cp02186j

Cited by 22 publications

(10 citation statements)

References 73 publications

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“…Previous theoretical work proved that– the catalyst NHC can mainly act as Lewis base and nucleophile. To elucidate the role of catalyst NHC in this reaction, global reactivity index (GRI) analyses were performed on the related minima.…”

Section: Resultsmentioning

confidence: 99%

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Xue

Tang

Wang

et al. 2018

Chemistry An Asian Journal

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One of the most challenging questions in the Lewis base organocatalyst field is how to predict the most electrophilic carbon for the complexation of N-heterocyclic carbene (NHC) and reactant. This study provides a valuable case for this issue. Multiple mechanisms (A, B, C, D, and E) for the intramolecular cyclization of aldimine catalyzed by NHC were investigated by using density functional theory (DFT). The computed results reveal that the NHC energetically prefers attacking the iminyl carbon (AIC mode, which is associated with mechanisms A and C) rather than attacking the olefin carbon (AOC mode, which is associated with mechanisms B and D) or attacking the carbonyl carbon (ACC mode, which is associated with mechanism E) of aldimine. The calculated results based on the different reaction models indicate that mechanism A (AIC mode), which is associated with the formation of the aza-Breslow intermediate, is the most favorable pathway. For mechanism A, there are five steps: (1) nucleophilic addition of NHC to the iminyl carbon of aldimine; (2) [1,2]-proton transfer to form an aza-Breslow intermediate; (3) intramolecular cyclization; (4) the other [1,2]-proton transfer; and (5) regeneration of NHC. The analyses of reactivity indexes have been applied to explain the chemoselectivity, and the general principles regarding the possible mechanisms would be useful for the rational design of NHC-catalyzed chemoselective reactions.

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Section: Resultsmentioning

confidence: 99%

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Xue

Tang

Wang

et al. 2018

Chemistry An Asian Journal

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“…Gaussian09 was employed for all the calculations. DFT is the most powerful method for understanding the compound structures and reaction mechanism . All the geometries including reactants, intermediates, transition states, and products were obtained at ωB97XD/def2‐SVP theory level .…”

Section: Computationsmentioning

confidence: 99%

Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

Liu

Sang

Chen

et al. 2018

J of Physical Organic Chem

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The combined Lewis acid Me3SiBr/InCl3 shows unique performance in multireactions. The topology and catalytic properties of Me3SiBr/InCl3 were investigated by DFT method for clarifying the nature of chemical bonds and interactions. Quantum theory of atoms in molecules (QTAIM) analysis showed that the interaction between Me3Si‐halide and In‐trihalide mainly belongs to the closed‐shell interaction. Natural bond order of Br─In is 0.610 in INT_0 while natural bond order of Cl─In in INT_1 is only 0.081 at SMD‐ωB97XD/def2‐SVP level. The coupling reaction mechanism of alcohol and allyltrimethylsilane catalyzed by the complex of Me3SiBr/InCl3 was investigated with DFT method. The combined Lewis acid activates the hydroxyl group by strong coordination to silicone center, which leads to the generation of carbocation. Me3Si+ moiety from the combined Lewis acid is consumed and converts into the side product Me3SiOSiMe3. Furthermore, the reactant allyltrimethylsilane is introduced into the system to bring out the final product, and the complex Me3SiBr/InCl3 is reproduced at the same time. The combined Lewis acid Me3SiBr/InCl3 not only works as the catalyst for the reaction but also involves in the generation of side product.

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“…1 has been demonstrated to be different from the Stetter reactions818, and the aldehyde-imine aza-benzoin reactions catalyzed by NHC have never been studied in theory, not to mention the competing relationship between them. Besides, our interest in NHC-catalyzed reactions also prompts us to investigate the origin of selectivities for the competing reactions in detail19202122232425262728293031. In the present study, the commonly used DFT theoretical investigation3233343536373839404142 on the reaction between R1 (in which Ar 1 = para chlorphenyl) and R2 (in which Ar 2 = phenyl) catalyzed by NHC depicted in Fig.…”

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confidence: 94%

Insights into the Competing Mechanisms and Origin of Enantioselectivity for N-Heterocyclic Carbene-Catalyzed Reaction of Aldehyde with Enamide

Qiao

Chen

Wei

et al. 2016

Sci Rep

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Hydroacylation reactions and aza-benzoin reactions have attracted considerable attention from experimental chemists. Recently, Wang et al. reported an interesting reaction of N-heterocyclic carbene (NHC)-catalyzed addition of aldehyde to enamide, in which both hydroacylation and aza-benzoin reactions may be involved. Thus, understanding the competing relationship between them is of great interest. Now, density functional theory (DFT) investigation was performed to elucidate this issue. Our results reveal that enamide can tautomerize to its imine isomer with the assistance of HCO3−. The addition of NHC to aldehydes formed Breslow intermediate, which can go through cross-coupling with enamide via hydroacylation reaction or its imine isomer via aza-benzoin reaction. The aza-benzoin reaction requires relatively lower free energy barrier than the hydroacylation reaction. The more polar characteristic of C=N group in the imine isomers, and the more advantageous stereoelectronic effect in the carbon-carbon bond forming transition states in aza-benzoin pathway were identified to determine that the imine isomer can react with the Breslow intermediate more easily. Furthermore, the origin of enantioselectivities for the reaction was explored and reasonably explained by structural analyses on key transition states. The work should provide valuable insights for rational design of switchable NHC-catalyzed hydroacylation and aza-benzoin reactions with high stereoselectivity.

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A DFT study on the reaction mechanism of dimerization of methyl methacrylate catalyzed by N-heterocyclic carbene

Cited by 22 publications

References 73 publications

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

Insights into the Competing Mechanisms and Origin of Enantioselectivity for N-Heterocyclic Carbene-Catalyzed Reaction of Aldehyde with Enamide

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A DFT study on the reaction mechanism of dimerization of methyl methacrylate catalyzed by N-heterocyclic carbene

Cited by 22 publications

References 73 publications

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Insights into the N‐Heterocyclic Carbene (NHC)‐Catalyzed Intramolecular Cyclization of Aldimines: General Mechanism and Role of Catalyst

Me3SiBr/InCl3 catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism

Insights into the Competing Mechanisms and Origin of Enantioselectivity for N-Heterocyclic Carbene-Catalyzed Reaction of Aldehyde with Enamide

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Me₃SiBr/InCl₃ catalyzed allylation of alcohols: Identifying the combined Lewis structure and investigating the reaction mechanism