Theoretical investigations towards the [4+2] cycloaddition of ketenes with 1-azadienes catalyzed by N -heterocyclic carbenes: mechanism and stereoselectivity

Ran, Yingying; Tang, Mingsheng; Wang, Yang; Wang, Yanyan; Zhang, Xiaoli; Zhu, Yanyan; Wei, Donghui; Zhang, Wenjing

doi:10.1016/j.tet.2016.06.057

Cited by 19 publications

(8 citation statements)

References 41 publications

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“…Ran et al. conducted a DFT study towards the NHC‐catalyzed [4+2] cycloaddition of ketenes with 1‐azadienes at the IEFPCM benzene ‐M06‐2X/6–311+G(d, p)//M06‐2X/6‐31G(d) level of theory . Similarly with the work by Zhang and co‐workers in 2012, two possible mechanisms were calculated in detail (as shown in Scheme ), but the results indicated that the “ketene‐first” mechanism is energetically favorable to the “azadiene‐first” mechanism, which is different with the reaction of ketene 2 with N ‐benzoyldiazene 18 .…”

Section: Nhc‐catalyzed [2+2] [4+2] and [2+2+2] Cycloaddition Reactimentioning

confidence: 97%

Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

2017

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The developments of theoretical studies on NHC‐catalyzed [n+2] (n=2, 3, 4) and other cycloaddition/annulation reactions have been summarized in this review. The detailed mechanisms, role of NHC, and origin of chemo‐ and stereoselectivity of these kinds of reactions were illustrated to provide valuable insights for rational design of new NHC‐catalyzed cycloaddition/annulation reactions with high selectivities. Moreover, computational and theoretical methods commonly used were also mentioned to open the door for deep exploration of the general principle for NHC‐catalyzed reactions within theoretical chemistry.

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Section: Nhc‐catalyzed [2+2] [4+2] and [2+2+2] Cycloaddition Reactimentioning

confidence: 97%

Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

2017

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“…On the basis of the experimental results and our previous work experiences, possible mechanism for the title reaction are suggested. The detailed calculated results are illustrated as follows.…”

Section: Resultsmentioning

confidence: 87%

Mechanisms of phosphine‐catalyzed [4 + 3] annulation of allenoates with C, N‐cyclic azomethine imines: A DFT investigation

Zhu

Guo

et al. 2018

Int J of Quantum Chemistry

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In this article, mechanisms of phosphine‐catalyzed [4 + 3] annulation of allenoates with C, N‐cyclic azomethine imines have been investigated using density functional theory. The catalytic cycle for the title reaction consists of five steps. Namely, the first step is the nucleophilic addition of phosphine catalyst, the second one is the CC bond formation, the third one is the proton transfer process, and the next one is the ring‐closure process, the last one is dissociation of the catalyst and the product generation. The calculated results indicate that the nucleophilic addition of phosphine catalyst is rate‐determining. With the use of Cat as the chiral catalyst, optically active products were obtained in good yields with excellent enantioselectivities while the CC bond formation is stereoselectivity‐determining. Furthermore, the theoretically predicted the main product is SS configuration, which is in good agreement with the experimental results. The special role of the catalysts and origin of stereoselectivity was also identified by NBO, GRI, and FMO analyses. This work might be helpful for understanding the significant roles of phosphine catalyst and thus provide valuable insights on the rational design of potential catalysts for this kind of reactions.

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“…We have continued to pay close attention to the NHC‐catalyzed cycloaddition/annulation reactions for a long time, and the mechanism and origin of selectivities of the NHC‐catalyzed annulations of imines as illustrated in Scheme (A) have also been studied in detail by both our and Fang's groups . Because of the very close relationship between the title reaction and the NHC‐catalyzed reaction of imines, we are highly intrigued regarding how this unexpected reaction occurs.…”

Section: Introductionmentioning

confidence: 98%

A density functional theory study on mechanism and substituent effects of a base‐free and catalyst‐free synthesis of functionalized dihydrobenzoxazoles

Zhang

Bai

Guo

et al. 2018

Int J of Quantum Chemistry

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The reaction mechanism and the substituent effects of a base‐free and catalyst‐free synthesis of functionalized dihydrobenzoxazole have been investigated in detail by using the density functional theory (DFT) method. The calculated results reveal that the whole reaction should occur through three processes, and the initial intramolecular nucleophilic attack reaction is the rate‐determining step. The possibility to afford crossover reaction products has been carefully excluded based on the extremely high barrier, which is well‐consistent with the experimental results that the crossover products cannot be observed. The substituent effects have been studied through exploring the correlation of the experimental yields and the theoretically predicted barriers, which proves that the more electron‐donating substituents of the imine should be more beneficial to the occurrence of the reaction.

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Theoretical investigations towards the [4+2] cycloaddition of ketenes with 1-azadienes catalyzed by N -heterocyclic carbenes: mechanism and stereoselectivity

Cited by 19 publications

References 41 publications

Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

Recent Advances on Computational Investigations of N‐Heterocyclic Carbene Catalyzed Cycloaddition/Annulation Reactions: Mechanism and Origin of Selectivities

Mechanisms of phosphine‐catalyzed [4 + 3] annulation of allenoates with C, N‐cyclic azomethine imines: A DFT investigation

A density functional theory study on mechanism and substituent effects of a base‐free and catalyst‐free synthesis of functionalized dihydrobenzoxazoles

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