Stepwise, zwitterionic course of hetero-Diels–Alder reaction between 1,2,4-triazine molecular systems and 2-cyclopropylidene-1,3-dimethylimidazoline

Jasiński, Radomir

doi:10.1007/s10593-022-03081-y

Cited by 6 publications

(5 citation statements)

References 23 publications

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Section: Resultssupporting

confidence: 80%

“…The substructures of addents adopted orientations which were favourable for the further formation of the transition state. Similar pre-reaction complexes were recently detected regarding different-type intermolecular cycloaddition reactions [26][27][28]. The further reduction of key interatomic distances along the reaction coordinates led to the formation of transition states (TSA and TSB, respectively, for paths A and B).…”

Section: Resultssupporting

confidence: 75%

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Understanding the Molecular Mechanism of Thermal and LA-Catalysed Diels–Alder Reactions between Cyclopentadiene and Isopropyl 3-Nitroprop-2-Enate

2023

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The molecular mechanism of the Diels–Alder reaction with the participation of cyclopentadiene and isopropyl 3-nitroprop-2-enate was examined based on wb97xd/6-311+G(d) (PCM) quantum chemical calculations. It was found that the type of mechanism for the conversion of addends depends significantly on the reaction conditions. In less-polar environments, a one-step polar mechanism is realised. In more polar solvents, the formation of “extended”-type zwitterionic intermediates is possible. In contrast, in the presence of an LA-type catalyst, the one-step mechanisms are replaced by respective stepwise mechanisms with zwitterionic or heterocyclic intermediates.

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Section: Resultssupporting

confidence: 80%

Section: Resultssupporting

confidence: 75%

Understanding the Molecular Mechanism of Thermal and LA-Catalysed Diels–Alder Reactions between Cyclopentadiene and Isopropyl 3-Nitroprop-2-Enate

2023

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“…Next, the GEDT values show without any doubts that the localized structures do not exhibit the nature of charge-transfer complexes ( Table 3 ). Similar types of pre-reaction complexes were identified very recently in different bimolecular processes [ 26 , 27 , 28 , 29 ].…”

Section: Resultssupporting

confidence: 64%

Understanding the Regioselectivity and the Molecular Mechanism of [3 + 2] Cycloaddition Reactions between Nitrous Oxide and Conjugated Nitroalkenes: A DFT Computational Study

2022

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Regiochemical aspects and the molecular mechanism of the [3 + 2] cycloaddition between nitrous oxide and conjugated nitroalkenes were evaluated on the basis of the wb97xd/6-311 + G(d) (PCM) computational study. It was found that, independently of the nature of the nitroalkene, all considered processes are realized via polar, single-step mechanisms. All attempts at the localization of hypothetical zwitterionic intermediates were unsuccessful. Additionally, the DFT computational study suggested that, in the course of the reaction, the formation of respective Δ2-4-nitro-4-R1-5-R2-1-oxa-2,3-diazolines was preferred from the kinetic point of view.

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“…Analysis of hte 264 points along the IRC revealed four phases, of which the most important aspects are: The analysis of the mechanism of formation of less favorable zwitterion N1-C5 (Table 6, Scheme 9) revealed ten phases during which the most important topological changes are: The kinetic parameters and essential properties of critical structures are presented in Tables 2 and 3. Consistent with the previous convention [70,71], in this paper, the letters MC and TS are designated to the pre-reaction complex and TS, respectively. They are distinguished by appending the letters A-D depending on the reaction pathway.…”

Section: Resultsmentioning

confidence: 93%

On the Question of Zwitterionic Intermediates in the [3+2] Cycloaddition Reactions between Aryl Azides and Ethyl Propiolate

Dresler,

Woliński,

Wróblewska

et al. 2023

Molecules

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The molecular mechanism of the [3+2] cycloaddition reactions between aryl azides and ethyl propiolate was evaluated in the framework of the Molecular Electron Density Theory. It was found that independently of the nature of the substituent within the azide molecule, the cycloaddition process is realized via a polar but single-step mechanism. All attempts of localization as postulated earlier by Abu-Orabi and coworkers’ zwitterionic intermediates were not successful. At the same time, the formation of zwitterions with an “extended” conformation is possible on parallel reaction paths. The ELF analysis shows that the studied cycloaddition reaction leading to the 1,4-triazole proceeds by a two-stage one-step mechanism. It also revealed that both zwitterions are created by the donation of the nitrogen atom’s nonbonding electron densities to carbon atoms of ethyl propiolate.

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Stepwise, zwitterionic course of hetero-Diels–Alder reaction between 1,2,4-triazine molecular systems and 2-cyclopropylidene-1,3-dimethylimidazoline

Cited by 6 publications

References 23 publications

Understanding the Molecular Mechanism of Thermal and LA-Catalysed Diels–Alder Reactions between Cyclopentadiene and Isopropyl 3-Nitroprop-2-Enate

Understanding the Molecular Mechanism of Thermal and LA-Catalysed Diels–Alder Reactions between Cyclopentadiene and Isopropyl 3-Nitroprop-2-Enate

Understanding the Regioselectivity and the Molecular Mechanism of [3 + 2] Cycloaddition Reactions between Nitrous Oxide and Conjugated Nitroalkenes: A DFT Computational Study

On the Question of Zwitterionic Intermediates in the [3+2] Cycloaddition Reactions between Aryl Azides and Ethyl Propiolate

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