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Nitroacetylene as dipolarophile in [2 + 3] cycloaddition reactions with allenyl-type three-atom components: DFT computational study.

Jasiński R - Monatsh. Chem. (2015)

Bottom Line: [2 + 3] Cycloaddition reactions of nitroacetylene with allenyl-type three-atom components take place according to the polar, but a one-step mechanism.Alternatively to cycloadducts, during the reaction between the aforementioned reagents, zwitterionic structures with "extended" conformation may be formally created.However, this route is supported by neither kinetic nor thermodynamic factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Organic Chemistry and Technology, Cracow University of Technology, Cracow, Poland.

ABSTRACT

Abstract: [2 + 3] Cycloaddition reactions of nitroacetylene with allenyl-type three-atom components take place according to the polar, but a one-step mechanism. Alternatively to cycloadducts, during the reaction between the aforementioned reagents, zwitterionic structures with "extended" conformation may be formally created. However, this route is supported by neither kinetic nor thermodynamic factors.

No MeSH data available.


Enthalpy profiles for reaction between nitroacetylene (1) and phenylazide (2b) in toluene according to DFT calculations at B3LYP/6-31G(d) theory level
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Fig2: Enthalpy profiles for reaction between nitroacetylene (1) and phenylazide (2b) in toluene according to DFT calculations at B3LYP/6-31G(d) theory level

Mentions: Analysing conversion routes for reagent pairs 1 + 2b, paths leading to zwitterionic structures were found (Fig. 2). However, these are not the expected zwitterions 5 and 6 with “cyclic” conformation (see. Scheme 3) but zwitterions with “extended” conformation 7 and 8 (see Scheme 4). Their conversion to adducts can be executed via a step of dissociation into individual reagents and (in the next step) a stage of cycloaddition according to a one-step mechanism. These paths should be treated as formally forbidden from the kinetic point of view. Thermodynamic factors also do not favour formation of zwitterions 7 and 8.Fig. 2


Nitroacetylene as dipolarophile in [2 + 3] cycloaddition reactions with allenyl-type three-atom components: DFT computational study.

Jasiński R - Monatsh. Chem. (2015)

Enthalpy profiles for reaction between nitroacetylene (1) and phenylazide (2b) in toluene according to DFT calculations at B3LYP/6-31G(d) theory level
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495019&req=5

Fig2: Enthalpy profiles for reaction between nitroacetylene (1) and phenylazide (2b) in toluene according to DFT calculations at B3LYP/6-31G(d) theory level
Mentions: Analysing conversion routes for reagent pairs 1 + 2b, paths leading to zwitterionic structures were found (Fig. 2). However, these are not the expected zwitterions 5 and 6 with “cyclic” conformation (see. Scheme 3) but zwitterions with “extended” conformation 7 and 8 (see Scheme 4). Their conversion to adducts can be executed via a step of dissociation into individual reagents and (in the next step) a stage of cycloaddition according to a one-step mechanism. These paths should be treated as formally forbidden from the kinetic point of view. Thermodynamic factors also do not favour formation of zwitterions 7 and 8.Fig. 2

Bottom Line: [2 + 3] Cycloaddition reactions of nitroacetylene with allenyl-type three-atom components take place according to the polar, but a one-step mechanism.Alternatively to cycloadducts, during the reaction between the aforementioned reagents, zwitterionic structures with "extended" conformation may be formally created.However, this route is supported by neither kinetic nor thermodynamic factors.

View Article: PubMed Central - PubMed

Affiliation: Institute of Organic Chemistry and Technology, Cracow University of Technology, Cracow, Poland.

ABSTRACT

Abstract: [2 + 3] Cycloaddition reactions of nitroacetylene with allenyl-type three-atom components take place according to the polar, but a one-step mechanism. Alternatively to cycloadducts, during the reaction between the aforementioned reagents, zwitterionic structures with "extended" conformation may be formally created. However, this route is supported by neither kinetic nor thermodynamic factors.

No MeSH data available.