Investigating the regio-, chemo- and stereoselectivities of the [3 + 2] cycloaddition reaction of 1-pyrroline-1-oxide and C, N-diphenyl nitrone with a 1, 2-cyclooctadiene carboxylate: a DFT study.

Autor:	Donkor, Gideon, Aniagyei, Albert, Obuah, Collins, Kumi, Joshua Atta, Adei, Evans
Předmět:	RING formation (Chemistry) ACTIVATION energy ELECTRON density POLAR vortex DENSITY functional theory
Zdroj:	Theoretical Chemistry Accounts: Theory, Computation, & Modeling; Nov2024, Vol. 143 Issue 11, p1-11, 11p
Abstrakt:	The [3 + 2] cycloaddition (32CA) reaction holds promise for synthesizing of biologically active heterocyclic compounds. However, to fully exploit its synthetic potential and utilize the reactivity of 1,2-cyclooctadiene as convenient building blocks in the one-step formation of complex cycloadducts, it is crucial to understand the regio- and stereochemical considerations associated with this reaction. Herein, density functional theory (DFT) study has been carried out to explore the chemo-, regio- and stereoselectivities of the 32CA reaction of 1-pyrrolidine-1-oxide (cyclic nitrone) and a C, N-diphenyl nitrones (acyclic nitrone) with a 1,2-cyclooctadiene carboxylate at the M062X/6-311G (d, p) level of theory. The preferred pathway involves the addition of the acyclic nitrone to the substituted olefinic bond of the allene to form 4-methylene isoxazolidine. The free activation energy of 1.8 kcal/mol and the associated rate constant of 7.50 × 1011 s−1 are calculated for the process. This is 113.5 times higher than the formation of 5-methylene isoxazolidine, its regioisomeric product. For the formation of 5-methylene isoxazolidine, the calculated free activation energy is 5.4 kcal/mol. Strong electron-releasing and electron-withdrawing groups lower the activation energies to speed up the reaction. Substituents on B2 (R = CH3 and CH2CH3) have slightly high activation energies compared to the parent reaction. The decrease in activation energies relative to the parent is CH3 < CH2CH3 < OCH3 < NH2. The acyclic and cyclic nitrone derivatives add across the atomic centers with the largest atomic spin densities as evidenced by the local electrophilic (PK+) and nucleophilic (PK−) Parr functions of the various reaction centers. Results from the global electron density transfer (GEDT) reveal the low polar nature of the reactions. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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