Quantum chemical modeling of superbase-catalyzed reactions of acetophenone and methyl mesityl ketone with acetylene
- Authors: Kobychev V.B.1, Orel V.B.1, Zankov D.V.1, Vitkovskaya N.M.1, Trofimov B.A.2
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Affiliations:
- Irkutsk State University
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences
- Issue: Vol 66, No 12 (2017)
- Pages: 2227-2233
- Section: Full Article
- URL: https://journals.rcsi.science/1066-5285/article/view/241742
- DOI: https://doi.org/10.1007/s11172-017-2006-2
- ID: 241742
Cite item
Abstract
The mechanisms of furan formation and the competitive reaction of 1,5-diketone formation from 1-mesitylbut-2-en-1-one (1a) and 1-phenylbut-2-en-1-one (1b) were studied using the B3LYP/6-311++G**//B3LYP/6-31+G* quantum chemical approach taking into account solvation effects in terms of the IEFPCM model. The addition to 1a of the ethynide ion to form β-acetylene enolate ion (2a) occurs with the activation energy ΔG≠ = 13.3 kcal mol–1, while the further intramolecular O-vinylation with the closure of 2a to the dihydrofuran cycle of the dihydrofuran carbanion is the rate-determining step in the reaction pathway of substituted furan formation needing the activation energy G≠ = 19.5 kcal mol–1. The alternative addition of the mesitylethenolate ion to 1a to form the 1,5-diketone carbanion is associated with a higher (by 3.4 kcal mol–1) free activation energy than that of ethynide ion addition. In contrast, in the case of 1b, the addition at the C=C bond of the phenylethenolate ion rather than of the ethynide ion to form the 1,5-diketone carbanion is more preferable, since its activation free energy is 1.5 kcal mol–1 lower. The quantum chemical calculation results are consistent with the experimental data.
About the authors
V. B. Kobychev
Irkutsk State University
Email: orelv@isu.ru
Russian Federation, 1 ul. Karla Marksa, Irkutsk, 664003
V. B. Orel
Irkutsk State University
Author for correspondence.
Email: orelv@isu.ru
Russian Federation, 1 ul. Karla Marksa, Irkutsk, 664003
D. V. Zankov
Irkutsk State University
Email: orelv@isu.ru
Russian Federation, 1 ul. Karla Marksa, Irkutsk, 664003
N. M. Vitkovskaya
Irkutsk State University
Email: orelv@isu.ru
Russian Federation, 1 ul. Karla Marksa, Irkutsk, 664003
B. A. Trofimov
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences
Email: orelv@isu.ru
Russian Federation, 1 ul. Favorskogo, Irkutsk, 664033