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Competing pathways in the [2+2] cycloadditions of cyclopentyne and benzyne. A DFT and ab initio study
Date
2004-08-06
Author
Özkan, İlker
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The [2 + 2] cycloadditions of cyclopentyne and benzyne to ethylene are explored at the B3LYP and CASSCF levels, supplemented by CCSD(T) and CAS-MP2 calculations at the stationary points. The biradical path in the benzyne system is computed to be about 4.1 kcal/mol lower than the concerted path, consistent with the experimentally observed loss of original stereochemistry in this cycloaddition. However, computations fail to confirm the 99% stereoretention in the corresponding reaction of cyclopentyne. The concerted and biradical paths in the latter reaction are found to involve nearly isoenergetic barriers, thus predicting only about 75% stereoretention. More sophisticated theoretical methods seem to be needed to resolve the issue in the cyclopentyne system.
Subject Keywords
Generalized gradient approximation
,
Stereochemistry
,
Exchange
URI
https://hdl.handle.net/11511/31181
Journal
JOURNAL OF ORGANIC CHEMISTRY
DOI
https://doi.org/10.1021/jo049542f
Collections
Graduate School of Natural and Applied Sciences, Article
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İ. Özkan, “Competing pathways in the [2+2] cycloadditions of cyclopentyne and benzyne. A DFT and ab initio study,”
JOURNAL OF ORGANIC CHEMISTRY
, pp. 5390–5394, 2004, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/31181.