このエントリーをはてなブックマークに追加
ID 25572
file
creator
Kohno, Yuji
Ueda, Kazuyoshi
Suezawa, Hiroko
Nishio, Motohiro
NDC
Chemistry
abstract
Ab initio MO calculations were carried out, at the MP2/6-311++G(d,p)//MP2/6-311G(d,p) level, to investigate the Gibbs energy of conformational isomers of (R)-α-phellandrene and related 5-alkyl-1,3-cyclohexadienes. It has been found that the conformer bearing the 5-alkyl group in axial orientation is more stable than the equatorial congener. The result is consistent with experimental evidence that the axial-isopropyl conformer prevails in the conformational equilibrium of α-phellandrene. The reason for the stability of the folded conformer has been sought in the context of the CH/π hydrogen bond. A number of short non-bond distances have been disclosed in the axial conformers, between CHs in the 5-alkyl group and sp2-carbons of the cyclohexadiene ring. We suggest that the stability of the folded conformation often observed in conjugated diene compounds of natural origin, such as α-phellandrene and levopimaric acid, is attributed to an attractive molecular force, the CH/π hydrogen bond.
journal title
Tetrahedron
volume
Volume 64
issue
Issue 24
start page
5773
end page
5778
date of issued
2008-06
publisher
Elsevier Ltd
issn
0040-4020
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
author
rights
Copyright (c) 2008 Elsevier Ltd
relation is version of URL
http://dx.doi.org/10.1016/j.tet.2008.04.007
department
Graduate School of Science