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Conformational analysis of some 1 R ,4 S ‐2‐arylidene‐ p ‐menthan‐3‐ones by 1 H NMR spectroscopy and molecular simulation
Author(s) -
Pivnenko Nikolay S.,
Drushlyak Tatyana G.,
Kutulya Lidiya A.,
Vashchenko Valeriy V.,
Doroshenko Andrey O.,
Goodby John W.
Publication year - 2002
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1068
Subject(s) - chemistry , conformational isomerism , substituent , cyclohexane conformation , isopropyl , ring (chemistry) , cyclohexanone , stereochemistry , crystallography , benzene , alkyl , nuclear magnetic resonance spectroscopy , computational chemistry , molecule , medicinal chemistry , hydrogen bond , organic chemistry , catalysis
Based on 1 H NMR spectral analysis combined with molecular simulation, conformational states of the cyclohexanone ring were studied for some 1 R ,4 S ‐2‐(4‐X‐benzylidene)‐ p ‐menthan‐3‐ones (X = COOCH 3 or C 6 H 5 ) in CDCl 3 and C 6 D 6 . The co‐existence of chair conformers with an axial orientation of both alkyl substituents and twist‐boat forms was established for the compounds studied at room temperature (22–23° C). The substituent X does not influence appreciably the ratio of these conformers, but the fraction of twist‐boat forms increases noticeably in benzene solutions as compared with CDCl 3 solutions. Rotameric states of the isopropyl fragment were also characterised for the compounds studied. Distinctions in conformational states for the 1 R ,4 S ‐2‐arylidene‐ p ‐menthan‐3‐ones and (−)‐menthone were revealed and are discussed. Copyright © 2002 John Wiley & Sons, Ltd.