Conformational analysis of some 1R,4S-2-arylidene-p-menthan-3-ones by 1H NMR spectroscopy and molecular simulation

✍ Scribed by Nikolay S. Pivnenko; Tatyana G. Drushlyak; Lidiya A. Kutulya; Valeriy V. Vashchenko; Andrey O. Doroshenko; John W. Goodby

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 152 KB
• Volume: 40
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1068

✦ Synopsis

Abstract

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.