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Conformational equilibrium in 8‐methyl‐ cis ‐2‐thiahydrindane and 8‐methyl‐ cis ‐2‐oxahydrindane by 13 C NMR spectroscopy
Author(s) -
Willer Rodney L.
Publication year - 1981
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270160403
Subject(s) - conformational isomerism , cyclohexane , chemistry , methyl group , ring (chemistry) , chemical shift , nuclear magnetic resonance spectroscopy , spectroscopy , stereochemistry , crystallography , group (periodic table) , molecule , organic chemistry , physics , quantum mechanics
The preferred conformation of 8‐methyl‐ cis ‐thiahydrindane has been both estimated by 13 C NMR chemical shifts and determined by low temperature 13 C NMR spectroscopy to be the conformer with the methyl group equatorial with respect to the cyclohexane ring. This result is in disagreement with the interpretation of the temperature dependence of the CD spectra of (+) and (−) 8‐methyl‐ cis ‐2‐thiahydrindane, whereby the conformation with the methyl group axial with respect to the cyclohexane ring was claimed to be the preferred conformation. The preferred conformation of the related oxygen heterocycle, 8‐methyl‐ cis ‐2‐oxahydrindane, has been estimated by 13 C NMR chemical shifts to be the conformer with the methyl group axial with respect to the cyclohexane ring. Possible reasons for these observations are discussed.