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13 C and 17 O chemical shifts and conformational analysis of mono‐ and di‐methyl‐substituted thiane 1‐oxide and thiane 1,1‐dioxide
Author(s) -
Barbarella Giovanna,
Dembech Pasquale,
Tugnoli Vitaliano
Publication year - 1984
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.1270220612
Subject(s) - conformational isomerism , chemical shift , chemistry , oxide , ring (chemistry) , crystallography , stereochemistry , medicinal chemistry , molecule , organic chemistry
The 13 C and 17 O (natural abundance) chemical shifts of several mono‐ and di‐methyl ring‐substituted thiane 1‐oxides and thiane 1,1‐dioxides are reported. The cis and trans isomers of methyl‐substituted thiane 1‐oxide are readily identified by 13 C and 17 O NMR. In particular, the 17 O NMR signals of axial SO groups are found several ppm upfield of those of the equatorial counterparts. The proportion of axial and equatorial conformers of thiane 1‐oxide in different solvents has been measured by low‐temperature 13 C NMR. In THF the proportion of the axial conformer is higher than in CD 2 Cl 2 whereas in CDCl 3 or CHF 2 Cl the conformational preference is reversed and the equatorial conformer is slightly favoured.