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Carbon‐13 NMR Studies: 82. Carbon‐13 spectra of several 10‐methyl‐ cis ‐decalins. Conformational preferences of some cis ‐decalin derivatives
Author(s) -
Browne L. M.,
Klinck R. E.,
Stothers J. B.
Publication year - 1979
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.1270121004
Subject(s) - decalin , chemistry , spectral line , carbon fibers , conformational isomerism , stereochemistry , computational chemistry , organic chemistry , materials science , molecule , physics , astronomy , composite number , composite material , catalysis
The 13 C spectra of a series of 21 cis ‐decalins, 17 of which bear 10‐methyl substituents, have been recorded to examine geometrical and conformational effects on the 13 C shieldings. Although the data for a few of the simpler examples have been reported, these compounds were examined to obtain results for a common medium and temperature. All of the derivatives are conformationally mobile and their spectra were examined as a function of temperature to obtain shieldings representative of the slow exchange limit. The examples include compounds which populate both available chair‐chair conformations equally, some which exhibit a preference for one of these conformations and some which exist essentially in a single conformation. The data for the latter group combined with the observed temperature dependencies and results for other decalin systems led to specific assignments for each carbon. The internal consistency of the entire body of data offers strong support for these assignments. The conformational preferences observed for a number of decalones and Δ 3 ‐10‐methyldecalin derivatives are discussed.