Accurate measurement of conformational equilibria using NMR chemical shifts at the fast exchange limit: Dual anancomeric models for 1-methyl-1-chlorocyclohexane
Carr CA., Robinson MJT., Tchen CDA.
3-Methyl- and cis-3,5-dimethyl- derivatives of 1-methyl-1-chlorocyclohexane (1) provide anancomeric model compounds from which to derive reliable estimates of the 13C NMR chemical shifts of the 1-methyl substituents in the two chair conformers of 1 at the fast exchange limit and thence ΔH° = 4.74 kJ mol-1, ΔS° = 1.9 J mol-1 K-1 for 1E→1A in toluene. © 1987.