13C chemical-shift assignments in cyclooctyl derivatives from the spectra of deuterioisotopomers. Deuterium isotope effects on chemical shifts and conformational equilibria
Abstract
The 13C NMR spectra of some derivatives of (Z)-cyclooctene, cyclooctanols and cyclooctanone have been assigned by consideration of substituent effects, 1H–13C correlated spectra, and 2H isotope effects. Some four-bond downfield 2H effects (+4Δ) on certain chemical shifts have been measured and attributed to conformational equilibrium perturbations and trans-annular 1H–1H interactions. The data provide a basis for further assignments in these systems.