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.