Application of 13C nuclear magnetic resonance to the conformational analysis of vicinally di- and trisubstituted cyclohexanes: halohydrins, methoxyhalohydrins, and their acetates

Abstract

Low temperature 13C nuclear magnetic resonance spectroscopy has been employed to obtain the chemical shifts and to examine the conformational equilibria of the four chlorohydrins and bromohydrins of 3-methoxycyclohexene. The corresponding acetates and the unsubstituted halohydrins have also been examined. The observed chemical shifts were compared with those calculated from additivity considerations. Limitations of this approach are discussed. Relative peak area measurements have been used to obtain conformational free energies in favourable cases.