Interproton allylic spin-spin coupling involving exocyclic groups

Abstract

N.m.r. parameters for 55 compounds incorporating exocyclic groups were obtained. In unstrained structures the relative (as well as the absolute) magnitudes of transoid and cisoid allylic coupling constants depend on the magnitudes of the dihedral angles but additional effects were also identified. The magnitudes of geminal coupling constants between the protons of exocyclic methylene groups and of homoallylic coupling constants involving exocyclic ethylidene and isopropylidene groups vary systematically with ring size.