Spin-spin coupling between protons bonded to sp2 and sp3 hybridized benzylic carbon atoms and ring protons

Abstract

Deviations from symmetry in inherently symmetrical N.M.R. spectra were used to study long-range spin-spin coupling between benzylic protons and ring protons. With both sp2 and sp3 hybridized benzylic carbon atoms, maximum coupling to the ortho ring protons appears to be associated with out-of-plane conformations of the benzylic proton and that to the meta ring protons with in-plane conformations.