Magnetic non-equivalence of methylene protons in dissymmetric benzylamines

As a result of the lack of a plane of symmetry in identically α,α′-trans-disubstituted heterocyclic amines, the methylene protons of their N-benzyl derivatives are stereochemically and magnetically non-equivalent. The resultant splitting in the NMR spectrum enables an easy differentation between cis and trans isomers.