Conformation of non‐aromatic ring compounds‐LIV: The calculation of dihedral angles from vicinal proton coupling constants in six‐membered ring compounds

For six‐membered ring compounds existing in solution as an equilibrium mixture of two equivalent conformers, and having a ‐ CH2 ‐ CH2‐ or a ‐ CH2 ‐CHR‐ moiety, the ratio of the vicinal coupling constants R = Jtrans/Jcis is expressed as a function of the ring dihedral angle ψ in that fragment. From the experimental coupling constants of a number of compounds the ψ values are calculated and compared with the corresponding dihedral angles obtained from X‐ray or electron diffraction data. In most cases the difference between the two results does not exceed 1‐2°.