Conformation of non‐aromatic ring compounds. Part 68. The calculation of dihedral angles from vicinal proton coupling constants in six‐membered ring compounds. Part 2

For six‐membered ring compounds having a −CH 2 ‐CH 2 ‐ fragment for which four vicinal coupling constants follow from the NMR spectrum (ABCD type), the ratio R = ( J trans + J′ trans /( J cis + J′ cis is equated to the ring torsional angle ψ in that fragment. The ψ values calculated from experimental coupling constants of trans ‐2,3‐dichloro‐1,4‐dioxane (I) and ‐oxathiane (II), 2‐ p ‐chlorophenyl‐1,3‐dioxane (III), 2‐phenyl‐1,3‐dithiane (IV), trimethylene sulfite (V) and 2‐oxo‐2‐phenoxy‐1,3,2‐dioxaphosphorinane (VI) show an excellent agreement with the corresponding torsional angles obtained from X‐ray diffraction data.