NMR‐Experiments on Acetals: XXIII The Ring Shape of m‐Dioxanes, m‐Dithianes and m‐Thioxanes

Abstract
It is shown that the criterion of Lambert (allowing the description of ring shape) and the recent extension by Buys (allowing the calculation of torsion angles of parts of the ring) can be applied to unequal‐populated conformational pairs and to anancomeric systems. The results so obtained for m‐dioxanes, m‐dithianes, and m‐thioxanes are discussed in the light of the pecularities of these ring systems.