An unambiguous structural differentiation of B/C‐cis‐ and B/C‐trans‐morphinan derivatives (thebainone‐A and β‐thebainone‐A and their 7,8‐dihydro derivatives) is provided. The structures were confirmed by NOE difference spectroscopy and selective 2D J‐INEPT experiments. In addition, full a priori 1H and 13C NMR assignments of the isomeric pairs studied are presented.
QC 20220915