Synthesis of purpuroine A, nakirodin A and MDN-0104: The hidden puzzles and risk of error in their configurational assignments

Abstract The unusual ( R ) configuration previously assigned (with seemingly undoubted evidence) to purpuroin A and nakirodin A was disproved by synthesis. The optical rotation and NMR data for structure assigned for salt-free nakirodin A were made available for the first time. The difficulty and potential risk of error in configurational assignments of diastereomers for remote stereocenters were exemplified through MDN-0104. However, comparisons of the delicate 13 C NMR deviations may still provide solutions to such problems.