Total Synthesis of the Cytotoxic Marine Triterpenoid Isodehydrothyrsiferol Reveals Partial Enantiodivergency in the Thyrsiferol Family of Natural Products

Recently, the phenomenon of enantiodivergence was uncovered as a new phenomenon in the biosynthesis of natural products. In nature, chiral natural products are usually produced in optically active form, but both enantiomers sometimes arise in different genera and/or species or in a single species. Here we show through enantioselective total synthesis that the natural product isodehydrothyrsiferol shows partial enantiodivergency in that six of the nine or ten asymmetric centers are enantiomeric to those of other members of the marine squalene‐derived triterpenoid thyrsiferol family. In addition, isodehydrothyrsiferol and dehydrothyrsiferol, which show partial enantiodivergency, were isolated from the same producer, the red alga Laurencia viridis. These results demonstrate that partial enantiodivergence can develop even between natural products originating from a single species. Man muss beide Seiten sehen: Eine enantioselektive Totalsynthese des zytotoxischen marinen Triterpenoids Isodehydrothyrsiferol belegt eine partielle Enantiodivergenz: Sein ABC‐Ringsystem ist enantiomer zu demjenigen anderer Naturstoffe derselben Familie. Diese partielle Enantiodivergenz wird für Dehydrothyrsiferol und Isodehydrothyrsiferol beobachtet – zwei Naturstoffe aus ein und derselben Spezies, der Rotalge Laurencia viridis.