Syntheses of the Hexahydroindene Cores of Indanomycin and Stawamycin by Combinations of Iridium-Catalyzed Asymmetric Allylic Alkylations and Intramolecular Diels-Alder Reactions
Short and concise syntheses of the hexahydroindene cores of the antibiotics indanomycin (X‐14547 A) and stawamycin are presented. Key methods used are an asymmetric iridium‐catalyzed allylic alkylation, a modified Julia olefination, a Suzuki–Miyaura coupling, and an intramolecular Diels–Alder reaction.
(S)-N-Methyl-2-hydroxysuccinimide, easily available from natural (S)-malic acid, supplements the previously introduced (R)-pantolactone as chiralauxiliary for asymmetricDiels-Alderreactions of enoates, but yields products of opposite configuration. Practical large-scale preparations of enantiomer pairs of synthetically important Diels-Alder adducts, including adducts from crotonates, are described