Myrmenaphthol A is a structurally
unique phenolic steroid with
a naphthyl AB-ring system and an unusual C2 hydroxy group. Herein,
we report the first total synthesis of this natural product in 10
steps from inexpensive, commercially available sitolactone. Key features
of the synthesis include a Baran decarboxylative coupling and a Friedel–Crafts
cyclization/olefin isomerization/aromatization cascade that rapidly
assembled the tetracyclic core framework. This synthetic strategy
is expected to be readily amenable to the synthesis of other phenolic
steroids.
A 10-step gram-scale synthesis of 9,11-secosteroid pinnisterol E from the inexpensive ergosterol is reported. This synthesis features a series of highly selective redox transformations such as regioselective olefin hydrogenation (PtO 2 ), acid-sensitive endoperoxide reduction (Al−Ni alloy, Zn), and regio-and diastereoselective dienone oxidation. The robustness of this strategy is clearly demonstrated through the formal synthesis of 11(9 → 7)abeo-steroid pleurocin B and the divergent synthesis of 9,11-secosteroids glaciasterol B and 6-keto-aplidiasterol B from the inexpensive cholesterol.Letter pubs.acs.org/OrgLett
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