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Asymmetric Synthesis of the Antiviral Diterpene Wickerol A

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posted on 18.06.2017, 00:00 by Shu-An Liu, Dirk Trauner
Wickerol A (1) is an unusual diterpene with remarkable activity against the H1N1 influenza virus. Its tetracyclic skeleton contains three quaternary carbons and is marked by several syn-pentane interactions which force a six-membered ring into a twist-boat conformation. We present an asymmetric synthesis of wickerol A (1) that is based on a Jung Diels–Alder reaction, an intramolecular alkylation to complete the 6–5–6–6 ring system, and a conjugate addition, all of which overcome considerable steric strain. During the synthesis, we isolated an unexpected cyclopropane that presumably stems from a carbonium ion intermediate.