Asymmetric Synthesis of the Antiviral Diterpene Wickerol A
Shu-An Liu1, Dirk Trauner1,2
1Department of Chemistry and Center for Integrated Protein Science, Ludwig-Maximilian University Munich , Butenandtstraße 5-13, 81377 Munich, Germany.
Abstract:
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.
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