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Asymmetric Total Synthesis of ent-Pyripyropene A

Shinichiro Fuse^1,2, Ayako Ikebe³, Kazuya Oosumi³

¹Department of Applied Chemistry, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan). sfuse@res.titech.ac.jp.

Chemistry (Weinheim an Der Bergstrasse, Germany)

|May 28, 2015

Abstract:

An asymmetric total synthesis of ent-pyripyropene A was achieved by a convergent synthetic route. We used our originally developed Ti(III) -catalyzed radical cyclization to construct an AB-ring portion that consisted of a trans-decalin skeleton with five contiguous stereogenic centers. The coupling between the AB-ring and the DE-ring portions, and a subsequent C-ring cyclization, led to the total synthesis of ent-pyripyropene A. An evaluation of the insecticidal activity of ent-pyripyropene A against two aphid species revealed that ent-pyripyropene A was 35-175 times less active than naturally occurring pyripyropene A. This result indicated that the biological target of pyripyropene A recognizes the absolute configuration of pyripyropene A.

Keywords:

insecticidal activity meroterpenoids natural products radical reactions titanium

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