115(P54) ビスセンブラノイド類の親ジエン部分、メチルサルコエートの合成研究(ポスター発表の部)

概要

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Methyl sarcoate (1) was isolated from Okinawan soft coral Sarcophyton glaucum by Kakisawa et al. They also isolated methyl sarcophytoate (3), which is considered to be formed by Diels-Alder reaction of 1 and the diene unit 2. Furthermore, methyl neosartortuate acetate (5) and its diene-dienophile pair, 1 and 4, were isolated by Bowden et al. We now report the synthetic studies of methyl sarcoate (1). The methylketone 12, the C2-C12 segment of 1, was synthesized from citronellol in ten steps including the one-pot, three carbon homologation of ester to allylalchol as a key reaction. The tetrahydrofranone 14, the C13, C14, C15, C1 segment of 1, was synthesized from α-hydroxy-γ-butyrolactone in five steps. Aldol reaction of 14 with the anion derived from 12 and NaHMDS proceeded smoothly to give the coupling product 15 in 95% yield. Treatment of the mesylate of 15 with TBAF resulted in the desired elimination between C1 and C2 to give the hydroxyaldehyde, which was silylated to afford the aldehyde 17. This was converted to the allylphosphate 20c in good yield. The Nozaki-Hiyama cyclization of the acyclic precursor 20c gave the 14-membered product 21 in 59% yield. After the conversion of 21 to the unsatuated keto-ester 25, the desired C4-C5 olefin was introduced by selenylation and oxidation to give 26. Total synthesis of 1 from 26 is now in progress.
天然有機化合物討論会の論文
1996-09-02