A chemoenzymatic total synthesis of the phytotoxic undecenolide (−)-cladospolide A
作者:Martin G. Banwell、David T. J. Loong
DOI:10.1039/b401829j
日期:——
An eleven-step synthesis of the title compound (1) from biocatalytically-derived and enantiomerically pure âbuilding blocksâ alcohol (R)-(â)-9 and ester 13 is described. Attempts to construct the twelve-membered lactone ring of cladospolide A in a direct manner by using a ring-closing metathesis (RCM) reaction failed. However, a ten-membered lactone, 19, could be constructed by such means and this was then subject to a two-carbon homologation sequence involving, inter alia, WadsworthâHornerâEmmons and Yamaguchi lactonisation reactions in the closing stages of the synthesis. The impact of substituent stereochemistries and protecting groups on the RCM reaction leading to various ten-membered lactones is also described.
标题化合物 (1) 的十一步合成方法被描述,它从生物催化衍生和光学纯的“构建块”醇 (R)-(+)-9 和酯 13 开始。试图通过环闭合复分解(RCM)反应直接构建十二元内酯环的 cladospolide A 失败了。然而,通过这种方法可以构建十元内酯 19,然后通过包括 Wadsworth-Horner-Emmons 和 Yamaguchi 内酯化反应在内的二碳同系化序列在合成的最后阶段进行处理。在导致各种十元内酯的 RCM 反应中,取代基立体化学和保护基团的影响也被描述。