A chemoenzymatic total synthesis of the undecenolide (−)-cladospolide B via a mid-stage ring-closing metathesis and a late-stage photo-rearrangement of the E-isomer
作者:Kerrie A. B. Austin、Martin G. Banwell、David T. J. Loong、A. David Rae、Anthony C. Willis
DOI:10.1039/b417685e
日期:——
A sixteen-step synthesis of the twelve-membered macrolide (-)-cladospolide B(2) from the microbially-derived cis-1,2-dihydrocatechol 5 is described. Pivotal steps include the ring-closing metathesis (RCM) of diene 12 to give the ten-membered lactone 13 together with small amounts of the head-to-tail and head-to-head dimers 14 and 15, respectively. The saturated lactol 19 derived from compounds 13 and
从微生物衍生的顺式1,2-二氢邻苯二酚5描述了十二元大环内酯(-)-cladospolide B(2)的十六步合成。关键步骤包括二烯12的闭环复分解(RCM),以得到十元内酯13以及少量的头对尾和头对头二聚体14和15。衍生自化合物13和14的饱和乳糖醇19易于参与Wadsworth-Horner-Emmons反应,得到E-构型的α,β-不饱和酯20。然后,通过在Yamaguchi上进行Yaguguchi内酯化反应,将最后的化合物转化。衍生的酸22进入大环内酯23,大环内酯23除去双缩醛保护基后,提供化合物24,为目标2的E-异构体。