De Novo Asymmetric Synthesis of Milbemycin β<sub>3</sub> via an Iterative Asymmetric Hydration Approach
作者:Miaosheng Li、George A. O'Doherty
DOI:10.1021/ol061439k
日期:2006.8.1
achieved in 22 steps and 2.8% overall yield from an achiral dienoate. The spiroketal ring system was installed by three sequential asymmetric hydrations followed by sprioketalization. Both the absolute and relative stereochemistry of milbemycin beta3 was introduced by two Sharpless asymmetric dihydroxylations, two pi-allylpalladium-catalyzed reductions, and an iridium-catalyzed hydrogen migration/Claisen
螺酮缩醛/大环内酯天然产物米尔倍霉素β3的对映选择性合成已通过22个步骤完成,非手性二烯酸酯的总收率为2.8%。通过三个连续的不对称水合作用,然后进行sprioketalization安装了spiroketal环系统。米尔贝霉素beta3的绝对和相对立体化学都是通过两次Sharpless不对称二羟基化,两次π-烯丙基钯催化的还原反应以及铱催化的氢迁移/克莱森重排引入的,以安装C-12立体中心。