作者:Motohiro Nakajima、Haruhiko Fuwa、Makoto Sasaki
DOI:10.1246/bcsj.20120152
日期:2012.9.15
Stereoselective synthesis of the C1–C16 fragment of the antifungal marine polyether macrolide goniodomin A is described. A Stille-type coupling of organostannanes and thioesters was exploited as the key carbon–carbon bond-forming process, namely for the formation of the C7–C8 and C11–C12 bonds. Construction of the spiroacetal domain via acid-catalyzed acetalization of a triol-enone 30 unexpectedly provided a mixture of natural 11S spiroacetal 2, unnatural 11R spiroacetal 32, and constitutional isomer 33. Fortunately, it was eventually found that protection of the C5 hydroxy group as its acetate facilitated the isolation of natural 11S isomer 47 via acid-catalyzed equilibration of unnatural 11R isomer 48 and avoided the formation of a constitutional isomer, thereby increasing the efficacy of the spiroacetalization process.
描述了一种抗真菌海洋聚醚大环化合物Goniodomin A的C1–C16片段的立体选择性合成。利用Stille型偶联反应,将有机锡化合物与硫酯结合,作为关键的碳-碳键形成过程,尤其用于C7–C8和C11–C12键的形成。通过三醇-酮30的酸催化醚化构建螺烯醚区域,意外地得到了天然11S螺烯醚2、不天然11R螺烯醚32和构型异构体33的混合物。幸运的是,最终发现将C5羟基保护为其醋酸酯促进了通过酸催化的平衡反应将不天然11R异构体48转化为天然11S异构体47的分离,并且避免了构型异构体的形成,从而提高了螺烯醚化过程的效率。