Total Synthesis of the Antitumor Macrolides, (+)-Brefeldin A and 4-Epi-Brefeldin A from <scp>d</scp>-Glucose: Use of the Padwa Anionic Allenylsulfone [3 + 2]-Cycloadditive Elimination To Construct Trans-Configured Chiral Cyclopentane Systems
作者:Ziyue Xiong、Karl J. Hale
DOI:10.1021/acs.orglett.6b02002
日期:2016.9.2
A new synthesis of (+)-brefeldin A is reported via Padwa allenylsulfone [3 + 2]-cycloadditive elimination. Cycloadduct 13 was initially elaborated into iodide 27, which, following treatment with Zn, gave aldehyde 28 whose C(9) stereocenter was epimerized. Further elaboration into enoate 38 and Julia–Kocienski olefination with 5 subsequently afforded 39, which was deprotected at C(1) and O(15). Yamaguchi
通过Padwa烯基砜[3 + 2]-环加成消除法报道了一种新的(+)-布雷菲德菌素A合成方法。首先将环加合物13精制为碘化物27,用Zn处理后,得到醛28,其C(9)立体中心被差向异构化。进一步加工成烯酸酯38和Julia-Kocienski与5的烯烃,随后得到39,在C(1)和O(15)脱保护。所述的山口macrolactonization开环-酸之后,得到大环化合物将经历O型脱甲硅基和反演在C(4),得到(+) -后的脱保护布雷菲德菌素A。