Synthesis of 3-Epi-6,7-dideoxyxestobergsterol A.
作者:Yuko KAJI、Takeshi KOAMI、Atsuko NAKAMURA、Yoshinori FUJIMOTO
DOI:10.1248/cpb.48.1480
日期:——
3-Epi-6, 7-dideoxyxestobergsterol A (2), an analogue of xestobergsterol A, has been synthesized from dehydroepiandrosterone (3) in 15 steps. The key synthetic intermediate, 15β, 16α-dioxypregn-17(20)E-ene derivative 8, was prepared from the corresponding 15β, 16β-epoxide 6 by reating with acetic acid and titanium tetraisopropoxide. The 23-oxo side chain was constructed stereoselectively by orthoester Claisen rearrangement of 8 followed by introduction of an isobutyl group. Basic treatment of the 15, 23-diketone 12 followed by deprotection gave the title compound 2.
3-表异构体-6, 7-去氧酮甾醇A (2),作为酮甾醇A的类似物,经过15步反应由脱氢表雄酮 (3) 合成而得。关键合成中间体15β, 16α-二羟孕-17(20)E-烯衍生物8是通过将相应的15β, 16β-环氧化物6与醋酸和四异丙氧化钛反应制备而成。23-氧侧链通过8的邻醇克莱森重排以立体选择性方式构建,随后引入异丁基。对15, 23-二酮12进行碱性处理后去保护,最终得到了目标化合物2。