Total Syntheses of Lepadiformine Marine Alkaloids with Enantiodivergency, Utilizing Hg(OTf)
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‐Catalyzed Cycloisomerization Reaction and their Cytotoxic Activities
作者:Keisuke Nishikawa、Kengo Yamauchi、Seiho Kikuchi、Shinnosuke Ezaki、Tomoyuki Koyama、Haruka Nokubo、Kunihiro Matsumura、Takeshi Kodama、Momochika Kumagai、Yoshiki Morimoto
DOI:10.1002/chem.201701475
日期:2017.7.18
The enantioselective total syntheses of lepadiformine marine alkaloids, azatricyclic natural products isolated from marine tunicates, were completed. These alkaloids have a unique chemical structure characterized by the trans‐1‐azadecalin (AB ring system) fused with the spirocyclic ring (AC ring system). Here we found that a cycloisomerization reaction from functionalized linear substrates to a 1‐azaspiro[4
从海洋被膜分离出的氮杂三环天然产物lepadiformine海洋生物碱的对映选择性总合成完成了。这些生物碱具有独特的化学结构,其特征是与螺环(AC环系统)稠合的反式-1氮杂钙素(AB环系统)。在这里,我们发现催化量的三氟甲磺酸汞(Hg(OTf)2)。通过新型的环异构化反应,(-)-lepadiformines A和B的总合成分别以28%和21%的总收率实现。(+)-和(-)-lepadiformine C盐酸盐的合成也使我们能够确定天然lepadiformine C的绝对构型。已发现一种对映体现象发生在来自单一海洋被膜的lepadiformine生物碱中,克氏藻。评估了合成的盐酸乙哌丁胺盐及其合成中间体的细胞毒活性。