The first total synthesis of the hexacyclic indole alkaloid (±)-corymine is described. Starting from the readily available N-protected tryptamine, the title compound was achieved in 21 steps in 3.4 % overall yield. Key steps of the synthesis include: a) the addition of a malonate to a 3-bromooxindole to afford 3,3-disubstituted oxindole, b) the formation of a 12-membered cyclic enol ether by intramolecular O-propargylation, immediately followed by propargyl Claisen rearrangement to provide the α-allenyl ketone stereospecifically, c) DMDO oxidation to install a hydroxy group in a highly stereoselective manner, and d) the SmI₂-mediated reductive C−O bond cleavage to remove the α-keto carboxyl group.

中文翻译：

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（±）-甘氨酸的全合成

描述了六环吲哚生物碱（±）-胭脂红的第一全合成。从容易获得的N-保护的色胺开始，以21个步骤获得标题化合物，总产率为3.4％。合成的关键步骤包括：a）将丙二酸酯添加到3-溴代吲哚中，得到3,3-二取代的羟吲哚，b）通过分子内O-炔丙基化，立即接着炔丙基形成12元环烯醇醚克莱森重排以立体定向地提供α-烯丙基酮，c）DMDO氧化以高度立体选择性的方式安装羟基，d）SmI ₂介导的还原性C-O键裂解以去除α-酮基羧基。