Intramolecular Additions of Various π-Nucleophiles to Chemoselectively Activated Amides and Application to the Synthesis of (±)-Tashiromine
作者:Guillaume Bélanger、Robin Larouche-Gauthier、Frédéric Ménard、Miguel Nantel、Francis Barabé
DOI:10.1021/jo052141v
日期:2006.1.1
are usually not compatible with tethered nucleophiles, except for indoles and aromatic rings which have already been reported. This paper describes the comprehensive study of intramolecular addition of silyl enol ethers, allylsilanes, and enamines to chemoselectively activated formamides, aliphatic amides, and lactams. Good to excellent yields were obtained for the 5-exo, 6-exo, and 6-endo modes of cyclization
尽管迄今为止仅报道了单环化,但事实证明,Vilsmeier-Haack型环化对于生成许多生物碱的多环核心部分特别有效。为了快速有效地构建多环生物碱,我们决定通过利用连续生成并被束缚的亲核试剂捕获的亚胺离子来开发Vilsmeier-Haack反应。为了制定这样的策略,我们必须设置第一个环化。这本身就构成了巨大的挑战,因为酰胺的活化条件通常与拴系的亲核试剂不相容,除了已经报道的吲哚和芳环。本文描述了分子内将甲硅烷基烯醇醚,烯丙基硅烷和烯胺加到化学选择性活化的甲酰胺上的综合研究,脂族酰胺和内酰胺。5-的收率好到极好exo, 6- exo和6- end模式的环化。此外,我们证明了环化后溶液中的亚种是亚胺离子。这对于制定双环化战略非常令人鼓舞。还报道了快速合成(±)-tashiromine的方法。