The Combination of Diallylboration and Ring-Closing Metathesis in the Synthesis of Spiro-β-Amino Alcohols and (±)-Cephalotaxine
作者:Nikolai Yu. Kuznetsov、Galina D. Kolomnikova、Victor N. Khrustalev、Denis G. Golovanov、Yuri N. Bubnov
DOI:10.1002/ejoc.200800755
日期:2008.11
single-crystal X-ray analysis. The dehydrobromination of the tricyclic bromides with tBuOK produced olefins in good yields, which underwent allylic-type rearrangement in the presence of MgBr2·Et2O. Alkaline hydrolysis of the rearranged carbamates led to diastereomerically pure spiro-β-amino alcohols. The structure of the dimethyl-substituted amino alcohol was proved by single-crystal X-ray analysis. rac-(5R*
详细阐述了制备各种螺-β-氨基醇的方便实用的方法。该方法涉及烯丙基硼化和闭环复分解以制备螺双环化合物,然后将其修饰为含有四至六元氮杂环的螺-β-氨基醇。N-Boc 保护的氮杂螺环烯烃与 NBS 在溶剂中回流反应得到三环溴环氨基甲酸酯。其中一种溴化物的结构是通过单晶 X 射线分析确定的。三环溴化物与 tBuOK 脱溴化氢以良好的收率生产烯烃,在 MgBr2·Et2O 存在下进行烯丙基型重排。重排氨基甲酸酯的碱性水解导致非对映异构纯的螺-β-氨基醇。通过单晶X射线分析证明了二甲基取代氨基醇的结构。rac-(5R*,6S*)-1-Azaspiro[4.4]non-7-en-6-ol 用于头孢噻肟的正式合成。 (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany , 2008)