From an Acyclic, Polyunsaturated Precursor to the Polycyclic Taxane Ring System: The [4+2]/[2+2+2] and [2+2+2]/[4+2] Cyclization Strategies
作者:Gaëlle Chouraqui、Marc Petit、Phannarath Phansavath、Corinne Aubert、Max Malacria
DOI:10.1002/ejoc.200500762
日期:2006.3
cobalt(I)-mediated cyclotrimerization and a [4+2] reaction is described as a new entry into the ABC core of taxanes. The [4+2]/[2+2+2] and the [2+2+2]/[4+2] pathways both lead to the expected ABC core of the title compound. Mechanistic proposals are described to understand the formation of the side products during the [2+2+2] cycloaddition and to apply useful modifications of the highly substituted unsaturated
钴 (I) 介导的环三聚和 [4+2] 反应的组合被描述为进入紫杉烷 ABC 核心的新入口。[4+2]/[2+2+2] 和 [2+2+2]/[4+2] 通路都导致预期的标题化合物的 ABC 核心。描述了机制建议,以了解 [2+2+2] 环加成过程中副产物的形成,并应用对高度取代的不饱和前体的有用修饰。事实上,我们证明,对于第一种方法,炔丙基位置的取代对环化有显着影响。对于第二个序列,我们观察到双键末端位置的硅基团可以改变环加成的化学选择性。此外,在 [2+2+2] 环加成反应中使用临时硅系链提供了对高度复杂的分子 38 的快速访问,该分子展示了用于进一步合成转化的潜在功能。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)