对Pt(II) 介导的级聚烯循环的立体选择性的可逆性效应
Jeremiah A Feducia1, Michel R Gagné
1Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA.
Journal of the American Chemical Society
|December 22, 2007
概括
(((II) 复合物催化了从1,5-dienes中形成多环分子的催化作用. 连接体的特性和反应条件决定了动力或热力学产品的形成,在循环化反应中观察到的高 stereoselectivity.
科学领域:
- 有机金属化学 有机金属化学
- 有机合成 有机合成
- 催化剂是一种催化剂.
背景情况:
- 电友循环反应对于构建复杂的分子架构至关重要.
- ((II) 复合物为调解有机转化提供独特的反应性概况.
- 了解连接体电子和反应途径之间的相互作用是控制立体化学结果的关键.
研究的目的:
- 通过使用电友三啡结Pt(II) 复合物,研究1,5-二烯的循环化.
- 阐明影响多环Pt-基物种及其中间体形成的因素.
- 探索联结物特性和反应条件对循环化产品施加的立体化学控制.
主要方法:
- 合成和特征的三啡链绑定Pt(II) 复合物.
- 携带核陷的1,5-二烯与Pt(II) 复合物的反应.
- 使用光谱技术 (NMR) 和X射线晶体学分析反应产物.
- 连接物基本性,溶剂极性和基质结构的系统变化,以探测反应机制.
主要成果:
- 通过Pt(eta2-alkene) 中间体观察到多环Pt-基物种的形成.
- 在Pt ((β2-烯) 和Pt-基中间体之间建立了平衡,对联体基本性,酸强度,溶剂和环大小敏感.
- 观察到的动力产物 (斯托克-埃申莫泽定理) 与电子贫富的配体,而热力学产物是快速回循环的结果.
- 在动力和热力学控制下,通过远程甲基替代剂实现了高立体选择性.
- 三循环化中的长距离立体控制归因于新生的环组织,而双循环化中的多重选择性则来自可逆级联循环化.
结论:
- 三素结Pt(II) 复合物有效催化1,5-二烯的循环形成多环结构.
- 反应路径和立体化学结果可以通过连接体设计和反应条件进行调整,从而获得动力或热力学产品.
- 该研究提供了对由介导的复杂级联循环中立体控制机制的见解.
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