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Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
对α-化基基的结构/反应性研究:实验电荷密度的化学解释
Holger Ott1, Christian Däschlein, Dirk Leusser
1Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen, Germany.
Journal of the American Chemical Society
|August 16, 2008
概括
嵌合体替代的基化合物使立体选择性合成成为可能. 它们的电子性质,特别是原子的α效应,解释了电友攻击期间的配置逆转.
科学领域:
- 有机化学 有机化学
- 立体化学是一种立体化学.
- 有机金属化学 有机金属化学
背景情况:
- 对现代有机合成至关重要,特别是对天然产品的合成.
- 基化合物是产生立体物质的关键中间体.
- 替代的基化合物提供了在碳中保持立体信息的潜力.
研究的目的:
- 为了研究替代化合物的立体化学行为.
- 阐明控制这些中间体的立体选择性反应的电子因素.
- 了解原子在稳定和指导相邻的碳原子反应中的作用.
主要方法:
- 合成基聚合物丰富的基西兰.
- 使用NMR光谱法 (13C NMR) 来生成和表征替代的甲中间体.
- 关键中间体的X射线衍射分析以确定绝对配置.
- 与电友 (三甲基) 发生反应,以捕获carbanion.
- 高分辨率衍射数据和拓分析用于电子结构研究.
主要成果:
- 成功合成 (R,S) - 2 x 奇努克利丁,由酶体丰富的基基.
- 通过X射线衍射确定金属化碳的绝对配置.
- 通过13C NMR合观察溶液中的固定碳接触.
- 使用三甲基酸捕获的立体选择性捕获,产生 (S,S) -4具有高二聚合物比率 (>98:2) 和配置反转.
- 电子分析显示,环中的电荷合最小,上有显著的正电荷,解释了α效应和立体化学结果.
结论:
- 替代的甲化合物可以作为立体化学保持剂.
- 原子的α效应,由静电强化驱动,决定了电友攻击的立体化学过程.
- 实验电静电电位映射证实了背面攻击机制,导致立体化学的反转,具有高立体选择性.
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