在C2-对称 bis ((oxazolinato) lanthanide催化剂中,用于对分子内部的胺化/循环化
Sukwon Hong1, Shun Tian, Matthew V Metz
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-3113, USA.
Journal of the American Chemical Society
|December 4, 2003
概括
新的合性C(2) - 对称 bis(oxazolinato) 兰化物复合物有效地催化了反选择性的分子内胺化/循环化反应. 这些在现场生成的前催化剂显示出高的周转频率和选择性,特别是在较大的类离子中.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 不对称的合成方法
背景情况:
- 化兰化物复合物越来越多地被探索为不对称转换的催化剂.
- 有效的酶选择性分子内胺化/循环化反应对于合成含的异环非常重要.
- 开发用于这些反应的新型前催化剂仍然是活跃的研究领域.
研究的目的:
- 开发和评估新型C(2) - 对称 bis(oxazolinato) lanthanide复合物,作为对enantioselective分子内胺化/循环化的前催化剂.
- 为了研究连接物结构和胺离子半径对催化活性和选择性的影响.
- 阐明触媒过程中涉及的机制和活性物种.
主要方法:
- 合成和表征C(2) - 对称 bis(oxazolinato) lanthanide复合物.
- 在现场生成从兰化金属前体和 bis ((oxazoline) 连接剂的前催化剂.
- 选各种bis ((oxazoline) 连接体和兰坦化金属以获得最佳的催化性能.
- 用X射线晶体学来确定预催化剂物种的结构.
- 动力学研究,以了解反应机制.
主要成果:
- 开发的前催化剂有效地催化了氨基和氨基的酶选择性内分子胺化/循环化.
- 具有较大的离子半径 (例如,La) 的兰化物表现出更高的周转频率和选择性.
- 连接物结构,特别是烯基立体导向组和oxazolin环的5位置换,显著影响了催化效率.
- 优化的前催化剂实现了高达67% ee的反体过量,与现有的性有机类催化剂相比或超过.
- 动力学研究表明一种单体活性物种和一种涉及氨酸插入的机制,其次是质溶解.
结论:
- 2-对称双------------------------------------------------------------------------------------------------------------------------------------------------------------------------
- 催化剂的性能可以通过连接体设计和选择类金属来调整.
- 这些系统为现有的催化剂提供了一个有希望的替代品,用于合成含有的性化合物.
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