Bifunctional Lewis Acid-Nucleophile-Based Asymmetric Catalysis: Mechanistic Evidence for Imine Activation Working in Tandem with Chiral Enolate Formation in the Synthesis of β-Lactams
作者:Stefan France、Meha H. Shah、Anthony Weatherwax、Harald Wack、Justine P. Roth、Thomas Lectka
DOI:10.1021/ja044179f
日期:2005.2.1
work in conjunction with Lewis acids to produce beta-lactams in high chemical yield, diastereoselectivity, and enantioselectivity. Chiral cinchona alkaloid derivatives work best when paired with Lewis acids based on Al(III), Zn(II), Sc(III), and, most notably, In(III). Homogeneous bifunctional catalysts, in which the catalyst contains both Lewis acidic and Lewis basic sites, were also studied in detail
我们报告了一项基于机械的双功能催化剂系统研究,其中手性亲核试剂与路易斯酸结合,以高化学产率、非对映选择性和对映选择性生产 β-内酰胺。手性金鸡纳生物碱衍生物与基于 Al(III)、Zn(II)、Sc(III) 和最显着的 In(III) 的路易斯酸配对时效果最佳。还详细研究了均相双功能催化剂,其中催化剂同时含有路易斯酸性和路易斯碱性位点。机理证据使我们能够得出结论,手性亲核试剂形成与金属配位亚胺反应的两性离子烯醇化物。根据我们的观察,假设金属结合的烯醇化物的替代方案不受欢迎。