New Perfluoroalkyl-Substituted Bisoxazolines as Chiral Ligands in Asymmetric CuII-Catalyzed Reactions
作者:Barbara Simonelli、Simonetta Orlandi、Maurizio Benaglia、Gianluca Pozzi
DOI:10.1002/ejoc.200400035
日期:2004.6
and in the ene reaction between α-methylstyrene and ethylglyoxalate in the presence of Cu(OTf)2 (up to 74% ee). We compared the reactivities of the new ligands with those of two other chiral fluorous bisoxazolines that we have reported previously. In both cases, the F-Box that has the lower fluorine content performed better, in terms of chemical yield and enantioselectivity, than the more-fluorinated
两种新的对映体纯全氟烷基取代的双恶唑啉 (F-Box) 已通过反应序列制备,该反应序列包括形成适当功能化的 Box,然后引入一个或两个 n-C8F17 残基。这些配体首次用于 Cu(OTf)2 (高达 85% ee) 促进的甲硅烷基烯酮硫代缩醛向甲基丙酮酸的向山羟醛加成,以及在 Cu(OTf) 存在下α-甲基苯乙烯和乙醛酸乙酯之间的烯反应)2(高达 74% ee)。我们将新配体的反应性与我们之前报道的其他两种手性氟代双恶唑啉的反应性进行了比较。在这两种情况下,氟含量较低的 F-Box 在化学产率和对映选择性方面都比氟化程度更高的 F-Box 表现更好。配体的回收和再循环通过反应溶剂的相分离或通过短的含氟硅胶塞过滤来实现。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)