Studies on the Bisoxazoline- and (−)-Sparteine-Mediated Enantioselective Addition of Organolithium Reagents to Imines
作者:Scott E. Denmark、Noriyuki Nakajima、Cory M. Stiff、Olivier J.-C. Nicaise、Michael Kranz
DOI:10.1002/adsc.200800017
日期:2008.5.5
The enantioselective addition of organolithium reagents to N-anisyl aldimines promoted by chiral bisoxazolines and (-)-sparteine as external ligands is described. This reaction proceeds readily with a wide range of aldimine substrates (aliphatic, aromatic, olefinic) and organolithium nucleophiles (Me, n-Bu, Ph, vinyl) in excellent yields (81-99%) and with high enantioselectivities (up to 95.5:4.5 er)
描述了在手性双恶唑啉和(-)-金雀花碱作为外部配体的促进下,有机锂试剂对映选择性加成到N-茴香基醛亚胺上。该反应可以使用多种醛亚胺底物(脂肪族、芳香族、烯烃)和有机锂亲核试剂(Me、n-Bu、Ph、乙烯基)轻松进行,收率优异(81-99%),并且具有高对映选择性(高达 95.5: 4.5 尔)。外部配体可以亚化学计量的量使用,尽管对映选择性略有减弱。对双恶唑啉结构特征的系统评估揭示了 C(4) 取代基的主要贡献和桥接取代基的次要影响。计算分析 (PM3) 为对映选择性的起源提供了清晰的合理解释。