Highly enantioselective Friedel–Crafts alkylation of indoles with α,β-unsaturated ketones with simple Cu(II)–oxazoline–imidazoline catalysts
作者:Assem Barakat、Mohammad Shahidul Islam、Abdullah M.A. Al Majid、Zeid Abdullah Al-Othman
DOI:10.1016/j.tet.2013.04.063
日期:2013.6
developed ligands efficiently affect the copper-catalyzed enantioselective addition of indole to α,β-unsaturated ketones, yielding the corresponding adducts in good yield and high enantiomeric excess. The fine-tuning capability of these ligands plays a significant role in achieving high enantioselectivity in the asymmetric alkylation (up to 99% ee). The higher enantioselectivity of the reaction could
已开发出一系列具有咪唑啉-恶唑啉骨架的新型手性配体L1 - L4,作为新型的非对称N,N-双齿配体。所有手性配体均由2,2-二乙基丙二酸和对映体纯的(S)-2-氨基-3-甲基-1-丁醇分四个步骤,具有优异的光学纯度。这些新开发的配体有效地影响了铜催化的吲哚向α,β-不饱和酮的对映选择性加成,从而以高收率和高对映体过量产生相应的加合物。这些配体的微调能力在不对称烷基化(高达99%ee)中实现高对映选择性方面起着重要作用。该反应较高的对映选择性可能是由于1,4-金属键合模型的协同作用,使烯类配合的手性路易斯酸金属配合物的活化和不对称诱导。