Chiral ferrocenyl P,S-ligands for highly efficient copper-catalyzed asymmetric [3+2] cycloaddition of azomethine ylides

摘要

A series of chiral ferrocenyl P,S-ligands based on benzimidazole and imidazole backbones have been prepared from Ugi's amine through a three-step transformation. These ligands were successfully employed in the Cu-catalyzed asymmetric [3+2] cycloaddition of azomethine ylides with various electron-deficient olefins, giving the corresponding cycloadducts in high endo-selectivities and excellent enantioselectivities (up to 99% ee). (C) 2015 Elsevier Ltd. All rights reserved.