Chiral ferrocenyl P,S-ligands for highly efficient copper-catalyzed asymmetric [3+2] cycloaddition of azomethine ylides
作者:Fu-Zhong Han、Sai-Bo Yu、Cheng Zhang、Xiang-Ping Hu
DOI:10.1016/j.tet.2015.01.003
日期:2016.5
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 azomethineylides with various electron-deficient olefins, giving the corresponding cycloadducts in high endo-selectivities and excellent enantioselectivities (up to 99% ee).
Enantiodivergent Brucine Diol-Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with α,β-Unsaturated Ketones
作者:Jian-Yuan Li、Hun Young Kim、Kyungsoo Oh
DOI:10.1002/adsc.201500958
日期:2016.3.17
Enantiodivergent catalyst systems were developed using metals with different ionic radii and a multifunctional brucine diol (BD) ligand. The catalytic use of purported 1:1 Cu‐BD complexes in the 1,3‐dipolar cycloaddition of azomethine ylides with chalcones resulted in the selective formation of endo‐pyrrolidines in 87–96% ees with an absolute stereochemical outcome of (2R,3S,4R,5S). In contrast, an
New Chiral Ferrocenyl P,S-Ligands for Highly Diastereo-/Enantioselective Catalytic [3 + 2] Cycloaddition of Azomethine Ylides with Cyclic and Acyclic Enones
developed and successfully applied in a highly endo-selective catalytic asymmetric cycloaddition of azomethine ylides with various enones, including cyclic and acyclic α-enones. For cyclic α-enones, a [Cu(CH3CN)4]ClO4/(Rc,SFc)-2f complex catalyzed the cycloaddition to give the sole endo-cycloadducts in perfect enantioselectivities (normally 99% ee), while an AgOAc/(Rc,SFc)-2f catalytic system exhibited good