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).
A novel Fe(II)/diaryl prolinol catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with alkenes
作者:Haisheng Wu、Bo Wang、Hongqiang Liu、Lei Wang
DOI:10.1016/j.tet.2010.11.091
日期:2011.2
A novel Fe(II)/diaryl prolinol catalyzed asymmetric1,3-dipolarcycloaddition of azomethineylides with alkenes has been developed. In the presence of FeCl2 (10 mol %) and α,α-bis(3,5-bistrifluoromethylphenyl)prolinol L1 (10 mol %), [3+2] cycloaddition of azomethineylides with electronic-deficient olefins underwent smoothly in CH3CN at room temperature to generate the desired endo-adducts in moderate
Asymmetric [3+2] Cycloaddition of Azomethine Ylides Catalyzed by Silver(I) Triflate with a Chiral Bipyrrolidine-Derived Phosphine Ligand
作者:Zhen-Jiang Xu、Chi-Ming Che、Xin Gu、Vanessa Lo
DOI:10.1055/s-0032-1316779
日期:——
bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized. The ‘AgOTf + L1’ protocol catalyzes the asymmetric [3+2] cycloaddition of azomethineylides with alkenes to give highly substituted pyrrolidines in good yields (up to 90%) with moderate to high diastereoselectivities (up to >19:1 dr) and enantioselectivities (up to 76%). Two novel chiral bipyrrolidine-derived phosphine ligands L1 and L2 were synthesized
AgOAc catalyzed asymmetric [3+2] cycloaddition of azomethine ylides with chiral ferrocene derived P,S ligands
作者:Wei Zeng、Yong-Gui Zhou
DOI:10.1016/j.tetlet.2007.04.101
日期:2007.6
Ferrocene derived P,S-heterodonor ligands were effectively used in AgOAc catalyzed asymmetriccycloaddition of azomethineylides. The roles of planar chirality and electronic properties of the phosphorous substituents have been examined, and up to 93% ee was obtained.
Hydrogen-Bonding Directed Reversal of Enantioselectivity
作者:Wei Zeng、Guo-Ying Chen、Yong-Gui Zhou、Yu-Xue Li
DOI:10.1021/ja067346f
日期:2007.1.1
successful stereochemical reversal was achieved in AgOAc catalyzed [3+2] cycloaddition by the formation of hydrogen bonding between ligand and reactant. This strategy provides an efficient and convenient route to prepare both enantiomers of a chiral compound. DFT studies proposed a reasonable mechanism of the reversal of the enantioselectivity; hydrogen bonding changed the transition state. The strategy