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).
Highly <i>Endo</i>-Selective and Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Ylide with α-Enones Catalyzed by a Silver(I)/ThioClickFerrophos Complex
A silver(I)/ThioClickFerrophos complex catalyzed the highly endo-selective asymmetric 1,3-dipolar cycloaddition reaction of methyl N-benzylideneglycinate (the source of azomethine ylides) with (E)-acyclic α-enones having an endo/exo ratio of 90/10 to 99/1. The highly functionalized endo-4-acyl pyrrolidines were obtained in good yields with high enantioselectivities (up to 98% ee). The complex also
Catalytic Asymmetric 1,3-Dipolar Cycloaddition of Azomethine Ylides with α,β-Unsaturated Ketones
作者:Jorge Hernández-Toribio、Ramón Gómez Arrayás、Belén Martín-Matute、Juan C. Carretero
DOI:10.1021/ol802664m
日期:2009.1.15
α,β-Unsaturatedketones are no longer the missing dipolarophiles in catalyticasymmetric 1,3-dipolar cycloaddition of azomethine ylides. In the presence of CuI−Fesulphos complexes as catalysts (5 mol %), these substrates combine high reactivity, wide substitution tolerance, moderate to good endo/exo selectivities, and high enantiocontrol. The endo/exo-diastereoselectivity of the reaction is strongly
α,β-不饱和酮不再是偶氮甲亚胺催化的不对称1,3-偶极环加成反应中缺少的偶极亲和剂。在Cu I -Fesulphos络合物作为催化剂(5摩尔%)的存在下,这些底物结合了高反应活性,宽取代取代度,中等至良好的内/外选择性和高对映体控制性。反应的内/外-非对映体选择性强烈取决于烯酮部分的顺式或反式性质。