An enantioselective synthesis of biologically important imidazolidines has been achieved via a tandem [3 + 2] cycloaddition/1,4-addition reaction of azomethine ylide and aza-o-quinone methides. With the use of this tool, various imidazolidinederivatives are obtained in good yields with excellent diastereoselectivities and enantioselectivities.
Cu(I)-Catalyzed Highly Enantioselective [3 + 3] Cycloaddition between Two Different 1,3-Dipoles, Phthalazinium Dicyanomethanides and Iminoester-Derived Azomethine Ylides
The Cu(I)-catalyzed highly enantioselective [3 + 3] cycloadditionbetween two different 1,3-dipoles, phthalazinium dicyanomethanides and iminoester-derived azomethine ylides, has been achieved under mild reaction conditions, providing novel chiral heterocyclic compounds, 2,3,4,11b-tetrahydro-1H-pyrazino[2,1-a]phthalazine derivatives, in high yields with excellent diastereo- and enantioselectivies (up
在温和的反应条件下,已实现了Cu(I)催化的两个不同的1,3-偶极,酞菁双氰胺和亚氨基酯衍生的偶氮甲碱的高对映选择性[3 + 3]环加成反应,提供了新颖的手性杂环化合物2,3 ,4,11b-四氢-1 H-吡嗪并[ 2,1- a ]酞嗪衍生物,高收率,具有出色的非对映和对映选择性(高达99%收率,99%ee,> 20:1 dr)。
Enantioselective Copper-Catalyzed [3+3] Cycloaddition of Azomethine Ylides with Azomethine Imines
The more dipoles, the merrier: An asymmetric [3+3] cycloaddition of azomethineylides derived from imines 1 with azomethineimines 2 in the presence of a chiral ferrocenylphosphine–copper catalyst afforded highly functionalized heterocyclic products 3 in high yield with excellent enantio‐ and diastereoselectivity (see scheme; DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene). The 1,3‐dipolar reaction partners
Synthesis of new chiral ferrocenyl P,N-ligands with a benzoxazole ring and their application in Ag-catalyzed asymmetric [3+2] cycloaddition
作者:Sheng Yan、Cheng Zhang、Ya-Hui Wang、Zhong Cao、Zhuo Zheng、Xiang-Ping Hu
DOI:10.1016/j.tetlet.2013.05.003
日期:2013.7
New chiral ferrocenyl P,N-ligands with a benzoxazole ring as the N-donor group have been synthesized from 2-aminophenol through a three-step transformation and successfully employed in the Ag-catalyzed asymmetric [3+2] cycloaddition of azomethine ylides with electron-deficient alkenes. High diastereoselectivities, excellent enantioselectivities, and good yields have been achieved for a variety of substrates, demonstrating the potential of these new P,N-ligands in asymmetric catalysis. (C) 2013 Elsevier Ltd. All rights reserved.
Metal-Catalyzed [6 + 3] Cycloaddition of Tropone with Azomethine Ylides: A Practical Access to Piperidine-Fused Bicyclic Heterocycles
The first metal-catalyzed [6 + 3] cycloaddition of tropone with azomethine ylides has been developed. With the use of a chiral ferrocenylphosphine-copper(I) complex as the catalyst, the asymmetric variant of the [6 + 3] cycloaddition has also been successfully achieved. The reactions proceeded smoothly under mild conditions, affording piperidine-fused bicyclic heterocycles in moderate to high yields with good to excellent diastereo- and enantioselectivies. The procedures are operationally simple and the catalysts are cheap and readily accessible, thus providing a practical approach to piperidine-fused bicyclic heterocycles.