N-tert-Butanesulfinyl imine and aromatic tertiary amide derived non-biaryl atropisomers as chiral ligands for silver-catalyzed endo-selective [3+2] cycloaddition of azomethine ylides with maleimides

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• 作者：Xing-Feng Bai^a ; ^b ; Jin Zhang^b ; Chun-Gu Xia^a ; ^{cgxia@licp.cas.cn" class="auth_mail" title="E-mail the corresponding author} ; Jian-Xing Xu^b ; Li-Wen Xu^a ; ^b ; ^{liwenxu@hznu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Cycloaddition ; Asymmetric catalysis ; Sliver ; Azomethine ylide ; Phosphine ; Atropisomer
• 刊名：Tetrahedron
• 出版年：2016
• 出版时间：26 May 2016
• 年：2016
• 卷：72
• 期：21
• 页码：2690-2699
• 全文大小：819 K

文摘

Simple modifications of our novel ligand (Xing-Phos) were presented in this work, and a series of aromatic tertiary amide derived non-biaryl atropisomers were successfully synthesized in good yields. In addition, it was found that the multifunctional aromatic tertiary amide derived non-biaryl atropisomers exhibited an excellent endo-selectivity in the silver-catalyzed [3+2]-cycloaddition of azomethine ylides with N-aromatic maleimide. And especially, good to high levels of enantioselectivity (up to 98% ee) was obtained with a wide range of substrates in the presence of syn-(R, R_S)-2a (Xing-Phos). Furthermore, on the basis of the experimental data, it was demonstrated that a trace amount of water play an important role in the enhancement of enantioselectivity.