对不对称肽催化剂H ‐ D ‐Pro‐Pro‐Asp‐NH 2的结构和功能要求的分析导致紧密相关的多肽H ‐ D ‐Pro‐Pro‐Glu‐NH 2的开发醛与硝基烯烃不对称共轭加成反应的催化剂。在低至1 mol%的H ‐ D ‐Pro‐Pro‐Glu‐NH 2存在下,各种各样的醛和硝基烯烃容易相互反应。所得的γ-硝基醛在室温下以优异的收率和立体选择性获得。在肽催化剂的结构内,D‐Pro‐Pro母题是导致高立体选择性的主要因素。C末端酰胺和C末端氨基酸侧链中羧酸的间隔基负责立体选择性的微调。肽催化剂不仅可以在温和的条件下实现高效的不对称催化,而且还可以在没有添加剂的情况下发挥作用。
A novelbifunctional organocatalyst library combining both aminocatalysis and phosphonicacid activation was used for the first time as an efficient tool for the stereoselectiveMichaeladdition of aldehydes with several aromatic nitroalkenes with good selectivities up to 95:5 dr and 93:7 er. Due to their high water solubility, the catalysts were easilyrecyclable and could be reused over several cycles
for high enantioselectivity and diastereoselectivity compared with those obtained from common trans-pyrrolidine catalysts. Not only configurational but also polymeric effects contribute to the high diastereoselectivity and enantioselectivity. Polymer catalysts were also successfully applied in a continuous-flow process. Acceleration of the reaction rate, an increase in diastereoselectivity, and an improvement
Polystyrene-Supported Diarylprolinol Ethers as Highly Efficient Organocatalysts for Michael-Type Reactions
作者:Esther Alza、Sonia Sayalero、Pinar Kasaplar、Diana Almaşi、Miquel A. Pericàs
DOI:10.1002/chem.201101730
日期:2011.10.4
addition of aldehydes to nitroolefins and of malonates or nitromethane to α,β‐unsaturated aldehydes. The combination of the catalytic unit, the triazole linker, and the polymeric matrix provides unprecedented substrate selectivity, in favor of linear, short‐chain aldehydes, when the organocatalyzed reaction proceeds by an enamine mechanism. High versatility is noted in reactions that proceed via an iminium
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether as a highly efficient bifunctional organocatalyst for Michael addition of ketones and aldehydes to nitroolefins
作者:Chao Wang、Chun Yu、Changlu Liu、Yungui Peng
DOI:10.1016/j.tetlet.2009.02.211
日期:2009.5
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether bifunctionalorganocatalyst 3a is a highly efficient catalyst for the asymmetric Michaeladdition reactions of ketones and aldehydes to nitrostyrenes, leading to syn-selective adducts with excellent yields (>99%), high diastereoselectivities (up to 99:1 dr) and excellent enantioselectivities (up to 99% ee). Control experiments suggested that the
Highly enantioselective Michael addition reactions in water catalyzed by an insoluble MPS-supported 4-sulfonamidyl prolinol tert-butyldiphenylsilyl ether
作者:Yongming Chuan、Guihua Chen、Yungui Peng
DOI:10.1016/j.tetlet.2009.04.011
日期:2009.6
The development of a highly efficient, insoluble, and non-swelling MPS-supported organocatalyst for the direct asymmetric Michael reaction of ketones and aldehydes to nitrostyrenes at room temperature in water is described. Excellent yields (up to 100%) and high stereoselectivities (up to 94% dr and 93% ee) were achieved with 10 mol % of the catalyst. The resin-bound catalyst was simply separated and