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
Epiandrosterone-derived prolinamide as an efficient asymmetric catalyst for Michael addition reactions of aldehydes to nitroalkenes
作者:Yongchao Wang、Shen Ji、Kun Wei、Jun Lin
DOI:10.1039/c4ra03075c
日期:——
Epiandrosterone derivatives-organocatalyzed asymmetricMichaeladdition of aldehydes to nitroalkenes was investigated. Among the various catalysts, a novel type of epiandrosterone-derived L-prolineamide catalyst was synthesized and exhibited better performance in both catalytic activity and stereoselectivity, providing the products with high yields (up to 98%), excellent enantioselectivities (up to
active chiral moieties along the network. The hybrid material was studied by means of different characterization techniques (TGA, NMR and IR spectroscopy, chemical and elemental analyses, TEM, and textural measurements), verifying the stability and integrity of the asymmetric active sites in the solid. The hybrid material, HybPyr, is an excellent asymmetric heterogeneous and recyclable catalyst for enantioselective
基于硅质骨架 HybPyr 中包含的吡咯烷单元,合成了一种新型手性介孔杂化材料,并由特定的双甲硅烷基化前体整合到有机-无机结构中。在软合成条件下且在没有复杂的结构导向剂的情况下,氟化物溶胶-凝胶方法可以产生介孔结构,活性手性部分沿网络均匀分布。通过不同的表征技术(TGA、NMR 和 IR 光谱、化学和元素分析、TEM 和结构测量)对杂化材料进行了研究,验证了固体中不对称活性位点的稳定性和完整性。杂化材料 HybPyr 是一种优异的不对称多相且可回收的催化剂,用于线性醛与 β-硝基苯乙烯衍生物的对映选择性迈克尔加成反应,并对反应产物具有高度立体控制。
A Visible‐Light‐Powered Polymerization Method for the Immobilization of Enantioselective Organocatalysts into Microreactors
A versatile one‐step photopolymerization approach for the immobilization of enantioselectiveorganocatalysts is presented. Chiral organocatalyst‐containing monoliths based on polystyrene divinylbenzene copolymer were generated inside channels of microfluidic chips. Exemplary performance tests were performed for the monolithic Hayashi–Jørgensen catalyst in continuous flow, which showed good results
Prolylprolinol-Catalyzed Asymmetric Michael Addition of Aliphatic Aldehydes to Nitroalkenes
作者:Dengfu Lu、Yuefa Gong、Weizhou Wang
DOI:10.1002/adsc.200900687
日期:2010.3.8
Several novel prolylprolinol catalysts have been designed and synthesized. This type of compound showed high catalytic efficiency on promoting the direct addition of unmodified aldehydes to nitroalkenes. Among the catalysts surveyed, the least bulky member (8d) exhibited the best performance on both efficiency and stereoselectivity, providing the products with up to 97% ee value with 1.5–5 mol% catalyst