基于均相催化剂在多壁碳纳米管(MWNTs)纤维网络中的自组装,已经开发了一种易于回收的不对称催化剂。酰胺基手性配体与合适的间隔基二聚可通过添加Er(O i Pr)3进行自组装,有效地形成非均相催化剂。自组装在MWNT纤维网络中进行,组装好的催化剂的小团簇被限制在MWNT中,产生易于处理的固相催化剂。所得的MWNT受限催化剂在催化不对称曼尼希型反应中表现出良好的催化性能,可以在重复批处理系统和连续流平台中进行。
Enantio- and Diastereoselective Mannich-Type Reactions of α-Cyano Ketones with<i>N</i>-Boc Aldimines Catalyzed by Chiral Bifunctional Urea
作者:Ju Hee Lee、Dae Young Kim
DOI:10.1002/adsc.200900268
日期:2009.8
The catalytic enantioselective electrophilic Mannich-typereaction promoted by chiralbifunctional organocatalysts is described. The treatment of α-cyanoketones with N-Boc-aldimines under mild reaction conditions afforded the corresponding β-amino-α-cyano ketones with excellent diastereoselectivities (up to syn/anti=100/0), and excellent enantioselectivities (up to 99% ee).
描述了由手性双官能有机催化剂促进的催化对映选择性亲电曼尼希型反应。在温和的反应条件下,用N -Boc-醛亚胺处理α-氰基酮,得到相应的β-氨基-α-氰基酮,具有非对映选择性(高达syn / anti = 100/0)和出色的对映选择性(高达99) %ee)。
Linking Structural Dynamics and Functional Diversity in Asymmetric Catalysis
Proteins, the functional molecules in biological systems, are sophisticated chemical devices that have evolved over billions of years. Their function is intimately related to their three-dimensional structure and elegantly regulated by conformational changes through allosteric regulators and a number of reversible or unidirectional post-translational modifications. This functional diversification in response to external stimuli allows for an orderly and timely progression of intra- and extracellular events. In contrast, enantioselective catalysts generally exhibit limited conformational flexibility and thereby exert a single specific function. Exploiting the features of conformationally flexible asymmetric ligands and the variable coordination patterns of rare earth metals, we demonstrate dynamic structural and functional changes of a catalyst in asymmetric catalysis, leading to two distinct reaction outcomes in a single flask.