A chiral organocatalytic polymer-based monolithic reactor
作者:Valerio Chiroli、Maurizio Benaglia、Alessandra Puglisi、Riccardo Porta、Ravindra P. Jumde、Alessandro Mandoli
DOI:10.1039/c4gc00031e
日期:——
properly modified enantiomericallypure imidazolidinone inside a stainless steel column in the presence of dodecanol and toluene as porogens afforded the first example of a chiral organocatalyst immobilized onto a monolithic reactor. Organocatalyzed cycloadditionsbetween cyclopentadiene and cinnamic aldehyde were performed under continuous-flow conditions; by optimizing the experimental set up, excellent
evaluation of surface areas, pore dimensions, and catalyst loading. They were used in organocatalyzed Diels–Alder cycloadditions between cyclopentadiene and different aldehydes, affording results comparable to those obtained with the nonsupported catalyst (up to 91% yield and 92% ee in the model reaction between cyclopentadiene and cinnamic aldehyde). The catalysts were recovered from the reaction mixture
据报道,利用两个不同的锚定位点和两个不同的接头,在中孔二氧化硅纳米粒子上合成手性咪唑烷酮。催化剂1 - 4制备来自开始升-苯丙氨酸或升-酪氨酸甲基酯和通过接枝协议或叠氮化物-炔烃铜(I) -催化的环加成支撑所述咪唑啉酮在硅胶上。四种催化剂均通过固态NMR N 2进行了充分表征物理吸附,SEM和TGA,以提供结构评估,包括表面积,孔尺寸和催化剂载量的评估。它们用于环戊二烯与不同醛之间的有机催化Diels-Alder环加成反应,其结果可与无载体催化剂获得的结果相媲美(在环戊二烯与肉桂醛之间的模型反应中,收率高达91%,ee为92%)。通过简单的过滤或离心从反应混合物中回收催化剂。活性最高的催化剂循环使用两次,但催化效率有所降低,而ee的侵蚀也很小。
Stereoselective DielsAlder Reactions Promoted under Continuous-Flow Conditions by Silica-Supported Chiral Organocatalysts
with silica bearing chiral organocatalysts to realize chiral “homemade” reactors. The influence of the material properties and immobilization procedures on the chemical and stereochemical activities of the chiral HPLC columns was studied by performing organocatalyzed DielsAlder reactions between cyclopentadiene and α,β‐unsaturated aldehydes undercontinuous‐flowconditions. In some cases, excellent
The invention provides a heterogeneous catalyst comprising a catalytic group coupled to a mesocellular siliceous foam support. The catalytic group is capable of catalysing a reaction selected from the group consisting of a Friedel-Craft reaction and a Diels-Alder reaction.
作者:Julie L. Cavill、Richard L. Elliott、Gareth Evans、Ian L. Jones、James A. Platts、Antonio M. Ruda、Nicholas C.O. Tomkinson
DOI:10.1016/j.tet.2005.08.110
日期:2006.1
The α-effect can be used as an effective means to promote iminiumion catalysed transformations, providing acyclic scaffolds to aid in catalyst design. A thorough investigation of the structure–activity relationship of the catalyst architecture reveals optimal substituents of a disubstituted carbamate and a secondary alkyl group around a hydrazine scaffold. Molecular modelling investigations provide