Chirally Functionalized SBA-15 as Efficient Heterogeneous Catalyst for Asymmetric Ketone Reduction
作者:Umesh Balakrishnan、Sivan Velmathi
DOI:10.1166/jnn.2013.7418
日期:2013.4.1
Chiral amine catalyst was synthesized using (1R, 2S)-(-)-norephedrine and 5-chlorosalicylaldehyde by reductive amination. The structure of the catalyst was confirmed using 1H-NMR and 13C-NMR spectroscopic method. The catalyst was immobilized onto SBA-15 via covalent bonding using 3-chloropropyltrimethoxysilane as a reactive surface modifier under reflux condition using toluene as a solvent. The supported chiral catalyst was characterized using various physico-chemical techniques like XRD, SEM, N2 adsorption isotherm, FTIR and UV-DRS to study the morphology, pore dimension, functional group analysis and catalyst loading in the mesoporous material. The immobilized catalyst was studied for prochiral ketone reduction using 30 mol% of chiral catalyst and boranedimethylsulphide as a stoichiometric reductant in toluene under inert atmosphere for 30 minutes. Secondary alcohols were formed up to 79% enantiomeric excess for selective ketones. Catalyst was recycled from the reaction mixture and used for further reaction without much effect on the catalytic conversion.
手性胺催化剂通过还原胺化反应,使用(1R, 2S)-(-)-去甲麻黄碱和5-氯水杨醛合成。通过1H-NMR和13C-NMR光谱方法确认了催化剂的结构。催化剂通过使用3-氯丙基三甲氧基硅烷作为反应性表面修饰剂,在回流条件下以甲苯为溶剂,通过共价键固定在SBA-15上。通过XRD、SEM、N2吸附等温线、FTIR和UV-DRS等多种物理化学技术对载体的催化剂进行了表征,研究了介孔材料中的形态、孔径尺寸、官能团分析和催化剂负载量。对于非对映酮的还原,使用30 mol%的手性催化剂和二甲基硫化硼烷作为化学计量还原剂,在惰性气氛下在甲苯中反应30分钟,产生了高达79%的对映体过量的高选择性酮次醇。催化剂从反应混合物中回收,并在催化转化率没有大幅影响的情况下用于进一步反应。