(S)-α,α-Diphenylprolinol trimethylsilyl ether supported onto well-defined (5.7 ± 1.1 nm) superparamagnetic Fe3O4 nanoparticles was used as a highly active, magnetically recoverable and reusable catalyst for the asymmetric, organocatalytic Michael addition of propanal to nitroolefins leading to high enantioselectivities. The assembly of the catalytic functional nanoparticles involves two successive steps: (i) introduction of a 3-azidopropyl unit through the formation of Si–O bonds, and (ii) integration of the organocatalytic unit by means of a copper-catalysed alkyne–azide cycloaddition reaction leading to a 1,2,3-triazole linker. Neither the process of nanoparticle assembly nor its catalytic use in dichloromethane solution provokes particle growth or agglomeration, this behaviour being key for the observation of high catalytic activity and for recyclability.
(S)-α,α-二苯基
丙醇内酰胺三甲基
硅醚负载于定义良好的(5.7 ± 1.1 纳米)超顺磁性
Fe3O4纳米粒子上,被用作一种高活性、磁性可回收和可重复使用的催化剂,用于不对称有机催化米克尔加成反应,其中
丙醛与硝基烯烃加成,得到高对映选择性产物。催化功能纳米粒子的组装涉及两个连续步骤:(i)通过形成Si–O键引入3-
叠氮丙基单元,以及(ii)通过
铜催化的
炔烃-
叠氮环加成反应将有机催化单元整合到
1,2,3-三唑连接子上。无论是在纳米粒子组装过程中还是在
二氯甲烷溶液中的催化使用过程中,都不会引发粒子生长或聚集,这种行为对于观察到高催化活性和可回收性至关重要。