Magnetic nanoparticle supported amine: An efficient and environmental benign catalyst for versatile Knoevenagel condensation under ultrasound irradiation
The condensation of phenylacetonitrile with 4-methoxybenzaldehyde can be carried out by two solvent-free methods: i) using neat powdered KOH at room temperature with equivalent amounts of aldehyde, nitrile and base for 3 min, and ii) using K2CO3 in the presence of a phase transfer agent for 3 min under microwave activation or conventional heating. By extending the reaction time up to 10 min, four different
Magnetic nanoparticle supported amine: An efficient and environmental benign catalyst for versatile Knoevenagel condensation under ultrasound irradiation
作者:Anguo Ying、Limin Wang、Fangli Qiu、Huanan Hu、Jianguo Yang
DOI:10.1016/j.crci.2014.05.012
日期:2015.2
Résumé Amine functionalized silica coated Fe3O4 nanoparticles (SiO2@MNP-A) were successfully prepared as a novel heterogeneous amine. The catalyst was characterized by XRD, FT-IR, TEM, magnetic measurement, elemental analysis and was found to be a magnetically separable and highly active catalyst for ambient Knoevenagel condensation of aromatic aldehydes and α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water under ultrasonic irradiation to afford the corresponding products in good to excellent yields. Very interestingly, SiO2@MNP-A successfully catalyze the reaction of the non-cyano substituted compound with benzaldehyde to achieve a key intermediate for the preparation of Atorvastatin calcium in green and atom-economic manner. In addition, the catalyst SiO2@MNP-A can be reused for 8 times without any obvious loss of its activity. The role of ultrasonication in the Knoevenagel condensation was also discussed with the assistance of UV–vis spectrometry.