Immobilization of ephedrine-based ligands on magnetic nanoparticles for applications in heterogeneous phase asymmetric catalysis
Heterogeneous phase catalysis has attracted scientific community in the last few decades because, supporting chiral catalysts on solid supports, it is possible to easily recover and reuse them for several catalytic cycles. Especially the use of magnetic nanoparticles is highly advantageous, both for their high dispersibility in organic solvents that the simple and non-expensive recovery by magnetic decantation. Our attention has been focused on the modification of known efficient chiral ligands’ structure, in order to let them be anchorable on Fe3O4@SiO2 nanoparticles. We have chosen ephedrine, that has showed excellent catalytic activity in various asymmetric reactions. Two ephedrine-based ligands have been synthetized, with a different linker between the catalytic site and the anchoring function, that have been tested in the addition of diethylzinc to aldehydes. Having obtained promising results, we started the heterogeneous phase tests.