The synthesis of supported proline-derived ligands and their application in asymmetric diethylzinc addition to aldehydes

Attachment of the proline-derived ligand 5 to two types of polymers, i.e. aminomethylated polystyrene resin and respectively MeO-PEG, was achieved via a succinyl linkage from the 4-hydroxy group. Both of the supported ligands (7 and 8) were proved to be highly active with good enantioselectivity (up to 90% ee) for the catalyzed asymmetric diethylzinc addition to aldehydes. The insoluble polymer-supported catalyst could be easily recovered and was reusable for several consecutive catalytic runs without significant loss in enantioselectivity.

Graphical abstractPolymer (aminomethylated polystyrene resin and MeO-PEG) supported proline-derived ligands have been prepared facilely, and shown to be highly active with good enantioselectivity (up to 90% ee) for the catalyzed asymmetric diethylzinc addition to aldehydes. Particularly, the insoluble polymer-supported catalyst could be reused for several catalytic runs without significant loss of enantioselectivity after readily recoverable procedure. Figure optionsDownload full-size imageDownload as PowerPoint slide