Polymer-bound pyridine-bis(oxazoline). Preparation through click chemistry and evaluation in asymmetric catalysis

A pyridine-bis(oxazoline) ligand was efficiently immobilized by copper(I)-catalyzed azidealkyne cycloaddition onto a polystyrene resin. The so obtained click-pybox resin 1a was associated with various metal salts (YbCl3, LuCl3, CuOTf) and the resulting resin-bound catalysts were explored in ring-opening of cyclohexene oxide, silylcyanation of benzaldehyde and alkynylation of imines. These new polymer-supported catalysts exhibit good to excellent performances in terms of catalytic activity, enantioselectivity and recyclability.