Synthesis and application of phosphorus dendrimer immobilized azabis(oxazolines)

Phosphorus dendrimer immobilized azabis(oxazoline) ligands can be efficiently synthesized up to the third generation with 48 ligand molecules being attached to the periphery using click chemistry. The so-assembled macromolecules were evaluated in copper(II)-catalyzed asymmetric benzoylations, showing good yields and enantioselectivities. Moreover, the copper(II)-catalysts could be readily recovered and reused in several cycles. The globular structure of the dendritic ligands seems to prevent interference of the triazole moieties in the catalysis, contrasting MeOPEG or polystyrene bound ligands of the same type.