Beyond reuse in chiral immobilized catalysis: The bis(oxazoline) case

Development of efficient immobilized chiral catalysts has been an area of increasing interest during the last decades, in spite of the excellent results obtained in some cases and the inherent advantages of heterogeneous systems, the application of these catalysts is quite limited. This is due, in part, to the fact that synthetic effort necessary to prepare them is not justified by only some reuses, furthermore some “dogmas” about these catalysts should be removed for a faster improvement in this area. In this revision we do a critical and historical analysis of this field, taking bis(oxazoline) based catalyst as an example. We show that a deeper knowledge of the catalytic system allows improving the catalyst, so easily prepared immobilized catalysts, lead to results comparables or even better than those obtained in solution, by simply using a ligand better adapted to immobilization. Furthermore the use of the support as a “friend” cooperating in the stereodiscrimination, allows obtaining stereochemical results different from those obtained in solution, which increases the interest of these catalysts. To sum up, the consideration of the immobilized catalyst as a joint, including the support and the comprehension of the catalytic mechanism allows the design of more efficient chiral heterogeneous systems.