Recent advances in the immobilization of chiral catalysts containing bis(oxazolines) and related ligands

Bis(oxazoline) ligands have been used to prepare chiral catalysts for a large variety of enantioselective reactions. This versatility has attracted interest towards its immobilization, to profit from the advantages of using heterogeneous catalysis with respect to catalyst separation, possible recycling or even use as a multipurpose catalyst. In this review recent results dealing with the immobilization of bis(oxazoline) and related ligands are presented, to show the scope and limitations of the different immobilization strategies. As the behavior of grafted catalysts is related to the reaction in which is used, the review is ordered by type of reaction. The influence of the immobilization on the results and the problems related to catalyst recovery and reuse are discussed in each case. Although most of the examples are referred to solid/liquid systems, immobilization is considered from a broader point of view and some liquid/liquid approaches are also presented. (c) 2007 Elsevier B.V. All rights reserved.