Development of efficient methods for the immobilisation of multicomponent asymmetric catalysts

Immobilisation of multicomponent asymmetric catalysts has been achieved utilizing soluble polymers and dendrimers containing BINOL ligands. A novel approach based on the use of "catalyst analogue" helps to position the ligands suitably on the polymer backbone. Utilizing metal-bridged polymers, a simple and efficient method for immobilisation without the need for a polymer support has also been realized. Heterogeneous Al-Li-bis(binaphthoxide) and μ-oxodititanium complexes thus obtained have been used as catalysts for the asymmetric Michael addition and the asymmetric carbonyl-ene reactions respectively. The catalysts displayed high activity affording the corresponding products with high enantiomeric excesses. In many cases, the catalysts could be recovered and reused.