Immobilization via a Covalent Link

2 Heterogeneous Enantioselective Catalysis Using Inorganic Supports 

The most striking examples for the positive confinement effect of supports on enantioselectivity have been provided by Thomas and Johnson s research group [13, 14, 16], who demonstrated that even nonenantioselective catalysts can show significant asymmetric induction when anchored onto a suitable support. The Pd catalyst 14 covalently supported within the pores of MCM-41 affected the hydrogenation of ethyl 1,4,5,6-tetrahydronicotinate (16) to afford nipecotic acid ethyl ester (17) at 17% ee (turnover number (TON) = 291), whereas the use of 15, the 

Using 8-Ru (homo) 80% ee, 98% yield Using 9-Ru (hetero) 97%ee, 100% yield 

Immobilization via Hydrogen Bonding, Ionic and Other Interactions 

Bianchini et al. [25] disclosed a highly interesting immobihzahon approach which involves a hydrogen-bonding interaction between the silanol groups of silica and 

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