Multipurpose box- and azabox-based immobilized chiral catalysts

Abstract

Azabis(oxazolines) can be used as chiral ligands in the copper-catalyzed enantioselective Mukaiyama aldol reaction. When supported on solids, azabis(oxazoline)-copper complexes are more easily deactivated than their analogous bis(oxazoline)-copper complexes, and are not compatible with the use of coordinating solvents in the method of preparation. The performance of the immobilized catalysts (up to 86 % ee) depends on the support and the reaction solvent, with some positive effect on enantioselectivity due to surface effects. The deactivation is not irreversible and the deactivated catalysts show excellent performance in the cyclopropanation reaction, providing added value to the supported multipurpose catalysts.