Cinchona alkaloid-based polymer-bound phase-transfer catalysts: efficient enantioselective alkylation of benzophenone imine of glycine esters.

Cross-linked polystyrene-bound and poly(ethylene glycol)-bound phase-transfer catalysts as well as homopolymers of cinchona alkaloid derivatives have been synthesised. Both soluble and insoluble polymers have been investigated. The enantioselective alkylation of N-diphenyl methylene glycine t-butyl ester has been successfully carried out in heterogeneous and homogeneous systems. High enantioselectivities (up to 96%) have been obtained. The polymer-bound catalysts have been easily recovered and conditions for efficient recycling have been studied.