Polymer-Supported Chiral Quaternary Ammonium Salts

Significance

The preparation of polymer-supported chiral quaternary ammonium salts 8-12 and their catalytic application in the asymmetric benzylation of glycine derivative 13 were reported. Thus, polymerization of N-substituted cinchonidinium p-styrenesulfonates and p-vinylbenzoate (2, 4 and 5) with styrene and divinylbenzene afforded the corresponding polymeric chiral PTC 8, 9 and 11. Catalyst 10 was prepared from N-9-benzylcinchonidinium chloride 7 and resin 6. The asymmetric benzylation of 13 was carried out with catalysts 8-10 to give 14 in 66-84% yield with 78-95% ee. The sulfonate polymer catalyst 10 was reused twice (1^st use: 73% yield, 95% ee, 2^nd use: 70% yield, 96% ee, 3^rd use: 61% yield, 96% ee).