Highly efficient polymer supported phase-transfer catalysts containing hydrogen bond inducing functional groups

Merrifield resin supported cinchona ammonium salts bearing 2′-fluorobenzene, 2′-cyanobenzene and 2′-N-oxypyridine groups were prepared and applied to the phase-transfer catalytic alkylation of N-(diphenylmethylene)glycine tert-butyl ester for the enantioselective synthesis of α-amino acids (76-96% ee).