The asymmetric methylation of the N-benzylidene-DL-phenylalanine methyl ester was carried out in the presence of lithium salts of secondary amines derived from (S)-proline. The lithium amides of poly(imino-1-isobutylethylene) and its corresponding low-molecular-weight model compound, derived from (S)-leucine, were similarly used in order to examine the polymer effects with regard to the stereoselectivity