OPTICAL RESOLUTION AND ASYMMETRIC TRANSFORMATION OF (RS)-N-ALKYL-2-PHENYLGLYCINE AND (RS)-N,N-DIALKYL-2-PHENYLGLYCINE

Optical resolution of (RS)-N-methyl-2-phenylglycine [(RS)-Mpg] and (RS)-N-ethyl-2-phenylglycine [(RS)-Epg] was carried out by using (1S)-10-camphorsulfonic acid [(S)-CS] as resolving agents, and that of (RS)-N-ethyl-N-methyl-2-phenylglycine [(RS)-Emp] by (R)- and (S)-l-phenylethylamine. Racemization rates of optically active Mpg, Epg, Emp, N,N-dimethyl-2-phenylglycine [Dmp], and six a-amino acids were measured by heating in carboxylic acids. The electron-donating amino acid side chain and N-substituted alkyl group decreased the rate to inhibit the formation of intermediary carbanions, whereas the electron-withdrawing side chain increased it. Asymmetric transformation of (RS)-Mpg, (RS)-Epg, and (RS)-Dmp was carried out on the basis of the results of optical resolution and racemization to give the corresponding enantiomers of approximately 100% optical purities in over 70% yield based on the starting racemates.