Stereoselective alkylation of C-2-symmetric chiral N-phthaloylglycinamidesin the preparation of enantiopure alpha-amino acids

The novel, chiral glycinamides (S,S)-3 and (S,S)-4 were prepared in good yi elds from C-2-symmetric chiral amines (S,S)-1 and (S,S)-2, respectively. En olate formation and addition to methyl iodide and benzyl bromide proceeded in good yield and high diastereoselectivity, especially in the presence of LiCl or DMPU. Removal of the phthaloyl protecting group with hydrazine, fol lowed by hydrolysis with 6N HCl, converted the benzylated product (S,S,S)-7 to enantiopure (S)-phenylalanine. (C) 2000 Elsevier Science Ltd. All right s reserved.