VERSATILE STEREOSELECTIVE SYNTHESIS OF COMPLETELY PROTECTED TRIFUNCTIONAL ALPHA-METHYLATED ALPHA-AMINO-ACIDS STARTING FROM ALANINE
A new route to completely protected alpha-methylated alpha-amino acids starting from alanine is described (see Scheme). These derivatives, which are obtained via base-catalyzed opening of the oxazolidinones (2S,4R)- and (2R,4S)-2, can be directly employed in peptide synthesis. The synthesis of both enantiomers of Z-protected alpha-methylaspartic acid beta-(tert-butyl)ester (O4-(tert-butyl) hydrogen 2-methylaspartates (R) or (S)4a, alpha-methylglutamic acid gamma-(tert-butyl) ester (O5-(tert-butyl) hydrogen 2-methylglutamate (R)- or (S)-4b), and of N-epsilon-bis-Boc-protected alpha-methyllysine (N6 ,N6-bis[(tert-butyloxy)carbonyl]-2-methyllysine (R)-or (S)-4c) is described in full detail.
Record created on 2006-02-09, modified on 2016-08-08