Versatile Stereoselective Synthesis of Completely Protected Trifunctional α-Methylated α-Amino Acids Starting from Alanine

✍ Scribed by Eva Altmann; Kurt Nebel; Manfred Mutter

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: German
• Weight: 478 KB
• Volume: 74
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19910740414

✦ Synopsis

Abstract

A new route to completely protected α‐methylated α‐amino acids starting from alanine is described (see Scheme). These derivatives, which are obtained via base‐catalyzed opening of the oxazolidinones (2__S__,4__R__)‐ and (2__R__,4__S__)‐2, can be directly employed in peptide synthesis. The synthesis of both enantiomers of Z‐protected α‐methylaspartic acid β‐(tert‐butyl)ester (O^4^‐(tert‐butyl) hydrogen 2‐methylaspartates (R) or (S)‐4a), α‐methyl‐glutamic acid γ‐(tert‐butyl) ester (O^5^‐(tert‐butyl) hydrogen 2‐methylglutamate (R)‐ or (S)‐4b), and of N^ε^‐bis‐Boc‐protected α‐methyllysine (N^6^,N^6^‐bis[(tert‐butyloxy)carbonyl]‐2‐methyllysine (R)‐ or (S)‐4c) is described in full detail.