Enantioselective Preparation of 2-Aminomethyl Carboxylic Acid Derivatives: Solving the β2-Amino Acid Problem with the Chiral Auxiliary 4-Isopropyl-5,5-diphenyloxazolidin-2-one (DIOZ). Preliminary Communication

✍ Scribed by Dieter Seebach; Laurent Schaeffer; François Gessier; Pascal Bindschädler; Corinna Jäger; Delphine Josien; Sascha Kopp; Gérald Lelais; Yogesh R. Mahajan; Peter Micuch; Radovan Sebesta; Bernd W. Schweizer

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: German
• Weight: 296 KB
• Volume: 86
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200390149

✦ Synopsis

Abstract

Multigram amounts of suitably protected β^2^‐amino acids with 17 of the 20 proteinogenic side chains are prepared by diastereoselective reactions of Li, B, or Ti enolates of the corresponding 3‐acyl‐4‐isopropyl‐5,5‐diphenyloxazolidin‐2‐ones (acyl‐DIOZ; 1) with appropriate electrophiles (amidomethylation, hydroxyalkylation, (benzyloxycarbonyl)methylation) in yields of 55–90% and with diastereoselectivities of 80 to >97% (Scheme). The primary products 2–8 thus obtained are converted to protected β^2^‐amino acids by standard procedures (Table 1). Many of the DIOZ derivatives are highly crystalline compounds (31 X‐ray crystal structures in Table 2). The chiral auxiliary DIOZ, readily prepared in either enantiomeric form, is recovered with high yield.