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

• Published in: Helvetica chimica acta Vol. 86; no. 6; pp. 1852 - 1861
• Main Authors: Seebach, Dieter, Schaeffer, Laurent, Gessier, François, Bindschädler, Pascal, Jäger, Corinna, Josien, Delphine, Kopp, Sascha, Lelais, Gérald, Mahajan, Yogesh R., Micuch, Peter, Sebesta, Radovan, Schweizer, Bernd W.
• Format: Journal Article
• Language: English
• Published: 01.06.2003
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.200390149

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.