631899-14-4Relevant academic research and scientific papers
Enantioselective synthesis of beta-amino acids using hexahydrobenzoxazolidinones as chiral auxiliaries
Reyes-Rangel, Gloria,Jimenez-Gonzalez, Erika,Olivares-Romero, Jose Luis,Juaristi, Eusebio
experimental part, p. 2839 - 2849 (2009/06/18)
A practical synthetic route for the asymmetric synthesis of β2-amino acids is described. In the first step, the procedure involves the N-acylation of readily available, enantiopure hexahydrobenzoxazolidinone (4R,5R)-1 with 3-methylbutanoyl chloride 2, 4-methylpentanoic acid 3, and 3-(1-tert-butoxycarbonyl)-1H-indol-3-yl)propanoic acid 4 to afford derivatives 5a, 5b, and 5c, respectively, which were alkylated with high diastereoselectivity by means of reaction between their sodium enolates and benzyl bromoacetate. Removal of the chiral auxiliary from the alkylated products followed by hydrogenation and hydrolysis gave β2-amino acids (S)-10a, (S)-10b, and (S)-10c, which were N-protected with Fmoc. Enantiomeric (R)-10a-c were similarly prepared from the isomeric hexahydrobenzoxazolidinone (4S,5S)-1; thus, the route presented here provides access to both enantiomers of valuable highly enantioenriched β2-amino acids.
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)
Seebach, Dieter,Schaeffer, Laurent,Gessier, Francois,Bindschaedler, Pascal,Jaeger, Corinna,Josien, Delphine,Kopp, Sascha,Lelais, Gerald,Mahajan, Yogesh R.,Micuch, Peter,Sebesta, Radovan,Schweizer, Bernd W.
, p. 1852 - 1861 (2007/10/03)
Multigram amounts of suitably protected β2-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 β2-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.
