Thiazolidine-4(R)-carboxylic acids derived from sugars: Part I, C-2-epimerisation in aqueous solutions

✍ Scribed by Jan Radomski; Andrzej Temeriusz

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 861 KB
• Volume: 187
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(89)80005-9

✦ Synopsis

Reactions of L-cysteine (1) with L-xylose, D-ribose, D-lyxose, D-arabinose, D-glucose, L-rhamnose, and L-fucose in aqueous ethanol yielded crystalline 2(S)-(polyhydroxyalkyl)thiazolidine-4(R)-carboxylic acids. Likewise, glycolaldehyde and L-glyceraldehyde, n-xylose, L-arabinose, D-mannose, n-galactose, and D-fucose gave crystalline 2(R),4(R) p e imers. The reaction of 1 and D-glyceraldehyde gave a syrupy mixture of 2(S),4(R) and 2(R),4(R) compounds. The same substrates, but with no ethanol present, gave the 2(S),4(R) epimers for glycolaldehyde, L-xylose, L-fucose, and L-arabinose, and the 2(R),4(R) p e imers for D-lyxose, L-rhamnose, D-mannose, D-galactose, and D-fucose. The reactions of D-ribose, D-arabinose, Dxylose, and D-glucose gave syrupy mixtures of epimers. The crystalline reaction products, when dissolved in water, undergo rapid epimerisation as reflected by mutarotation and changes in the tH-and 13C-n.m.r. spectra.