Synthesis and NMR spectroscopy of nine stereoisomeric 5,7-diacetamido-3,5,7,9-tetradeoxynon-2-ulosonic acids

Citation
Ye. Tsvetkov et al., Synthesis and NMR spectroscopy of nine stereoisomeric 5,7-diacetamido-3,5,7,9-tetradeoxynon-2-ulosonic acids, CARBOHY RES, 335(4), 2001, pp. 221-243
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Agricultural Chemistry","Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
CARBOHYDRATE RESEARCH
ISSN journal
0008-6215 → ACNP
Volume
335
Issue
4
Year of publication
2001
Pages
221 - 243
Database
ISI
SICI code
0008-6215(20011015)335:4<221:SANSON>2.0.ZU;2-L
Abstract
Derivatives of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids are essen tial constituents of some bacterial polysaccharides and glycoproteins. In o rder to establish reliably the configuration of the natural sugars, nine st ereoisomeric 5,7-diacetamido-3,5,7.9-tetradeoxynon-2-ulosonic acids were sy nthesized, including di-N-acetyl-legion-aminic and -pseudaminic acids (the D-glycero-D-galacto and L-glycero-L-manno isomers, respectively) and their isomers at C-4, C-5, C-7, and C-8 having the L-glycero-D-galacto, D-glycero -D-talo, L-glycero-D-talo, D-glycero-L-altro, L-glycero-L-altro, D-glycero- L-manno, and L-glycero-L-gluco configurations. Synthesis was performed by c ondensation of 2,4-diacetamido-2,4,6-trideoxy-L-gulose, -D-mannose, -D-talo se, and -L-allose with oxalacetic acid under basic conditions, the reaction of the last two precursors being accompanied by epimerisation at C-2. The H-1 and C-13 NMR data of the synthetic compounds are discussed. Acetylated methyl esters of the C-7 and C-8 isomeric nonulosonic acids were prepared a nd used for analysis of the side-chain conformation by NMR spectroscopy. (C ) 2001 Published by Elsevier Science Ltd.