A comparative analysis of mono- and disaccharide benzyl fucopyranosides
摘要:
The syntheses and X-ray analyses of two fucopyranosides, the monosaccharide benzyl 3,4-di-O-acetyl-2-hydroxy-beta-D-fucopyranoside, C17H22O7, and the disaccharide 1-benzyl O-(2,3-di-O-acetyl-4,6-O-benzylidene-beta-D-glucopyranosyl)-(1 --> 2)3,4-O-isopropylidene-beta-D-fucopyranoside, C33H40O12, are described. The different substituents induce small conformational changes on the fucopyranoside ring. However, the conformation of the benzyl group varies from (+)gauche for the monosaccharide to synperiplanar for the disaccharide.
Synthetic Study toward Saccharomicin Based upon Asymmetric Metal Catalysis
作者:Bhawna Barpuzary、Mijin Kim、Young Ho Rhee
DOI:10.1021/acs.orglett.1c02060
日期:2021.8.6
metal-catalyzed approach toward the stereoselective glycosidic bond formation in saccharomicin. The signature step is highlighted by the Pd-catalyzed asymmetric coupling of ene-alkoxyallenes and highly functionalized alcohol substrates. The reaction showed high chemo-, regio-, and ligand-driven diastereoselectivity. In combination with the ring-closing metathesis and late-stage functionalization, this method
Preparation of carbohydrate isopropylidene derivatives with 2,2-dimethoxypropane in the presence of toluene-p-sulphonic acid
作者:András Lipták、János Imre、Pál Nánási
DOI:10.1016/s0008-6215(00)85991-1
日期:——
Synthesis and identification in bacterial lipopolysaccharides of 5,7-diacetamido-3,5,7,9-tetradeoxy-d-glycero-d-galacto- and -d-glycero-d-talo-non-2-ulosonic acids
作者:Yury E. Tsvetkov、Alexander S. Shashkov、Yuriy A. Knirel、Ulrich Zähringer
DOI:10.1016/s0008-6215(01)00041-6
日期:2001.4
5,7-Diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto- and -D-glycero-D-talo-non-2-ulosonic acids were synthesized by condensation of 2,4-diacetamido-2,4,6-trideoxy-D-mannose with oxalacetic acid. Comparison of the H-1 and C-13 NMR data and the specific optical rotation values of these monosaccharides and the corresponding L-glycero-D-galacto and L-glycero-D-talo isomers synthesized earlier [Tsvetkov, Y. E.; Shashkov, A. S.; Knirel, Y. A.; Backinowsky, L. V.; Zahringer, U. Mendelera Commun. 2000, 90-92] with data of the natural compounds enabled the identification in bacterial lipopolysaccharides of derivatives of 5,7-diamino-3,5,7,9-tetradeoxy-D-glycerogalacto-non-2-ulosonic (legionaminic) acid and epimers of legionaminic acid at C-4 and C-8. (C) 2001 Elsevier Science Ltd. All rights reserved.