D-fucose

Scheme 10 details the synthesis of A-ring glycosyl acceptor 19. The stereochemical relationship of 19 to D-fucose (21) is obvious. Peracetylation of D-fucose provides tetraacetate 58 in nearly quanti-... 

Deoxy-L-galactose (L-fucose) is common, and has only been found as the a- or )3-pyranoside. The rare D-fucose has, however, been found both as a-pyranoside, in the LPS frorn Pseudomonas cepacia serotypes B and E, and as a-furanoside, in the cell-wall antigen from Eubacterium saburreum L 452 and the O-antigens from different strains of Psuedomonas syrin-gae The a-furanoside, as in 3, has a cis relationship between the aglycon and OH-2. The corresponding P form has not yet been found. 6-Deoxy-o-and -L-talose are components of the extracellular polysaccharides from some strains of Butyrivibrio fibrisolvens and of the LPS from some strains of E. coli respectively. 

D-galactose to D-galactonolactone in the presence of the coenzyme NAD+, is more specific and enzyme preparations are available for which the only other substrates are a-L-arabinose and /3-D-fucose. The generation of NADH is conveniently monitored at 340 nm and permits quantitation of the galactose ... 

From his time at the Squibb research laboratories, he was interested in the chemistry of antibiotics, and in this area, he elucidated the partial structure of curamycin, an antibiotic produced by Streptomyces curacoi. From curamycin, he isolated and characterized the new natural sugar derivatives D-curacose (4-O-methyl-D-fucose), curacin [4-0-(dichlo-roisoeveminyl)-2,6-dideoxy-D-araW/io-hexose], and curamycose (2,6-di-O-methyl-D-mannose). 

For a-D-Fuc and o-D-Xyl the higher conformational energy of the complexes suggest that a-D-Fuc and a-D-Xyl will be weaker inhibitors than a-D-Gal. a-D-Fuc will, however, be better than a-D-Xyl. In the case of the ABP-a-D-fucose complex (Figure 6), 0H(1) forms a hydrogen bond with Asp 89, 0H(2) with Lys 10 and 0H(3) with Asn 205. 0H(4) can form two hydrogen bonds with Arg... 

GP Glycoprotein with oligosaccharide /V-acetyl-D-glucosamine O D-Galactose O D-Fucose... 

Synthesis of a Functionalized D-Fucose Derivative of a Program in Aliyiboronate Chemistry... 

A cyclic hexaacetyl oxime (XII) was also isolated by mild acetylation of D-galactose oxime and by treatment with sodium acetate and acetic anhydride. A cyclic aldoxime acetate (XIII) was also obtained by Voto6ek from D-fucose oxime, and by Restelli de Labriola and Deulofeu ... 

D-Fucose (Rhodeose). Voto6ek obtained tetraacetyl-D-fucononitrile in 25% yield by treating D-fucose oxime with sodium acetate-acetic anhydride. The nitrile, degraded with ammonia and silver oxide, yielded 5-desoxy-D-lyxose diacetamide in 40% yield. The diacetamide compound was hydrolyzed with 5% hydrochloric acid and the 5-desoxy-D-lyxose was obtained in solution and characterized as the p-bromo-phenylosazone. Hydrolysis of the diacetamide compound with 6 N sulfuric acid was realized by Voto6ek and Valentin and the 5-desoxy-D-lyxose was isolated as a sirup. 

Fig. 9 Compounds obtained from D-xylose (7), D-lactose (51), D-fucose (52), D-arabinose (8), and 3-deoxy-D-arabinose (53)...

A mutant strain of Escherichia coli Y-10, defective in L-rhamnose synthesis, accumulates109 a considerable amount of thymidine diphosphate sugars. Three of them were identified110 as the esters of thymidine 5 -pyrophosphate with 6-deoxy-a-D-xyZo-hexopyranos-4-ulose (28), 6-deoxy-D-glucose, and D-fucose. The fourth component was found to be a 4-acetamido-4,6-dideoxy-D-galactose derivative111,112 (29) it occurs also in Pasteurella pseudotuberculosis102 and its... 

Treatment of the reaction mixture with sodium borohydride-f followed by acidic hydrolysis led to major fractions of 6-deoxy-D-glucose-f and D-fucose-t, together with a minor fraction of D-galac-tose-4-f.422 This fact indicates that 109 is formed as an enzyme-bound intermediate, and allows the exclusion of a possible, alternative mechanism, shown in Fig. 3 as B, for the conversion of 107a into 108a through an intermediate glycos-5-ene derivative 111. 

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