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Deoxy talose

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. [Pg.283]

The legioselectivity of electrophilic additions of the C=C double bond in 7-oxabicyclo[2.2.1]hept-5-en-2-yl (7-oxanorbom-5-en-2-yl) derivatives depends on the nature of the substituents at C(2). The adducts so-obtained can be transformed into the corresponding 5,6-disubstituted 7-oxanorboman-2-ones, which can be mono-substituted at C(3) stereoselectively, giving products with the same stereochemical information as hexoses. Thus, optically pure 7-oxanorbom-5-en-2-yl derivatives can be viewed as "naked sugars" Applications to the total, asymmetric syntheses of L-daunosamine, 2-deoxy-L-fucose, D- and L-aUose, D- and L-talose, D- and L-ribose,... [Pg.197]

The (—)-anisomycin work is presented in Scheme 35. Its key step centered around the formation of a pyrrolidine ring that possessed all three of the asymmetric centers present in the target this was done by nucleophilic displacement of a 3-tosyloxy function in an appropriately functionalized 6-amino-6-deoxy-p-i.-talose derivative, whose 1,2-diol was later released and oxidatively cleaved with sodium periodate. Grignard coupling, O-acetylation, and catalytic hydrogenation then furnished the desired natural-product target. [Pg.48]

A. C. Richardson and K. A. McLauchlan, 3-Amino-3-deoxy-derivatives of L-glucose, L-galactose and L-talose,/. Chem. Soc. (1962) 2499-2506. [Pg.61]

Quite analogous ring-closures occur when the 1-O-acetyl derivatives of the rhamnopyranose and talopyranose derivatives are treated with sodium azide in N,N-dimethylformamide. l-O-Acetyl-6-deoxy-2,3-0-isopropylidene-4-0-mesyl-a-L-mannopyranose is converted exclusively into l,4-anhydro-6-deoxy-2,3-0-isopropylidene-/3-L-talo-pyranose. In this instance, the azide nucleophile attacks the l-O-ace-tyl group, liberating an 0-1 oxide ion which reacts with inversion of C-4. The 4-epimeric, l-O-acetyl-6-deoxy-talose derivative gives 60% of the direct inversion product l,4-anhydro-6-deoxy-2,3-0-isopropyli-dene-a-L-mannopyranose, together with other products.50... [Pg.166]

The deamination of 2-amino-2,6-dideoxy-L-talose resembles that of 2-amino-2-deoxy-D-mannose, in that substitution with inversion of configuration is the major reaction, the product being tentatively... [Pg.40]

Deoxy-3-C-methyl-D-mannose (15) 6-Deoxy-3-C-methyl-2-0-methyl-L-talose (16)... [Pg.72]

Conversion of L-fucosyl- and 3 -0-methyl-D-glycosyl-purines into nucleosides of two naturally occurring, rare sugars, 6-deoxy-L-talose and 3-O-methyl-D-mannose, could be achieved57 by stereospecific reduction at C-2 of 7-(6-deoxy-3,4-0-isopropylidene-/ -L-h/xo-hexopyranosyl-2-ulose)theophylline (35a) and 7-(4,6-0-benzylidene-3-0-methyl-/ -D-orobtno-hexopyranosyI-2-ulose)theophylline (8). Treatment of 35a and 8 with sodium borohydride in ethanol afforded the expected 7-(6-deoxy-3,4-0-isopropylidene-/ -L-talopyranosyI)theophylline (84) and 7-(4,6-... [Pg.254]

Jones and Nicholson234 have observed that treatment of 2-O-sulfonyl sugars with base leads to epimerization at C-2. In this way, 2-O-p-tolyl-sulfonyl-L-fucose (42) was converted into 6-deoxy-L-talose (44) in high yield. A possible intermediate might be the 1,2-anhydro sugar (43). [Pg.179]

The 2-0-(2-amino-2-deoxy-D-galactosyl)glycerol (34, R = H) was smoothly degraded by nitrous aoid to glycerol and 2,5-anhydro-D-talose (3S), and the W-acetyl derivative (35, R = Ac) reduced 1 molar proportion of periodate, giving neither formaldehyde nor formic acid during (84) P. J. Stoffyn and R. W. Jeanlos, Arch. Biochem. Biophyi., 52, 373 (1054). [Pg.348]

Non-stereospecific reduction of GDP-6-deoxy-D-/yxo-hexos-4-ulose (7c) to derivatives of 6-deoxy-D-mannose (D-rhamnose) and 6-deoxy-D-talose (see Section III,l,c) was found to occur with an enzyme from an unidentified,... [Pg.291]

The instability of TDP-6-deoxy-L-talose should be mentioned. When using the routine procedure for the isolation of TDP-rhamnose, a consistent loss of the 6-deoxy-L-talose nucleotide was observed. A systematic study revealed that in contrast to the rhamnose derivative, the 6-deoxy-L-talose nucleotide was extremely labile to alkali. Prolonged exposure to pH 8.0 at 37 °C resulted in significant degradation. The degradation products are TMP and 6-deoxy-L-talose monophosphate. Careful degradation studies provided experimental evidence for its identification as cyclic-l,2-monophospho-6-deoxy-L-talose. The extreme alkali lability... [Pg.404]


See other pages where Deoxy talose is mentioned: [Pg.33]    [Pg.460]    [Pg.460]    [Pg.460]    [Pg.460]    [Pg.460]    [Pg.20]    [Pg.20]    [Pg.75]    [Pg.153]    [Pg.154]    [Pg.264]    [Pg.15]    [Pg.291]    [Pg.302]    [Pg.150]    [Pg.257]    [Pg.302]    [Pg.315]    [Pg.70]    [Pg.71]    [Pg.63]    [Pg.85]    [Pg.247]    [Pg.25]    [Pg.44]    [Pg.233]    [Pg.179]    [Pg.181]    [Pg.348]    [Pg.296]    [Pg.296]    [Pg.296]    [Pg.338]    [Pg.399]    [Pg.399]    [Pg.403]    [Pg.404]    [Pg.405]    [Pg.406]   
See also in sourсe #XX -- [ Pg.257 ]

See also in sourсe #XX -- [ Pg.173 ]

See also in sourсe #XX -- [ Pg.224 ]




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