Total, deoxy sugars

Residues of non-N-substituted 2-amino-2-deoxy-D-glucose constitute only a tiny fraction (if any) of the total amino sugar of heparin and heparan sulfate. Although free amino groups are produced in the biosynthesis20,23 of heparin (between stages 1 and 2, see Scheme 1), the small proportions occasionally found in heparin and heparan sulfate preparations are most probably the result of some N-desulfation during extraction, or purification, or both. 

Fraction Mol. wt. D-Mannose D-Galactose L-Fucose D-Glucose Total neutral sugar 2-Ami no-2-deoxy-D-glucose 2-Amino-2- deoxy-D- galactose Total hexo- samine Sialic acid Total sugar Refer- ences... 

A. Kirschning, M. Jesberger, and K. U. Schoning, Concepts for the total synthesis of deoxy sugars, Synthesis (2001) 507-540. 

Figure 9.27 Relative abundance (%) of deoxy sugars as a function of total neutral sugar yields in decomposing mangrove leaves, smooth cordgrass, and cypress needles during a 4-year laboratory incubation study. (Modified from Opsahl and Benner, 1999.)...

An investigation by paper chromatograi y of the products of hydrolysis of a mixed polysaccharide 28) indicated that the mixed poly-s charide contained, in addition to ucose units, repeating units of four amino sugars, two of which were identified as 3-deoxy-3-amino-altrose and 2-deoxy-2-aminoglucose. The 3-aminoaltrose formed was found to be 80% of the total amino sugar content of the hydrolysate. 

Danishefsky diene, 619 L-Daunosamine, 597 total synthesis, 601 Deoxy sugars, 151 Deoxygenation, 151... 

Concepts for the total synthesis of deoxy sugars 01S507. 

Fig. 11 Hyperconjugative stabilization of the oxocarbenium ion of 2-deoxy sugars. Using the empirically derived angular dependence of hyperconjugation, where hypercomugation oc exp(cos 0), and 6 is the dihedral angle defined by p-orbital-Cl -C2 -H2 S, the total amount of hyperconjugative stabilization is plotted as a function of the angle 6.

The amino sugar counterparts of D-glucuronic acid and nonsulfated L-iduronic acid in heparin are either N-acetylated, or nonsulfated at C-6, or both. 2-Acetamido-2-deoxy-D-glucosyl residues account for only a minor proportion of the total hexosamine in heparin, and are especially low in beef-lung preparations (see Table II).8,138,147 -149 In contrast, they... 

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,... 

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