Mannosyl

Mannosides are difficult to obtain since here a 2-O-acyl group blocks the -position. 2-O-Benzyl-a-mannosyl bromides give, however, high yields of pure -glycosides with a heterogeneous silver silicate catalyst preventing anomerization and SnI reaction of the bromide H. Paulsen, 1981 B, Q. 

Approximately half of the terminal D-mannosyl residues have pymvate present as 4,6-0-(l-carboxyethyhdene) substituents. The pymvate content has been shown to vary with culture conditions (337,338) and strains of A. campestris (339). The internal D-mannosyl residue is acetylated at the 0-6 position. 

Methyl a-D-mannopyranoside was treated in succession with p-toluene-sulfonyl chloride, carbonyl chloride, and benzoyl chloride, and, without isolating the intermediates, there was obtained in 37% yield methyl 4-0-l enzoyl-2,3-O-carbony 1-6-0-(p-tolylsulfonyl ) -D-mannoside. The tos-yloxyl group of the latter was replaced by iodine, and hydrogenation of the 6-iodo derivative in the presence of a nickel boride catalyst gave methyl 4-0-benzoyl-2,3-0-carbonyl-6-deoxy- -D-mannoside. Treatment of the latter with hydrogen bromide in acetic acid gave crystalline 4-0-benzoyl-2,3-0-carbonyl-6-deoxy-a-D-mannosyl bromide (8) (16). The... 

A distinct feature that may not be readily noticeable is that the chemical shift of the C-l atom of an a-D-mannosyl residue is highly dependent on its residue linkage to another a-D-mannosyl unit. The chemical shift for C-1 of an a-D-mannosyl linked to 0-2 or 0-3 of another a-D-mannosyl residue resonates at 103.5 p.p.m., whereas that of an a-D-mannosyl residue linked to 0-6 of another a-D-mannosyl unit will resonate at — 100.6 p.p.m. Moreover, if 0-2 of an a-D-mannosyl residue is glycosylated, the chemical shift of C-l of that residue will move —1.5 p.p.m. from its expected position. 

Alloprinol riboside Mannosylated poly-L-lysine Mouse [297]... 

In a more recent paper, Roy et al. reported on the synthesis and biological pro -perties of mannosylated Starburst dendrimers [46]. In addition to the presence of good biological properties in ligand- and inhibitor-tests, these dendrimers were shown to constitute novel biochromatography materials of high affinity for the rapid and easy isolation and purification of carbohydratebinding proteins from crude mixtures. 

D. Page, D. Zanini, and R. Roy, Macromolecular recognition Effect of multivalency in the inhibition of binding of yeast mannan to concanavalin A and pea lectins by mannosylated dendrimers, Bioorg. Med. Chem., 4 (1996) 1949-1961. 

Preliminary biological data on this series of mannosylated clusters indicated interesting potency in the inhibition of agglutination of E. coli x7122 by baker s yeast, with approximately a hundred times improved efficiency than those obtained with monomeric D-mannose. 

Fig. 13. Mannosylated prophyrin clusters prepared by Ballut et al. for liposome preparation.

Fig. 15. Various mannosylated glycoclusters built around carbohydrate scaffolds.160-162...

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