D-Mannoside

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... 

Structure and Reactivity of Anhydro-sugars. Part I. Branched-chain Sugars. Part I. Action of Di-ethylmagnesium on Methyl 2 3-Anhydro-4 6-0-benzylidene-a-D-mannoside, A. B. Foster, W. G. Overend, M. Stacey, and G. Vaughan,/. Chem. Soc., (1953) 3308-3313. 

J. J. Grimaldi, B. D. Sykes 1975, (Con-canavalin A a stopped flow nuclear magnetic resonance study of conformational changes induced by Mn++, Ca++, and alpha-methyl-D-mannoside),/. Biol. Chem. 250, 1618. 

Carbon atom D-Gulose Me a-D-guIoside D-Mannose Me a-D-mannoside... 

The methyl 2,3,4-trimethyl-a-D-mannuronoside (XLI) was synthesized from methyl 2,3,4-trimethyl-a-D-mannoside by the method pre-... 

Three routes to the synthesis of D-mannuronic acid (XLIII) are now known. The first42 was based on the original method of Fischer and Piloty48 and involved the reduction of D-mannosaccharodilactone (XLII) with sodium amalgam. The second44 utilized methyl 2,3-isopropyli-dene-a-D-mannoside (XLIV) which was oxidized at C6 with alkaline potassium permanganate to methyl isopropylidene-a-D-mannuronoside ... 

Recently, Gouin et al. have designed a tetravalent cluster (60)84 based on a potent E. coli FimH ligand heptyl x-D-mannoside (59)85 that has been preliminarily recognized as a strong binder to FimH, with a KD of 5 nM, as determined by SPR measurements (Fig. 5). Furthermore, this derivative inhibited both adhesion of... 

T. K. Lindhorst, S. Kotter, U. Krallmann-Wenzel, and S. Ehlers, Trivalent a-D-mannoside clusters as inhibitors of type-1 fimbriae-mediated adhesion of Escherichia coli Structural variation and biotinylation, J. Chem. Soc. Perkin Trans., 1 (2001) 823-831. 

In summary, for O-glycosides, a-anomers (a-D and oc-l) are thermodynamically more stable than the p-anomers (p-D and p-L) due to the anomeric effect. Therefore l,2-c -a-D- or a-L-glycosides are preferentially obtained, in general. On the other hand, the lower stability of glycosides such as p-D-arabinosides and p-D-mannosides requires special methods for their preparation, thus promoting the development of new synthetic methodologies. 

Scheme 3 Synthesis of P-D-mannosides and P-L-rhammnosides by glycosylation via locked anomeric configuration.

Shortly after the above work appeared, Bolliger and Prins90 reported a similar synthesis leading to a 3- rather than a 2-desoxy derivative. Methyl 2,3-anhydro-4,6-benzylidene-a-D-mannoside (LXIV), upon treatment with sodium thiomethoxide, was converted into methyl 3-methyl-thio-4,6-benzylidene-a-D-altroside (LXV) which, after desulfurization and rebenzylidenation, gave methyl 3-desoxy-4,6-benzylidene-a-D-man-noside (LXVI). Methylation of LXV with methyl iodide and silver oxide followed by desulfurization gave methyl 2-methyl-3-desoxy-4,6-benzylidene-a-D-mannoside in poor yield. 

C3 and C4 of the glucon is an absolute one. Phenyl a-D-glucoside, phenyl /J-D-mannoside (II), methyl /S-D-guloside (III), involving reversal of the addenda at Cl, at C2, at C3 and C4, respectively, are not appreciably hydrolyzed by almond emulsin.29 Phenyl /3-D-glucoside (I) and phenyl... 

Figure 13.IS. Glucose displacement assay using an insoluble polymeric acceptor AMCA-Con A J.exc = 356 nm / = 224 mHz, Inset a-melbyl-D-mannoside.

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