Synthesis of C-Oligosaccharides

Troels Skrydstrup, Boris Vauzeilles, and Jean-Marie Beau 

1) by direct coupling of intact carbohydrate units via (i) anionic or (ii) radical pathways  

2) by the de novo synthesis of one or all of the sugar units in the C-disaccharide or C-oligomer or 

3) by applying a cycloaddition reaction to connect the two sugar units. 

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In an approach towards the synthesis of C-oligosaccharide containing a-D-Man-(l )-D-Man repeating units, C-4 allylated building block 183 was designed [69]. However, the allyla-tion of iodide 181 at C-4 with allyltributyltin and AIBN or dilauoryl peroxide (DLP) slow-... 

In general, the de novo approach applied by the Kishi group for the synthesis of C-oligosaccharides relies on acyclic stereocontrol for the construction of the contiguous chiral centers of at least one of the carbohydrate moieties. The first examples of this approach were reported by this group in 1987 and involved the synthesis of four C-disaccharides, including the C-analogs of methyl maltoside and cellobio-side, from a common synthetic intermediate [70]. 

PCC in the presence of 4 A MS to afford the corresponding keto sugars (175, 176), which after Tebbe methylenation led to the corresponding exoglycals, valuable intermediates for the synthesis of C-disaccharides. Dondoni el al.159 made use of PCC in the presence of powdered 4 A MS to introduce suitable formyl groups in the carbohydrate, and allowing the synthesis of >6)-linked oligosaccharides,... 

G. F. Herrmann, Y. Ichikawa, C. Wandtey, F. C. A. Gaeta, J. C. Paulson, and C.-H. Wong, A new multi-enzyme system for a one-pot synthesis of sialyl oligosaccharides Combined use of P-galactosidase and a(2,6)-sialyltransferase coupled with regeneration in situ of CMP-sialic acid, Tetrahedron Lett. 34 3091 (1993). 

Y. Ichikawa, G.-I. Shen, and C.-H. Wong, Enzyme-catalyzed synthesis of sialyl oligosaccharide with in situ regeneration of CMP-sialic acid, J. Am. Chem. Soc. 113 4698 (1991). 

K. C. Nicolaou New strategies and methods for the synthesis of complex oligosaccharides... 

Vetere A, Galateo C, Paoletti S. All-aqueous, regiospecific transg-lycosylation synthesis of 3-0-alpha-L-fucopyranosyl-2-acetamido-2-deoxy-D-glucopyranose, a building block for the synthesis of branched oligosaccharides. Biochem. Biophys. Res. Commun. 1997 234 358-361. 

Kolar, C, Kneissl, G, Semisynthetic rhodomycins novel glycosylation methods for the synthesis of anthracycline oligosaccharides, Angew. Chem. Int. Ed. Engl, 29, 809-811, 1990. 

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