1,2-Disaccharides synthesis

Schwartz, B.A., and Gray, G.R. (1977) Proteins containing reductively aminated disaccharides. Synthesis and chemical characterization. Arch. Biochem. Biophys. 181, 542-549. 

Scheme 8.13. Disaccharide synthesis in the presence of a sterically hindered pyridine.

Figure 10. Disaccharide synthesis with a fluorous benzyl group...

Classically, Bronsted acids are the promoters of the Fischer glycosylation. Though substrate complexity is still limited in scope, recent developments in these reagents more commonly allows for disaccharide synthesis (Scheme 3.3). For instance, Koto et al. have reported that the combination of methanesulfonic acid (30 mol%) and... 

Another mode of carbon-based activation of hemiacetals relies on carbonyl-centered electrophiles 89 (Scheme 3.14). These reagents have demonstrated the highest efficiency for disaccharide synthesis among electrophilic carbon activating agents. In the event, the hemiacetal 1 is activated with electrophile 89 for in situ... 

Scheme 4.69 Disaccharide synthesis on a soluble polyethylene glycol support.

Scheme 4.70 Disaccharide synthesis by ring-closing glycosylation.

Scheme 1.5 Disaccharide synthesis on a solid support using a cyclic horonic acid ester linker.

Scheme 3.14 Disaccharide synthesis using the sulfoxide glycosylation method.

Parquette et al. reported on a disaccharide synthesis on a hyperbranched polyester support (Boltorn hyperbranched polymer) (16) (Fig. 7.9) [44]. This polymer was obtained in a one-step synthesis and offers low cost, high-loading capacities (8.8 mmol OH-groups g ), and the intermediates were soluble in most aprotic solvents. 

Scheme 7.4 Disaccharide synthesis using a hyperbranched polymer (Boltorn polymer) as a soluble support.

R. U. Lcmieux, Some implications in carbohydrate chemistry of theories relating to the mechanisms of replacement reactions, Adv. Carbohydr. Chem. Biochem 9 1 (1954). H. Tsu-tsumi and Y. Ishido, Syntheses of 1-O-acylaldose derivatives via the corresponding 0-glycosyI-pseudourcas, Carbohydr. Res. Ill 75 (1982). S. Horvat, L. Varga, and J. Horvat, A new utility of O-glycosylpseudoureas for synthesis of glucopeptides and (1— 6)-disaccharides, Synthesis 209 (1986). 

Scheme 3 Disaccharide synthesis with O-benzyl MOP glycosyl donors using MeOTf as catalyst.

Scheme 4 Disaccharide synthesis with 0-benzyl MOP glycosyl donors using Cu(OTf)2 as promoter.

Scheme 6 1,2-tranj-Disaccharide synthesis using CH3CN as solvent. 

Scheme 7 1,2-rranj-Disaccharide synthesis using MOP-leaving group. 

Except for the disaccharide synthesis, in which introduction of natural sugars produced optically active diastereoisomers at the dihydropyran ring stage, most transformations leading to sugars was done with racemic substrates. Alcohol 3 was resolved into enantiomers by crystallization of its 6-O-camphanyl ester and subsequent hydrolysis. Recent discoveries of enantioselective catalysts and reagents permit one to obtain basic... 

The use of ester-cleaving enzymes is probably going to be one of the most useful biological-chemical methods in the synthetic laboratory. No example of this type of reaction has hitherto been published in the Organic Syntheses series of procedures. So far, the only biological-chemical Organic Synfheses-procedures are two yeast reductions,4 5 one oxidation with horse-liver-alcohol-dehydrogenase,6 and a disaccharide synthesis catalyzed by emulsin.7 The procedure described here is... 

F. Animati, F. Arcamone, M. Berettoni, A. Cipollone, M. Franciotti, and P. Lombardi, New anthracycline disaccharide. Synthesis of L-daunosaminyl-a(l->4)-2-deoxy-L-rhamnosyl and of L-daunosamyl-a(l->4)-2-deoxy-L-fucosyl daunorubicin analogues, J. Chem. Soc. Perkin Trans. 

B. A. Schwartz and G. R. Gray, Proteins containing reductively aminated disaccharides synthesis and characterization, A rch. Biochem. Biophys. 181 542-549 (1977). 

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