Disaccharides derived

Maltose and cellobiose (Section 25.14) are examples of disaccharides derived from D-glucopyranosyl units. 

Application of the ring opening reaction to disaccharide derivatives such as 4,6 4, 6 -di-0-benzylidene-a,a-trehalose affords the corresponding 6,6 -dibromo-4,4 -dibenzoate in good yield. 

Treatment of the disaccharide derivative, 2,3,6-tri-0-acetyl-4-0-(2,3,4,6-tetra-O - acetyl -fi-D- galactopyranosyl) -fi-D- glucopyranosyl-amine (46), with 71 also gave50 a mixture of protected L-aspart-1- and -4-oyl disaccharide derivatives (77 and 78). The almost identical yields of... 

The disaccharide derivative 0-(2,3,4,6-tetra-0-acetyl-/ -D-galactopy-ranosyl)-(l— 3)-0-(2-acetamido-6-0-benzoyl-2-deoxy-/ -D-glucopyran-osyl)-(l— 3)-N-(benzyloxycarbonyl)-L-serine methylamide (192) was prepared by condensation of 3-0-(2-acetamido-2-deoxy-6-0-benzoyl-/ -D-glucopyranosyl)-N-(benzyloxycarbonyl)-L-serine methylamide (191) with tetra-O-acetyl-a-D-galactopyranosyl bromide147 (110) under the conditions of the Helferich-Wedemeyer procedure. Treatment of 192 with methylamine in methanol at 0° gave89 193. 

The disaccharide derivatives 196 and 197 of N-tosyl-L-serine, of interest for the study of D-galactose-binding lectins, were prepared by Kaifu and Osawa148 from 194 and 195, respectively, by protection of 0-4 and -6 with a benzylidene group, condensation of the acetal with tetra-O-acetyl-a-D-galactopyranosyl bromide (110) under Koenigs-Knorr conditions, and deprotection. 

Worth, L.L. et al., ImmTher, a lipophilic disaccharide derivative of muramyl dipeptide, up-regulates specific monocyte cytokine genes and activates monocyte- mediated tumoricidal activity, Cancer Immunol Immunother., 48, 312, 1999. 

The glycosylations were carried out in dry dichloromethane in the presence of 0.1 equiv of triphenylmethylium perchlorate. It was assumed that the triphenylmethy-lium cation attacks the nitrogen of the thiocyanate group whereas the oxygen of the trityl ether attacks the anomeric carbon in a push-pull fashion. The trityl isothiocyanate formed was found to be unreactive under the reaction conditions. The disaccharide derivatives with (1-6), (1-4), (1-3) and (1-2) linkages have been obtained in good yields. 

Fig. 39 Dipolar cycloaddition methodology in the synthesis of disaccharide derivatives.

Hanemann, T. Haase, W. Lichtenthaler, F. W. Disaccharide-derived liquid crystals. Liquid Cryst., 1997, 22, 47-50. 

N-Iodosuccinimide also promotes the cyclization to give the a-gluco-side derivative, and the disaccharide derivative is synthesized with high stereoselectivity starting from a hydroxy vinylether (39). 

Another recurrent theme of the Richardson-Hough team was the selective sulfo-nylation of disaccharide derivatives, which led to many interesting papers, some involving trehalose and others sucrose. For example, in 1986, they reported (with Mukund K. Gurjar and Lee V. Sincharoenkul) that selective tosylation of 6,l 6 -tri-<9-tritylsucrose at room temperature for 2 days afforded the 2-tosyl ester in 52% yield... 

In fact, the altered disaccharide derivative itself (42) has strong antibacterial activity, even if not attached to the rest of the large vancomycin molecule [92]. This compound, however, acts via a different mechanism than vancomycin. It inhibits the transglycosylation step that precedes the transpeptidase step blocked by vancomycin itself. This finding explains the complex mechanism of action of derivative 41. 

Scheme 57 illustrates an example of this process coupling of the lithio reagent derived from vinyl stannane 237 with epoxide 242 leads to the C-disaccharide derivative 243 in good yield. A double transmetallation to give an organocopper reagent 244 can facilitate the C-glycosylation reaction with allyl halides [80] (Scheme 58). 

The separation and identification of disaccharides is often an important step in the elucidation of the structure of a natural polysaccharide, and Percival484 has published useful data on the O-trimethyl-silyl derivatives of a variety of disaccharides and their reduction products. In some instances, the trimethylsilyl ethers of the disaccharide alditols have lower retention times than those of the disaccharide derivatives. The per-O-trimethylsilyl derivatives of gentiobi-itol and maltitol were encountered in studies on the structure of Pneumococcus Type II capsular polysaccharide.4843... 

A disaccharide derivative (42) of more conventional structure has also been isolated from hen oviduct.177 Its structure was confirmed by its conversion into L-fucose and uridine 5 -(2-acetamido-2-deoxy-a-D-glucopyranosyl pyrophosphate) after treatment with a-L-fucosi-dase. Mild, acidic hydrolysis of the ester 42 produces a disaccharide whose structure was confirmed by periodate oxidation. Human milk and colostrum,178 or milk and colostrum of pig,128 are also sources of... 

Further examples of selective deacylation in disaccharide derivatives were provided by the reaction of 2,3,6,2, 3, 4, 6 -hepta-0-acetyl-maltosyl bromide and 2,3,6,2, 3, 4, 6 -hepta-0-acetyllactosyl bromide with pyridine115 the former yielded 3,6,2, 3, 4, 6 -hexa-0-acetyl-maltosylpyridinium bromide, whereas the latter gave 3,3, 4 -tri-0-acetyl- and 3,6,3, 4, 6 -penta-0-acetyl-lactosylpyridinium bromide. 

Structural studies on the oligosaccharide derivatives obtained by partial, acid hydrolysis of fully methylated polysaccharides often furnish valuable information on the positions at which the oligosaccharides were linked in the original polysaccharide. When the folly methylated Klebsiella O group 9 lipopolysaccharide,27 which contains D-galactopyranose and D-galactoforanose residues, was subjected to mild, acid hydrolysis, and the product reduced with lithium aluminum deuteride and remethylated with trideuteriomethyl iodide, a good yield of the disaccharide derivative 10 was obtained. 

On consecutive treatment with base and acid, the disaccharide derivative 48 yielded the /8-D-xylopyranoside of 5-(hydroxymethyl)-2-furaldehyde (49) (see Scheme 6).108 S. A. Barker and coworkers... 

Kochetkov and coworkers studied the deamination of two model disaccharide derivatives. Benzyl 2-amino-2-deoxy-3-0-/3-D-galac-topyranosyl-a-D-glucopyranoside (99) yielded 2,5-anhydro-3-0-j3-D-galactopyranosyl-D-mannose (100), which was reduced, the product... 

Among the unsaturated ketonucleosides may be classified the disaccharide derivative 74, which is an analog of the biologically active compound 68c. The key intermediate for the synthesis of this unsaturated ketodisaccharide nucleoside was the partially protected, disaccharide nucleoside 73, which was prepared by two separate routes,56 Treatment of 73 with the Me2SO-acetic anhydride reagent for two days at room temperature afforded 7-[2,3-di-0-benzoyl-4-0-(3-0-benzoyl-2,6-di-deoxy - / - d - glycero - hex - 2 - enopyranosyl - 4 - ulose) - 6 - deoxy - / - d -glycopyranosyl]theophylline (74), isolated crystalline.56... 

A. Marra and P. Sin3y, A novel stereoselective synthesis of N-acetyl-a-neuraminosyl-galactose disaccharide derivatives, using anomeric S-glycosyl xanthates, Carbohydr. Res. 795 303 (1990). 

This method has been successfully extended to the iterative synthesis of oligosaccharides. The disaccharides, derived from selective activations of unprotected MOP donors and partially esterified MOP acceptors, can be converted into reactive donors simply by deacylation. The newly generated unprotected MOP disaccharide donor can be subjected to another cycle of glycosylation by repeating the same process. Schemes 7 and 8 illustrate... 

High a-selectivities were observed when the D-galactosyl donor 10 was used for the coupling with secondary hydroxy groups in carbohydrate acceptors including 9 (see Scheme 5). With the trichloroacetimidate method [5], the yields of disaccharides derived from 6 and 7 were 85% (10 1, a/p) and 87% (only a), respectively. The condensation of 10... 

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