Isomaltose 0-, acetate

A much more systematic approach involves the use of p-chlorides carrying non-participating groups at C-2 as is exemplified by the Wolfrom synthesis of p-isomaltose octa-acetate from 1,2,3,4-tetra-O-acetyl-p-D-glucopyranose and 3,4,6-tri-0-acetyl-2-0-nitro-p-D-glucopyranosyl chloride In this work silver carbonate was used as acid acceptor and soluble silver perchlorate was fmmd to exert valuable catalytic influence, but later the perchlorate itself was used in an application to a tiisacchar-ide s mthesis which incorporated the trityl ether modification 2 ). 

After partial (75%), acid hydrolysis of 5 g. of rabbit-liver glycogen, chromatography of the acetylated sugars yielded 92 mg. of /3-isomaltose octa-acetate "" none was formed by acid reversion during a similar treatment of amylose. The isolation of a derivative of isomaltose provides evidence for a-D-(l —> 6)-glucosidic linkages in the polysaccharide. 

Fig. 3-25. Gradient elution of different sugar alcohols and saccharides. - Separator column Ion Pac AS6A eluent (A) water, (B) 0.05 mol/L NaOH + 0.0015 mol/L acetic acid gradient 7% B isocratically for 15 min, then to 100% B in 10 min flow rate 0.8 mL/min detection pulsed ampero-metry on a Au working electrode (post-column addition of NaOH) injection volume 50 pL solute concentrations 15 ppm inositol (1), 40 ppm sorbitol (2), 25 ppm fucose (3), deoxyribose (4), 20 ppm deoxyglucose (5), 25 ppm arabinose (6), rhamnose (7), galactose (8), glucose (9), xylose (10), mannose (11), fructose (12), melibiose (13), isomaltose (14), gentiobiose (15), cellobiose (16), 50 ppm turanose (17), and maltose (18).

Figure 5. N-Bromosuccinimide (NBS) treatment of glucoamylase G1 (12 pM in 50 mM sodium acetate pH 43) in the absence ( ) and in the presence of 50 mM isomaltose (O), 50 mM isomaltotriose (x), 56 mM maltose ( ), 0.15 mM acarbose (A), 50 mM isomaltose plus 24 mM gluconolactone (O), 50 mM isomaltose plus 56 mM maltose (A) and isomaltose plus 0.15 mM acarbose ( ).

The further, conformationally restricted isomaltose analogues (38) and (39) were prepared by glucosylation using 2,3,4,6-tetra-0-benzyl-Z>-glucosyl acetate and TMS triflate as catalyst, and the tran5-decalin cis-diol. The products were obtained in the proportions 83 5 with 12% of /3-linked products. ... 

Reactions carried out on disaccharide derivatives included the conversion of peracetates to l-phenylthio- 3-derivatives by use of phase-transfer methods and the epimerization at C-2 by calcium -amine systems (CaCl2.2H20, EtjN, for example). By this means maltose, lactose, isomaltose and melibiose were converted into the corresponding glucosyl-D-mannoses. An extensive range of variously substituted maltosyl fluorides have been made from maltose derivatives as substrates for cyclodextrin transferase. Only the 6 -methyl ether and 6 -acetate were transformed into cyclic products. In the course of the work the thio-derivatives (83) and (84) were made. ... 

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