Disaccharide methyl ester synthesis

Synthesis of the disaccharide J.. The reaction of the known ( 1 3) methyl ketoside-methyl ester derivative 2 ... 

Alternate synthesis of the 2— 4-linked disaccharide J,. Upon glycosidation of 18 with the methyl ester-ketopyranosy 1 bromide under the modified Koenigs-Knorr conditions given for the synthesis of above, a 7 1 mixture of the B and o >-, 2— 4-linked disaccharide derivatives 19 and 20 was obtained in 27%... 

Synthesis of Ascorbic acid and of Disaccharides (i) The synthesis of Vitamin C (75), ascorbic acid from D-galactose (ref.72) and that from D-glucose (ref.73) were described in the same year which also saw the development of the the latter as an industrial route. Sorbitol obtained by the reduction of D-glucose was oxidised with the bacterium Acetobacter suboxvdans to L-sorbose which as the bis-acetonylidene derivative was next oxidised to the corresponding acid, L-2-oxogulonic acid, the methyl ester of which was base-catalysed to afford the final product as illustrated. 

Mono- and disaccharides are highly hydrophilic substances. They are produced in large volumes, are available in highly pure form, and are relatively cheap [4,5]. They may be, and indeed have been, used as hydrophilic substrates for the synthesis of nonionic surfactants. In 1999, the worldwide production of the latter was about 3.6 3.8 million metric tons, i.e., approximately 38% of total surfactant production [6]. The majority of the conventional nonionic surfactants are oligooxyethylene (and oxypropylene) chain-containing compounds obtained in the reaction of oxirane (ethylene oxide) or methyloxirane (propylene oxide) with hydrophobic intermediates that contain a functional group with an active hydrogen atom [7]. Only recently, the direct reaction of oxirane with fatty acid methyl esters in the... 

Also attention has been paid to the synthesis of sialodisaccharides, having sialic acid in reducing position. By condensation of tetra-O-acetyl-a-D-glucopyranosyl bromide or tetra-O-acetyl-a-D-galactopyranosyl bromide with methyl 5-acetamido-2,4,7,8-tetra-0-acetyl-3,5-dideoxy-9-0-trityl-D-g/> c ro-D-ga/ac/o-2-nonulopyranosonate in nitromethane under the influence of silver perchlorate, followed by 0-deacetylation, the methyl esters of the corresponding (5(1 9) disaccharides were obtained in 67 and 46% yield, respectively (Khorlin and Privalova 1968). 

From this brief survey, it is seen that there were few features of carbohydrate metabolism in plants that escaped Hassid s touch, and much that we now know about the role of sugar nucleotides in the interconversion of carbohydrates in plants is a direct result of his persistent effort. From the incorporation of labelled precursors into monosaccharides, to the conversion of the monosaccharides into their glycosyl phosphates, to the action of the pyrophosphorylases in the synthesis of glycosyl esters of nucleoside pyrophosphates, to the interconversion of the resulting sugar nucleotides, to the polymerization of the activated monosaccharides to yield disaccharides and the homopolysaccharides, and, finally, to the modification of the polysaccharides by methylation—in summary, to almost every aspect... 

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