Disaccharide methyl ester

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%... 

Like the parent compounds, the methyl ethers of aldobiouronic acids are resistant to acid hydrolysis, and it is difficult to carry out hydrolysis without some decomposition of the product. This difficulty has recently been overcome by reduction of the uronic acid residue with lithium aluminum hydride66-67 the resulting disaccharide then undergoes hydrolysis without difficulty. The first reduction of the uronic acid residue of a methylated aldobiouronic acid methyl ester was accomplished by Levene, Meyer and Kuna,69 who reduced the methylated aldobiouronic acid from gum arabic with hydrogen in the presence of copper chromite catalyst under the conditions previously used701 for reducing the acety-... 

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. 

Simultaneous reduction of the benzyl ethers and the azide proved unsatisfactory in the presence of methyl esters. An alternate procedure utilized thioacetic acid to reductively A-acetylate the azide. Thus, treatment of III.18 and III.19 with thioacetic acid afforded the corresponding 2-deoxy-2-acetamido derivatives III.20 and III.21, respectively. Hydrogenolysis followed by sulfation with the sulfur trioxide-tri-methylamine complex gave the corresponding 4- and 6-O-sulfated disaccharides III.22 and III.23. Final saponification of 111.22 and III.23 with aqueous sodium... 

The 6-6>-sulfated derivative III.8 was prepared from disaccharide III.34, where oxidation followed by esterification with diazomethane gave the methyl ester III.37. Reductive N-acetylation, saponification, and sulfation produced derivative III.38, and subsequent hydrogenation afforded the target disaccharide III.8. 

O-Dechloroacetylation of IV.61 by treatment with thiomea gave IV.62, which was subsequently reprotected as the hydrogenolyzable 4-methoxybenzyl ether with 4-methoxybenzyl trichloroacetimidate and triflic acid under phase transfer catalysis conditions [104]. Saponification of the benzoate and methyl esters with lithium hydroperoxide followed by methanolic sodium hydroxide and acidification then gave the acid IV.63. O-Sulfonation of IV.63 was achieved with the sulfur trioxide-tri-methylamine complex to give the disulfate IV.64 as the sodium salt. Finally, hydro-genolysis of IV.64 with Pd/C in aqueous methanol afforded the target disaccharide IV.51. 

The glycosidic alkaloid grandifoline (amorphous) from this plant was shown to have structure 139 in which R is a 2-0- -D-gluoopyrano-syl-L-arabinose residue. Acid methanalysis yielded laburnine and the disaccharide as well as the chroman derivatives of the presumed intermediate methyl ester of 3,5-diisopentenyl-4-hydroxybenzoic acid 162). 

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