Mannuronic acid, methyl glycoside

Ault, Haworth and Hirst47 first synthesized the methyl a-D-glycoside methyl ester of 2,3,4-tri-O-methyl-D-mannuronic acid by successive treatment of potassium (methyl a-D-mannopyranosid)uronate with dimethyl sulfate and sodium hydroxide, and then methyl iodide and silver oxide. Although no crystalline derivatives were isolated, there is little doubt about its structure, since the authors48 subsequently proved the presence of a pyranose ring in the starting material for the synthesis, methyl 2,3-O-isopropylidene-a-D-mannoside. The uronic acid has also been synthesized by Smith, Stacey and Wilson,28 who oxidized methyl... 

Proof of the structure of the uronic acid was obtained by Hirst, Jones and Jones,46 who isolated the methyl glycoside methyl ester by methyla-tion of the products from the graded methanolysis of alginic acid. The tri-O-methyl-D-mannuronic acid was converted to the diamide of 2,3,4-tri-O-methyl-D-mannaric acid, which had previously been prepared from... 

Figure 5. Separation by GLC of some hexuronic acids as the methyl glycosides-methyl esters. The chromatograph was temperature-programmed from 140 to 200° at 0.5°/min. Peaks are numbered in their order of emergence and are identified as follows guluronic acid 1,3,7 iduronic acid 2, glucuronic acid 4,10, galacturonic acid 5,8,9, and mannuronic acid 6.

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