36 単糖ヒドロキシメチル部位のキラル重水素化標識法の開発とその利用

概要

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A genaral synthetic method of D-hexoses and D-pentoses with chirally deuterated hydroxymethyl groups was presented. The method involves two key steps of a stereospecific photobromination of 1,6-anhydro-D-hexopyranose or 1,5-anhydro-D-pentofuranose derivatives and a deuteride reduction of C6-exo (or C5-exo) brominated sugars with n-Bu_3SnD or LiEt_3BD. These deuterated sugars are strongly expected to be useful not only for the biosynthetic or enzymatic studies on carbohydrates but also for their NMR or Mass analyses. Here, we applied our deuterium labeling method to the study on the stereochemical patlways of galactose oxidase reaction and conformational analyses of mono-, di- and trisaccharides in solutions. The galactose oxidase (Dactylium dendroides) reactions of 100% e.e. (6S)- and (6R)-(6-^2H_1)-Me-β-D-galactopyranosides revealed that there were two mechanisms for the dehydrogenation process: an efficient pro-S hydrogen atom specific and far less efficient nonspecific or pro-R specific oxidations. ^1H-NMR studies on the mono, (1→6)-disaccharides and branched trisaccharides with chirally deuterated hydroxymethyl groups clarified conformational preferences about the C5-C6 bond of these sugars in aqueous solution. The conformations were discussed in terms of the configurations at C1, C2 and C4 positions and also of glycosidic linkages.
天然有機化合物討論会の論文
1986-09-09