32 α-D-グルコピラノサイドの立体選択的合成

概要

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The preparation of α-D-glucopyranoside in high yield still remains one of the most important problems in carbohydrate chemistry. Although several methods have been reported the yields are not so high. The mechanism of and the solvent effects in the Koenigs-Knorr reaction of glycosyl halides having non-participating group at C_2 position using silver perchlorate as catalyst were studied. It is considered that the reactions substantially proceed via a common intermediate, the glycosyl perchlorate. By the application of this result, β-isomaltose octaacetate was obtained in 75% yield from 3,4,6-tri-O-acetyl-2-O-benzyl-β-D-glucopyranosyl chloride with one molar equivalent of 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose using silver perchlorate and sym-collidine in ether, followed by debenzylation and acetylation. Similarly, β-maltose octaacetate, β-nigerose octaacetate, and α-kojibiose octaacetate were obtained in 43.6, 57, and 47% yields, respectively. We are indebted to Dr. B. Lindberg for kind gift of seed crystals of β-isomaltose octaacetate.
天然有機化合物討論会の論文
1972-10-01