원문정보
초록
영어
Chemo-enzymatic glycosylation has become an attractive methodology in the field of synthetic carbohydrate chemistry. The use of glycosidases possesses several merits: Typical glycosidases are stable, easy to handle, and produced on an industrial scale. In principle, glycosidase-catalyzed transglycosylation reactions require activated glycosidic compounds such as glycosyl fluorides and p-nitrophenyl glycosides. However, the preparation of these compounds necessitates the laborious task including the protection and deprotection of the hydroxy groups and the purification of the products. Novel chemo-enzymatic procedures by using 4,6-dimethoxy-1,3,5-triazin-2-yl glycosides1 and sugar oxazolines2 as glycosyl donors have been developed. These glycosyl donors have directly been prepared starting from the corresponding unprotected sugars in aqueous media without the use of any protection and deprotection of hydroxy groups. This is the first example of chemo-enzymatic glycosylation, where both of the glycosyl donor synthesis and the successive glycosylation can be achieved without any protecting and deprotecting steps in water. The new technique of direct activation of the anomeric hydroxyl group3-5 will pave a way to the “one-pot chemo-enzymatic glycosylation” without isolating the glycosyl donors. On the basis of this concept, one-pot syntheses of oligoxyloglucans and chitoheptaose have been demonstrated.