Yamada's carbohydrate chemistry

Abstract

This chapter describes the 21-year history of research conducted by Professor Hidetoshi Yamada. Sugars often exist in a six-membered ring structure, and the equatorial-rich chair conformation is stable. In contrast, its pyranose ring in a biological glycosylation is easily deformed and changed by various factors. Therefore, controlling the steric conformation of the pyranose ring is a great starting point to influence the stereoselectivity of the glycosylation reaction. His research developed stereoselective glycosylation reactions by deforming the sugar ring from the most stable equatorial-rich chair conformation. Initially, the research began to restrict the pyranose ring into the axial-rich chair form. The evolution to the locked skew-boat system allowed highly selective glycosylation by bulky silyl-protected or o-xylylene-bridged glycosyl donors. Development of the 1,1'-(ethane-1,2-diyl)dibenzene-2,2'-bis(methylene) bridging group created that which is known as the supple conformation system, which when combined with an α-selective glycosylation, led to the remarkable synthesis of the smallest cyclodextrins on record. Professor Yamada's consistent research in these areas willfully contributed to the development of carbohydrate chemistry.

Keywords: 1,1’-(ethane-1,2-diyl)dibenzene-2,2’-bis(methylene) group; Axial-rich chair; Cyclodextrin; Selective glycosylation; Skew-boat; Supple conformation; o-Xlylylene group.