[Dehydrative glycosidation and partially benzylated sugar derivatives].
Dehydrative glycosidation reactions reported by the authors' group are reviewed. The authors' efforts were concentrated on developing reagent systems usable for one-stage-one-pot glycosidation. Such systems could simplify the glycosidation step using 1-OH sugar derivatives, since any preactivation stage for the hemiacetal OH group could be omitted. The systems, utilizing the dehydration potential of sulfonyl chloride, such as the p-nitrobenzenesulfonyl chloride-silver trifluoromethanesulfonate-triethylamine system as well as the p-nitrobenzenesulfonyl chloride-silver trifluoromethanesulfonate-N,N-dimethylacetamide-triethylamine system, were useful for the syntheses of many kinds of oligosaccharides. As a system free from any metals, the authors developed the trimethylsilyl trifluoromethanesulfonate-pyridine (TP) system. During the study of the system containing cobalt (II) bromide, the authors found that the bromide converts 1-OH sugar into the corresponding 1-Br derivative, which is then activated with the cobalt salt to undergo glycosidation with alcohol. To prepare partially benzylated sugar derivatives used as acceptors in the authors' studies, controlled benzylation and forced tritylation were carried out. Short syntheses of a variety of useful sugar derivatives using such convenient procedures are described. As a novel protecting group for the hemiacetal OH group, the authors used the 2-methoxyethyl group. Many kinds of trehalose-type disaccarides we prepared.
Koto
Shinkiti
S
School of Pharmaceutical Sciences, Kitasato University, Minato-ku, Tokyo 108-8641, Japan. shin993100@aol.com
Hirooka
Motoko
M
D000606:Amino Sugars; D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D002625:Chemistry, Organic; D006027:Glycosides / Q000737:chemistry*; D007202:Indicators and Reagents; D018942:Macrolides / Q000138:chemical synthesis / Q000737:chemistry; D008968:Molecular Conformation; D009578:Nitrobenzenes / Q000737:chemistry; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D055601:Organic Chemistry Phenomena; D013441:Sulfinic Acids; D014199:Trehalose
D000606:Amino Sugars; D002241:Carbohydrates; D006027:Glycosides; D007202:Indicators and Reagents; D018942:Macrolides; D009578:Nitrobenzenes; D009844:Oligosaccharides; D013441:Sulfinic Acids; C466027:trehalosamine; C044255:sulfonyl chloride; D014199:Trehalose