PROTECTION OF THE AMINO GROUP OF AMINO SUGARS BY THE ACYLVINYL GROUP: PART I, GLYCOSIDE FORMATION BY THE FISCHER REACTION

Article abstract of DOI:10.1016/0008-6215(84)85008-9

2-Deoxy-2-<(2,2-dimethoxycarbonylvinyl)amino>- (1) and 2-deoxy-2-<(2,2-diethoxycarbonylvinyl)amino>-α-D-glucopyranose (3), prepared in almost quantitative yields from the appropriate 3-alkoxy-2-alkoxycarbonylacrylic ester and 2-amino-2-deoxy-D-glucose hydrochloride, were used as N-protected derivatives in the preparation of glycosides by the Fischer procedure.Glycosidation of 1 with boiling methanolic hydrogen chloride afforded a mixture of methyl 2-deoxy-2-<(2,2-dimethoxycarbonylvinyl)amino>-α- (7α) and -β-D-glucopyranoside (7β), and minor amounts of methyl 2-deoxy-2-<(2,2-dimethoxycarbonylvinyl)amino>-α-D-glucofuranoside (18); 7α was easily isolated (55percent yield).Using Amberlyst-15 (H¹⁺) resin as catalyst, the proportion of the furanoside 18 was higher and 21percent could be isolated.Reaction of 3 with hot ethanolic hydrogen chloride afforded a good yield of ethyl 2-deoxy-2-<(2,2-diethoxycarbonylvinyl)amino>-α-D-glucopyranoside.On the other hand, attempted glycosidations of 2-deoxy-2-<(2,2-diacetylvinyl)amino>-α-D-glucopyranose under similar conditions were unsuccesfull.The 2,2-diacylvinyl group could be removed selectively under non-acidic conditions using chlorine, ammonia, or Amberlite IRA-400 (HO^1-) resin.