N-Glycosidation of D-arabino-hex-2-ulosonic acid

Two approaches to N-functionalized D-arabino-hex-2-ulosonic acid derivative s were established by nucleophilic substitution of methyl (3,4,5-tri-O-acet yl-beta -D-arabino-hex-2-ulopyranosyl)onate bromide (1). Reaction of 1 with amino compounds in the presence of mercury(II) cyanide led to the 2,3-cis configured beta -D-arabino N-glycosides. On the other hand, the reaction of bromide 1 with azide, followed by catalytic hydrogenation led to 2,3-trans alpha -D-arabino glycosyl amine methyl 3,4,5-tri-O-acetyl-2-amino-alpha -D -arabino-hex-2-ulopyranosonate, which was easily rearranged to the thermody namically more stable beta -D-arabino N-acetyl derivative methyl 4,5-di-O-a cetyl-2-acetylamino-3-hydroxy-beta -D-arabino-hex-2-ulopyranosonate. The as signment of configuration of the tertiary anomeric centre and conformation of all products was based on H-1 NMR H,H coupling constants and NOE differe nce experiments. (C) 2000 Elsevier Science Ltd. All rights reserved.