Synthesis of a novel N–O-interglycosidic disaccharide

Abstract

The carbohydrate subunits carrying an N–O-interglycosidic bond play a very important role in the biological activity of the enediyne antibiotics. Condensation of O-(α- and β- d-glucopyranosyl)hydroxylamine ( 5a and 5b) with the hex-3-ulopyranoside ( 6) furnished methyl 4,6- O-benzylidene-2,3-dideoxy-3-(2,3,4,6-tetra- O-benzyl-α- d-glucopyranosyloxy)imino-α- and β- d- erythro-hexopyranoside ( 7a and 7b). Stereoselective reduction of the CN bond of 7a and 7b with sodium cyanoborohydride resulted in the formation of the required protected N–O-interglycosidic disaccharides ( 8a and 8b). Finally, catalytic hydrogenation of 8a afforded methyl 2,3-dideoxy-3-(α- d-glucopyranosyloxy)amino-α- d- ribo-hexopyranoside ( 9a). Under similar conditions the β anomer 8b underwent decomposition.