Condensation of dimeric 3,4,6-tri- O-acetyl-2-deoxy-2-nitroso-α- D-glucopyranosyl chloride (1) with 1,2- O-isopropylidene-α- D-glucofuranurono-6,3-lactone (2) gave 1,2- O-isopropylidene-5- O-(3,4,6-tri- O-acetyl-2-deoxy-2-hydroxyimino-α- D- arabino-hexopyranosyl)-α- D-glucofuranurono-6,3-lactone (3). Benzoylation of the hydroxyimino group with benzoyl cyanide in acetonitrile gave 1,2- O-isopropylidene-5- O-(3,4,6-tri- O-acetyl-2-benzoyloxyimino-2-deoxy-α- D- arabino-hexopyranosyl)-α- D-glucofuranurono-6,3-lactone (4). Compound 4 was reduced with borane in tetrahydrofuran, yielding 5- O-(2-amino-2-deoxy-α- D-glucopyranosyl)-1,2- O-isopropylidene-α- D-glucofuranose (5), which was isolated as the crystalline N-acetyl derivative (6). After removal of the isopropylidene acetal, the pure, crystalline title compound (10) was obtained.