Convenient Preparation of Perbenzylated 2-Azido and 2-<i>N</i>-Acetylamino-2-Deoxy-<scp>d</scp>-Hexono-1,5-Lactones by Oxidation of the Corresponding Lactols

Abstract

Abstract 2-Azido-3,4,6-tri-O-benzyl-2-deoxy-d-galacto, gluco and mannopyranoses (1, 2, 3) were oxidized with DMSO in the presence of acetic anhydride. From 1 and 2 the corresponding lactone derivatives were obtained in good yield (89-92%), whereas from 3, glucono-1,5-lactone was obtained (92%) after complete epimerization at C-2. 2-N-Acetylamino-3,4,6-tri-O-benzyl-2-deoxy-d-galacto, gluco and mannopyranoses (7, 8, 9) were obtained from the corresponding 2-azido phenylselenoglycopyranosides (13, 14, 15) by reduction, N-acetylation and hydrolysis catalyzed by mercury trifluoroacetate. Oxidation of 7 and 8 by tetra-n-propylammonium tetra-oxoruthenate (VII) in the presence of 4-methylmorpholine-N-oxide afforded the corresponding lactones in good yield (90%) and high purity. Epimerization at C-2 occurred during oxidation of 9 and perbenzylated d-glucono-1,5-lactone (11) was obtained (90%). Notes Compound 7 was previously prepared from 2-N-acetylamino-2-deoxy-D-galactopyranose in 16% overall yield.2 Compound 8 was previously prepared from 2-N-acetylamino-2-deoxy-D-glucopyranose in 49% overall yield.2