Oxidation of carbohydrates with chromium trioxide in acetic acid. I. Glycosides

Abstract

Fully acetylated methyl β-D-hexopyranosides are oxidized by chromium trioxide in acetic acid to acetylated methyl 5-hexulosonates. Catalytic hydrogenation of these keto esters leads into the L-series. The corresponding a-D-glycosides are not oxidized in the same way, with the exception of methyl tetra-O-acetyl-α-D-idopyranoside. Both α- and β-anomers of the acetylated fnranosides are oxidized to aoetylated methyl 4-hexulosonates. The octaacetates of α- and β-lactose are similarly oxidized, the ring of the galactose moiety being opened. The methyl pyranoside of a branched-chain sugar, with no hydrogen atom on C5, is oxidized to a 4-keto ester, acetyl migration occurring from O4 to O5.