Abstract
α-d-Galactopyranuronic acid was converted to 1,2,3-tri-O-acetyl-4-deoxy-β-l-threo-4-hexenopyranuronic acid (3) and 3-acetoxy-6-(diacetoxymethyl)-2H-pyran-2-one respectively by treatment with acetic anhydride-4-(dimethylamino)pyridine or acetic anhydride-acetic acid-pyridine. Further degradation of 3 in acetic anhydride-triethylamine gave comanic acid.