Enantioselective Keto-Enol Tautomerism of 3-Hydroxyflavones Upon Molecular Complex Formation of Their alpha-Diketo Forms with Carbohydrates in Aqueous Solutions

摘要

Complementary physicochemical methods (UV, IR, ORD) found that the alpha-diketo tautomer of 3-hydroxyflavones formed complexes with carbohydrates in water. The contribution of the flavone alpha-diketone increased sharply because it was stabilized after reacting with a carbohydrate cis-diol. The newly formed chiral center of the tautomeric diketo flavones was induced asymmetrically. The complexing ability of the carbohydrates was inversely proportional to their degree of hydration (and decreased in the order maltoseglucose-galactose-arabinose).