Synthesis of 2,2-Dimethyl-2H-pyran-fused Flavonols Using the Modified Algar-Flynn-Oyamada Reaction

Abstract

6-Acetyl-2,2-dimethylchromenes when separately condensed with p-anisaldehyde in the presence of ethanolic NaOH and subsequently oxidized with alkaline hydrogen peroxide without isolating the intermediate chalcones afforded the corresponding 2,2-dimethyl-2H-pyran-fused flavonols respectvely in good yield. Thus, flavonols having free 3-hydroxyl and fused with 2,2-dimethyl-2H-pyran can be synthesized easily.