Synthesis of Novel 3-Alkyl-3′,4′,5,7-Tetrahydroxyflavones

Novel 3-alkyl-3′,4′,5,7-tetrahydroxyflavones have been prepared. The synthetic strategy involves the preparation of 1-(2-hydroxy-4,6-dimethoxyphenyl)alkan-1-ones from the Friedel–Crafts acylation of phloroglucinol followed by methylation. These key compounds were submitted to the three-step Baker–Venkataraman method, giving the 3-alkyl-3′,4′,5,7-tetramethoxyflavones, which were demethylated with boron tribromide.