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-(2hydroxy-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.