Formation of the unexpected 3-alkylated flavonoids in the alkylation of B-ring substituted 5,7-dihydroxy flavones

Treatment of B-ring substituted 5,7-dihydroxy flavones with alkyl halides in the presence of potassium carbonate gave unexpected 3-alkylated flavonoids. Related experiments were carried out to explain the formation of 3-alkylated flavonoids and a ring opening followed by alkylation and ring closure mechanism was proposed.