By condensation of 4-(2-quinolinylmethoxy)benzaldeyde (I) with 2-hydroxy-5(1H-tetrazol-5-yl)acetophenone (II) by means of KOH in ethanol/water. The intermediates (I) and (II) have been obtained as follows: Benzaldehyde (I): By condensation of 2-(chloromethyl)quinoline (III) with 4-hydroxybenzaldehyde (IV) by means of K2CO3 in hot DMF. Acetophenone (II): The acetylation of 4-hydroxybenzonitrile (V) with acetic anhydride/sulfuric acid and AlCl3 gives 5-cyano-2-hydroxyacetophenone (VI), which is then cyclized with sodium azide and ammonium chloride in hot DMF.

The intermediate acetophenone (III) was prepared from 5-chlorosalicylic acid (I) by O-acetylation with acetic anhydride and a catalytic amount of sulfuric acid, followed by Fries rearrangement of the resulting acetate (II) on heating with aluminum chloride. Condensation of 2-methylquinoline (IV) with an excess of 1,3-benzene dicarboxaldehyde (V) in a refluxing mixture of acetic anhydride and xylene provided aldehyde (VI), which was then condensed with acetophenone (III) by treatment with KOH in a mixture of ethanol and tetrahydrofuran to give chalcone (VII). Finally, oxidative ring closure by refluxing with selenium dioxide in dioxan yielded the desired flavone.

The intermediate acetophenone (III) was prepared from 5-chlorosalicylic acid (I) by O-acetylation with acetic anhydride and a catalytic amount of sulfuric acid, followed by Fries rearrangement of the resulting acetate (II) on heating with aluminum chloride. Condensation of 2-methylquinoline (IV) with an excess of 1,3-benzene dicarboxaldehyde (V) in a refluxing mixture of acetic anhydride and xylene provided aldehyde (VI), which was then condensed with acetophenone (III) by treatment with KOH in a mixture of ethanol and tetrahydrofuran to give chalcone (VII). Finally, oxidative ring closure by refluxing with selenium dioxide in dioxan yielded the desired flavone.