A method for the synthesis of 2-methyl-benzimidazolyl isoflavone derivatives has been developed. Deoxybenzoin (3) was prepared by using the resorcinol and substituted phenylacetic acids as starting materials in microwave-mediated. Then the compound 3 was reacted with acetic anhydride to produce compound 4 which was hydrolyzed to convert compound 5 in the acid-mediated. The compound 5 was reacted with the 1,2-dibromo-ethane or 1,3-dibromo-propane under refluxing condition with acetone as solvent to give compounds 6 or 7, respectively. Lastly, the title compounds were synthesized from compound 6 or compound 7 reacted with 2-methyl-benzimidazole catalyzed by anhydrous potassium carbonate in acetone solution under refluxing condition. The structures of target compounds were confirmed by IR, ¹H NMR, ¹³C NMR, elemental analysis. During synthesis of all target compounds, not only the reaction condition of building C—O bond and C—N bond have been optimized but also the microwave promoting method has been successfully applied to our protocol which shortened the reaction time enough. The antioxidative ability of the twelve target compounds has been investigated and the results indicate that all target compounds possess good capacity of scavenging free radical.

Key words: isoflavone, 2-methyl-benzimidazole, 2-methyl-benzimidazolyl isoflavone derivatives, microwave assisting, antioxidative activity