Efficient synthesis and antioxidation activities of ferrocenylpyrano-fused quinolines

Abstract:

Fifteen known ferrocenylpyrano-fused quinolines were synthesized efficiently via three-component Povarov reaction of 4-methyl-7-aminobenzopyranone, aromatic aldehydes, and ferrocenyl acetylene in the presence of cerium trifluoromethylsulfonate (Ce(OTf)3) and scandium trifluoromethylsulfonate (Sc(OTf)3), with yields ranging from 40.0% to 66.8%. The structures of the compounds were characterized by 1H NMR, 13C NMR, and HR-MS (ESI). The antioxidant activities of the compounds were evaluated by inhibiting oxidation reaction of DNA induced by hydroxyl radical (HO·) and reductive glutathione radical (GS·), and the effects of the type, position and number of substituents on the antioxidant abilities of ferrocenylpyrano-fused quinolines were investigated. The results showed that the fifteen target compounds exhibited strong radical scavenging activities to protect DNA against oxidation induced by HO· and GS·. The absorbance percentages of thiobarbituric acid reactive substances (TBARS) of the fifteen target compounds were 36.6%~83.3% in inhibiting HO· induced oxidation of DNA, and 22.9%~67.2% in inhibiting GS· induced oxidation of DNA, respectively. The antioxidant activity could be further enhanced by introduction of electron-donating groups (such as -N(CH3)2, -OCH3, and -OH) in ferrocenylpyrano-fused quinolines structures, while antioxidant activity was reduced when electron-withdrawing group (-Cl) was introduced. The ferrocenylpyrano-fused quinolines exhibited better antioxidant performance than ferrocenyl quinolines and are potential powerful antioxidants.

Key words:Complex catalysis, Povarov three-component reaction, ferrocene, pyrano-fused quinoline; antioxidant, free radical