Indium-mediated Reductive Intramolecular Cyclization Of 2-Nitrochalcones To Quinolines

To extend the utilization of indium in organic synthesis, shorten the synthetic step of quinolines from 2-nitrochalcones, we carried out this investigation.In chapter 1, first, we introduce some applications of indium powder and the general syntheses of quinoline nucleus.In chapter 2, we attempted several methods of preparing 2-nitrochalcones, i.e. starting materials, and found out that the no-solvent method was a better one. Fourteen 2-nitrochalcone derivatives (3a-3n) were obtained in good yields by using this simple and efficient method. And these compounds were typed by ¹H-NMR.We also attempted to search for the optimized condition for utilizing indium powder to synthesize 2-phenylquinoline from 2-nitrochalcone. The optimum condition was obtained with 2-nitrochalcone (1 equiv.) / In (5 equiv.) in MeOH/sat-NH₄Cl (v/v=3:1) at reflux under nitrogen.In chapter 3, in order to test the utilization of the optimum condition, the reductive intramolecular cyclization of 2-nitrochalcones to quinolines was carried outin the presence of indium powder with methnaol and saturated ammonium chloride solution at reflux. The reductive intramolecular cyclization was rapidly occurred and 2-nitrochalcones were transformed into the corresponding fourteen quinolines (4a-4n) in good yields and these compounds were typed by lH-NMR, 13C-NMR, IR, and MS. Among them, one compound (4i) was not reported until now.The reductive intramolecular cyclization of 2-nitrochalcones to quinolines by using indium powder was first reported here.