Studies On The Metal-free Catalyzed Approaches Of Several N-heterocycles

Part I: Solvent and Substituent Effects on the Conversion of 4-methoxypyridines to N-methyl-4-pyridonesObjective To investigate the solvent and substituent effects on the conversion of 4-methoxypyridines to N-methyl-4-pyridones.Methods Various substituted 4-methoxypyridines were used as reaction substrates to react with iodide alkanes in the solvent acetone.The ratios of two products N-methyl-4-pyridones and N-methylpyridinium salts were investigated.Results When the pyridine was substituted by an electron withdrawing group,only Nmethyl-4-pyridones derivative was not formed either in the presence or absence of acetone;when only an electron donating group was substituted at the the pyridine ring,only pyridinium was afforded in the absence of any solvent,whereas a mixture of pyridones and pyridiniums was obtained in the presence of solvent.Conclusion Electron withdrawing groups on the pyridine ring also favours this conversion.Thus,the N-methyl-4-pyridones can be directly prepared by 4-methoxypyridine via this conversion.Part II: Three-component One-pot Synthesis of 3-azabicyclo[3.3.1]nonane Scaffold(3-ABNs)Objective To construct a 3-azabicyclo[3.3.1]nonane skeleton via a one-pot tandem Mannich process with aryl ketone,dimethylamine and paraformaldehyde as reaction components.Methods Acetophenone was used as the substrate to investigate the effects of various amines,various types of acids,various solvents and reaction temperatures on the yield,and the best reaction conditions were selected.Results 12 novel 3-azabicyclo[3.3.1]nonane derivatives were synthesized by optimizing the reaction conditions.All structures were verified by 1~H NMR?13~C NMR and HMRS.Conclusion This method is of simple operation with broad substrate scope and ideal reaction yield.It is also suitable for practical synthesis in virtue of environment-friendly.