The Study Of Multicomponent Reactions Of Benzimidazolium Salts And Phenanthrolinium Salts

Benzimidazole and its derivatives are a class of heterocyclic compounds with promising biological activity. Its copper, zinc and other metal complexes have special catalytic properties and play an important role in the simulation of metal enzymes. The research on synthesis and applications of benzimidazole has attracted much attention for several decades and is still very active due to its structure characteristics, physical activity, reactivity, and other excellent characteristics. On the other hand phenanthroline is also a class of nitrogen-containing aromatic hetercyclic compounds with rigid plan structure. Phenanthroline and its derivatives can activate or inhibit the in vivo activity of the enzyme, and react as a fused hetercyclic conjugate integrated ligand as well as have applications in in crystallography, coordination, catalysis and many other areas. Phenanthrolines could also be used as important intermediates in organic synthetic reactions. In this thesis we investigaed the reactivity of N-benzylbenzimidazolium bromides and phenanthrolinium bromides in several multicomponent reactions, found some new reaction pattern and reported the efficient synthesis of versatile nitrogen-containing heterocyclic compounds.1. The three-component reactions of in situ formed N-benzylbenzimidazolium salts, aromatic aldehydes, and active methylene compounds in the presence of triethylamine showed very interesting molecular diversity. The reactions with Meldrum’s acid or barbiturate in acetonitrile gave a series of the novel zwitterionic salts in high yields. Under similar reaction conditions, the reactions with malononitrile or ethyl cyanoacetate produced functionalized pyrrolo[1,2-a]benzimidazoles in good yields with an unprecedented regioselectivity. All products were characterized by IR,1H NMR,13CNMR, LC-MS spectroscopy. The single crystal structures of three products were determined by X-ray diffraction method.2. The three-component reactions of N-benzylbenzimidazolium salts, isatins and malononitrile or ethyl cyanoacetate showed very interesting molecular diversity depended on the structures of benzimidazolium salts. The reactions of N-benzyl-N’-p-nitrobenzyl-benzimidazolium salts gave a series of the novel zwitterionic salts in good yields. Under similar reaction conditions the reactions of N-benzyl-N’-phenacylbenzimidazolium salts resulted in the unexpected products with opening of the imidazole ring. All the products were characterized by IR,1H NMR,13CNMR, LC-MS spectroscopy. The single crystal structures of two products were determined by X-ray diffraction method.3. N-p-Nitrobenzyl-or N-phenacylphenanthrolinium bromides reacted with a series of cyclic1,3-dicarbonyl compounds in acetonitrile in the presence of triethylamine as base catalyst to give the unprecedented C-alkylated products and tandem alkylated/intramolecular O-alkylated oxazabicyclic compounds according to the structure of cyclic1,3-dicarbonyl compounds. Under similar conditions, the one-pot domino reaction of4,5-diazafluoren-9-one, reactive alkyl halides and cyclic1,3-dicarbonyl compounds yielded the complex bridged1,5-oxazabicycles in good yields. All the products were characterized by IR,1H NMR,13CNMR, LC-MS spectroscopy. The single crystal structures of three products were determined by X-ray diffraction method.