Rhodium(Ⅲ)-Catalyzed Intramolecular Annulation For The Synthesis Of Pyrrolo[1,2-a] Quinoline Compounds

Pyrrolo[1,2-a]quinoline compounds have a special skeleton of polycyclic heteroaromatics which is an important component of natural products,bioactive compounds,drugs and organic materials.It is necessary to develop a method that can synthesize this skeleton directly.Based on the research work of our group,we have proposed for intramolecular cascade cyclodehydrogenation reactions to generate pyrrolo[1,2-a]quinoline polycyclic compounds and attempted it experimentally.The main research of this work is focused on the synthesis of pyrrolo[1,2-a]quinoline polycyclic compounds by the rhodium(Ⅲ)-catalyzed intramolecular tandem ring closure and oxidative dehydrogenation.The main research work of this thesis includes three parts below:In the first part,we discuss the research significance and background of the synthesis of pyrrolo[1,2-a]quinoline derivatives.In the second part,we explore optimum reaction conditions for the synthesis 5-methyl-4-phenyl-pyrrolo[1,2-a]quinoline using 1-(2-((5-phenylpent-4-yn-1-yl)amino)phenyl)ethanone as raw material.The optimal reaction conditions are finally determined through a series of condition screening(reaction atmosphere,reagent concentration,oxidant and amount,temperature,additives):pentamethylcyclopentadienyl chloride rhodium dimer(5 mol%)was used as catalyst,Copper acetate monohydrate(50 mol%)as oxidant,1,2-dichloroethane as solvent,and reaction was carried out at 100 ℃ under argon for 12 h.The third part is the exploration discussing the generality of the reaction.Raw material with different substituents can be converted with a moderate yield under optimal conditions.The pyrrolo[1,2-a]quinoline derivative was structurally characterized by 1H-NMR,13C-NMR,high-resolution mass spectrometry and the mechanism was speculated.In summary,in this article we have developed a new approach for the catalytic synthesis of pyrrole[1,2-a]quinoline compounds using transition metals,providing new theoretical and experimental references for the synthesis of pharmaceuticals and optoelectronic materials and the position of the substituent in products can be controlled very well.