Logic Design And Synthesis Of 1,2-disubstituted Benzimidazoles And 2-aryl-imidazo[1,2-a] Pyridines

Over the past two decades,there has been an explosive growth in the development of methods for C-H functionalization,and the C-H functionalization reactions have become a powerful tool in organic synthesis and these technologies have been applied to the synthesis of complex targets such as natural products and pharmaceutical agents.Today,a large and varied number of C-H functionalization methods are available in the total synthesis of natural products and occupie very important position.Heterocyclic compounds are well known for their vital function and wide distribution in nature.Many compounds play a physiological role in animals and plants containing heterocyclic structure.As an important class of nitrogen-containing heterocycles,benzimidazoles and their derivatives are very useful intermediates for the development of molecules.They not only can be used as fruit antistaling agent,and can also be used as livestock insect repellents.Because of their good biological activities,physiological activities and structural characteristics,benzimidazoles and their derivatives synthetic and application study has been a hot spot and never disconnected these decades.With these proofs as a guiding ideology,firstly,we summarizes he present research about sp3C-H functionalization and the application in organic synthesis.Secondly,we develop a novel and convenient one-pot protocol for the synthesis of 1,2-disubstituted benzimidazoles from aromatic ketones and N-methyl o-phenylendiamines.This process undergoes a logic route of consecutive iodination,Kornblum oxidation and cyclization in the presence of I2/DMSO.Finally,an efficient one-pot synthetic protocol was developed for the synthesis of 2-aryl-imidazo[1,2-a]pyridines from easily available starting materials:aromatic ketones and 2-aminopyridines.In chapter 1,since the large bond energy of C-H bond especially sp C-H bond as well as the inertness in the reaction,C-H functionalization has been the research topic in the field of organic synthesis for a long tim.Particularly,our attention was focused on the new research progress of using of C-H functionalization to construct new C-C,C-N,C-O bond respectively.In chapter 2,based on the cognition of the importance of 1,2-disubstituted benzimidazoles,we continue our study on the base of our previous work of I2/DMSO system.A novel one-pot protocol has been developed for the synthesis of 1,2-disubstituted benzimidazoles based on a logic route of consecutive iodination,Komblum oxidation and cyclization sequences from aromatic ketones and N-methyl o-phenylendiamines.All the compounds of quinoxalines are characterized by 1H NMR,13C NMR,IR,HRMS.In chapter 3,Imidazo[1,2-a]pyridines are very important heterocycles which have been found to be the core scaffold of many natural products and drugs.They have received considerable interest from the pharmaceutical industry because of their important biological activities and interesting therapeutic properties,In our previous studies,we reported an I2-promoted direct one-pot protocol for the synthesis of 2-aryl-3-(pyridine-2-ylamino)imidazo[1,2-a]pyridines from aromatic ketones and 2-aminopyridines in DMSO.As a continuous work,we develop an efficient one-pot synthetic protocol for the synthesis of 2-aryl-imidazo[1,2-a]pyridines from aromatic ketones and 2-aminopyridines in MeOH under the media of I2/CuO.