Rh(?)-/Metal-free-catalyzed Construction Of Five-membered N-containing Heterocyclic Compounds

Nitrogen-containing heterocyclic compounds as important part of heterocyclic compounds are widely distributed in many alkaloids.The indoles,oxazoles and triazolyl pyridines are the most typical five-membered nitrogen heterocyclic compounds,whose skeletons are widely presented in many natural products and compounds with biological activity.Therefore,researchers paid more and more attention to synthesize these five-membered nitrogen-containing heterocyclic compounds via simply,efficiently,and quickly methods.This dissertation focuses on the synthesis of five-membered nitrogen-containing heterocyclic compounds starting from simple and readily available substrates.1.We outlined the transition metal-catalyzed C-H activation reaction,summarized the application of different orientation groups in the transition metal-catalyzed C-H activation reaction in the first chapter and then summarized the synthesis of complex indole compounds in the second chapter.2.On the basis above,we developed Rh?III?-catalyzed C-H activation of arylnitrones and coupling with diazo compounds?the third chapter?or olefin compounds?the fourth chapter?to synthesize NH indoles with high selectivity and more efficiently.In these reactions,nitrone compounds act as the weakly-directed group and undergo C-H activation and cyclization reactions selectively at specific positions.These methods have good adaptability,high regioselectivity,and can obtain target products of different substituents in medium to excellent yields.3.As an inexpensive and readily available reaction substrate,?,?-unsaturated aldehydes/ketones can participate in the construction of many nitrogen heterocyclic compounds.We proposed a method to synthesis of 2,5-diphenyloxazoles using?,?-unsaturated aldehyde/ketone compounds as starting materials and ammonia acetate as nitrogen source under the action of iodobenzene acetate?the fifth chapter?.The reaction with high atom-economical transformation and does not require addition of any metal catalyst and special additives.A series of 2,5-diphenyl oxazole compounds with different substituents can be obtained at higher yield at room temperature.4.N-benzenesulfonyl hydrazide can be obtained by p-toluenesulfonyl hydrazide directly reacting with a simple aldehyde or ketone compound.As an easily leaving group,p-toluenesulfonyl group?Ts-?is widely used in the synthesis of nitrogen heterocyclic compounds.We proposed the usage of a simple and readily available N-benzene sulfonyl hydrazide directly react with 2-aminopyridine compound under the catalytic system of I₂/TBHP to construct a new C-N bond through the cleavage of theC-Nbondof2-aminopyridinetosynthesisofaseriesof1,2,4-triazolo[4,3-?]pyridines?the sixth chapter?.