Palladium-Catalyzed Intramolecular C(sp~3)-H Functionalization Reaction

In this paper,we demonstrated the research of construction of nitrogen-containing heterocycles by C-H bond functionalization and palladium-catalyzed ligand-directed C-H functionalization reactions.The synthesis method of 3-oxo-l-picolinoylindolin-2-yl acetate was introduced.The article is divided into three parts:Nitrogen-containing heterocycles,including pyridines and indoles,are found in a myriad of biologically active compounds and natural products.For this reason,chemists continue to be interested in the construction and functionalization of heterocyclic cores.Among the many strategies available,C-H functionalization has shown increasing popularity over the past decade.Although the use of classical methods for achieving heterocycle synthesis remain the modern,norm approaches can save money,time and resources,which can ultimately make these approaches more attractive.Synthetic chemists are now beginning to use readily available materials combined with C-H functionalization to prepare common nitrogen-containing heterocycles.The development of methods for the direct conversion of C-H bonds into C-O,C-N,C-C,C-S,C-X bonds remains a severe challenge in organic synthesis.This type of mild and high-selective transformations will undoubtedly apply widely across organic chemistry,including in the synthesis of natural products,pharmaceuticals,polymers,agrochemicals and feedstock commodity chemicals.Traditional approaches for the construction of such functional groups depend on prefunctionalized starting materials for both selectivity and reactivity.However,the requirement for installing a functional group prior to the desired carbon-oxygen,carbon-halogen,carbon-nitrogen,carbon-sulfur,or carbon-carbon bond adds costly chemical steps to the overall formation of a molecule.As such,circumventing this issue will not only increase atom economy but also improve the overall efficiency of multistep synthetic sequences.We developed an efficient method for the synthesis of indoline derivatives by palladium catalysis.The strategy involves various substituted picolinamide-protected ortho-acetylaniline substrates to ultimately generate indoline compounds by sp3 C-H functionaliztion and intramolecular amination.These reactions proceed under mild conditions and obtain good yields.