Studies On Synthesis Of Heterocycles Through Free-radical Initiated Sp~3C-H Bond Activation

The sp~3C-H bond is one of the most common chemical bonds in nature.The direct C-H bond activation and functionalization is considered as the Holy Grail in chemistry.Prof.R.G.Bergman even said that C-H bond activation would promote the next industrial revolution.Selectively activation and functionalization of the sp~3C-H bond has been one of the most difficult topics of chemistry in the past decades.This thesis focuses on the selective activation and functionalization of saturated C-H bond.Our studies on this project are demonstrated in the following two parts.In the first part,the recent development of the C-H bond activation is reviewed and depicted.Especially,the saturated sp~3C-H bond activation and functionalization is emphasized here.In addition,the activation of sp~3C-H bond through single-electron transfer(SET)and free radical processes has been discussed.In the second part,our initial studies and results on the activation of sp~3C-H bond are described in details.Firstly,we developed an efficient strategy for the preparation of heterocylces via a catalyzed aerobic dehydrogenative coupling reaction of 2-hydropyrrolyl-benzoic acids and its derivatives through an intramolecular SET process.Secondary,an intramolecular oxidative dehydrogenation of 2-hydropyrrolyl-benzylic alcohols has been realized via a free radical process.These methods allow facile synthesis of N-,and O-atom containing heterocycles.Finally,the results and the possible mechanisms for these transformations are discussed.