Cheap Transition Metal Mediated/catalyzed C-H Activated Alkylation With Free Radicals

The construction of carbon-carbon bonds and carbon-heteroatom bonds via transition metal catalyzed C-H bond activation becomes the focus and hotspot of chemists’research around the world,simultaneously,plays an indispensable and important role in drug sythesis and functional molecules sythesis.With the full and well devolopment of precious metal including palladium,rhodium and ruthenium catalyzed cross-coupling reactions,the cheap transtion metal catalyzed or mediated reaction has gradually moved on to the centre of organic sythesis.and it becomes a vital and promising sythetical method with the involvement of bidentate ligand as a directing group in C-H activated functionalizations.On the other hand,free radicals as a kind of highly electrophilic and highly nucleophilic particles have a strong reation activity,which results in the rarity in reports of C-H activated functionalizations with free radicals as a coupling reagent.A relatively stable and appropriate reaction active radical is crucial for an efficient C-H activated functionalization.Herein,we discuss the devolopment of novel,highly efficient C(sp~2)-C(sp~3)bonds formation reactions combining radical generating process through optical or thermal radiation with transition metal mediated or catalyzed chelation assisted orth C-H activation.The following thesis is divided into four key chapters encompassing a literature review and three research chapters.Chapter 1 commences with a general review on the development of transition metal catalyzed C-H activated functionalizations and C-H activation containing radical process,followed by a focus on cheap trasition metal mediated or catalyzed functionalizations via C-H clevage.Chapter 2 examines Photocatalytic/Cu-promoted C-H activations:Visible light inducedortho-selectiveperfluoroalkylationofbenzamidesbearingan8-aminoquinoline group.Significant decrease in yield occurs in the presence of otho-substituted benzamide derivative,which means formation of target products is sensitive with coupling reagents’steric hindrance.To highlight the uniqueness of this new transformation,a proposed mechanism was discussed based on several control experiments and previous reports.Chapter 3 discusses nickel catalyzed chelation assisted benzamides derivatives otho C-H activated methylation with DTBP as a methylating reagent.The optimized condition was obtained from the cyclization of 3-trifluoromethylbenzamide using various nickel salts,base additives,ligands and solvents.Various substituted benzamides gained high yield with the optimized condition saying that DTBP is a kind of efficient and consice methylating reagent.In addition,a plausible mechanism for the nickel catalyzed methylation is proposed on the basis of a series of control experiments and literature reports.Chapter 4 devolops an efficient method for synthesis of diarylmethane via cobalt catalyzed otho C-H activated benzylation with benzyl radicals.To obtain optimized condition,numerous reactions were conducted with different cobalt catalyst and base additives proved to be on affact to cobalt catalyzed benzylation and a variety of substituted benzamides were subject to the optimized condition to furnish good yields.A free radical capture experiments were conducted supporting the radical process,then a plausible mechanism was proposed based on radical process.