Studies On Transition-metal-catalyzed Remote C-H Bonds Functionalization Reactions

Direct C-H bonds functionalization would be an atom-and step-economical approach for the construction of C-C bonds,and has attracted significant attention in recent years.In this paper,transition-metal-catalyzed remote C(sp~3)-H bonds arylation and meta-C(sp~2)-H bonds alkylation reactions were realized.We accomplished remote C(sp~3)-H bonds arylation via regioselective cross-dehydrogenative coupling(C DC)of remote C(sp~3)-H bonds and C(sp~2)-H bonds,and we also realized meta-C(sp~2)-H bonds alkylation through three-component coupling reaction.This paper contained the following four chapters.Chapter ?In part one,though considerable progresses have been achieved in ortho-arenes C-H bonds functionalization,the remote meta-C(sp~2)-H bonds transformation still remains challenging.In this part,we introduced the strategies that enabled the remote meta-arene C-H bonds functionalization,and systematacially introduced the ruthenium-catalyzed?-activation strategy to realize the meta-arene C-H bonds transformation.In the Ru-catalyzed?-bond activation-assisted remote meta-C(sp~2)-H bonds functionalization,the cyclometalated intermediates that generated from ortho-C(sp~2)-H bonds activation influenced the arene electronically and enabled the para-functionalization to the C-metal bond of the cyclometalated intermediates rather than proceeded oxidative addition/reductive elimination chemistry,and accomplished the meta-C(sp~2)-H bonds functionalization.In part two,the method of hydrogen atom transfer(HAT)is one of the most effective tools in the activation of C(sp~3)-H bonds.However,the activation of C(sp~3)-H bonds through this strategy generally lacks regioselectivity.The Hofmann–L(?)ffler–Freytag(HLF)reaction based on intramolecular HAT was well studied and has been turned out be an efficient approach for the regioselective functionalization of remote unactivated C(sp~3)-H bonds in complex molecules.In this section,we introduced the research progress of the HLF reaction.Chapter ?Alkylated polyfluoroarenes are important organic skeletons in pharmaceuticals and materials science due to their unique effect on compound properties.In this section,a novel C u-catalyzed cross-dehydrogenative coupling reaction between N-fluorocarboxamides and polyfluoroarenes to construct alkylated polyfluoroarenes has been achieved.This reaction is characterized by its exquisite regioselectivity,redox-neutral conditions and broad substrate scope.The mechanism presented was supported by density functional theory(DFT)calculations and control experiments.Chapter ?Construction of C-C bond via cross-dehydrogenative coupling has made great progress for its atom-and step-economy.In this section,a novel photoinduced photocatalyst/Ru-cocatalyzed regioselective CDC of dual remote C-H bonds,including remote meta-C(sp~2)-H bonds in arenes and inert?-C(sp~3)-H bonds in amides,to construct meta-alkylated arenes has been developed.This reaction exhibited high compatibility,redox-neutral conditions and excellent regioselectivity.DFT calculations and control experiments explained the site-selectivity and the mechanism of this transformation.Chapter ?Intermolecular three-component dicarbofunctionalization of alkenes provides useful strategy for the synthesis of complex molecules from simple compounds.However,three-component dicarbofunctionalization of alkenes through C_Ar-H bonds functionalization process is rare.In this part,we developed a novel Ru-catalyzed regioselective alkylarylation of styrenes with alkyl halides and arenes via meta-C_Ar-H bonds functionalization to construct 1,1-diarylalkanes that generally show bioactivity.A wide range of primary,secondary and tertiary alkyl bromides,and arenes with diverse functional groups were tolerated in this reaction.In this transformation,both C(sp~3)-C(sp~3)and C(sp~3)-C(sp~2)bonds were constructed in one step.