Transition-metal-catalyzed Sp~2 Carbonhydrogen Bond Activation And Carbonheteroatom Bond Formation

Carbon hydrogen bond activation has drawn great researchers’ attention. Noble C-H bond of organic molecular is used instead of organic metal reagents which are difficult to be prepared and structural unstable. Environmental pollution in synthesizing intermediates can be avoided and the efficiency of organic synthesis can be improved. Through the transformation of many different types of carbon hydrogen bond, a convenient and rational synthetic route can be designed. This thesis focuses on the activation and functionalization of C(sp2)-H bond and the formation of C-S,C-X( X = Cl, Br, I) bond.In the first part, the activation of C(sp2)-H bond and the formation of C-S bond of enamides have been developed with the catalysis of silver, furnishing biologically important arylvinyl sulfides in a simple, efficient way. This method is compatible with diaryl and dialkyl disulfides. This method can also be applied to vinylic C-H selenation of enamides with diaryl diselenide. A plausible non-chain radical mechanism was proposed to understand this novel sulfenylation based on the mechanistic studies.In the next part, a cationic RhIII-catalyzed aromatic C(sp2)-H activation and electrophilic chlorination, bromination and iodination have been developed with the cheap and abundant NXS(N-halosuccinimide) as the halogen source under oxidant and additive-free condition. These halogenations can be directed by an acetamido or urea group and exhibit excellent functional group tolerance and regioselectivity. A plausible mechanism, in which the RhIII acts as a “dual activation” catalyst, is proposed to rationalize this reaction.