| Transition-metal-promoted C-H bond activation reaction serves as efficient and green synthetic methods in organic synthesis,exhibiting broad application in material sciences,natural products and pharmaceutical industries,etc..In the presence of transition metals,some specific functional molecules are synthesized from a direct transformation of C-H bonds into various C-C、C-X(X = O、N、S et al).In addition,the introduction of some directing groups can increase the reactivity and regioselectivity of C-H bands.In this thesis,we studied the transition-metal-promoted C-H bond activation/cyclization to synthesize heterocyclic compounds such as isocoumarins and phenazines.The thesis mainly includes the following two parts:(1)The Rhodium-catalyzed directing group-assisted annulation of arene C-H bond with vinylene carbonate toward isocoumarins: In the presence of rhodium catalyst,an annulation between sulfinylidene benzamides and vinylene carbonate was developed,proceeding with directing group-assisted ortho-C-H coupling and intramolecular alcoholysis toward nonsubstituted isocoumarins in moderate to good yields.The H/D exchange experiment indicated the cleavage of the ortho-C-H bond was probably reversible in this reaction.(2)The silver-mediated annulation of arylcarbamic acids and nitrosoarenes toward phenazines: This reaction proceeded with the sequential ortho-C-H activation of arylcarbamic acids,insertion to nitroso group and subsequent decarboxylative annulation,where carboxyamino acted as a traceless directing group,leading to a series of phenazine derivatives in moderate to good yields with complexity and diversity.Intramolecular and intermolecular KIE experiments indicated that the cleavage of the ortho-C-H bond of arylcarbamic acids rather than nitrosoarenes was probably involved as the rate-determining step in this reaction.The radical-capturing reactions showed that a radical process should be involved in this reaction. |
