Rh(Ⅲ)-catalyzed C-H Activation Construction Of Heterocyclic And Axial Chiral Compounds

Transitional metal catalyzed cross-coupling has become an effective strategy for chemical synthesis.In this field,direct C-H bond conversion is one of the most effective processes for constructing new C-C or C-X bonds.In the past decades,rhodium-catalyzed C-H functionalization has attracted much attention due to its versatility and wide application.A series of C-X(X=N or O)bond formation reactions can be achieved from the corresponding C-H bonds by using rhodium catalysts.Various studies on rhodium-catalyzed C-H functionalization reactions have been reported and significant progress has also been made in tandem,mechanism,and computational studies.Despite the high potential of the Cp*Rh(Ⅲ)complex,the studies of corresponding catalytic enantioselective transformation are still lag behind.Lacking of suitable chiral cyclopentadiene(Cp~X)ligands is an key obstacle to the development of such asymmetric reactions.In this regard,an effective set of chiral Cp~X ligands can be used with a variety of different transition metals,which can release great potential for application.In recent years,a lot of work has been reported in the construction of chiral Cp~X ligands and has been successfully applied to the asymmetric C-H bond functionalization catalyzed by transition metals,opening a new way to control the stereoselectivity of the reaction.In this paper,the construction of chiral compounds catalyzed by chiral Rh(Ⅲ)and the C-H functionalization cyclization of arenes and coupling reagents catalyzed by Cp*Rh(Ⅲ)were studied.1、Rh(Ⅲ)-Catalyzed asymmetric synthesis of axially chiral biindolyls by merging C-H activation and nucleophilic cyclization.Enantiomeric access to pentatomic biaryls is challenging due to their relatively low rotational barrier.Reported herein is the mild and highly enantioselective synthesis of 2,3′-biindolyls via underexplored integration of C-H activation and alkyne cyclization using a unified chiral Rh(Ⅲ)catalyst.The reaction proceeded via initial C-H activation followed by alkyne cyclization.A chiral rhodacyclic intermediate has been isolated from stoichiometric C-H activation,which offers direct mechanistic insight.2、Rh(Ⅲ)-Catalyzed C-H bond activation and nucleophilic cyclization to synthesis of five-five biaryls.The oxidative coupling of Indoles and o-alkynylanilines/phenols was explored by Rh(Ⅲ)catalyzed C-H bond activation with nucleophilic cyclization,generating a series of five-five biaryls with high efficiency.The reaction went smoothly in a mild conditions and with a wide substrate scope.3、Rh(Ⅲ)-Catalyzed C-C coupling of diverse arenes and 4-Acyl-1-sulfonyltriazoles via C-H activation.4-Acyl-1-sulfonyltriazoles act as versatile carbine reagents in Cp*Rh(Ⅲ)-catalyzed ortho-selective coupling with arenes via C-H activation.The coupling led to olefination with possible cyclization,depending on the nature of the arene.4、Rhodium(Ⅲ)-Catalyzed redox-neutral synthesis of isoquinolinium salts via C-H activation of imines.Redox-neutral synthesis of isoquinolinium salts via C-H activation of presynthesized or in situ formed imines and coupling withα-diazo ketoesters has been realized,where a zinc salt promotes cyclization as well as provides a counteranion.Under three-component conditions,both ketone and aldehydes are viable arene sources.The coupling of imines with diazo malonates under similar conditions afforded isoquinolin-3-ones as the coupling product.5、Rh(Ⅲ)-Catalyzedα-fluoroalkenylation of N-nitrosoanilines with 2,2-difluorovinyl tosylates via C-H bond activation.Rh(Ⅲ)-Catalyzedα-fluoroalkenylation of N-nitrosoanilines with 2,2-difluorovinyl tosylates has been realized.This reaction proceeded via chelation-assisted C–H activation,olefin insertion andβ-F elimination,leading to the synthesis of monofluoroalkenes with high Z-selectivity with respect to the olefin.This catalytic system is highly efficient over a broad range of substrates under mild and redox-neutral conditions.