An exclusive catalytic C4-selective fluoroalkylation of indoles with highly active (1H, 1H-perfluoroalkyl)mesityliodonium triflate has been described. The key to its high regioselectivity is the appropriate choice of an easily accessible, cheap and removable directing group at the C3 position in the presence of a Pd(OAc)2 catalyst. Besides indole fluoroalkylation, the application of this strategy in other heteroarenes such as benzo[b]thiophene is also described.

AbstractA copper catalytic system was established for the stereoselective hydrodefluorination of gem-difluoroalkenes through C−F activation to synthesize various Z fluoroalkenes. H2O is used as the hydrogen source for the fluorine acceptor moiety. This mild catalytic system shows good-functional group compatibility, accepting a range of carbonyls as precursors to the gem-difluoroalkenes, including aliphatic, aromatic, and α,β-unsaturated aldehydes and even ketones. It serves as a powerful synthetic method for the late-stage modification of complex compounds.

AbstractThe first example of intermolecular olefination of cyclobutanone oximes with alkenes via selective C−C bond cleavage leading to the synthesis of nitriles in the presence of a cheap copper catalyst is reported. The procedure is distinguished by mild and safe reaction conditions that avoid ligand, oxidant, base, or toxic cyanide salt. A wide scope of cyclobutanones and olefin coupling components can be used without compromising efficiency and scalability. The alternative visible-light-driven photoredox process for this coupling reaction was also uncovered.

AbstractModification of commercially available monophosphine ligands with either aryl bromides or chlorides by rhodium(I)-catalyzed, tertiary phosphine directed C−H activation is described. A series of ligand libraries containing mono- and diaryl-substituted groups, having different steric and electronic properties, were obtained in high yields. Based on the outstanding properties of their parent scaffolds, the modified ligands have been found to be powerful in organic reactions.

AbstractModification of commercially available monophosphine ligands with either aryl bromides or chlorides by rhodium(I)-catalyzed, tertiary phosphine directed C−H activation is described. A series of ligand libraries containing mono- and diaryl-substituted groups, having different steric and electronic properties, were obtained in high yields. Based on the outstanding properties of their parent scaffolds, the modified ligands have been found to be powerful in organic reactions.

The first example of direct and site-selective arylation of indoles at the C6 position has been reported. The key to this high regioselectivity is the appropriate choice of the N–P(O)tBu2 directing group and the use of diaryliodonium triflate salts as the coupling partners in the presence of catalytic CuO. The protocol is distinguished by mild reaction system that avoids ligand and additives, exhibiting wide scope of indole and arene coupling components without compromising its efficiency and scalability, thus representing a significant advancement in the implementation of regioselective direct arylation of indoles.

The nickel-catalyzed direct borylation and silylation of phenolic esters has been established. The key to this highly efficient acyl C–O bond borylative and silylative cleavage depends on the appropriate choice of different ligands and additives in the presence of nickel catalyst. Both transformations exhibit good functional group compatibility and can serve as powerful synthetic tools for late-stage functionalization of complex compounds. The elucidation of key mechanistic features of this newly developed acyl C–O bond activation in esters was confirmed by two well-characterized organonickel(II) intermediates.Keywords: borylation; decarbonylation; esters; nickel; silylation

A regioselective direct arylation of arenes and olefins at the ortho position is reported. The key to the high selectivity is the appropriate choice of diaryliodonium salts as the arylating reagent in the presence of a cationic iridium(III) catalyst. The coordination of the metal with an oxygen atom or a nitrogen atom and subsequent C–H activation allows for direct arylation with coupling partners. This reaction proceeds under mild reaction conditions and with a high tolerance of various functional groups including many halide functional groups.

By developing a mild Ni-catalyzed system, a method for direct borylation of sp2 and sp3 C–N bonds has been established. The key to this hightly efficient C–N bond borylative cleavage depends on the appropriate choice of the nickel catalyst Ni(COD)2, ICy·HCl as a ligand, and the use of 2-ethoxyethanol as the cosolvent. This transformation shows good functional group compatibility and can serve as a powerful synthetic tool for gram-scale synthesis and late-stage C–N borylation of complex compounds.

A new strategy is reported for intramolecular sp3 C–H amination under mild reaction conditions using iodoarene as catalyst and m-CPBA as oxidant. This C–H functionalization involving iodine(III) reagents generated in situ occurs readily at sterically hindered tertiary C–H bonds. DFT (M06-2X) calculations show that the preferred pathway involves an iodonium cation intermediate and proceeds via an energetically concerted transition state, through hydride transfer followed by the spontaneous C–N bond formation. This leads to the experimentally observed amination at a chiral center without loss of stereochemical information.

In the past decade, direct C–H arylation of indoles has been developed with high selectivity at the C2 and C3 positions via transition-metal-catalyzed cross-coupling reactions. Here we show that C–H activation can be directed to the C7 position with high selectivity in Pd-catalyzed coupling of indoles with arylboronic acids. The key to this high regioselectivity is the appropriate choice of a phosphinoyl directing group and a pyridine-type ligand in the presence of Pd(OAc)2 catalyst. This previously elusive transformation should provide insight for the design of other cross-couplings as well.

By developing a new Ir(III)-catalyzed C–C cross-coupling, a versatile method for direct arylation of sp2 and sp3 C–H bonds in ketoximes, nitrogen-containing heterocycles, various arenes, and olefins has been established. The key to this arylation depends on the appropriate choice of catalyst and the use of diaryliodonium triflate salts as the coupling partners. This transformation has good functional group compatibility and can serve as a powerful synthetic tool for late-stage C–H arylation of complex compounds. Mechanistic studies by density functional theory calculations suggested that the sp3 C–H activation was realized by a triflate-involved concerted metalation–deprotonation process, and the following oxidation of Ir(III) to Ir(V) is the most favorable when a bistriflimide is contained in the diaryliodonium salt. Calculations indicated that both steps are enabled by initial anion exchange between the reactant complexes.

An exclusive catalytic C4-selective fluoroalkylation of indoles with highly active (1H, 1H-perfluoroalkyl)mesityliodonium triflate has been described. The key to its high regioselectivity is the appropriate choice of an easily accessible, cheap and removable directing group at the C3 position in the presence of a Pd(OAc)2 catalyst. Besides indole fluoroalkylation, the application of this strategy in other heteroarenes such as benzo[b]thiophene is also described.

A regioselective direct arylation of arenes and olefins at the ortho position is reported. The key to the high selectivity is the appropriate choice of diaryliodonium salts as the arylating reagent in the presence of a cationic iridium(III) catalyst. The coordination of the metal with an oxygen atom or a nitrogen atom and subsequent C–H activation allows for direct arylation with coupling partners. This reaction proceeds under mild reaction conditions and with a high tolerance of various functional groups including many halide functional groups.

A Pd(II)-catalyzed selective β-arylation of O-methyl ketoximes was developed using iodoarenes as the coupling partners. This transformation has good functional group compatibility and can serve as a powerful synthetic tool for late-stage C–H arylation of complex compounds. Moreover, when employing 2-iodobenzoic acids as the substrates in this developed catalytic system, a type of unexpected five-membered lactones could be formed by tandem sp3 C–H arylation and oxygenation.