Rhodium(III)‐Catalyzed Enantioselective Coupling of Indoles and 7‐Azabenzonorbornadienes by C−H Activation/Desymmetrization

Abstract

Chiral rhodium(III) cyclopentadienyl catalysts (CpXRhIII) play significant roles in asymmetric arene C−H activation. Rh/Ir‐catalyzed couplings of arenes and strained rings have been well‐studied, but they have been limited to racemic systems. Reported in this work is the CpxRhIII/AgSbF6‐catalyzed enantioselective desymmetrizative C−C coupling of N‐pyrimidylindoles and 7‐azabenzonorbornadienes with high efficiency and enantioselectivity. The role of AgSbF6 has been established by mechanistic studies. AgSbF6 enhances the catalytic activity by suppressing the C3−H activation of the indoles, activation which would otherwise lead to catalytically inactive species.

Transition metal-catalyzed coupling of heterocyclic alkenesviaC–H functionalization: recent trends and applications

“…Li and co-workers developed the coupling of indole with 7-azabenzonorbornadiene using a Cramer-type Cp x Rh(III) complex (Scheme 78). 113 In search of additives, AgOAc/Ag 2 SO 4 proves to be a good choice, which activates the alkene and facilitates the C-H activation. A variety of indoles and azabenzonorbornadienes tolerate the reaction.…”

An Enantioselective CpxRh(III)‐Catalyzed C−H Functionalization/Ring‐Opening Route to Chiral Cyclopentenylamines

“…[26] Thet ransformation is enabled by the combination of achiral Cp x Rh I (cod) complex with amatching aroyl peroxide additive for the oxidative catalyst activation. [26] Thet ransformation is enabled by the combination of achiral Cp x Rh I (cod) complex with amatching aroyl peroxide additive for the oxidative catalyst activation.…”

“…In summary,w eh ave reported an enantioselective C À H activation/ring-opening sequence of aryl ketoxime ethers and 2,3-diazabicyclo[2.2.1]hept-5-enes for the construction of highly functionalized 2-arylated cyclopentenyl amines. [26] Thet ransformation is enabled by the combination of achiral Cp x Rh I (cod) complex with amatching aroyl peroxide additive for the oxidative catalyst activation. Notably,b oth the cyclooctadiene group and the aroyl peroxide additive displayed pronounced effects on the reaction efficiency and enantioinduction, supplying additional options for catalyst fine-tuning in asymmetric Rh III catalysis.M oreover,a symmetric alkenyl C À Hf unctionalizations of a,b-unsaturated oxime ethers were realized for the first time with Cp x Rh III catalysts.Further studies to deepen our understanding of the various additive effects on the catalytic performance and apply these catalysts in other transformations are underway in our laboratory.…”

Catalyzing Sustainable Water Splitting with Single Atom Catalysts: Recent Advances

“…SACs distributed active sites can affect electronic states, which can influence catalytic activity [33,34] . Furthermore, the selectivity toward the target products can be improved by fine‐tuning its morphology [35,36] …”