This article describes a strategy for the copper-catalyzed asymmetric heteroarylation of yne-thiophene carbonates with indoles via remote substitution. The key to the success of this strategy lies in the design of the alkynyl group at the ortho-position of the heterocycle thiophene, enabling the formation of a triarylmethane moiety via very remote substitution. The concept of remote copper-catalyzed asymmetric transformation extends not only to yne-allylic esters but also to yne-aryl esters. The reaction readily provides a diverse array of chiral triarylmethanes with high efficiency, enantioselectivity, and excellent functional group compatibility. Moreover, facile follow-up transformations underscore their potential utility in the synthesis of various enantioenriched building blocks. Preliminary mechanistic studies support the plausibility of the remote substitution pathway.
Copper-catalyzed asymmetric propargylic substitutions have attracted considerable attention over the past fifteen years. Stereochemical control is achieved through the nucleophilic addition at the γ-position of copper-allenylidene intermediates, representing a noteworthy example of remote stereo control. As the copper-allenylidene possesses only one reactive site, nucleophilic addition exclusively displays regioselectivity at the γ-position. Many catalytic systems and activation models have been developed, resulting in diverse chiral propargylic skeletons. In 2023, Lin and He et al. reported a robust copper-catalyzed convergent regio- and enantioselective alkynylallylic substitution of yne-allylic esters, albeit still limited to the γ-position. However, the stereocontrol of copper-allenylidene with additional remote reactive sites has been studied less due to the challenges in controlling both enantioselectivities and regioselectivities. In 2022, Fang et al. disclosed copper-catalyzed remote substitution reactions of yne-allylic esters with C/N-containing nucleophiles, initiated by nucleophilic addition at the ε-position of copper complexes. Subsequently, our group reported a remote enantioselective substitution/Conia-ene annulation of yne-allylic esters with 1,3-dicarbonyl compounds, achieving a remote chiral center five bonds distant away from the copper for the first time. C=C bond installed in propargylic esters generated two reactive sites (γ and ε). Achieving the catalytic asymmetric substitution reactions of such molecules was extremely challenging but offered numerous opportunities for chemists to explore new activation modes and create new chiral chemicals. Consequently, expanding the application of copper-catalyzed remote substitutions is highly desirable.This article describes a strategy for the copper-catalyzed asymmetric heteroarylation of yne-thiophene carbonates with indoles via remote substitution. The key to the success of this strategy lies in the design of the alkynyl group at the ortho-position of the heterocycle thiophene, enabling the formation of a triarylmethane moiety via very remote substitution. The concept of remote copper-catalyzed asymmetric transformation extends not only to yne-allylic esters but also to yne-aryl esters. The reaction readily provides a diverse array of chiral triarylmethanes with high efficiency, enantioselectivity, and excellent functional group compatibility. Moreover, facile follow-up transformations underscore their potential utility in the synthesis of various enantioenriched building blocks. Preliminary mechanistic studies support the plausibility of the remote substitution pathway.
Copper-catalyzed asymmetric propargylic substitutions have attracted considerable attention over the past fifteen years. Stereochemical control is achieved through the nucleophilic addition at the γ-position of copper-allenylidene intermediates, representing a noteworthy example of remote stereo control. As the copper-allenylidene possesses only one reactive site, nucleophilic addition exclusively displays regioselectivity at the γ-position. Many catalytic systems and activation models have been developed, resulting in diverse chiral propargylic skeletons. In 2023, Lin and He et al. reported a robust copper-catalyzed convergent regio- and enantioselective alkynylallylic substitution of yne-allylic esters, albeit still limited to the γ-position. However, the stereocontrol of copper-allenylidene with additional remote reactive sites has been studied less due to the challenges in controlling both enantioselectivities and regioselectivities. In 2022, Fang et al. disclosed copper-catalyzed remote substitution reactions of yne-allylic esters with C/N-containing nucleophiles, initiated by nucleophilic addition at the ε-position of copper complexes. Subsequently, our group reported a remote enantioselective substitution/Conia-ene annulation of yne-allylic esters with 1,3-dicarbonyl compounds, achieving a remote chiral center five bonds distant away from the copper for the first time. C=C bond installed in propargylic esters generated two reactive sites (γ and ε). Achieving the catalytic asymmetric substitution reactions of such molecules was extremely challenging but offered numerous opportunities for chemists to explore new activation modes and create new chiral chemicals. Consequently, expanding the application of copper-catalyzed remote substitutions is highly desirable.