Manganese‐Catalyzed Hydroarylation of Unactivated Alkenes

Abstract

Transition‐metal‐catalyzed hydroarylation of unactivated alkenes with strategic use of remote coordinating functional groups has received significant attention recently to address the issues of both low reactivity and poor selectivity. The bidentate 8‐aminoquinoline amide group is the most successfully adopted in unactivated alkenes for Pd and Ni catalysis. We describe the first manganese‐catalyzed hydroarylation of unactivated alkenes bearing diverse simple functionalities with arylboronic acids. A series of δ‐ and γ‐arylated amides, ketones, pyridines, and amines was accessed with excellent regioselectivity and in high yields. Hydroalkenylation of unactivated alkenes was also shown to be applicable under this manganese‐catalysis regime. The method features earth‐abundant manganese catalysis, easily available substrates, broad functional‐group tolerance, and excellent regioselective control.

Ligand‐Controlled Regiodivergence in Nickel‐Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**

“…[2][3] Within the expansive alkene functionalization toolkit, hydroarylation is ar apidly evolving area of synthetic methodology. [4][5][6][7][8] In these reactions,s imple arenes (ArH) or pre-functionalized arenes (ArX or ArM) can be activated for alkene addition through avariety of mechanistic pathways to furnish the corresponding hydroarylated product.…”

“…Hence,developing aligand-controlled regiodivergent version of this catalytic paradigm that is compatible with nonconjugated alkenes bearing only native functionality [12] would be synthetically enabling and would complement other regioselective/divergent catalytic hydroarylation methodology involving ArH or ArX coupling partners. [4][5][6][7][8] Previously,o ur lab has described as ingle example of regio-switchable hydrofunctionalizationu nder Pd II catalysis, [13] where regioselectivity is hypothesized to stem from ad ifference in palladacycle stability with at ridentate versus bidentate directing group (Scheme 1C). In the absence of ap olydentate directing auxiliary,w er easoned that regioselectivity control could alternatively arise from the combination of aw eakly coordinating directing group and an appropriate ancillary ligand (Scheme 1D).…”

Ligand‐Controlled Regiodivergence in Nickel‐Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids**

“…In this context, systems that offer reliable and predictable access to either regioisomer from common reagents are highly desirable (Scheme 1 A). [2–3] Within the expansive alkene functionalization toolkit, hydroarylation is a rapidly evolving area of synthetic methodology [4–8] . In these reactions, simple arenes (ArH) or pre‐functionalized arenes (ArX or ArM) can be activated for alkene addition through a variety of mechanistic pathways to furnish the corresponding hydroarylated product.…”

Ligand-Controlled Regiodivergence in Nickel-Catalyzed Hydroarylation and Hydroalkenylation of Alkenyl Carboxylic Acids

“…[2][3] Within the expansive alkene functionalization toolkit, hydroarylation is a rapidly evolving area of synthetic methodology. [4][5][6][7][8] In these reactions, simple arenes (ArH) or pre-functionalized arenes (ArX or ArM) can be activated for alkene addition through a variety of mechanistic pathways to furnish the corresponding hydroarylated product.…”

“…Hence, developing a ligand-controlled regiodivergent version of this catalytic paradigm that is compatible with nonconjugated alkenes bearing only native functionality [11] would be synthetically enabling and would complement other regioselective/divergent catalytic hydroarylation methodology involving ArH or ArX coupling partners. [4][5][6][7][8] Previously, our lab has described a single example of regioswitchable hydrofunctionalization under Pd(II) catalysis, [12] where regioselectivity is hypothesized to stem from a difference in palladacycle stability with a tridentate versus bidentate directing group. In the absence of a polydentate directing auxiliary, we reasoned that regioselectivity control could alternatively arise from the combination of a weakly coordinating directing group and an appropriate ancillary ligand.…”