Rhodium(I)-Catalyzed Aryl C–H Carboxylation of 2-Arylanilines with CO₂

Abstract

An unprecedented Rh­(I)-catalyzed, amino-group-assisted C–H carboxylation of 2-arylanilines with CO2 under redox-neutral conditions has been developed. This reaction was promoted by a phosphine ligand with t-BuOK as the base and did not require the use of additional strong organometallic reagent. It enabled an efficient direct conversion of a broad range of 2-(hetero)­arylanilines including electron-deficient heteroarenes to various phenanthridinones. Possible intermediates of the reaction were also evaluated in the preliminary mechanistic studies.

Spirocyclizative Remote Arylcarboxylation of Non-Activated Arenes with CO2 via Visible-Light-Induced Reductive Dearomatization

“…90 Surprisingly, a chemoselective dearomatization of non-activated phenyl ring via 6-exo-trig cyclization occurred with 2-phenyl indoles substates under our reaction conditions, leading to products that were distinct from those of Yu's work (Scheme 1c). In line with our continuous interest in catalytic utilization of CO2, 91,92 which is an abundant, lowcost, sustainable and nontoxic C1 building block, herein, we report a spirocyclizative remote arylcarboxylation of arenes with CO2 by visible-light-induced reductive dearomatization of aromatics bearing naphthalenyl, phenyl, and quinolinyl groups via RPCC, providing a rapid access to valuable complex three-dimensional frameworks (Scheme 1c). Notably, a novel type of Hantzsch ester reaductant, i.e., 4-potassium carboxylate HE (4-CO2K-HE), was discovered during our study.…”

Synthetic Strategies in the Preparation of Phenanthridinones

“…Based on experimental results, a plausible mechanism was proposed. Initially, the o-arylaniline 21 reacted with the adduct of 1,5,7-triazabicyclo [99]. The reaction was carried out in the presence of a phosphine ligand and t BuOK as base.…”

“…Scheme 11. Transition metal free carboxylative cyclization of o-arylanilines.In 2019, Gao et al developed an amino group-assisted C-H carboxylation of 2-arylanilines with CO 2 through Rh(I) catalysis under redox neutral condition (Scheme 12)[99]. The reaction was carried out in the presence of a phosphine ligand and t BuOK as base.…”

Transient imine directing groups for the C–H functionalisation of aldehydes, ketones and amines: an update 2018–2020

“…Li later showed a rhodium catalysed carboxylation/ lactamisation of biaryl amines to afford δ-lactams (Scheme 28b). 82 A broad scope of biaryl amines were effective in the reaction, including some pyridine containing heteroaromatics. Secondary arylamines were not demonstrated to be reactive.…”