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

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.