Ruthenium(ii)-catalyzed intermolecular synthesis of 2-arylindolines through C-H activation/oxidative cyclization cascade.

Herein, we report a ruthenium-catalyzed 1,2-carboamination through C-H activation for the synthesis of 2-arylindolines from readily available, inexpensive, protected anilines and vinyl arenes. In earlier reports, indoline synthesis through C-H activation was demonstrated using sterically or electronically biased olefins suppressing β-hydride elimination. However, in the present protocol a ruthenium(ii)-catalyzed indoline synthesis via interrupted Heck-type manifold with unbiased styrenes is demonstrated. Mechanistically, the reaction proceeds through pyrimidine directed electrophilic ortho metalation, alkene insertion, amine coordination, and reductive elimination to construct the indoline nucleus.