p -TsOH-Mediated Intramolecular C2-Arylation on NH-Indoles: Access of 5,10-Dihydroindeno[1,2- b ]indoles.

5,10-Dihydroindeno[1,2- b ]indole has served as an important starting precursor for BARAC-fluor reagent in medicinal chemistry. Herein, an unprecedented p -TsOH assisted intramolecular C2-arylation of NH-indoles via C(sp 2 )-CN/C(sp 2 )-H coupling, offering a series of 5,10-dihydroindeno[1,2- b ]indoles with moderate to good yields, has been showcased under redox-neutral conditions. Furthermore, successful scalability and synthetic applications highlight the practical nature of the method.