Direct C-H bond activation: palladium-on-carbon as a reusable heterogeneous catalyst for C-2 arylation of indoles with arylboronic acids

Direct C(sp 2 )-H bond functionalization of indoles with arylboronic acids is achieved using palladium supported on carbon as a reusable heterogeneous catalyst in the presence of an oxidant under mild conditions. The current protocol formed exclusive C-2 selective products without the aid of any ligand or directing group. The catalyst is reusable for up to four catalytic cycles with the retention of catalytic efficiency. We report a methodology for exclusive C-2 arylated indoles without the aid of any ligand or directing group in air.