Thioether-Directed C4-Selective C-H Acylmethylation of Indoles Using α-Carbonyl Sulfoxonium Ylides.

Site-selective direct functionalization of an indole benzenoid core has been a great challenge due to its inherently poor reactivity. We herein demonstrate an iridium-catalyzed C4-selective acylmethylation of indoles using α-carbonyl sulfoxonium ylides as carbene precursors. This method exhibits high efficiency and broad functional group compatibility. The directing group was easily removed or converted to other functionalities after the catalysis. The potential synthetic utility of the coupling products was highlighted by constructing medium-sized polycyclic indoles.