The development of a rational strategy to achieve the complete regioselectivity and the capability to switch regioselectivity is an appealing, yet challenging, puzzle in transition-metal-catalyzed oxidative Ar–H/Ar–H cross-coupling. Disclosed herein is an iridium-catalyzed C2/C4 regioselective C–H heteroarylation of indoles with the help of a pivaloyl group at the C3 position. The judicious choice of the catalytic systems allows the C2-heteroarylation of indole via a concerted metalation–deprotonation (CMD) process and the C4-heteroarylation via a trimolecular electrophilic substitution (SE3) pathway. The oxidants Cu­(OAc)2·H2O and Ag2O are demonstrated to play a vital role in the C2/C4 regioselectivity. In this Article, a heteroaryl–Ir­(III)–heteroaryl complex prior to reductive elimination is successfully isolated and characterized, which represents the first example of capturing the bis­(hetero)­aryl metallic intermediate in oxidative Ar–H/Ar–H cross-coupling. The regiodivergent heteroarylation of indoles developed herein provides an opportunity to rapidly assemble diverse C4- and C2-heteroarylated indoles.

An efficient Ir-catalyzed amidation of indoles with sulfonyl azides is disclosed, affording diverse C4-amidated indoles exclusively under mild conditions. In this protocol, a variety of indoles with commonly occurring functional groups such as formyl, acetyl, carboxyl, amide, and ester at the C3 position are well tolerated.

Disclosed herein is a highly efficient one-pot synthetic strategy to phenanthrone-type polyheterocycles via tandem rhodium­(III)-catalyzed ortho-C–H heteroarylation of indolyl ketones and copper­(II)-promoted intramolecular cyclization. This protocol enables a library of blue-emitting fluorophores with high quantum yields and narrow full widths at half-maximum to be rapidly built from readily available substrates, among of which 6,6,7,9,12-pentamethyl-6,12-dihydro-5H-benzofuro­[2,3-a]­carbazol-5-one (4a) exhibits pure blue emission with Commission Internationale de I’Eclairage coordinates of (0.15, 0.09) and a high quantum yield of 85% in CH2Cl2 solution.