Ir/Ni Metallaphotoredox Catalysis for the C(sp)─H Bond α-Arylation and Alkylation of N-Alkyl N-Heterocycles.

In this work, we report a regioselective C(sp)─H bond α-arylation and alkylation of N-alkyl heterocycles (carbazoles, indoles and indazoles) using a Ir/Ni metallaphotoredox catalysis. This approach enables the direct functionalization of unactivated C(sp)─H bonds at the α-position of nitrogen heterocycles, offering an efficient alternative to traditional Sn methods and providing complementary regioselectivity to transition metal catalysis, which often results in C(sp)─H bond arylation. The reaction employs [Ir(dF(CF)ppy)(dtbbpy)][PF] as the photocatalyst and NiCl(dtbbpy) as the nickel source, facilitating single-electron transfer (SET) to promote radical generation and organometallic elementary cross-coupling steps. The methodology allows the use of diverse aryl chlorides and alkenes demonstrating broad substrate scope and high functional group tolerance. Mechanistic investigations, including radical trapping and and Stern-Volmer experiments, support a photocatalytic radical pathway. This metallaphotoredox protocol presents a robust and atom-economical route to synthesizing valuable N-alkyl-N-aryl heterocycles.