Work

Indole Photocatalysts and Secondary Amine Ligands Enable Nickel-Photoredox C(sp 2 )–Heteroatom Couplings

Year: 2025

Type: article

Abstract: )-heteroatom coupling reactions have emerged as a powerful tool for constructing diverse molecular architectures. However, most existing methods rely on expensive photocatalysts or specialized ligands, limiting their practicality and scalability. Here, we introduce a photocatalytic initiation strategy driven by inexpensive indoles, eliminating the need for designer photocatalysts. Additionally, we demonstrate the effectiveness of highly tunable secondary amine ligands in facilitating coupling while suppressing side reactions that sequester the Ni catalyst off-cycle. Our approach enables a broad range of amination and etherification reactions with good yields and functional group tolerance, providing a scalable platform for C-N and C-O couplings that relies on a readily available photocatalyst and cost-effective, modular ligands. Finally, mechanistic investigations suggest that the reaction operates via an unconventional aryl radical-initiated Ni(I/III) catalytic cycle, distinguishing it from traditional Ni-photoredox processes. This initiation mode, in which aryl radicals are generated under mild conditions compatible with organometallic catalysis, is expected to serve as a generalizable platform for other synthetic transformations beyond Ni-catalyzed processes.

Source: ACS Catalysis

DOI: 10.1021/acscatal.5c03251