1. Indole Nucleophile Triggers Mechanistic Divergence in Ni‐Photoredox N–Arylation
- Author
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Liang, Kevin J, Taylor, Olivia R, López, Angie L, Woo, Russell J, and Bahamonde, Ana
- Subjects
Inorganic Chemistry ,Chemical Sciences ,indole functionalization * Ni-photoredox * mechanistic study ,General Chemistry ,Chemical sciences - Abstract
This study presents a Ni-photoredox method for indole N-arylation, broadening the range of substrates to include indoles with unprotected C3-positions and base-sensitive groups. Through detailed mechanistic inquiries, a Ni(I/III) mechanism was uncovered, distinct from those commonly proposed for Ni-catalyzed amine, thiol, and alcohol arylation, as well as from the Ni(0/II/III) cycle identified for amide arylation under almost identical conditions. The key finding is the formation of a Ni(I) intermediate bearing the indole nucleophile as a ligand prior to oxidative addition, which is rare for Ni-photoredox carbon-heteroatom coupling and has a profound impact on the reaction kinetics and scope. The pre-coordination of indole renders a more electron-rich Ni(I) intermediate, which broadens the scope by enabling fast reactivity even with challenging electron-rich aryl bromide substrates. Thus, this work highlights the often-overlooked influence of X-type ligands on Ni oxidative addition rates and illustrates yet another mechanistic divergence in Ni-photoredox C-heteroatom couplings.
- Published
- 2024