Combined Gold and Photoredox Catalysis: Synthesis of 3-Alkenyl-2H-Indazoles from 2-Alkynylazobenzenes

Clara Mañas, Estíbaliz Merino*

We disclose the intramolecular synthesis of 3-alkenyl-2H-indazoles from 2-alkynylazobenzenes, promoted by a dual catalysis using AuCl3 and a ruthenium photocatalyst under visible light irradiation. This reaction proceeds through hydroamination of the alkynyl fragment. The yields are influenced by electronic factors. Control experiments suggest that both radical and polar mechanisms operate in parallel. This transformation involves C−N bond formation and a 1,2-hydride shift. Additionally, derivatization was performed to demonstrate the versatility of this methodology..

Adv. Synth. Cat. 2025
DOI: 10.1002/adsc.202400990