Application of a Dual Catalytic Nickel/Iridium-Based Photoredox Reaction to Synthesize 2-Alkyl-N-Arylindoles in a Continuous Flow

• Jasmin C. Wilson
• Michael J. Boyd
• Simon Giroux
• Upul K. Bandarage*

• Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States

A versatile one-pot procedure for the preparation of 2-alkyl-substituted N-arylindoles is described. The method combines a visible light-mediated Ni/Ir-photoredox dual catalytic N-arylation of alkynyl anilines under continuous flow conditions with a subsequent base-mediated cyclization to afford the desired substituted indoles. The initial Ni/Ir photoredox-promoted N-arylation of alkynylanilines proceeds efficiently in a continuous flow to afford the desired products in moderate to excellent yields with a short residence time (20 min) and mild conditions at ambient temperature and without the exclusion of air. The methodology was amenable for a multi-gram scale-up to deliver 2-alkyl-N-arylindoles in high yields followed with only a single purification step.

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