Photoredox Fischer Indole Synthesis

Abstract

Visible light photoredox conditions were applied to the traditional Fischer indole synthesis. N,N-Diarylhydrazones were efficiently converted into the corresponding indoles even at 30 °C by treatment with bromotrichloromethane in the presence of Ru(bpy)₃Cl₂·6H₂O as the photocatalyst. Electrochemical study revealed the viability of oxidative quenching cycle for the photocatalysis, which set the basis for proposing the redox-based reaction mechanism.

Key words

Fischer indole synthesis - [3,3]-sigmatropic rearrangement - photoredox - radicals - hydrazones - cyclic voltammetry

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