Synthesis of 3-nitroindoles by sequential paired electrolysis

Org Biomol Chem. 2021 Sep 22;19(36):7903-7913. doi: 10.1039/d1ob01453f.

Abstract

3-Nitroindoles are synthetically versatile intermediates but current methods for the preparation hinder their widespread application. Herein, we report that nitroenamines undergo electrochemical cyclisation to 3-nitroindoles in the presence of potassium iodide. Detailed control experiments and cyclic voltammogram studies infer the reaction proceeds via a sequential paired electrolysis process, beginning with anodic oxidation of iodide (I-) to the iodine radical (I˙), which facilitates cyclisation of the nitroenamine to give a 3-nitroindolinyl radical. Cathodic reduction and protonation generates a 3-nitroindoline that upon oxidation forms the 3-nitroindole.

Publication types

  • Research Support, Non-U.S. Gov't