A review on indole synthesis from nitroarenes: classical to modern approaches

Abstract

Indoles are highly privileged and versatile heterocyclic pharmacophores that play a crucial role in natural product synthesis, drug discovery, pharmaceuticals, and medicinal chemistry. This review provides a comprehensive analysis of various synthetic approaches to indoles with a particular emphasis on nitroarenes as key precursors. Although indoles and their derivatives have been extensively explored for their bioactivity in natural and pharmacological contexts, several classical synthetic methodologies remain underutilized. Traditionally, indole synthesis from ortho-substituted nitroarenes has been achieved through methods such as Bartoli, Reissert, Cadogan, and Leimgruber–Batcho approaches. However, recent advancements have introduced novel one-pot and tandem strategies that effectively integrate redox and hydrogenation reactions to streamline indole formation. Emerging photochemical and electrochemical techniques have also enabled the selective conversion of nitroarenes into indoles bearing well-defined functional groups. Beyond their intrinsic biological activity, indoles serve as valuable intermediates for further derivatization into compounds such as isatins and oxindoles, expanding their synthetic potential. These advancements continue to enhance the synthetic toolkit for constructing biologically active indoles, with far-reaching applications in pharmaceuticals, agrochemicals, and advanced materials.

Graphical abstract: A review on indole synthesis from nitroarenes: classical to modern approaches

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Article information

Article type
Review Article
Submitted
26 Feb 2025
Accepted
29 May 2025
First published
30 May 2025
This article is Open Access
Creative Commons BY-NC license

Org. Biomol. Chem., 2025, Advance Article

A review on indole synthesis from nitroarenes: classical to modern approaches

A. Chandra, S. C. Yadav, S. R. Cheekatla and A. Kumar, Org. Biomol. Chem., 2025, Advance Article , DOI: 10.1039/D5OB00338E

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