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Australian Journal of Chemistry Australian Journal of Chemistry Society
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RESEARCH ARTICLE

Friedel–Crafts chemistry. Part 64. Facile syntheses of fused azepinoindoles by Jourdan–Ullmann and Friedel–Crafts approaches

Hassan A. K. Abd El-Aal https://orcid.org/0000-0003-4158-6960 A *
+ Author Affiliations
- Author Affiliations

A Chemistry Department, Faculty of Science, Assiut University, Assiut, 71516, Egypt.


Handling Editor: John Wade

Australian Journal of Chemistry 78, CH25003 https://doi.org/10.1071/CH25003
Submitted: 10 January 2025  Accepted: 16 July 2025  Published online: 5 August 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing.

Abstract

Facile and concise procedures for the construction of indole fused N-heterocyclic systems were described. A series of benzo-, pyrido-, thieno-, naphtho-fused azepinoindolones and indolo-azepinoquinolinones has been prepared starting from indol-2-acetic acids. The required starting carboxylic acids 3ae were readily obtained by the N-arylations of indoleacetic acid 1 with various aromatic halides 2ae. Subsequent carboxylic acids were esterified, followed by the addition of Grignard reagents to afford the corresponding indole-based alcohols 5ae. The key step in this protocol is the Friedel–Crafts cyclisations of these precursors promoted by AlCl3/CH3NO2 or trifluoromethanesulfonic acid (TfOH) or polyphosphoric acid (PPA) catalysts to form the desired condensed indoles in moderate to good yields.

Keywords: azepino[3,4-b]quinolinones, azepinoindolones, carbocations, Friedel–Crafts reactions, Grignard reagents, indole-fused N-heterocycles, TfOH, trifluoromethanesulfonic acid.

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