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Updated: Aug 16, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
HCl-Promoted Indole Ring Opening toward 3-Aminoaryl-2-methylquinolines: A Divergent Route to Azepino[4,5-b]quinolones
Pooja Sivaganesan1, Akheel Ahmed A1, Mrinal Kanti Das2
1Organic and Bio-Organic Chemistry Laboratory, CSIR-Central Leather Research Institute (CSIR-CLRI), Chennai600020, India.
Abstract:
A concise stepwise strategy for the synthesis of tetrahydrobenzazepinoquinoline derivatives from 2-methylindole substrates is described. C3-alkylation followed by acid-mediated intramolecular cyclization furnishes 3-aminoaryl 2-methylquinoline derivatives. Subsequent treatment with aromatic aldehydes under the same conditions enables a Pictet-Spengler-type annulation, providing access to diverse tetrahydrobenzazepinoquinoline frameworks. The method proceeds under metal-free conditions and enables rapid assembly of structurally complex fused nitrogen-containing heterocycles. The practicality of the protocol is demonstrated through scale-up synthesis, and all compounds were characterized by NMR and Mass spectroscopic analysis.
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