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Synthesis 2005(3): 480-484  
DOI: 10.1055/s-2004-834939
PAPER
© Georg Thieme Verlag Stuttgart · New York

Indium(III) Bromide: A Novel and Efficient Reagent for the Rapid Synthesis of 1,5-Benzodiazepines under Solvent-Free Conditions

J. S. Yadav*, B. V. S. Reddy, S. Praveenkumar, K. Nagaiah
Division of Organic Chemistry, Indian Institute of Chemical Technology, Hyderabad-500 007, India
Fax: +91(40)27160512; e-Mail: yadav@iict.ap.nic.in;
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Publication History

Received 27 July 2004
Publication Date:
01 December 2004 (online)

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Abstract

o-Phenylenediamines (OPDA) undergo rapid condensation with ketones having hydrogens at the α-position in the presence of 10 mol% indium(III) bromide under extremely mild reaction conditions to afford the corresponding 1,5-benzodiazepines in excellent yields with high selectivity. The remarkable features of this new procedure are high conversions, short reaction times, cleaner reaction profiles, high regioselectivity in the case of unsymmetrical ketones, solvent-free conditions, and simple experimental and work-up procedures. This method works well for both electron-rich as well as electron-deficient o-phenylenediamines.

Keywords

indium - ketones - heterocycles - benzodiazepines - solvent-free reaction - drugs