Synthesis 2006(8): 1283-1288  
DOI: 10.1055/s-2006-926407
PAPER
© Georg Thieme Verlag Stuttgart · New York

Microwave-Assisted Oxidative Aromatization of Hantzsch 1,4-Dihydro­pyridines using Manganese Dioxide

Mark C. Bagley*, M. Caterina Lubinu
School of Chemistry, Main Building, Cardiff University, Park Place, Cardiff, CF10 3AT, UK
Fax: +44(29)20874030; e-Mail: Bagleymc@cardiff.ac.uk;
Further Information

Publication History

Received 14 October 2005
Publication Date:
27 March 2006 (online)

Abstract

4-Aryl- and 4-alkyl-1,4-dihydropyridines, prepared by microwave-assisted Hantzsch reaction, are readily and efficiently aromatized in only one minute using commercial manganese dioxide in the absence of an inorganic support at 100 °C under microwave irradiation. This rapid procedure is more efficient than microwave-assisted aromatization using Pd/C, iodine or o-iodoxybenzoic acid (IBX) and gives the dehydrogenated or 4-dealkylated product in 91-100% yield (13 examples).