LETTER	Synlett 2006: 0091-0095   DOI: 10.1055/s-2005-922760
© Georg Thieme Verlag Stuttgart · New York
Microwave-Assisted, Solvent-Free Bischler Indole Synthesis
Vellaisamy Sridharan, Subbu Perumal, Carmen Avendaño, J. Carlos Menéndez*
Departamento de Química Orgánica y Farmacéutica, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain Fax: +34(91)3941822; e-Mail: josecm@farm.ucm.es;
Received 6 September 2005

Abstract

The solid-state reaction between anilines and phenacyl bromides in the presence of an equimolecular amount of sodium bicarbonate gives N-phenacylanilines. Microwave irradiation of mixtures of these compounds with anilinium bromides at 540 W for 45-60 s provides a mild, general, and environmentally friendly method for the synthesis of 2-arylindoles in 50-56% overall yields. A one-pot variation of the method, involving irradiation of 2:1 mixtures of anilines and phenacyl bromides, was also developed, allowing a simplified experimental procedure and leading to improved yields (52-75%).

Key words

indole synthesis - aniline monoalkylation - solvent-free synthesis - microwave-assisted synthesis