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Microwave-Assisted Graphite-Support Synthesis of Imidazolones Samieh Fozooni Æ Ahmad Momeni Tikdari

Received: 2 August 2007 / Accepted: 20 September 2007 / Published online: 10 October 2007 Ó Springer Science+Business Media, LLC 2007

Abstract 5(4H)-Oxazolones react with ammonium acetate under microwave irradiation and using graphite as support in an eco-friendly process. The reaction was carried out under solvent-free conditions and the imidazolones were obtained quantitatively. Moreover the reaction time was reduced too. Keywords irradiation

Graphite
Imidazolone
Microwave

1 Introduction Imidazolones have received considerable attention over the last few years due to their interesting biological activities. Some imidazolones exhibited promising pharmacological activities while some of its derivatives have been successfully applied in crop protection. Therefore, these compounds have become an attractive target for combinatorial chemistry groups involved in drug discovery and crop protection. However, attempts have been reported to synthesize these compounds by several other methods via solution or solid phase. It is notable that in most solid phase approaches the imidazolone ring is formed by an intramolecular nucleophilic attack of a guanidine moiety onto an ester or amid carbonyl [1–3].

S. Fozooni
A. M. Tikdari (&) Department of Chemistry, Shahid Bahonar University of Kerman, Kerman 76135-133, Iran e-mail: [email protected] S. Fozooni e-mail: [email protected]

5(4H)-Imidazolones were obtained by condensing glycine ester of acetimidic or phenylacetimidic acid in the presence of solvents, such as benzene, dioxane and acetone [4–7]. During the last 15 years numerous papers dealing with the use of microwave (MW) irradiation, rather than conventional heating, in organic and inorganic chemistry have reported dramatic reductions in reaction time and significant enhancement of yields and purity of the products despite the possibility of operating with pressurized reactors. However, MW irradiation of chemical reactions involving low boiling reagents and/or products can involve serious safety problems. Consequently, MWassisted solvent-free reactions (‘‘dry media’’) have been widely investigated in organic synthesis. Because most organic compounds do not interact appreciably with MW irradiation, therefore, such a support could be an ideal ‘‘sensitizer’’, able to absorb, convert, and transfer energy provided by a MW source to the chemical reagents [8, 9]. For reactions which require high temperatures the idea of using a reaction support which takes advantage of both strong MW coupling and strong adsorption of organic molecules has enthused great interest. Amorphous carbon and graphite, in their powdered form, if irradiated at 2.45 GHz, rapidly (within 1 min) reach very high temperatures ([1,300 K) and this property has been used to explain MW-assisted syntheses of inorganic solids. In these syntheses carbon is a secondary suscepter which assists the initial heating but does not react with other reactants [10].