SIMCM-41 as support for heteropolyacid based catalysts in the preparation of ethyl b-arylamino crotonates, intermediates in the synthesis of 2-methyl-4-quinolones

L. PIZZIO, G. ROMANELLI, P. VÁZQUEZ, J.C. AUTINO, C. CÁCERES, M. BLANCO.

Paris, Francia

Congreso; 13er. Congreso Internacional de Catálisis; 2004

Sociedad Internacional de Catálisis

The catalysts based on heteropolyacids with Keggin structure (HPA) and related compounds are less corrosive and produce lower amount of wastes than conventional acid catalysts, so they can be used as replacement in ecofriendly processes. The HPA were supported on several carriers in order to use these catalysts in heterogeneous liquid reactions, with the advantage of easy product recovery. The behavior of SiMCM-41 supported tungstophosphoric (TPA) and molybdophosphoric (MPA) acids in the esterification of acetic acid with isoamyl alcohol was studied. The surface of this support was also modified by attachment of amino groups to the siloxy groups, to avoid the HPA leaching. On the other hand, 4-quinolones are important compounds and valuable synthetic intermediates for derivatives that have biological activities belonging to various types, e. g. tuberculostatic. Some 4-quinolones are used as antibacterials, e. g. ciprofloxacin and other 6-fluoroquinolones. The Conrad-Limpach reaction between anilines and a ketoester is a general method to synthesize 4-quinolones. The aromatic amines react with methyl acetoacetate yielding alkyl arylaminocrotonates, acetoacetanilides, diphenylureas or 4- quinolones, depending on the temperature, solvent and molar ratio of the reactants. In this work we describe a simple procedure for the selective preparation of arylaminocrotonates, using TPA and MPA supported on SiMCM-41 and amino functionalized SiMCM-41 as catalysts. These compounds can be cyclized to 4-quinolones by heating in diphenyleter.