Ferric chloride/tetraethyl orthosilicate as an efficient system for synthesis of dihydropyrimidinones by Biginelli reaction
Ivica Cepanec, Mladen Litvić, Anamarija Bartolinčić and Marija Lovrić
*BELUPO Pharmaceuticals, Research Department, Radnička c. 224, 10000 Zagreb,
Croatia, Email: ivica.cepanec
belupo.hr
I. Cepanec, M. Litvić, A. Bartolinčić, M. Lovrić, Tetrahedron, 2005, 61, 4275-4280.
DOI: 10.1016/j.tet.2005.02.059
Abstract
An efficient method for the Biginelli reaction of aldehydes, acetoacetate esters and urea employing tetraethyl orthosilicate in the presence of ferric chloride allows the preparation of a wide variety of substituted dihydropyrimidinones in high yields and purity under mild reaction conditions.
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Details
The document discusses an efficient method for synthesizing dihydropyrimidinones using the Biginelli reaction, which involves the condensation of aldehydes, acetoacetate esters, and urea. The study focuses on using tetraethyl orthosilicate (Si(OEt)4) in the presence of ferric chloride (FeCl3) as a catalyst. This method is particularly effective for producing a wide variety of substituted dihydropyrimidinones, including those with significant steric hindrance, in high yields and purity under mild conditions. The research compares various catalysts and finds that anhydrous FeCl3 is the most efficient, achieving yields up to 94%. The reaction is optimized by adding methyl acetoacetate dropwise to prevent polymerization. The method is applicable to both aromatic and aliphatic aldehydes, and the choice of isopropanol as the solvent minimizes transesterification by-products. The study concludes that the Biginelli reaction can be efficiently performed using Si(OEt)4 and FeCl3 in refluxing isopropanol, providing a simple and effective approach to synthesizing dihydropyrimidinones. The document also includes detailed experimental procedures and analytical data for the synthesized compounds.
Key Words
Biginelli Reaction, Multicomponent Reactions
ID: J72-Y2005-2810
