Other resolutions: 320 × 200 pixels | 640 × 400 pixels | 800 × 500 pixels | 1,024 × 641 pixels | 1,280 × 801 pixels. According to a mechanism proposed by Sweet in 1973 the aldol condensation of ethylacetoacetate 1 and the aryl aldehyde is the rate-limiting step leading to the carbenium ion 2. Mechanism, references and reaction samples of the Biginelli Reaction Remarkably, a second urea molecule catalyzes nearly every step of the reaction.

Still date there is a number of ChemFiles 2006, 6.7, 9. Biginelli Reaction. The theoretical calculations are in accordance with the proposed mechanism of action of the iron catalyst. (b) Prior reports show that no reaction takes place at room-temperature in the absence of a catalyst. 1 ESI mass spectrum of the Biginelli reaction … The most favorable pathway starts with the condensation of the urea and benzaldehyde, followed by the addition of ethyl acetoacetate. Antimony(III) chloride-catalysed Biginelli reaction: a versatile method for the synthesis of dihydropyrimidinones through a different reaction mechanism. Scheme 3 (a) Acid-catalyzed Biginelli produced products in high yields.

Fig. Scheme 2 Our report of themicrodroplet-catalyzed Biginelli reaction using theta tip. The Biginelli reaction is a three-component reaction between an aldehyde (in many cases aromatic aldehydes give much better results than aliphatic ones), a β-keto ester (α-acidic compound) and urea or thiourea (some mono N-substituted ureas can also be employed).The Biginelli reaction was discovered in 1891 by the chemist Pietro Biginelli []. The recently developed artificial force induced reaction (AFIR) method was applied to search systematically all possible multicomponent pathways for the Biginelli reaction mechanism. The reaction mechanism of the Biginelli reaction is a series of bimolecular reactions leading to the desired dihydropyrimidinone. DOI: 10.1016/j.tet.2007.09.045. Size of this PNG preview of this SVG file: 494 × 309 pixels. This produces an iminium intermediate that is the electrophile for the nucleophilic addition of the ketoester enol. The Biginelli reaction.

proposed a mechanism in 1987 which losses the beauty of Biginelli reaction and in 1997, C. O. Kappe proposed a mechanism with high supported spectroscopic data. The mechanism for this reaction is believed to first be the condensation between the aldehyde and the urea.

Tetrahedron 2007, 63 (48) , 11822-11827. Reaction mechanism.