Researches on Pyrimidines. CXXXVI. The Mechanism of Formation of Tetrahydropyrimidines by the Biginelli Reaction<sup>1</sup>

Folkers, Karl; Johnson, Treat B.

doi:10.1021/ja01336a054

Cited by 147 publications

(84 citation statements)

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“…Although different mechanistic pathways have been previously proposed, 35,36 we believe that the reaction may proceed through an initially N-acylimine 7 formed from aldehyde 3 and urea 5 (Scheme 2).…”

Section: Resultsmentioning

confidence: 85%

Multicomponent Biginelli's synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by SnCl2.2H2O

Russowsky

Lopes

Silva

et al. 2004

J. Braz. Chem. Soc.

102

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Neste trabalho é descrita a habilidade do SnCl 2 .2H 2 O como catalisador na reação de Biginelli tricomponente. Uma variedade de aldeídos aromáticos mono-e dissubstituidos foi utilizada na condensação com acetoacetato de etila e uréia ou tiouréia. A reação foi efetuada em etanol ou acetonitrila como solventes em meio neutro e os resultados representam um melhoramento com relação ao procedimento clássico de Biginelli e uma vantagem com relação ao uso de FeCl 3 .6H 2 O, NiCl 2 .6H 2 O e CoCl 2 .6H 2 O que são utilizados juntamente com HCl como co-catalisador. A síntese das 3,4-diidropirimidinonas foi conseguida em bons rendimentos.The ability of SnCl 2 .2H 2 O as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, ethyl acetoacetate and urea or thiourea is described. The reaction was carried out in acetonitrile or ethanol as solvents in neutral media and represents an improvement of the classical Biginelli protocol and an advantage in comparison with FeCl 3 .6H 2 O, NiCl 2 .6H 2 O and CoCl 2 .6H 2 O which were used with HCl as co-catalyst. The synthesis of 3,4-dihydropyrimidinones was achieved in good to excelent yields.

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Section: Resultsmentioning

confidence: 85%

Multicomponent Biginelli's synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by SnCl2.2H2O

Russowsky

Lopes

Silva

et al. 2004

J. Braz. Chem. Soc.

102

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“…Early work by Folkers and Johnson suggested that N,N''-benzylidenebisurea, i.e. the primary bimolecular condensation product of benzaldehyde and urea, is the first intermediate in this reaction [16]. In 1973 Sweet and Fissekis proposed that a carbenium ion, produced by an acid-catalyzed aldol reaction of benzaldehyde with ethyl acetoacetate, is the key intermediate and is formed in the first and limiting step of the Biginelli reaction [17].…”

Section: The Mechanism Of the Biginelli Reactionmentioning

confidence: 99%

4-Aryldihydropyrimidines via the Biginelli Condensation: Aza-Analogs of Nifedipine-Type Calcium Channel Modulators

Kappe

1998

Molecules

148

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“…During the 1930s, Folkers and Johnson proposed that 5 a, 6 a, and 7 a (Scheme 2) could be involved. [41] The N,N-benzylidenebis-A C H T U N G T R E N N U N G urea (5 a) would result from intermolecular condensation of benzaldehyde (2 a) and two equivalents of urea (4 a). InterKeywords: Biginelli reaction · density functional calculations · electrospray mass spectrometry · heterocyclic compounds · reaction mechanisms Abstract: Biginelli reactions have been monitored by direct infusion electrospray ionization mass spectrometry (ESI-MS) and key cationic intermediates involved in this three-component reaction have been intercepted and further characterized by tandem MS experiments (ESI-MS/MS).…”

Section: Introductionmentioning

confidence: 99%

The Three‐Component Biginelli Reaction: A Combined Experimental and Theoretical Mechanistic Investigation

Souza

Penha

Milagre³

et al. 2009

Chemistry A European J

112

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Biginelli reactions have been monitored by direct infusion electrospray ionization mass spectrometry (ESI-MS) and key cationic intermediates involved in this three-component reaction have been intercepted and further characterized by tandem MS experiments (ESI-MS/MS). Density functional theory calculations were also used to investigate the feasibility of the major competing mechanisms proposed for the Biginelli reaction. The experimental and theoretical results were found to corroborate the iminium mechanism proposed by Folkers and Johnson, whereas no intermediates directly associated with either the more energy demanding Knoevenagel or enamine mechanisms could be intercepted.

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Researches on Pyrimidines. CXXXVI. The Mechanism of Formation of Tetrahydropyrimidines by the Biginelli Reaction¹

Abstract: Researches on Pyrimidines. CXXXVI. The Mechanism of Formation of Tetrahydropyrimidines by the Biginelli Reaction1

Cited by 147 publications

References 0 publications

Multicomponent Biginelli's synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by SnCl2.2H2O

Multicomponent Biginelli's synthesis of 3,4-dihydropyrimidin-2(1H)-ones promoted by SnCl2.2H2O

4-Aryldihydropyrimidines via the Biginelli Condensation: Aza-Analogs of Nifedipine-Type Calcium Channel Modulators

The Three‐Component Biginelli Reaction: A Combined Experimental and Theoretical Mechanistic Investigation

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