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. 2012;7(8):e43078.
doi: 10.1371/journal.pone.0043078. Epub 2012 Aug 17.

Biginelli reaction catalyzed by copper nanoparticles

Manika Dewan  1 , Ajeet Kumar, Amit Saxena, Arnab De, Subho Mozumdar
Affiliations

Biginelli reaction catalyzed by copper nanoparticles

Manika Dewan et al. PLoS One. 2012.

Abstract

We recently reported a novel synthesis of copper nanoparticles from copper sulphate utilizing the charge-compensatory effect of ionic liquid [bmim]BF(4) and ethylene glycol. The nanoparticles were characterized and found to be stable for one year. Here we hypothesize that the stabilized nanoparticles should be able to catalyze one-pot multicomponent organic reactions. We show that the nanoparticles catalyzed Biginelli reaction at room temperature to give the product 3,4-dihydopyrimidinone (>90% yield in ~15 minutes) from aldehydes, β-diketoester (ethylacetoacetate) and urea (or thiourea). ). Remarkably, such high yields and rapid kinetics was found to be independent of the electronic density on the reactant aryl-aldehyde. This was probably because even the surface-active particles reacted faster in the presence of ionic liquid as compared to conventional methods. The heterocyclic dihydropyrimidinones (DHPMs) and their derivatives are widely used in natural and synthetic organic chemistry due to their wide spectrum of biological and therapeutic properties (resulting from their antibacterial, antiviral, antitumor and anti-inflammatory activities. Our method has an easy work-up procedure and the nanoparticles could be recycled with minimal loss of efficiency.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Synthesis of 3,4 dihydropyrimidin-2-ones at room temperature.
Figure 2
Figure 2. UV-Visible spectra of Copper nanoparticles formed in “[bmim]BF4 - ethylene glycol” system.
Figure 3
Figure 3. TEM images of Copper nanoparticles formed in “[bmim]BF4 - ethylene glycol” system.
Figure 4
Figure 4. Dynamic Light Scattering data of copper nanoparticles as prepared by this method “[bmim]BF4 - ethylene glycol” system.
Figure 5
Figure 5. XRD plot of Copper nanoparticles formed in “[bmim]BF4 - ethylene glycol” system.
Figure 6
Figure 6. Biginelli reaction catalyzed by ‘Ionic liquid- ethylene glycol’ protected copper nanoparticles at room temperaturea.
Figure 7
Figure 7. Proposed mechanism for the synthesis of 3,4-dihydropyrimidin-2-ones using ‘Ionic liquid- ethylene glycol’ protected copper nanoparticles.
See this image and copyright information in PMC

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