Abstract
One-pot solvent free three components coupling of aryl aldehydes, β-dicarbonyl compounds, urea or thiourea was performed to afford corresponding 3,4-dihydropyrimidine-2-ones and their sulfur analogs 3,4-dihydro-pyrimidine-2-thiones. It is the first report of BF 3 .ACN catalyzed the solvent-free synthesis of pyrimidone analogs.
Highlights
A mixture of benzaldehyde, ethyl acetoacetate and urea was refluxed in ethanol in the presence of BF3.ACN (Table 1) to obtain the corresponding 3,4dihydropyrimidine-2-one derivative
Among all the experimental variations, the 10 mol% BF3.ACN solvent-free condition at 90 ͦ C temperature gave the best results with 97% yield (Table 2)
Mp. 198-199°C; IR (KBr) ν: 3254, 3105, 2955, 1710, 1645, 1515, 1464, 1225 m−1; 1H NMR (300 MHz, CDCl3) δ: 1.13 (t, 3H), 2.24 (s, 3H), 3.38 (s, 3H), 4.1 (m, 2H), 5.11 (s, 1H), 6.90 (d, 2H), 7.16 (d, 2H), 7.71 (s, 1H), 9.14 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 168.0, 158.2, 152.4, 149.5, 136.7, 130.2, 123.3, 118.8, 62.4, 61.8, 49.7, 25.7, 19.7 ppm. It is the first report of cost-effective, solventfree mild protocol for the synthesis of 3,4dihydropyrimidine-2-one and 3,4-dihydropyrimidine-2thione derivatives using BF3.ACN as a catalyst
Summary
The multicomponent reactions (MCRs) are established as a simple, convenient method in synthetic chemistry.[1,2,3] MCRs are extremely economical, high yielding, less time consuming and with less side reactions.[4,5] the design of new MCRs with the green procedure has engaged huge attention, especially in the areas of drug discovery, organic synthesis and material science. Pyrimidines have extremely biological importance,[6,7,8,9,10,11] they and their analogs are considered as important bioactive heterocycles -+exhibiting interesting biological activities like antiviral,[12] antiprotozoan,[13] anti-proliferative,[14] cytotoxic activity[15] and anti-inflammatory .16. As a part of our ongoing efforts to develop new routes for the synthesis of heterocyclic compounds,[17] we like to report a solvent-free single step multicomponent synthesis of 3,4-dihydropyrimidine-2-one and 3,4-dihydropyrimidine2-thione derivatives
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