Z. Pourghobadi, F. Derikvand / Chinese Chemical Letters 21 (2010) 269–272
271
Scheme 3.
It is noteworthy to mention that the catalyst is recyclable and could be reused without significant loss of activity. It
was recovered by adding acetonitrile, filtration of product, evaporation of solvent and washing with diethyl ether. The
recycled catalyst could be used in other reactions. In the model reaction the results of the first experiment and the
subsequent were almost consistent in yield after two runs (95%, 91, 90; Table 1, entry 6). It could be the reason that the
heteropolyacid can be used in the catalytic amounts not in stoichiometric amounts.
In summary, we report here a high yielding synthesis of 4,6-diarylpyrimidin-2(1H)-ones from readily available
ketones, aldehydes and urea in the presence of TMSCl using a catalytic amount of H3PMo12O40 under solvent-free
conditions. The conditions are mild and a wide range of functional groups can be tolerated. In solvent-free reactions
the purification process is simplified and the reaction is cost efficient and environmentally friendly.
1. Experimental
Melting points are uncorrected. 1H NMR spectra were recorded on a Bruker ARX 300 and 500 MHz instrument. IR
spectra were recorded from KBr disk on the FT-IR Bruker Tensor 27. The reactions were monitored by TLC. All
solvents and reagents were purchased from Aldrich and Merck with high-grade quality, and used without any
purification. All of the products were known; their physical and spectroscopic data were compared with those of
authentic samples and found to be identical [5,7,12].
In a vial equipped with a condenser, a mixture of ketone (1 mmol), aldehyde (1 mmol), urea (1.5 mmol) and TMSCl
(1 mmol) was stirred in the presence of H3PMO12O40 (2 mol%) at 70 8C. After completion of the reaction (TLC),
acetonitrile was added to the reaction mixture and the obtained solid was washed with water (20 mL) and diethyl ether
(20 mL) to eliminate the remained starting materials. All pure products were obtained in excellent yields without any
recrystallization (90–95%).
After completion of the model reaction, acetonitrile was added to the reaction mixture and the solid was filtered off.
Acetonitrile containing the catalyst was evaporated under reduced pressure. The obtained solid was washed with
diethyl ether, dried and reused for the next reaction. In the case of the model reaction the catalyst recovered and reused
for three times with only a modest loss in activity (Table 1, entry 6).
1
1a: M.p. 238–242 8C; IR (KBr) nmax = 3358, 3159, 2960, 1612, 1502 cmÀ1; H NMR (DMSO-d6, 300 MHz): d
7.56–7.67 (m, 7H, H-5 and HAr), 8.15–8.18 (m, 4H, HAr). 2b: M.p. 296–298 8C; IR (KBr) nmax = 3324, 3216, 3075,
1
2920, 1689, 1498, 1450 cmÀ1; HNMR (DMSO-d6, 300 MHz): d 2.22 (d, 1H, J = 12.92 Hz, CH2), 2.31 (dd, 1H,
J = 12.92, 2.64 Hz, CH2), 4.01 (d, 1H, J = 3.2 Hz, CH), 6.92–6.97 (m, 2H, HAr), 7.21–7.26 (m, 2H, HAr and NH),
7.39–7.47 (m, 4H, HAr), 7.64–7.67 (m, 2H, HAr), 7.55 (s, 1H, NH).
Acknowledgments
The authors are thankful from Islamic Azad University of Khorram Abad Council for the financial support.
References
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[3] H. Li, L.T.L. Wallace, K.A. Richard, Cancer Res. 45 (1985) 532.
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[5] V.F. Sedova, O.P. Shkurko, Chem. Heterocycl. Compd. 40 (2004) 194.
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Pourghobadi, Zeinab
