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1,3-Diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione

Molbank 2004, 2004(1), M361; https://doi.org/10.3390/M361

Short Note
5-(3,4-Dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione
Chemistry Department, Faculty of Science, King Abdul-Aziz University, Jeddah 21413, P.O.Box 9028, Saudi Arabia
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Author to whom correspondence should be addressed.
Received: 13 September 2003 / Accepted: 4 February 2004 / Published: 24 February 2004
Molbank 2004 m361 i001
5-(3,4-Dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was prepared by Knoevenagel condensation of 3,4di-methoxybenzaldehyde 1 and N,N-diethylthiobarbituric acid 2 in ethanol using piperidine as a base [1,2].
N,N-diethylthiobarbituric acid 2 (6.0 g, 0.03 mol) and 3,4-dimethoxy- benzaldehyde 1 (5.0 g, 0.03 mol ) in ethanol (50 mL) was heated under reflux for ten minutes. Piperidine (1.5 mL) was added in one portion and the reflux was continued for further three hours. The reaction mixture was cooled to room temperature and the solid formed was filtered, washed with cooled ethanol (2x 50 mL) and dried. 5-(3,4-Dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was recrystallized from ethanol as deep yellow crystals (9.85 g, 94%).
M.p. 169 °C (EtOH, uncorrected).
UV 1max (nm; EtOH)/e (dm3.mol-1.cm-1) 260/2009, 370/2875 and 220/ 2475.
IR nmax (cm-1; KBr Disk) 1694 (C=O), 1670 (N-CO-N), 1632 (C=C).
1H-NMR (400 MHz; CDCl3; Me4Si) dH 8.48 (1H, s, olefinic Proton), 8.35 (1H), 7.84 (1H, d, J = 8.5 Hz), 6.96 (1H, d, J= 8.5 Hz), 4.51, 4.50 ( 4H, t, 2xCH2), 4.00, 3.98 (5H, s, 2xMeO), 1.33, 1.28 ( 6H, q, 2xCH3).
13C-NMR (100 MHz; CDCl3; Me4Si) d C 178.8 (C=S), 161.4, 160.9 (2xC=O), 154.74, 148.16 (CH olefinic), 133.6, 131.97, 122.5, 120.8, 117.38, 109.9, 55.4, 55.02 ( 2x CH3O), 44.1, 43.5 ( 2xCH2), 13.0, 12.7 (2xCH3).
Anal.Calc. for C17H20N2O4S ( 348.418): C 58.60, H 5.79 , N 8.04; found : C 58.45, H 5.89, N 7.95.

Supplementary materials

Supplementary File 1Supplementary File 2Supplementary File 3

References

  1. Jones, G. Org. React. 1967, 15, 204.
  2. Tanaka, K.; Chen, X.; Yoneda, F. Tetrahedron 1988, 44, 3241.
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