Molbank 2004, M359

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

Abdullah Mohamed Asiri^a*, Khaled Ahmed Alamry^a Abraham F. Jalbout^b,c and Suhong Zhang^b

^aChemistry Department, Faculty of Science, King Abdul-Aziz University, Jeddah 21413, P.O. Box 9028, Saudi Arabia. Tel.+966-2-6952293, Fax +966-2-6952293, E-mail: [email protected]

^bDepartment of Physics, Dillard University, New Orleans, LA 70112, USA

^cEJMAPS Organization, 1107 Carrolton Ave., Metairie, LA 70005, USA

Received: 13 September 2003 / Accepted: 24 October 2003 / Published: 24 February 2004

1,3-Diethyl-5-(2-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was prepared by Knoevenagel condensation of 2-methoxybenzaldehyde 1 and N,N-diethylthiobarbituric acid 2 in ethanol using piperidine as a base [1,2].

N,N-Diethylthiobarbituric acid 2 ( 1.50 g, 7.5 mmol) and 2-methoxybenzaldehyde 1 (1.02 g, 0.02 mol ) in ethanol ( 30 mL) were heated under reflux for five minutes. Piperidine (0.5 mL) was added in one portion and the reflux was continued for two hours. The reaction mixture was cooled to room temperature and the solid formed was filtered, washed with cold ethanol ( 2x 20 mL) and dried. 1,3-Diethyl-5-(2-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione 3 was recrystallized from ethanol as deep yellow crystals (2.03 g, 85%).

M.p. 108 ºC (recrystallized from EtOH, uncorrected).

UV l_max (nm; CHCl₃)/e (dm³.mol^-1.cm^-1) 406/16000 and 253/ 6060.

IR nmax ( KBr) cm^-12980, 1674 (C=O), 1632 (C=C), 1391 (CS).

Theoretical (cm^-1, AM1)= 1675.4, 1391.4, 1599.8

¹H-NMR (400 MHz; CDCL₃; Me₄Si) d 8.90 (1H, s, CH=C), 8.10 (1H, d, J = 7.84 Hz ), 7.5 (1H, d, J = 7.24 Hz, J = 7.14 Hz ), 7.02 (1H, t(dd), J= 7.6 Hz), 6.94 (1H, d, J = 8.42 Hz ), 4.51, 4.50 ( 4H, t, CH₂),3.99 ( 3H, s, CH₃O), 1.33, 1.28 ( 6H, q, CH₃).

¹³C-NMR (100 MHz, CDCL₃; Me₄Si) d 179 (C=S), 157.04, 155.6 (2xC=O), 148.16 (CH oliefinc), 134.4, 132.1, 122.5, 120.8, 119.2, 109.9, 43.7, 43.73 (CH₂), 13.3, 13.1 (CH₃).

Anal.Calc. for C₁₆H₁₈N₂O₃S ( 318.392): C 60.36, H 5.70 , N 10.07; found : C 60.21, H 5.82, N 10.16.

References

1. G. Jones, Org. React., 1967, 15, 204-599.

2. K. Tanaka, X. Chen and F. Yoneda, Tetrahedron, 1988, 44, 3241-3249.