˘
F. Aslanoglu et al.
1596
in yield 0.277 g (75%). mp 169–170◦C, IR(KBr): 1737, 1635 cm−1 (C O).
1H-NMR (CDCl3): δ 7.3–7.9 (m, 15H, Harom.), 6.0 (s, 1H, -CH), 3.9 (2H,
d, CH2, J = 8.8 Hz, A part of AB system), 3.8 (2H, d, CH2, J = 8.8 Hz,
B part of AB system). Anal. Calc. for C25H18N2O2S (410). C, 73.15; H,
4.42; N, 6.82. Found: C, 73.13; H, 4.41; N, 6.80.
7-Benzoyl-6,8-diphenyl-4-oxo-2,3-dihydro-6H-pyrimido[2,3-b]
Thiazine (10)
A mixture of 1 (0.370 g, 1 mmol), 3-bromopropionic acid (1.1 mmol),
anhydrous sodium acetate (2 mmol), and acetic anhydride (2 ml) in
acetic acid (20 ml) was heated under reflux for 2 h. The residue was
treated with water (100 ml), the precipitate filtered off, and the formed
crude product was recrystallized from 2-propanol. Compound 10 was
obtained in yield 0.288 g (78%). m.p. 202–203◦C, IR(KBr): 1699, 1624
cm−1 (C O), 1H-NMR (DMSO-d6): δ 7.0–7.8 (m, 15H, Harom.), 5.6 (s,1H,
-CH), 2.8–3.2 (m, 4H, thiazine -CH2). Anal. Calc. for C26H20N2O2S (424).
C, 73.56; H, 4.75; N, 6.60. Found: C, 73.58; H, 4.74; N, 6.58.
CONCLUSIONS
This article deals with the synthesis of the 5-benzoyl-4,6-diphenyl-
1,2,3,4-tetrahydro-2-thioxopyrimidine10 by Biginelli cyclocondensation
reaction under Bro¨nsted acid catalysis in acetic acid. This protocol
has got advantages of high yield (93%), and simple work-up proce-
dure. Thereafter, various derivatives of 5-benzoyl-4,6-diphenyl-1,2,3,4-
tetrahydro-2-thioxopyrimidine was prepared because of the high bio-
logical activity of the pyrimidine derivatives.1
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