750 Zayed
Asian J. Chem.
C, 43.16; H, 3.07; N, 14.38; S, 22.07 %. Calculated for
C21H18N6O6S4, C, 43.59; H, 3.11; N, 14.53; S, 22.14 %.
Synthesis of 1,3-diaryl-thiobarbituric acid (2):A mixture
of compound 1 (0.01 mol), CS2 (30 ml), DMF (50 mL) were
refluxed for 6 h, cooled then poured onto ice. The produced
solid was washed with cold ethanol and crystallized from
MeOH to give 2 m.p. 130 °C. IR (KBr, νmax, cm–1): 3100-2850
(b, aromatic & aliphatic CH), 1710, 1670 (2C=O) 1350
5H-pyrimidin-5yl)pyrimidine (8): Equimolar mixture of
compound 2 and ethyl 2-chloroacetoacetate or 3-chloroacetyl-
acetone and thiourea in sodium ethoxide (0.02 mol, 50 mL)
was refluxed for 4 h and cooled then pourd onto ice-HCl. The
obtained solid was filtered off and washed with cold water
and crystallized from EtOH to give 7 and 8, respectively 7
m.p. 221 °C; 8 m.p 265 °C.
IR (KBr, νmax, cm–1): 3120 (NH), 3000, 2980, 2870
(aromatic & aliphatic CH), 1700, 1680, 1660 & 1650 (4C=O),
1580 (C=N), 1350 (NCSN), 1480, 1440 (deformation Me),
1180 (C-S) cm-1. 1H NMR (DMSO-d6):7: δ 8.15 (s, 1H, NH),
7.9 (s, 1H, cyclic HC=C-), 7.7-7.2 (m, 12H, aromatic & thiazole
protons), 4.1 & 3.8 (each s, 2H, of Hα & Hβ of pyridine), 1.1
(s, 3H, CH3), 8: δ8.2 (s, 1H, NH), 7.8 (s, 1H, cyclic HC=C-),
7.6-7.15 (m, 12H, aromatic & thiazole protons), 4.1 (s, 1H, of
Hα of pyridine), 1.5 & 1.2 (s, two CH3) ppm. UV (DMF): 7
1
(SO2NH), 1180 (C-S) cm-1; H NMR (DMSO-d6): δ 8.8 (s,
1H, OH), 8.5 (s, 1H, cyclic -CH=), 8.2-7.3 (m, 12H, thiazole,
& aryl protons) ppm; 13C NMR (δ): 185.1 (C=S), 159.7 (C=\O),
27.5 (CH2-CO), 142 (C-N-C), 148.1 (C-S-12C), 156.8 (N-C-
S), 133.3 (C6-SO2), 131.36 (C1-N), 130.15, 129.3, 128.5, 127.2
(4C of aryl). UV (DMF), λmax 286 nm; MS: 620 (M+, 5.1), 576
(3.2), 520 (1.85), 293 (75.5), 155 (43.1), 84 (100 %). Found:
C, 42.19; H, 2.54; N, 13.17; S, 9.70 %. Calculated for
C22H16N6S5O6; C, 42.28; H, 2.58; N, 13.54; S, 9.92 %.
λ
max 286, 8 λmax 315 nm. Found (%) 7: C, 41.87; H, 2.57; N,
Synthesis of bis-fused Pyrido thiobarbituric acid (3):
A mixture of compound 2 (0.02 mol), 2-chloro-6-fluorobenzal-
dehyde (0.01 mol), ammonium acetate (0.01 mol) with few
drops of glacial acetic acid was fused under reflux for 4 h,
cooled then poured onto ice. The yielded solid was filtered off
and crystallized from DMF to give 3 m.p. 160°C. IR (KBr,
14.53; S, 24.93. Calcd. (%) for C27H20N8O7S6 C, 42.63; H,
2.63; N, 14.73; S, 25.26. Found (%) 8: C, 43.75; H, 2.84; N,
14.58; S, 24.84. Calcd. (%) for C28H22N8S6O6 C, 44.32; H,
2.90; N, 14.77; S, 25.32.
RESULTS AND DISCUSSION
ν
max, cm–1): 3140 (NH), 1710 (C=O), 1380 (NCSN), 1180
Heterocyclic ring plays an important role in biochemical
processes because the side groups of the most typical and
essential constituents of the living cells, DNA and RNA are based
on aromatic heterocycles16. Thus, a main aim of the present
work is to synthesize pyrimidinone as targets via warming of
preheated dimethyl malonate with sulfathiazole (1:2 by mole)
in dry conditions17 to produce 1,3-diketoamine 1. Heterocycli-
zation of compound 1 by refluxing with CS2 in DMF18
afforded 1,3-diarylthiobarbituric acid (2). Also, 6-aryl-1,4-
dihydro-2,4,8,10-tetraaryl-3,9-dithioxo-pyrido[2,3-d: 6,5-d]-
dipyrimidin-5,7-dione (3) was obtained from refluxing 2 with
2-chloro-6-fluorobenzaldehyde (2:1 by mole) in ammonium
acetate-glacial acetic acid (Scheme-I). Formation of 3 from 2
can be outlined in Scheme-II.
(C-S), 3010, 870 (aryl carbon), 450 (C-F) cm-1; H NMR
(DMSO-d6): δ 8.2, 6.8 (each s, NH, CH, of pyridine), 7.9-7.6
(m, 12H, thiazole & aryl protons), 7.5-7.2 (m, 3H of difluoro-
chlorophenyl) ppm; UV (DMF), λmax 320 nm. Found: C, 44.65; H,
2.30; N, 13.22; S, 23.22 %. Calculated for C51H32N13O10S10ClF;
C, 45.00; H, 2.85; N, 13.38; S, 23.52 %.
1
Trifluoroacetyl thiobarbituric acid derivative (4): A
mixture of compound 2 (2 g) and trifluoro acetic acid (5 mL)
in THF (50 mL) was refluxed for 2 h, cooled then poured onto
ice. The solid obtained filtered off and crystallized from EtOH
to give 4 m.p. 175°C.
IR (KBr, νmax, cm–1): 1710, 1680, 1650 (3C=O), 1200
(C-F), 1330 (NH-SO2-), 1180 (C-S), 3000 & 820 (str. & bending
aryl) cm-1; 1H NMR (DMSO-d6): δ 8.1, 7.2 (m, 12H, thiazole
& aryl protons), 8.2 (s, 1H, SO2NH), 3.8 (s, 1H, H-C5-CO)
ppm; Found, C, 39.82; H, 2.06; N, 11.57; S, 21.89 %. Calcu-
lated for C24H15N6O7S5F3; C, 40.22; H, 2.09; N, 11.73; S,
22.34 %.
Formation of 5-disubstituted methyl-N1,N3-diaryl-2-
thioxo-pyrimidin-4,6-diones (5 & 6):A mixture of compound
2 (0.01 mol) and 3-chloroacetyl acetone or ethyl 2-chloroaceto-
acetate (0.01 mol) in DMF (50 mL) was refluxed for 1 h, cooled
then poured onto ice. The produced solid was filtered off and
crystallized dioxane to give 5 and 6 from THF. 5 m.p. 202, 6
m.p. 285 °C.
IR (KBr, νmax, cm–1): 1720, 1710, (exocyclic 2C=O), 1680,
1660 (endocyclic 2 C=O) cm-1. Found (5): C, 44.47; H, 3.14;
N, 11.08; S, 21.11 %. Calculated for C28H24N6S5O9; C, 44.98;
H, 3.20; N, 11.22; S, 21.39 %. Found (6): C, 44.53; H, 3.02;
N, 11.35; S, 21.83 %. Calculated for C27H22N6S5O8; C, 45.12;
H, 3.06; N, 11.69; S, 22.28 %.
Presence of α-active proton of methylene group19 conta-
ining compound 2 was deduced from acylation using trifluoro-
acetic acid in boiling THF to give 5-trifluoroacetyl-1,3-diaryl-
2-thioxopyrimidin-4,6-(5H) dione (4) (Scheme-III).
It is interesting that a simple alkylation of α-active
proton of compound 2 via a nucleophilic attack to labile
chlorine atom containing α-halo alkylating agents20,21 such as
ethyl-2-chloroacetoacetate and/or 3-chloro acetyl acetone as
SN2 reactions in boiling DMF as basic-catalyzed to produce a
type of 5-alkyl derivatives 5 and 6 respectively (Scheme-III).
Finally, ring closure reactions of 1,3-bioxocompounds 5
and 6 by refluxing with thiourea in sodium ethoxide solution
afforded the thioxo pyrimidin-5-yl-pyrimidinone derivatives
7 and 8 respectively (Scheme-III). Formation of compound 8
from 2 may be takes place as shown in Scheme-IV.
Studies on static polarizabilities and hyper polarizabilities
have been performed extensively with increasing importance
of molecular orbitals calculation. Thus, a possible solubility
of the prepared compounds with sodium hydroxide solution
can be a good tool for obtaining some insight into molecular
property and as a result of tautomeric forms, in establishing
Synthesis of 2-thioxo-4-methyl-5,6-dihydro-5-(1,3-
diaryl-4,6-dioxo-5H-pyrimidin-5-yl)pyrimidin-6(1H)one
(7) and 4,6-dimethyl-2-thioxo-5-(1,3-diaryl-4,6-dioxo-