Synthesis of novel 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles as potential antimicrobial agents

Article abstract of DOI:10.1016/j.ejmech.2011.08.003

New series of 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles namely, 2-substitued thio-6-phenyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles (5a-d, 6, 7a-d, 8), 2-(4-chlorobenzylthio)-4-chloro-6-phenylpyrimidine-5-carbonitrile (9), 2-(4-chlorobenzylthio)-4-arylthio-6-phenylpyrimidine-5-carbonitriles (10a-d) and 2-(4-chlorobenzylthio)-4-arylamino-6-phenylpyrimidine-5- carbonitriles (11a-d) was synthesized and tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 5b, 5c, 6, 7a, 7b, 7c, 9 and 11a displayed marked antibacterial activity particularly against the tested Gram-positive bacteria, while compounds 6, 7c, 7d and 9 were moderately or weakly active against C. albicans.

Full text of DOI:10.1016/j.ejmech.2011.08.003

European Journal of Medicinal Chemistry 46 (2011) 4642e4647
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis of novel 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles
as potential antimicrobial agents
Ebtehal S. Al-Abdullah a, Abdul-Rahman M. Al-Obaid a, Omar A. Al-Deeb a,
,
Elsayed E. Habib b, Ali A. El-Emam a
*
a Department of Pharmaceutical Chemistry, P. O. Box 2457, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia
b Department of Microbiology, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
New series of 6-phenyl-2,4-disubstituted pyrimidine-5-carbonitriles namely, 2-substitued thio-6-
phenyl-3,4-dihydro-4-oxopyrimidine-5-carbonitriles (5aed, 6, 7aed, 8), 2-(4-chlorobenzylthio)-4-
chloro-6-phenylpyrimidine-5-carbonitrile (9), 2-(4-chlorobenzylthio)-4-arylthio-6-phenylpyrimidine-
5-carbonitriles (10aed) and 2-(4-chlorobenzylthio)-4-arylamino-6-phenylpyrimidine-5-carbonitriles
(11aed) was synthesized and tested for in vitro activities against a panel of Gram-positive and Gram-
negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 5b, 5c, 6, 7a, 7b,
7c, 9 and 11a displayed marked antibacterial activity particularly against the tested Gram-positive
bacteria, while compounds 6, 7c, 7d and 9 were moderately or weakly active against C. albicans.
Ó 2011 Elsevier Masson SAS. All rights reserved.
Received 6 May 2011
Received in revised form
1 August 2011
Accepted 2 August 2011
Available online 9 August 2011
Keywords:
Pyrimidines
Dihydro-4-oxopyrimidine
Antimicrobial activity
1. Introduction
2. Results and discussion
Pyrimidines occupy a distinct and unique place in medicine. The
chemotherapeutic efficacy of pyrimidine derivatives is related to
their ability to inhibit vital enzymes responsible for DNA biosyn-
thesis as dihydrofolate reductase (DHFR), thymidylate synthetase
(TSase), thymidine phosphorylase (TPase) and reverse transcriptase
(RTase). Large array of pyrimidine non-nucleoside derivatives
possess a variety of pharmacological properties. These properties
include anticancer [1e5], antiviral [6e14], antibacterial [15e18],
antifungal [19e22], antiprotozoal [23e29], antihypertensive
[30e32], antihistaminic [33,34], anti-inflammatory [35e37] and
central nervous activities [38e41]. Moreover, several pyrimidine
carbonitrile derivatives were reported to possess antiviral and
antimicrobial activities [42e45].
2.1. Chemistry
6-Phenyl-2-thiouracil-5-carbonitrile 4 was prepared via pro-
longed heating of benzaldehyde 1, ethyl cyanoacetate 2 and thio-
urea 3 in ethanol, in the presence of potassium carbonate [51].
Compound 4 was allowed to react with the appropriate benzyl- or
4-substituted benzyl chloride in the presence of potassium
carbonate, in DMF at room temperature for 12 h to yield the target
derivatives 5aed in 77e94% yields. The reaction of compound 4
with 2-bromomethyl-5-nitrofuran in acetone under the same
conditions yielded the 2-(5-nitrofuran-2-ylmethylthio) analogue 6
in 52% yield. Similarly, the 2-(2-alkyloxy- or alkylthioethylthio) and
the 2-(benzyloxymethylthio) derivatives 7a-d and 8 were obtained
in relatively lower yields via the reaction of compound 4 with the
appropriate 2-chloroethyl alkyl ether, 2-chloroethyl alkyl sulphide
or benzyl chloromethyl ether (Scheme 1, Table 1).
The reaction of compound 5c with phosphorus oxychloride and
N,N-dimethylaniline yielded the 4-chloropyrimidine derivative 9 in
62% yield. The pronounced reactivity of 4-halopyrimidines towards
nucleophilic reagents is utilized for the synthesis of several 2-(4-
chlorobenzylthio)-4-arylthio-6-alkylpyrimidine-5-carbonitriles.
Thus, attempted reaction of the 4-chloropyrimidines 9 with thio-
phenol or thiocresols in ethanol, in the presence of potassium
In continuation to our interest in the chemical and pharmaco-
logical properties of pyrimidine derivatives [46e50], we report
herein the synthesis of new series of 6-phenyl-2,4-disubstituted
pyrimidine-5-carbonitriles and related derivatives as potential
antimicrobial agents.
* Corresponding author. Tel.: þ966 1 4677350; fax: þ966 1 4676220.
E-mail address: elemam5@hotmail.com (A.A. El-Emam).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.08.003

E.S. Al-Abdullah et al. / European Journal of Medicinal Chemistry 46 (2011) 4642e4647
4643
O
N
O
CN
CHO
+
CN
NH2
NH2
CN
COOEt
HN
K2CO3
EtOH
ArCH2Cl
K2CO3
HN
+
S
S
S
N
H
1
2
3
5a-d
X
l
4
C
2
H
C
2
O2N
H
C
X
R
O3
C
O
K
K2
O
O
Br
2 C
O
CN
3
CN
HN
HN
X
O
S
N
S
N
R
O2N
O
6
7a-d
CN
HN
O
S
N
8
Scheme 1. Synthesis of compounds 5aed, 6, 7a,b, and 8.
carbonate, via prolonged heating for up to 24 h to yield the corre-
sponding 4-arylthio derivatives 10aed was unsuccessful, and the
starting materials were recovered unchanged. On the other hand,
carrying out the reaction in pyridine by heating for 4 h yielded the
target compounds in good yields. On the other hand, the more
nucleophilic arylamines were smoothly reacted with compound 9 in
boiling ethanol, in the presence of potassium carbonate as hydrogen
chloride acceptor to yield the corresponding 4-arylamino derivatives
11aed in 50e66% yields (Scheme 2, Table 1). The structures of all the
newly synthesized compounds were confirmed by elemental anal-
yses in addition to the IR, 1H NMR, 13C NMR, and ESI-MS spectral
data, which were in full agreement with their structures.
The results of the preliminary antimicrobial testing of
compounds 5aed, 6, 7aed, 8, 9, 10aed and 11aed (200 g/disc),
the antibacterial antibiotics Ampicillin trihydrate, Gentamicin
(100 g/disc) and the antifungal drug Clotrimazole (100 g/disc) are
m
m
m
shown in Table 2. The results revealed that the compounds showed
varying degrees of inhibition against the tested microorganisms. In
general, strong activity was displayed by the compounds 5b, 5c, 6,
7a, 7b, 7c, 9, 11a, which produced growth inhibition zones ꢀ18 mm
against one or more of the tested microorganisms. Meanwhile,
compounds 5a, 5d, 7d, 8, 10a, 10d, 11c and 11d showed moderate
activity (growth inhibition zones 14e17 mm), compound 11b
exhibited weak activity (growth inhibition zones 10e13 mm) and
compounds 10b and 10c were practically inactive against the tested
microorganisms. The Gram-positive bacteria B. subtilis and S. aureus
and to a lesser extent M. luteus are considered the most sensitive
among the tested microorganisms. The tested compounds were
generally inactive against the Gram-negative bacteria, only three
compounds (5b, 6 and 7c) showed strong activity against E. coli and
P. aeuroginosa. The inhibitory activity of the compounds against
C. albicans was rather lower than their antibacterial activity, only
compounds 6, 7c, 7d and 9 displayed moderate or weak activity.
The minimal inhibitory concentrations (MIC) [53] for the most
active compounds 5b, 5c, 6, 7a, 7b, 7c, 9 and 11a, which are shown
in Table 3, were in accordance with the results obtained in the
primary screening.
2.2. In vitro antimicrobial activity
The newly synthesized compounds 5aed, 6, 7aed, 8, 9, 10aed
and 11aed were tested for their in vitro growth inhibitory activity
against the standard strains of the Institute of fermentation of
Osaka (IFO) namely; Staphylococcus aureus IFO 3060, Bacillus sub-
tilis IFO 3007, Micrococcus luteus IFO 3232 (Gram-positive bacteria),
Escherichia coli IFO 3301, Pseudomonas aeuroginosa IFO 3448
(Gram-negative bacteria), and the yeast-like pathogenic fungus
Candida albicans IFO 0583. The primary screening was carried out
using the agar disc-diffusion method using Müller-Hinton agar
medium [52].
Table 1
Melting points, crystallization solvents, yield percentages, molecular formulae, molecular weights and of compounds 5aed, 6, 7aed, 8, 9, 10aed and 11aed.
Comp. No.
R
X
Cryst. Solvent
M.p. (ꢁC)
Yield (%)
Mol. Formula (Mol. Wt.)
18H13N3OS (319.38)
5a
5b
5c
5d
6
7a
7b
7c
7d
8
e
H
F
Cl
NO2
e
EtOH
EtOH
EtOH
EtOH
EtOH/H2O
EtOH/H2O
EtOH
EtOH
EtOH
EtOH/H2O
n-Hexane
EtOH
EtOH
EtOH
205e7
225e7
242e4
266e8
201e3
183e5
161e3
193e5
188e90
127e9
66e8
152e4
134e6
150e2
174e6
188e90
162e4
145e7
195e7
81
77
92
94
52
45
42
38
46
59
62
69
62
65
77
58
50
61
66
C
e
C18H12FN3OS (337.37)
C18H12ClN3OS (353.83)
C18H12N4O3S (364.38)
C16H10N4O4S (354.34)
C14H13N3O2S (287.34)
C15H15N3O2S (301.36)
C14H13N3OS2 (303.40)
C15H15N3OS2 (317.43)
C19H15N3O2S (349.41)
C18H11Cl2N3S (372.27)
C24H16ClN3S2 (445.99)
C25H18ClN3S2 (460.01)
C25H18ClN3S2 (460.01)
C25H18ClN3S2 (460.01)
C24H16ClFN4S (446.93)
C25H16ClF3N4S (496.93)
C25H16ClF3N4S (496.93)
C25H16ClF3N4S (496.93)
e
e
e
CH3
C2H5
CH3
C2H5
e
O
O
S
S
e
9
e
e
10a
10b
10c
10d
11a
11b
11c
11d
H
e
2-CH3
3-CH3
4-CH3
e
e
e
e
EtOH
4-F
2-CF3
3-CF3
4-CF3
EtOH/H2O
EtOH/H2O
EtOH
e
e
e
EtOH

4644
E.S. Al-Abdullah et al. / European Journal of Medicinal Chemistry 46 (2011) 4642e4647
Table 3
Cl
N
O
N
The minimal inhibitory concentrations (MIC, mg/ml) of compounds 5b, 5c, 6, 7a, 7b,
CN
CN
N
HN
7c, 9, 11a, the broad spectrum antibacterial drugs Gentamicin and Ampicillin against
Staphylococcus aureus IFO 3060 (SA), Bacillus subtilis IFO 3007 (BS), Micrococcus
luteus IFO 3232 (ML), Escherichia coli IFO 3301 (EC) and Pseudomonas aeuroginosa IFO
3448 (PA).
POCl3 / PhN(Me)2
Cl
S
S
9
5c
Cl
ArSH
Comp. No.
Minimal Inhibitory Concentration (MIC, m
g/ml)a
H
2
N
E
Pyridine
X
r
A
R
H
SA
BS
ML
EC
PA
O
t
5b
5c
6
7a
7b
7c
4
8
0.5
8
4
ND
2
2
2
8
1
2
4
8
1
2
4
8
1
ND
ND
ND
4
2
2
8
ND
2
ND
ND
ND
ND
0.5
2
ND
ND
4
ND
ND
ND
ND
1
HN
S
N
CN
CN
N
S
N
S
N
Cl
11a-d
Cl
10a-d
11a
Gentamicin
Ampicillin
Scheme 2. Synthesis of compounds 9, 10aed and 11aed.
2
0.5
2
a
ND: Not determined.
According to the results of the antimicrobial activity, it would be
conclude that the 2-(substituted thio) substituents in the 6-phenyl-
3,4-dihydro-4-oxopyrimidine-5-carbonitriles derivatives 5aed, 6,
7aed and 8, which are generally active, greatly influenced the
antibacterial activity. In the benzyl series 5aed, the activity of the
4-fluoro- and chlorobenzyl derivatives 5b and 5c was superior to
the benzyl and 4-nitrobenzyl analogues 5a and 5d. In addition, the
activity of the 2-alkoxyethylthio derivatives 7a and 7b were higher
than their alkythioethylthio analogues 7c and 7d, which possessed
higher activity against the tested Gram-negative bacteria, beside
moderate activity against C. albicans. The 2-(5-nitrofuran-2-
ylmethylthio) substituent (compound 6) was optimal for antimi-
crobial activity, while the 2-benzyloxymethylthio substituent
(compound 8) diminished the antimicrobial activity. The antimi-
crobial activity of the 2-(4-chlorobenzylthio)-4-substituted 6-
phenylpyrimidine-5-carbonitriles derivatives 9, 10aed and 11aed
derivatives was greatly influenced by the nature of the 4-
substituents, the optimal activity was attained in the 4-chloro
analogue 9 which possessed potent and broad spectrum activity.
The replacement of the 4-chloro substituent with an arylthio group
dramatically diminished the antimicrobial activity (compounds
10aed). On the other hand, the activity is partially retained against
the tested Gram-positive bacteria in the 4-arylamino derivatives
11aed.
3. Conclusion
In this study, new series of 6-phenyl-2,4-disubstituted pyrimi-
dine-5-carbonitriles were synthesized and their antimicrobial
activity against a panel of Gram-positive and Gram-negative
bacteria and the yeast-like pathogenic fungus C. albicans. Several
newly synthesized derivatives displayed promising antibacterial
activity compared to known antibacterial drugs. Though, the
mechanism of the antibacterial activity needs further investiga-
tions, which are in progress.
4. Experimental protocols
Melting points (ꢁC) were measured in open glass capillaries
using a Branstead 9001 electrothermal melting point apparatus and
are uncorrected. NMR spectra were obtained on a Bruker AC 500
Ultra Shield NMR spectrometer (Fällanden, Switzerland) operating
at 500.13 MHz for 1H and 125.76 MHz for 13C, the chemical shifts
Table 2
Antimicrobial activity of compounds 5aed, 6, 7aed, 8, 10aed and 11aed (200
8 mm disc), the broad spectrum antibacterial drugs Gentamicin (100 g/8 mm disc),
Ampicillin (100 g/8 mm disc) and the antifungal drug Clotrimazole (100 g/8 mm
disc) against Staphylococcus aureus IFO 3060 (SA), Bacillus subtilis IFO 3007 (BS),
Micrococcus luteus IFO 3232 (ML), Escherichia coli IFO 3301 (EC), Pseudomonas
aeuroginosa IFO 3448 (PA), and Candida albicans IFO 0583 (CA).
mg/
m
m
m
are expressed in
d (ppm) downfield from tetramethylsilane (TMS)
Diameter of Growth Inhibition Zone (mm)a
as internal standard; coupling constants (J) are expressed in Hz.
Electrospray ionization mass spectra (ESI-MS) were recorded an
Agilent 6410 Triple Quad tandem mass spectrometer at 4.0 and
3.5 kV for positive and negative ions, respectively. Elemental
analyses (C, H, N, S) were in full agreement with the proposed
structures within ꢂ0.4% of the theoretical values. Monitoring the
reactions and checking the purity of the final products were carried
out by thin layer chromatography (TLC) using silica gel precoated
aluminium sheets (60 F254, Merck) and visualization with ultravi-
olet light (UV) at 365 and 254 nm. The bacterial strains and
C. albicans fungus were obtained from the Institute of Fermentation
of Osaka (IFO), Osaka, Japan. The reference drugs Gentamicin
sulphate (CAS 1405-41-0), Ampicillin trihydrate (CAS 7177-48-2)
and Clotrimazole (CAS 23593-75-1) were obtained from Sigma-
Aldrich Chemie GmbH, Taufkirchen, Germany.
Comp. No.
SA
BS
ML
EC
PA
CA
5a
5b
5c
5d
6
7a
7b
7c
7d
8
9
10a
10b
10c
10d
11a
16
22
20
14
33
18
21
16
12
14
24
12
e
17
26
19
17
28
22
24
18
16
16
26
14
e
16
21
19
13
24
17
17
15
12
13
18
12
e
e
e
e
18
14
12
22
12
14
21
16
e
14
12
e
e
e
e
21
10
11
18
14
e
11
e
e
14
12
e
16
e
14
e
12
e
e
e
e
e
e
e
e
e
e
14
16
12
14
15
26
23
NT
13
18
12
14
17
25
21
NT
11
19
10
11
13
18
19
NT
e
e
e
e
e
e
11b
11c
11d
Gentamicin
Ampicillin
Clotrimazole
e
e
e
4.1. 2-(Benzyl- or 4-substituted benzylthio)-6-phenyl-3,4-dihydro-
4-oxopyrimidine-5-carbonitriles (5aed)
e
e
e
e
e
e
20
17
NT
19
17
NT
NT
NT
21
To a solution of compound 4 (2.13 g, 0.01 mol) in DMF (10 mL),
the appropriate arylmethyl chloride (0.01 mol) and anhydrous
potassium carbonate (1.38 g, 0.01 mol) were added and the mixture
a
(-): Inactive (inhibition zone < 10 mm). (NT): Not tested.

E.S. Al-Abdullah et al. / European Journal of Medicinal Chemistry 46 (2011) 4642e4647
4645
was stirred at room temperature for 12 h. Water (15 mL) was added
and the mixture was stirred for further 30 min. The separated solid
was filtered, washed with cold water, dried and crystallized from
CH3CH2), 3.65e3.67 (m, 2H, OCH2), 7.56e7.64 (m, 3H, AreH),
7.94e7.95 (m, 2H, AreH), 13.85 (s, 1H, NH). 13C NMR: 15.51 (CH3),
30.69 (CH2S), 65.90 (CH3CH2), 68.23 (OCH2), 93.59 (C-5), 116.43
(CN), 129.06, 129.15, 132.25, 135.75 (AreC), 161.46 (C-2), 166.39 (C]
O), 167.77 (C-6). ESI-MS, m/z (Rel. Int.): 300.3 (Mꢃ, 100), 76.0 (3). 7c:
ethanol. 5a: 1H NMR (DMSO-d6):
d 4.55 (s, 2H, CH2), 7.26e7.34 (m,
3H, AreH), 7.42 (d, 2H, AreH, J ¼ 7.0 Hz), 7.57e7.64 (m, 3H, AreH),
7.94 (d, 2H, AreH, J ¼ 7.0 Hz), 13.86 (s, 1H, NH). 13C NMR: 34.73
(CH2), 93.70 (C-5), 116.29 (CN), 127.99, 129.01, 129.06, 129.21,
129.52, 132.25, 132.70, 136.88 (AreC), 161.50 (C-2), 166.15 (C]O),
168.02 (C-6). ESI-MS, m/z (Rel. Int.): 317.3 (Mꢃ, 100), 91.1 (23). 5b:
1H NMR (DMSO-d6):
d 2.07 (s, 3H, CH3), 2.81e2.84 (m, 2H, SCH2),
3.45e3.48 (m, 2H, CH2S), 7.56e7.62 (m, 3H, AreH), 7.93e7.95 (m,
2H, AreH), 13.62 (s, 1H, NH). 13C NMR: 14.38 (CH3), 30.47 (CH2S),
32.96 (SCH2), 93.68 (C-5), 116.34 (CN), 129.01, 129.17, 132.24, 135.74
(AreC), 161.45 (C-2), 166.24 (C]O), 167.90 (C-6). ESI-MS, m/z (Rel.
1H NMR (DMSO-d6):
d 4.54 (s, 2H, CH2), 7.13e7.17 (m, 2H, AreH),
7.45e7.48 (m, 2H, Ar-H), 7.57e7.65 (m, 3H, AreH), 7.93e7.95 (m,
2H, Ar-H), 13.80 (s, 1H, NH). 13C NMR: 33.86 (CH2), 93.79 (C-5),
116.31 (CN), 115.71, 129.08, 128.20, 131.59, 132.27, 133.27, 135.69,
162.92 (AreC), 160.98 (C-2), 166.06 (C]O), 167.78 (C-6). ESI-MS, m/z
(Rel. Int.): 336.3 (Mꢃ, 100), 109.1 (11). 5c: 1H NMR (DMSO-d6):
Int.): 302.3 (Mꢃ, 100). 7d: 1H NMR (DMSO-d6):
d 1.12 (t, 3H, CH3,
J ¼ 7.2 Hz), 2.77e2.80 (m, 2H, SCH2), 3.38e3.41 (m, 4H, CH2S &
CH3CH2), 7.55e7.63 (m, 3H, AreH), 7.65e7.88 (m, 2H, AreH), 13.75
(s, 1H, NH). 13C NMR: 13.25 (CH3), 28.55 (CH2S), 31.85 (CH3CH2),
33.65 (SCH2), 94.05 (C-5),115.99 (CN),128.20,129.65,132.80,136.25
(AreC), 160.85 (C-2), 165.45 (C]O), 169.05 (C-6). ESI-MS, m/z (Rel.
d
4.54 (s, 2H, CH2), 7.37 (d, 2H, Ar-H, J ¼ 8.5 Hz), 7.44 (d, 2H, Ar-H,
J ¼ 8.5 Hz), 7.57e7.64 (m, 3H, AreH), 7.92e7.94 (m, 2H, AreH),
13.82 (s, 1H, NH). 13C NMR: 33.86 (CH2), 93.79 (C-5), 116.29 (CN),
128.93, 129.08, 129.20, 131.37, 132.27, 132.57, 135.64, 136.26 (AreC),
161.61 (C-2), 165.98 (C]O), 167.78 (C-6). ESI-MS, m/z (Rel. Int.): 354.1
(Mꢃ þ2, 29), 352.3 (Mꢃ, 100), 126.1 (6), 124.0 (22). 5d: 1H NMR
Int.): 316.4 (Mꢃ,100). 8: 1H NMR (DMSO-d6):
d
4.75 (s, 2H, PhCH2O),
5.58 (s, 2H, OCH2S), 7.21e7.65 (m, 10H, AreH), 13.08 (s, 1H, NH). 13
C
NMR: 69.65 (OCH2S), 77.89 (PhCH2O), 95.65 (C-5), 114.95 (CN),
127.22, 127.56, 128.0, 128.12, 128.26, 128.70, 135.74, 138.24 (AreC),
160.92 (C-6), 166.48 (C]O), 177.35 (C-2). ESI-MS, m/z (Rel. Int.):
348.3 (Mꢃ, 100), 91.1 (34).
(DMSO-d6):
d 4.44 (s, 2H, CH2), 7.47e7.48 (m, 3H, AreH), 7.69 (d,
2H, AreH, J ¼ 8.5 Hz), 7.68e7.76 (m, 2H, AreH), 8.15 (d, 2H, AreH,
J ¼ 8.5 Hz), 13.82 (s, 1H, NH). 13C NMR: 33.53 (CH2), 90.06 (C-5),
115.20 (CN), 120.15, 123.88, 128.57, 130.31, 130.48, 137.94, 146.78,
148.27 (AreC), 160.01 (C-2), 167.63 (C]O), 170.87 (C-6). ESI-MS, m/z
(Rel. Int.): 363.2 (Mꢃ, 100), 136.1 (8).
4.4. 2-(4-Chlorobenzylthio)-4-chloro-6-phenylpyrimidine-5-
carbonitrile (9)
Compound 5c (17.7 g, 0.05 mol) was added portionwise to
a mixture of phosphorus oxychloride (19.2 mL) and N,N-dimethy-
laniline (10.3 mL) over a period of 10 min with stirring. The mixture
was then heated under reflux for 1 h. On cooling, the mixture was
poured onto crushed ice (200 g), stirred for 30 min and extracted
with diethyl ether (2 ꢄ 200 mL). The ethereal extract was dried over
anhydrous sodium sulphate and evaporated under vacuum at room
temperature to yield the crude product as oily liquid. The crude
product was purified by flash silica gel column chromatography
4.2. 2-(5-Nitrofuran-2-ylmethylthio)-6-phenyl-3,4-dihydro-4-
oxopyrimidine-5-carbonitrile (6)
To a solution of compound 4 (2.13 g, 0.01 mol), in acetone
(15 mL), 2-bromomethyl-5-nitrofuran (2.06 g, 0.01 mol) and
anhydrous potassium carbonate (1.38 g, 0.01 mol) were added and
the mixture was stirred at room temperature for 12 h. The solvent
was then distilled in vacuo at room temperature. Water (15 mL) was
added to the residue the mixture was stirred for further 30 min. The
obtained solid was filtered, washed with cold water, dried and
using chloroform as an eluent. 1H NMR (DMSO-d6):
d 4.35 (s, 2H,
CH2), 7.24 (d, 2H, AreH, J ¼ 7.5), 7.20 (d, 2H, AreH, J ¼ 7.5),
7.23e7.46 (m, 5H, AreH). 13C NMR: 42.95 (CH2), 106.10 (C-5), 116.25
(CN), 127.31, 128.52, 128.90, 130.75, 132.01, 133.99, 134.80, 137.05
(AreC), 160.66 (C-4), 171.50 (C-6), 174.20 (C-2). ESI-MS, m/z (Rel.
Int.): 376.4 (Mþ þ4, 11), 374.4 (Mþ þ2, 70), 372.4 (Mþ, 100).
crystallized from aqueous-ethanol. 1H NMR (DMSO-d6):
d 4.71 (s,
2H, CH2), 6.72 (d, 1H, Furan-H, J ¼ 3.5 Hz), 7.55e7.59 (m, 2H, AreH),
7.62e7.65 (m, 2H, AreH), 7.96e7.98 (m, 2H, Furan-H & AreH), 13.88
(s, 1H, NH). 13C NMR: 27.18 (CH2), 93.85 (C-5), 116.17 (CN), 113.16,
129.08, 129.39, 132.38, 135.48 (AreC), 112.92, 114.76, 151.39, 155.79
(Furan-C), 161.85 (C-2), 165.06 (C]O), 167.74 (C-6). ESI-MS, m/z (Rel.
Int.): 353.2 (Mꢃ, 100).
4.5. 2-(4-Chlorobenzylthio)-4-arylthio-6-phenylpyrimidine-5-
carbonitriles (10aed)
To a solution of compound 9 (1.86 g, 5 mmol) in dry pyridine
(5 mL), the appropriate arylthiol (5 mmol) was added and the
mixture was heated under reflux for 4 h. On cooling, the solvent was
then distilled in vacuo, and water (10 mL) was added to the residue.
The separated precipitate was filtered, washed with cold water,
4.3. 2-(2-Alkoxyethylthio or 2-alkylthioethylthio)-6-phenyl-3,4-
dihydro-4-oxopyrimidine-5-carbonitriles (7a-d) and 2-
benzylyloxymethylthio-6-phenyl-3,4-dihydro-4-oxopyrimidine-5-
carbonitrile (8)
dried and crystallized from ethanol. 10a: 1H NMR (DMSO-d6):
d 4.09
To a solution of compound 4 (2.13 g, 0.01 mol) in DMF (10 mL),
the appropriate halide (2-chloroethyl alkyl ether, 2-chloroethyl
alkyl sulphide or benzyl chloromethyl ether) (0.01 mol) and
anhydrous potassium carbonate (1.38 g, 0.01 mol) were added and
the mixture was stirred at room temperature for 12 h. Water
(15 mL) was added and the mixture was stirred for further 30 min.
The separated solid was filtered, washed with cold water, dried and
(s, 2H, CH2), 6.80e7.22 (m, 5H, AreH), 7.26 (d, 2H, AreH, J ¼ 8.5 Hz),
7.50e7.64 (m, 7H, AreH). 13C NMR: 44.90 (CH2), 101.0 (C-5), 116.80
(CN), 124.66, 127.05, 128.24, 128.66, 129.0, 129.34, 130.08, 130.99,
132.60, 133.98, 136.90, 138.22 (AreC), 170.52, 172.98, 176.26 (C-2, C-4
& C-6). ESI-MS, m/z (Rel. Int.): 448.3 (Mþ þ2, 38), 446.3 (Mþ, 100).
10b: 1H NMR (DMSO-d6):
d 2.44 (s, 3H, CH3), 4.12 (s, 2H, CH2),
6.88e7.20 (m, 4H, AreH), 7.24 (d, 2H, AreH, J ¼ 8.5 Hz), 7.45e7.68
(m, 7H, AreH). 13C NMR: 20.05 (CH3), 44.91 (CH2), 100.95 (C-5),
116.80 (CN), 124.66, 125.28, 126.40, 128.04, 128.80, 129.45, 129.30,
130.06, 131.98, 132.65, 134.06, 136.95, 138.25, 143.50 (AreC), 169.88,
173.08, 176.20 (C-2, C-4 & C-6). ESI-MS, m/z (Rel. Int.): 462.3 (Mþ þ2,
crystallized. 7a: 1H NMR (DMSO-d6):
d 3.27 (s, 3H, CH3), 3.44e3.46
(m, 2H, CH2S), 3.62e3.64 (m, 2H, OCH2), 7.57e7.64 (m, 3H, AreH),
7.94 (d, 2H, AreH, J ¼ 7.0 Hz), 13.89 (s, 1H, NH). 13C NMR: 30.45
(CH2S), 58.41 (CH3), 70.21 (OCH2), 93.59 (C-5), 116.35 (CN), 129.08,
129.15, 132.25, 135.74 (AreC), 161.26 (C-2), 165.89 (C]O), 167.70 (C-
6). ESI-MS, m/z (Rel. Int.): 286.3 (Mꢃ, 100), 76.0 (4). 7b: 1H NMR
40), 460.3 (Mþ, 100). 10c: 1H NMR (DMSO-d6):
d 2.39 (s, 3H, CH3),
4.10 (s, 2H, CH2), 6.82e7.18 (m, 6H, AreH), 7.22 (d, 2H, AreH,
(DMSO-d6):
d
1.08 (t, 3H, CH3, J ¼ 7.0 Hz), 3.43e3.48 (m, 4H, CH2S &
J ¼ 8.5 Hz), 7.36e7.60 (m, 5H, AreH). 13C NMR: 21.26 (CH3), 44.90

4646
E.S. Al-Abdullah et al. / European Journal of Medicinal Chemistry 46 (2011) 4642e4647
(CH2), 98.85 (C-5), 117.06 (CN),125.25, 125.45, 127.44, 128.26, 129.06,
129.26, 129.35, 129.99, 131.25, 132.05, 136.25, 136.95, 138.25, 139.50
(AreC), 169.85, 173.10,176.55 (C-2, C-4 & C-6). ESI-MS, m/z (Rel. Int.):
concentration of 128
were prepared (128, 64, 32, ., 0.5
m
g/mL. The twofold dilutions of the solution
mg/mL). The microorganism
suspensions at 106 CFU/mL (colony forming unit/mL) concentra-
tions were inoculated to the corresponding wells. The plates were
incubated at 36 ꢁC for 24 and 48 h for the bacteria and C. albicans,
respectively. The MIC values were determined as the lowest
concentration that completely inhibited visible growth of the
microorganism as detected by unaided eye.
462.3 (Mþ þ2, 41), 460.3 (Mþ, 100). 10d: 1H NMR (DMSO-d6):
d 2.36
(s, 3H, CH3), 4.15 (s, 2H, CH2), 6.85 (d, 2H, AreH, J ¼ 8.5 Hz), 7.01e7.18
(m, 4H, AreH), 7.23 (d, 2H, AreH, J ¼ 8.5 Hz), 7.38e7.49 (m, 5H,
AreH). 13C NMR: 23.05 (CH3), 42.95 (CH2), 97.85 (C-5), 116.25 (CN),
125.35, 126.38, 126.90, 127.22, 127.98, 128.24, 128.98, 129.36, 130.05,
132.0, 136.16, 138.06 (AreC), 168.95, 173.15, 176.80 (C-2, C-4 & C-6).
EI-MS, m/z (Rel. Int.): 462.3 (Mþ þ2, 44), 460.3 (Mþ, 100).
Acknowledgements
4.6. 2-(4-Chlorobenzylthio)-4-arylamino-6-phenylpyrimidine-5-
carbonitriles (11aed)
The financial support of the Deanship of Scientific Research and
the Research Center of the College of Pharmacy, King Saud
University is greatly appreciated.
To a solution of compound 9 (1.86 g, 5 mmol) in ethanol (8 mL),
the appropriate aromatic amine (5 mmol) and anhydrous potas-
sium carbonate (0.7 g, 5 mmol) were added and the mixture was
heated under reflux for 6 h. On cooling, the solvent was then
distilled in vacuo, and water (10 mL) was added to the residue. The
separated precipitate was filtered, washed with cold water, dried
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