Synthesis and antimicrobial activity of some new 1,3-diphenylpyrazoles bearing pyrimidine, pyrimidinethione, thiazolopyrimidine, triazolopyrimidine, thio- and alkylthiotriazolopyrimidinone moieties at the 4-position

Article abstract of DOI:10.1080/10426500600754695

1,3-diphenyl-1H-pyrazole-4-carboxaldehyde (1) reacted with ethyl cyanoacetate and thiourea to give the pyrimidinethione derivative 2. The reaction of 2 with some alkylating agents gave the corresponding thioethers 3a-e and 7. Thione 2 was cyclized to 5 an

Full text of DOI:10.1080/10426500600754695

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Phosphorus, Sulfur, and Silicon
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Synthesis and Antimicrobial
Activity of Some New 1,3-
Diphenylpyrazoles Bearing
Pyrimidine, Pyrimidinethione,
Thiazolopyrimidine,
Triazolopyrimidine, Thio-and
Alkylthiotriazolop-Yrimidinone
Moieties at the 4-Position
T. I. El-Emary a & Sh. A. Abdel-Mohsen a
a Chemistry Department, Assiut University, Assiut,
Egypt
Version of record first published: 01 Feb 2007.
To cite this article: T. I. El-Emary & Sh. A. Abdel-Mohsen (2006): Synthesis
and Antimicrobial Activity of Some New 1,3-Diphenylpyrazoles Bearing
Pyrimidine, Pyrimidinethione, Thiazolopyrimidine, Triazolopyrimidine, Thio-and
Alkylthiotriazolop-Yrimidinone Moieties at the 4-Position, Phosphorus, Sulfur, and
Silicon and the Related Elements, 181:11, 2459-2474
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Phosphorus, Sulfur, and Silicon, 181:2459–2474, 2006
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500600754695
Synthesis and Antimicrobial Activity of Some New
1,3-Diphenylpyrazoles Bearing Pyrimidine,
Pyrimidinethione, Thiazolopyrimidine,
Triazolopyrimidine, Thio- and Alkylthiotriazolop-
Yrimidinone Moieties at the 4-Position
T. I. El-Emary
Sh. A. Abdel-Mohsen
Chemistry Department, Assiut University, Assiut, Egypt
1,3-diphenyl-1H-pyrazole-4-carboxaldehyde (1) reacted with ethyl cyanoacetate and
thiourea to give the pyrimidinethione derivative 2. The reaction of 2 with some alky-
lating agents gave the corresponding thioethers 3a–e and 7. Thione 2 was cyclized
to 5 and 6 upon a reaction with chloroacetic acid and with benzaldehyde, respec-
tively. Thioether 3c was cyclized to 4 upon boiling with sodium acetate in ethanol,
and 7 was cyclized to 8 upon boiling in an acetic anhydride-pyridine mixture. The
hydrazino derivative 9 was prepared either by boiling 2 and/or 3a with hydrazine.
The reaction of 9 with nitrous acid, acetylacetone, triethyl orthoformate, acetic
anhydride, and carbon disulfide gave 10–14. The alkylation of 14 with ethyl iodide,
phenacyl bromide, and ethyl chloroacetate afforded the alkythiotriazolo pyrimidi-
none derivatives 15a–c. The dialkyl derivative 16 was produced upon the treatment
of 2 with two equivalents of ethyl iodide. Boiling 16 with hydrazine afforded the
hydrazino 17. The reaction of 17 with nitrous acid, carbon disulfide, ethyl cyanoac-
etate, ethyl acetoacetae, and phenacyl bromide gave 18–22, respectively. Some of
the newly obtained compounds were tested for their antibacterial and antifungal
activities.
Keywords 1,3-diphenylpyrazole; pyrimidine; pyrimidinethione; thiazolopyrimidine;
thio- and alkylthiotriazolpyrimidinone; triazolopyrimidine
INTRODUCTION
The chemistry of the pyrazole nucleus has received much more atten-
tion during the last few decades,1−9 because of outstanding biologi-
cal activities. It acts as antipyretic, analgesic, antiinflammatory,10−13
antianxiety,14 kinase inhibitors,15−18 and as insecticides.19 It has
good properties as antibacterial, antifungal, and an antiparasitic, as
well.20−30 Considering all of these benefits and in continuation of our
Received January 9, 2006; accepted March 31, 2006.
Address correspondence to T. I. El-Emary, Al Jouf Teachers College, P.O. Box 269, Al
Jouf, Saudi Arabia. E-mail: emary768@hotmail.com
2459

2460
T. I. El-Emary and Sh. A. Abdel-Mohsen
work to synthesize new heterocycles starting from 1,3-diphenyl-1H-
pyrazole-4-carboxaldehyde,27,28 we introduce herein several new phar-
macophores, such as pyrimidine, pyrimidinethione, thiazolopyrimidine,
triazolopyrimidine, and tetrazolopyrimidine moieties onto the pyrazole
nucleus in an effort to obtain compounds with enhanced potency. Some
of the synthesized compounds were screened in vitro for their antibac-
terial and antifungal activities.
RESULTS AND DISCUSSION
A one-pot reaction of 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde (1),
ethyl cyanoacetate, and thiourea in absolute ethanol in the pres-
ence of potassium carbonate gave 6-(1,3-diphenyl-1H-pyrazolo-4-yl)-
5-cyano-4-oxo-1,2,3,4-tetrahydropyrimidine-2-thione (2). The alkylaion
of 2 with some alkylating agents, namely ethyl iodide, benzyl chloride,
phenacyl bromide, ethyl chloroacetate, and chloroacetonitrile, gave the
alkylated products 3a–e. Allowing 3c to be heated under reflux in
ethanol in the presence of anhydrous sodium acetate for 10 h led to
a ring closure and the formation of the thiazolopyrimidinone derivative
4 (Scheme 1).
The ternary condensation of 2, chloroacetic acid, and benzaldehyde,
in presence of fused sodium acetate and acetic anhydride, resulted in
the formation of 2-benzylidene-7-(1,3-diphenyl-1-H-pyrazol-4-yl)-2,3-
dihydro-6-cyanothiazolo[3,2-a]pyrimidin-3,5-dione 6. When the reac-
tion was performed without benzaldehyde, the product was identified as
thiazolopyrimidine derivative 5. Compound 6 had been independently
synthesized through the interaction of 5 with benzaldehyde in the pres-
ence of a catalytic amount of piperidine (Scheme 1).
The intermediate 6-(1,3-diphenyl-1H-pyrazol-4-yl)-2(3-pentan-2,4-
dione)thio-5-cyano pyrimidin-4(3H)-one (7) was obtained when 2 was
alkylated with 3-chloroacetylacetone at r.t. in ethanol in the presence
of potassium hydroxide. Boiling 7 in a mixture of acetic anhydride
and pyridine (1:1) gave rise to the thiazolopyrimidine derivative 8
(Scheme 1).
The formation of the hydrazinopyrimidineone 9 was achieved either
by heating 2 with hydrazine hydrate in pyridine under reflux for 6 h
or by heating 3a with hydrazine hydrate in absolute ethanol for 10 h29
(Scheme 2).
The synthetic potency of the hydrazino group of 9 was examined with
some reagents in mind to synthesize new 1,3-diphenylpyrazole mem-
bers bearing substituted pyrimidinonone, triazolopyrmidinone, and tri-
azolopyrmidinonethione groups at position 4. Thus, the treatment of 9
with nitrous acid30 afforded the azidopyrimidinone derivative 10 in a

New 1,3-Diphenylpyrazoles
2461
SCHEME 1
moderate yield. The IR spectrum of 10 showed an absorption band at
2180 cm−1, which is characteristic for the azido group. The condensa-
tion of 9 with acetylacetone29 gave the dimethylpyrazolyl derivative 11.
Boiling 9 in triethyl orthoformate and in acetic anhydride gave the tri-
azolopyrimidinone derivatives 12 and 13, respectively (Scheme 2). The

2462
T. I. El-Emary and Sh. A. Abdel-Mohsen
SCHEME 2
thione derivative 14 was obtained when 9 was interacted with carbon
disulfide in pyridine. The alkylation of 14 using ethyl iodide, phenacyl
bromide, and ethyl chloroacetate gave the alkylthiotriazolpyrimidinone
derivatives 15a–c (Scheme 2).
The dialkylation of 2 using two equivalents of ethyl iodide gave
6-(1,3-diphenyl-1H-pyrazol-4-yl)-5-cyano-3-ethyl-4-oxo-1,2,3,4-tetra-
hydropyrimidine-2-ethylthio (16) (Scheme 2).

New 1,3-Diphenylpyrazoles
2463
The replacement of the ethylthio group of 16 by the hydrazine group30
had been achieved when the later was heated under reflux with hy-
drazine hydrate in ethanol for 10 h to give the hydrazino derivative
17. Compound 17 is a key intermediate for producing new fused and
unfused heterocycles. Thus, upon the reaction of 17 with nitrous acid,
carbon disulfide, ethyl cyanoacetate, ethyl acetoacetate, and phenacyl
bromide, the tetrazolopyrimidine 18, the mercaptptriazolopyrimidine
19, the dipyrazolyl derivatives 20–21, and the triazinopyrimidine 22
were produced, respectively (Scheme 3).
SCHEME 3

2464
T. I. El-Emary and Sh. A. Abdel-Mohsen
EXPERIMENTAL
M.p.s were uncorrected and determined using a Kofler m.p. apparatus.
IR spectra were recorded on a Pye Unicam SP 3-100 spectrophotome-
ter using the KBr wafer technique. 1H NMR spectra were recorded
on a Varian EM-390 90 MHz spectrometer using TMS as an inter-
nal standard. MS spectra were measured on SSQ-7000 apparatus at
70 eV. Elemental analyses were carried out at the Microanalytical Cen-
ter of Cairo University (Cairo, Egypt) and at the Microanalytical unit
at Assuit University (Assuit, Egypt). The characterization data of all
newly synthesized compounds are given in Table I.
1,3-Diphenyl-1H-pyrazole-4-carboxaldehyde (1)
This compound was prepared according to a reported method.32
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydropyrimidine-2-thione (2)
A mixture of 1 (0.01 mol), ethyl cyanoacetate (0.01 mol), thiourea (0.01
mol), and potassium carbonate (0.03 mol) in absolute ethanol (60 mL)
was heated under reflux for 12 h, cooled, and neutralized with glacial
acetic acid. The product that isolated was crystallized from the proper
solvent to give a yellowish-orange 2. IR (cm−1): 3180 (NH), 2230 (CN),
1670 (CO), 1160 (C=S).1H NMR (DMSO-d6) δ: 7.3–7.9 (m, 10H, Ar-H),
8.2 (s, 1H, CH-pyrazole), 9.2 (s, 1H, NH), 9.8 (s, 1H, NH).
The Alkylation of 2: The Formation of Thioethers (3a–e)
A mixture of 2 (0.371 g, 0.001 mol) and alkyl (alkaryl) halides, namely
ethyl iodide, benzyl chloride, phenacyl bromide, ethyl chloroacetate,
and/or chloroacetonitrile (0.001 mol) in ethanol (30 mL) containing an-
hydrous sodium acetate (2 g) was refluxed for 2 h and then allowed to
cool. The precipitated product was filtered off and recrystallized from
the proper solvent.
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydropyrimidine-2-ethylthio (3a)
1
Pale yellow crystals. IR (cm−1): 3360 (NH), 2200 (CN), 1650 (CO). H
NMR (DMSO-d6)δ: 1.2–1.4 (t, 3H, CH3), 3.5–3.8 (q, 2H, CH2), 7.2–7.8
(m, 10H, Ar-H), 8.3 (s, 1H, CH-pyrazole), 9.10 (s, 1H, NH).

New 1,3-Diphenylpyrazoles
2465
TABLE I Analytical Data of the Newly Synthesized Compounds
Elemental analyses
Calcd./Found (%)
Compound
No.
Solvent
Cryst.
M.P.
[◦C]
Mol. Formula
(Mol. Wt.)
Yield
79
C
H
N
S
2
methanol
ethanol
dioxane
ethanol
ethanol
ethanol
ethanol
ethanol
acetic acid
acetic acid
dioxane
dioxane
ethanol
acetic acid
dioxane
ethanol
dioxane
ethanol
ethanol
ethanol
ethanol
acetic acid
benzene
dioxane
dioxane
dioxane
ethanol
195–196
.212–13
187
C20H13N5OS
(371.4)
64.68
64.37
66.15
66.50
70.26
70.40
68.70
69.12
63.01
63.41
64.38
64.77
71.32
71.65
64.22
64.50
69.73
70.06
63.95
64.37
66.50
66.10
65.03
65.48
63.15
62.87
69.27
68.88
66.48
66.12
67.17
67.42
61.30
61.69
62.85
63.12
65.74
66.12
60.35
60.59
67.43
67.12
66.49
66.13
64.70
65.05
62.86
63.18
64.65
64.28
67.38
67.70
72.42
72.12
3.53
3.51
4.29
4.11
4.15
4.30
3.91
4.12
4.19
3.80
3.44
3.12
3.63
3.41
3.18
3.25
3.43
3.12
4.08
4.28
3.80
3.92
4.09
4.19
3.18
3.44
4.42
4.19
3.45
3,41
3.84
3.81
3.18
3.25
3.90
4.10
3.63
3.64
3.85
3.81
4.95
5.21
4.82
5.01
3.95
4.12
3.90
3.91
4.34
4.12
4.57
4.88
4.66
4.80
18.86
19.02
17.53
17.81
15.18
15.36
14.31
13.95
15.31
15.60
20.48
20.69
14.85
14.70
17.02
17.38
14.02
14.06
14.92
15.06
15.51
15.87
26.54
26.10
29.46
29.87
22.62
22.61
25.84
25.40
24.92
25.00
23.83
24.10
22.31
22.05
18.51
18.60
19.71
20.20
16.38
16.69
24.67
25.05
27.44
27.80
22.31
22.18
24.12
24.36
21.15
21.50
19.71
20.05
8.63
8.88
8.03
8.34
6.95
7.07
6.55
6.81
7.01
7.35
7.81
8.20
6.80
7.15
7.79
8.06
6.42
6.50
6.83
6.61
7.10
7.50
—-
3a
3b
3c
3d
3e
4
69
62
74
72
70
61
63
65
69
59
66
53
93
82
63
71
62
71
72
64
70
50
69
52
49
53
C
C
C
C
C
C
C
C
C
C
C
C
22H17N5OS
(399.5)
27H19N5OS
(461.5)
28H19N5O2S
(489.6)
24H19N5O3S
(457.5)
22H14N6OS
(410.5)
28H17N5OS
(471.5)
22H13N5O2S
(411.4)
29H17N5O2S
(499.5)
25H19N5O3S
(469.5)
25H17N5O2S
(451.5)
20H15N7O
262
125–126
149
275–277
> 360
5
6
278–280
246–247
316–318
342–344
311–312
291–292
> 340
7
8
9
(369.4)
20H12N8O
(380.4)
10
11
12
13
14
15a
15b
15c
16
17
18
19
20
21
22
—
—
—
—
C25H19N7O
(433.5)
C
C
C
21H13N7O
(379.4)
22H15N7O
(393.4)
21H13N7OS
320–322
319–320
177–179
197–98
143–145
208–210
301–303
185–187
266–268
> 300
7.79
8.05
7.28
7.66
6.05
5.85
6.44
6.41
7.50
7.88
—
—
—
—
7.30
7.50
—
—
—
(411.4)
C23H17N7OS
(439.5)
C
C
C
C
C
C
C
29H19N7O2S
(529.8)
25H19N7O3S
(497.5)
24H21N5OS
(427.5)
22H19N7O
(397.4)
22H16N8O
(408.4)
23H17N7OS
(439.5)
25H20N8O2
(464.5)
C26H21N7O2
(463.5)
C30H23N7O
(497.6)
230–232
> 300
—
—
—

2466
T. I. El-Emary and Sh. A. Abdel-Mohsen
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydropyrimidine-2-benzylthio (3b)
1
Pale yellow crystals. IR (cm−1): 3350 (NH), 2220 (CN), 1660 (CO). H
NMR (DMSO-d6)δ: 3.5 (s, 2H, CH2), 6.9–7.3 (m, 15H, Ar-H), 8.2 (s, 1H,
CH-pyrazole), 9.2 (s, 1H, NH).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydropyrimidine-2-methylbenzoylthio (3c)
1
Yellow crystals. IR (cm−1): 3460 (NH),2210 (CN), 1650 (CO). H NMR
(DMSO−d6)δ: 4.5 (s, 2H, CH2), 6.9–7.8 (m, 15H, Ar-H), 8.3 (s, 1H, CH-
pyrazole), 9.0 (s, 1H, NH).
Ethyl [6-(1,3-diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydropyrimidine-2-thio]acetate (3d)
Yellow crystals. IR (cm−1): 3290 (NH), 2215 (CN), 1730 (CO), 1650
(CO).1H NMR (DMSO-d6)δ: 1.3–1.5 (t, 3H, CO2CH2CH3), 3.9–4.2 (q,
2H, CO2CH2CH3), 4.6 (s, 2H, CH2), 7.2–7.8 (m, 10H, Ar-H), 8.3 (s, 1H,
CH-pyrazole), 9.1 (s, 1H, NH). MS: m/z 457.12 (M+, 9.50%).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-4-oxo-1,2,3,4-
tetrahydro pyrimidine-2-cyanomethylthio (3e)
1
Yellow crystals. IR (cm−1): 3220 (NH), 2220 (CN),1680 (CO). H NMR
(DMSO−d6)δ: 3.3 (s, 2H, CH2), 7.2–7.8 (m, 10H, Ar-H), 8.3 (s, 1H, CH-
pyrazole), 8.9 (s, 1H, NH).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-3-phenyl-6-
cyanothiazolo[3,2-a]pyrimidin-5-one (4)
A mixture of 3c (0.001 mol) and anhydrous sodium acetate (2 g) in
ethanol (30 mL) was heated under reflux for 10 h and then left to cool.
The precipitated solid was collected and recrystallized from the proper
solvent to give 4 as pale brown crystals. IR (cm−1): 2230 (CN), 1660
(CO). 1H NMR (DMSO-d6)δ: 6.9–8.1 (m, 16H, Ar-H + CH thiazole), 8.4
(s, 1H, CH-pyrazole).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-2,3-dihydro-6-
cyanothiazolo[3,2-a]pyrimidin-3,5-dione (5)
A mixture of 2 (0.01 mol), chloroacetic acid (0.01 mol), and fused sodium
acetate (2 g) in a mixture of acetic acid/acetic anhydride (40 mL, 1:1)
was heated under reflux for 6 h and left to cool. The reaction mixture
was then diluted with water, shaken well, and allowed to stand 1 h. The

New 1,3-Diphenylpyrazoles
2467
solid product was filtered off and recrystallized from the proper solvent
to give 5 as yellow crystals. IR (cm−1): 2220 (CN), 1720 ( CO), 1680 (CO).
1H NMR(DMSO-d6)δ: 7.1–7.9 (m, 10H, Ar-H), 3.7 (s, 2H, CH2), 8.4 (s,
1H, CH-pyrazole).
2-Benzylidene-7-(1,3-diphenyl-1H-pyrazol-4-yl)-2,3-dihydro-6-
cyanothiazolo-[3,2-a]pyrimidin-3,5-dione (6)
Method A
A mixture of 2 (0.005 mol), chloroacetic acid (0.008 mol), benzalde-
hyde (0.005 mol), and fused sodium acetate (2.0 g) in a mixture of acetic
acid/acetic anhydride (30 mL, 1:1) was heated under reflux for 4 h and
left to cool. The reaction mixture was diluted with water. The solid
was filtered off and crystallized from the proper solvent to give 6 as
orange crystals. IR (cm−1): 2230 (CN), 1700 (CO), 1680 (CO). 1H NMR
(DMSO-d6)δ: 6.9–7.8 (m, 15H, Ar-H ), 8.0 (s, 1H, CH C), 8.4 (s, 1H,
CH-pyrazole).
Method B
To a mixture of 5 (0.001 mol) and benzaldehyde (0.001 mol) in abso-
lute ethanol (20 mL) was added piperidine (5 drops). The mixture was
heated under reflux for 2 h. The crystalline product thus obtained after
cooling was collected and recrystallized from the proper solvent to give
6 as orange crystals.
Compound 6 prepared by methods A and B have the same m.p. and
mixed m.p.
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-2(3-pentan-2,4-dione)thio-5-
cyanopyrimidin-4(3H)-one (7)
A mixture of 2 (0.01 mol) and potassium hydroxide (0.012 mol) in
ethanol (30 mL) was stirred for 5 min, and then chloroacetylacetone
(0.01 mol) was added dropwise while stirring for 2 h. The precipitate
was filtered off, washed several times with water, and crystallized from
the proper solvent to give 7 as orange crystals. IR (cm−1): 3130 (NH),
2210 (CN), 1670 (2CO), 1650 (CO). 1H NMR (DMSO-d6) δ: 2.35 (s, 6H,
2COCH3), 6.9–7.8 (m, 11H, Ar-H + S-CH), 8.2 (s, 1H, CH-pyrazole), 9.2
(s, 1H, NH).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-acetyl-3-methyl-6-
cyanothiazolo[3,2-a]pyrimidin-5-one (8)
A mixture of 7 (0.001 mol) and acetic anhydride (10 mL) and pyridine
(10 mL) was heated on a water bath for 6 h, cooled, and poured into ice

2468
T. I. El-Emary and Sh. A. Abdel-Mohsen
cold water. The precipitate that formed was collected by filtration and
recrystallized from the proper solvent to give 8 as brown crystals. IR
1
(cm−1): 2220 (CN), 1680 (CO), 1650 (CO). H NMR (DMSO-d6)δ: 2.65
(s, 3H, CH3), 3.35 (s, 3H, COCH3), 7.2–7.8 (m, 10H, Ar-H), 8.2 (s, 1H,
CH-pyrazole).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-2-
hydrazinopyrimidin-4(3H)-one (9)
Method A
A mixture of 2 (0.001 mol) and hydrazine hydrate (5 mL) was heated
under reflux in pyridine (30 mL) for 6 h and then left to cool. The solid
product was filtered off and recrystallized from the proper solvent to
give 9 as buff crystals. IR (cm−1): 3280–3200 (2NH + NH2), 2230 (CN),
1
1660 (CO). H NMR (DMSO-d6)δ: 3.9 (s, 1H, NH2), 7.2–7.8 (m, 10H,
Ar-H ), 8.2 (s, 1H, CH-pyrazole), 9.0 (s, 2H, 2NH).
Method B
A mixture of 3a (0.001 mol) and hydrazine hydrate (7 mL) in abso-
lute ethanol (20 mL) was refluxed for 10 h. The reaction mixture was
poured onto ice. The product was isolated and crystallized from the
proper solvent to give 9 as buff colored crystals. Compound 9 prepared
by Methods A and B have the identical m.p. and mixed m.p.
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-2-azidopyrimidin-
4(3H)-one (10)
A cold solution of sodium nitrite (2 g) in water (10 mL) was added to
an ice bath solution of 9 (0.001 mol) in acetic acid (20 ml) with stirring.
After the completion of the addition (30 min), the ice bath was removed,
and stirring was continued for 1 h. The solid product was filtered off
and recrystallized from the proper solvent to give 10 as yellow crystals.
IR (cm−1): 3450 (NH), 3369, 3120 (NH + NH2), 2210 (CN), 2180 (N3),
1660 (CO).1H NMR (DMSO-d6) δ: 7.4–7.9 (m, 10H, Ar-H), 8.2 (s, 1H,
CH-pyrazole), 9.0 (s, 1H, NH). MS: m/z 380.19 (M+, 15.35%).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-(3,5-dimethylpyrazol-1-yl)-
5-cyanopyrimidin-4(3H)-one (11)
A mixture of 9 (0.001 mol), acetylacetone (0.001 mol), and a few drops of
acetic acid in ethanol (15 mL) was heated under reflux for 4 h, concen-
trated, and allowed to cool. The precipitate that formed was collected
and recrystallized from the proper solvent to give 11 as yellow crystals.

New 1,3-Diphenylpyrazoles
2469
1
IR (cm−1): 3210 (NH), 2215 (CN), 1670 (CO). H NMR (DMSO-d6)δ:
2.9 (s, 3H, CH3), 3.1 (s, 3H, CH3), 7.2–7.8 (m, 10H, Ar-H), 8.2 (s, 1H,
CH-pyrazole), 8.4 (s, 1H, CH-pyrazole), 9.1 (s, 1H, NH).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-6-cyano-1,2,4-triazolo[4,3-
a]pyrimidin-5(8H)-one (12)
A mixture of 9 (0.002 mol) and triethyl orthoformate (15 mL) was heated
under reflux for 3 h. The precipitate that formed during heating was
collected and recrystallized from the proper solvent to give 13 as pale
1
yellow needles. IR (cm−1): 3120 (NH), 2200 (CN), 1660 (CO). H NMR
(DMSO-d6)δ: 4.8 (s, 1H, NH), 7.3–7.8 (m, 10H, Ar-H), 8.5 (s, 1H, CH-
pyrazole), 8.9 (s, 1H, CH-triazole).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-6-cyano-3-methyl-1,2,4-
triazolo[4,3-a]pyrimi-din-5(8H)-one (13)
A mixture of 9 (0.001 mol) and acetic anhydride (15 mL) was heated
under reflux for 6 h, and then allowed to cool, and poured onto ice cold
water. The precipitate that formed was collected, washed with water,
and recrystallized from the proper solvent to give 12 as shining yellow
crystals. IR (cm−1): 3130 (NH), 2210 (CN), 1660 (CO). 1H NMR (DMSO-
d6) δ: 2.6 (s, 3H, CH3), 4.4 (s, 1H, NH), 7.2–7.8 (m, 10H, Ar-H), 8.2 (s,
1H, CH-pyrazole).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-3-thioxo-2,3-dihydro-6-
cyano-1,2,4-triazolo[4,3-a]pyrimidin-5(8H)-one (14)
A mixture of 9 (0.002 mol) and carbon disulfide (2 mL) in dry pyridine
(15 mL) was heated under reflux on a steam bath for 12 h. The solid
product that separated after cooling was collected and recrystallized
from the proper solvent to give 14 as orange needles. IR (cm−1): 3200–
3180 (2NH), 2210 (CN), 1670 (CO). 1H NMR (TFA) δ: 7.3–7.8 (m, 10H,
Ar-H ), 8.7 (s, 1H, CH-pyrazole). MS: m/z 409.27 (M+-2, 10.15%).
The Alkylation of 14: The Formation of Thioethers (15a–c)
A mixture of 14 (0.001 mol), the appropriate halo compounds (0.01
mol), and 10% aqueous KOH (5.6 mL, 0.01 mol) in dimethyl formamide
(25 mL) was stirred at r.t. for 2 h and then diluted with water. The
precipitate formed was filtered off, was washed with water, dried, and
recrystallized from the proper solvent to give 15a–c.

2470
T. I. El-Emary and Sh. A. Abdel-Mohsen
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-3-ethylthio-2,3-dihydro-6-
cyano-1,2,4-triazolo[4,3-a]pyrimidin-5(8H)-one (15a)
Yellowish crystals. IR (cm−1): 3210 (NH), 2210 (CN), 1650 (CO).1H NMR
(DMSO-d6)δ: 1.2–1.4 (t, 3H, CH3), 3.5–3.7 (q, 2H, CH2), 7.2–7.7 (m, 10H,
Ar-H), 8.4 (s, 1H, CH-pyrazole), 9.2 (s, 1H, NH).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-3-methylbenzylthio-2,3-
dihydro-6-cyano-1,2,4-triazolo[4,3-a]pyrimidin-5(8H)-one (15b)
Yellowish crystals. IR (cm−1): 3220 (NH), 2215 (CN), 1680 (CO), 1660
1
(CO). H NMR (DMSO-d6)δ: 4.4 (s, 2H, CH2), 6.9–7.7 (m, 15H, Ar-H),
8.3 (s, 1H, CH-pyrazole), 9.3 (s, 1H, NH).
Ethyl [7-(1,3-diphenyl-1H-pyrazol-4-yl)-2,3-dihydro-6-cyano-
1,2,4-triazolo[4,3-a]pyrimidinthio] acetate-5(8H)-one (15c)
Yellowish crystals. IR (cm−1): 3220 (NH), 2215 (CN), 1735 (CO), 1660
1
(CO). H NMR (DMSO-d6)δ: 1.3–1.5 (t, 3H, CO2CH2CH3), 3.9–4.2 (q,
2H, CO2CH2CH3), 4.6 (s, 2H, CH2), 7.3–7.7 (m, 10H, Ar-H), 8.3 (s, 1H,
CH-pyrazole), 9.3 (s, 1H, NH).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-5-cyano-3-ethyl-4-oxo-
1,2,3,4-tetrahydropyrimidine-2-ethylthio (16)
A mixture of 2 (0.005 mol), ethyl iodide (0.015 mol), and anhydrous
sodium acetate (2 g) in ethanol (30 mL) was heated under reflux for 6
h, and then left to cool. The product that formed was filtered off and
recrystallized from the proper solvent to give 16 as pale yellow crystals.
1
IR (cm−1): 2220 (CN), 1650 (CO). H NMR (DMSO-d6) δ: 0.98-1.2 (t,
3H, N-CH2CH3), 1.2–1.4 (t, 3H, S-CH2CH3), 2.9–3.2 (q, 2H, N-CH2CH3),
3.5–3.8 (q, 2H, S-CH2CH3), 7.2–7.8 (m, 10H, Ar-H), 8.5 (s, 1H, CH-
pyrazole). MS: m/z 427 (M+, 10.25%).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-hydrazino-5-cyano-3-ethyl-
4-oxo-1,2,3,4-tetrahydropyrimidine (17)
A mixture of 16 (0.001 mol) and hydrazine hydrate (1 mL) in absolute
ethanol (15 mL) was heated under reflux for 10 h .and then poured
onto ice. The product that formed was collected by filtration and crys-
tallized from the proper solvent to give 17 as yellow crystals. IR (cm−1):
1
3330–3250 (NH + NH2), 2220 (CN), 1650 (CO). H NMR (DMSO-d6)δ:

New 1,3-Diphenylpyrazoles
2471
0.98–1.2 (t, 3H, N-CH2CH3), 2.8–3.0 (q, 2H, N-CH2CH3), 3.9 (s, 2H,
NH2), 7.3–7.8 (m, 10H, Ar-H), 8.3 (s, 1H, CH-pyrazole), 9.2 (s, 1H, NH).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-6-cyano-4-ethyl-5-oxo-
[1,2,3,4]-tetrazolopyrimid-ine (18)
A solution of sodium nitrite (0.005 mol) in the least amount of wa-
ter was added dropwise to an ice-cold solution of 17 (0.002 mol) in
a mixture of acetic acid (10 mL) and hydrochloric acid (5 mL), keep-
ing an ice bath at 0–5◦C. The reaction mixture was allowed to stand
overnight at r.t., then it was poured into water. The solid product ob-
tained was filtered off and recrystallized from the proper solvent to give
1
18 as pale brown needles. IR (cm−1): 2215 (CN), 1660 (CO). H NMR
(DMSO-d6)δ: 1.1-1.2 (t, 3H, N CH2CH3), 2.9–3.2 (q, 2H, N CH2CH3),
7.4–7.9 (m, 10H, Ar-H), 8.5 (s, 1H, CH-pyrazole). MS: m/z 408 (M+,
21.09%).
7-(1,3-Diphenyl-1H-pyrazol-4-yl)-1-mercapto-6-cyano-4-ethyl-
5-oxo-[1,2,4]tria zoloyrimidine (19)
A mixture of 17 (0.002 mol) and excess carbon disulphide (5.5 mL) in
ethanolic sodium hydroxide solution (0.01 mol in 20 mL of ethanol)
was heated under reflux at 80◦C on steam bath for 12 h. The reaction
mixture was allowed to cool to r.t., poured into water, and neutralized
by diluted acetic acid. The solid product obtained was filtered off, dried
and crystallized from the proper solvent to give 19 as orange crystals.
IR (cm−1): 2215 (CN), 1675 (CO). 1H NMR (DMSO-d6) δ: 1.2-1.4 (t, 3H,
N CH2CH3), 2.8–3.1 (q, 2H, N CH2CH3), 7.2–7.8 (m, 10H, Ar-H), 8.5
(s, 1H, CH-pyrazole).
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-(3-amino-pyrazol-5(4H)-
one-1-yl)-3-ethyl-5-cyaanopyrimidin-4(3H)-one (20)
A mixture of 17 (0.01 mol), ethyl cyanoacetate (0.01 mol), and sodium
ethoxide (0.01 mol) in absolute ethanol (20 mL) was stirred at a re-
flux temperature for 8 h and then allowed to cool to r.t., poured into
cold water, and neutralized by diluted acetic acid. The solid product
obtained was filtered off, dried, and crystallized from the proper sol-
vent to give 20 as orange crystals. IR (cm−1): 3360, 3290 (NH2), 2220
(CN), 1695 (CO), 1675 (CO). 1H NMR (DMSO-d6) δ: 1.1–1.3 (t, 3H, N-
CH2CH3), 2.9–3.1 (q, 2H, N-CH2CH3), 3.5 (s, 2H, CH2-pyrazole), 7.4–
7.8 (m, 10H, Ar-H), 8.4 (s, 1H, CH-pyrazole), 10.3 (br, 2H, NH2, D2O-
exchangeable).

2472
T. I. El-Emary and Sh. A. Abdel-Mohsen
6-(1,3-Diphenyl-1H-pyrazol-4-yl)-2-(3-methyl-pyrazol-5(4H)-
one-1-yl)-3-ethyl-5-cyanopyrimidin-4(3H)-one (21)
A mixture of 17 (0.001 mol) and ethyl acetoacetate (0.001 mol) in ab-
solute ethanol (30 mL) was stirred at a reflux temperature for 20 h.
The reaction mixture was allowed to cool to r.t. and then poured
into cold water. The precipitate that formed was filtered off, dried,
and crystallized from the proper solvent to give 21 as orange crys-
1
tals. IR (cm−1): 2215 (CN), 1685 (CO), 1665 (CO). H NMR (DMSO-
d6) δ: 1.3–1.5 (t, 3H, N-CH2CH3), 2.3 (s, 3H, CH3), 2.9-3.1 (q, 2H, N-
CH2CH3), 4.6 (s, 2H, CH2-pyrazole), 7.4–7.8 (m, 10H, Ar-H), 8.5 (s, 1H,
CH-pyrazole).
9-Ethyl-6-(1,3-diphenyl-1H-pyrazol-4-yl)-8-oxo-4-phenyl-2H-
pyrimido[2,1-c] [1,2,4]triazin-7-carbonitrile (22)
A mixture of 17 (0.002 mol) and phenacyl bromide (0.002 mol) in dry
xylene (30 mL) was heated under reflux for 5 h. The solid that separated
upon cooling was filtered off and crystallized from the proper solvent
to give 22 as yellowish crystals. IR (cm−1): 3400 (NH), 2215 (CN), 1660
(CO). 1H NMR (DMSO-d6)δ: 1.3–1.5 (t, 3H, N-CH2CH3), 2.9–3.1 (q, 2H,
N-CH2CH3), 7.3–8.1 (m, 15H, Ar-H ), 8.4 (s, 1H, CH-pyrazole), 9.2 (s,
1H, CH- triazine), 10.3 (s, 1H, NH-triazine).
ANTIMICROBIAL ACTIVITY
Ten compounds were screened in vitro for their antimicrobial activities
against two strains of bacteria (Bacillus cereus, Escherichia coli), two
strains of fungi (Botrytis, and Geotrichum candidum) and one strain of
yeast (Candida albicans) using the paper disc method.31 The screened
compounds were dissolved in DMSO to get a solution of 1% concentra-
tion. Filtered paper discs (Whatman No. 1 filter paper, 5 mm diameter)
were saturated with this solution. The discs were placed on the sur-
face of solidified nutrient agar dishes seeded by the tested bacteria or
Czapek’s Dox agar dishes seeded by the tested fingi. Inhibition zones
were measured at the end of an incubation period of 48 h (at 37 oC for
bacteria and at 28oC for fungi). Tioconazole (TyrosydR) was used as a
reference substance.
The results revealed that all tested compounds exhibit moderate to
strong activity against E. coli and were inactive against B. cereus. How-
ever, only compounds 4, 6, 8, 14, and 20 showed considerable potency
against two fungal species used. None of the tested compounds were
active against C. albicans (Table II).

New 1,3-Diphenylpyrazoles
2473
TABLE II Antibacterial and Antifungal Activities of Some
New Pyrazole Derivatives∗
Compound
B. cereus
E. coli
Botrytis G. candidum
C. albicans
∗∗
2
4
6
8
11
14
15a
19
—
14
23
20
31
9
26
10
30
17
28
32
7
—
10
20
6
30
—
—
12
—
33
—
12
16
10
—
14
9
—
—
—
18
—
—
—
—
—
—
—
—
—
—
41
—
—
—
—
—
—
—
—
—
25
20
22
Tioconazole
(TyrosydR)
The activity is expressed as diameter of the inhibition zone (mm).
∗∗No inhibition zone = —.
∗This antibacterial and antifungal screening has been done in the
Mycological Center, Faculty of Science, Assiut University, Egypt.
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