Regioselective synthesis and antitumor screening of some novel N-phenylpyrazole derivatives

Article abstract of DOI:10.1016/j.bmc.2007.10.015

The versatile, hitherto unreported 4-acetyl-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-pyrazole (3) was prepared via the reaction of 2-(2-phenylhydrazono)-2-chloro-N-phenylacetamide with pentan-2,4-dione in the presence of sodium ethoxide. Reaction of 3 with

Full text of DOI:10.1016/j.bmc.2007.10.015

Available online at www.sciencedirect.com
Bioorganic & Medicinal Chemistry 16 (2008) 881–889
Regioselective synthesis and antitumor screening
of some novel N-phenylpyrazole derivatives
Ahmad M. Farag,a,* Abdelrahman S. Mayhoub,b
Saber E. Barakatb and Ashraf H. Bayomic
aDepartment of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt
bDepartment of Pharmaceutical Chemistry, Faculty of Pharmacy, Al-Azhar University, Naser City, Cairo 11884, Egypt
cDepartment of Organic Chemistry, Faculty of Pharmacy, Al-Azhar University, Naser City, Cairo 11884, Egypt
Received 7 September 2007; revised 30 September 2007; accepted 9 October 2007
Available online 12 October 2007
Abstract—The versatile, hitherto unreported 4-acetyl-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-pyrazole (3) was prepared via the
reaction of 2-(2-phenylhydrazono)-2-chloro-N-phenylacetamide with pentan-2,4-dione in the presence of sodium ethoxide. Reaction
of 3 with dimethylformamide-dimethylacetal (DMF-DMA) furnished the corresponding 4-[(E)-3-(dimethylamino)acryloyl]-5-
methyl-1-phenyl-3-phenylcarbamoyl-1H-pyrazole (5). The latter product underwent regioselective 1,3-dipolar cycloaddition with
some nitrilimines to afford the non-isolable dihydropyrazole intermediates which then lose dimethylamine yielding the correspond-
ing pyrazole derivatives. The preliminary screening for the antitumor activity of all newly synthesized compounds was carried out
against Ehrlich Ascites Carcinoma tumor cells.
ꢀ 2007 Elsevier Ltd. All rights reserved.
1. Introduction
phenylcarboxamidopyrazole derivatives in good yields
and high purity, and test their inhibitory effect on tumor
growth, in order to study part of structure-activity rela-
tionship (SAR) of this new antitumor class in order to
get a new agent that could be optimized to be used as
a potent antitumor agent.
N-Arylpyrazole derivatives are a very interesting class of
heterocyclic compounds that have remarkable pharma-
cological activities as antibacterial-antifungal,1 hypogly-
cemic,2 tumor necrosis inhibitor,3 antithromboembolic
disorders,4 antiangiogenic agent,4 A3 Adenosine recep-
tor antagonist,5 neuropeptide Y Y5 receptor antago-
nists,6 kinase inhibitor for treatment of type
diabetes, hyperlipidemia, and obesity,7 insecticides,8
thrombopiotinmimetics,9 and anti-inflammatory.10,11
2
2. Results and discussion
2.1. Chemistry
Although many literatures discussed the antitumor
activity of pyrazole derivatives,12–20 recently few studies
have discussed the activity of 3-carboxamide (Fig. 1)21
and 5-carboxamidepyrazole derivatives.22 This article
describes our procedure to develop a facile, rapid,
three-step reaction for the synthesis of bis-system of 3-
The versatile, hitherto unreported 4-acetyl-5-methyl-1-
phenyl-3-phenylcarbamoyl-1H-pyrazole (3) was prepared
via the reaction of 2-(2-phenylhydrazono)-2-chloro-N-
phenylacetamide (1) with pentan-2,4-dione (2) in the
presence of sodium ethoxide (Scheme 1). Reaction of 3
with dimethylformamide-dimethylacetal (DMF-DMA)
(4) furnished the corresponding 4-[(E)-3-(dimethyl-
amino)acryloyl]-5-methyl-1-phenyl-3-phenylcarbamoyl-
1H-pyrazole (5) (Scheme 1).
Keywords: Phenylcarbamoyl-1H-pyrazole; 1,3-Dipolar cycloaddition;
Nitrilimines; Cytotoxicity; Antitumor agent; N-Phenylpyrazoles; Reg-
ioselective synthesis; Antitumor activity; Dimethylformamide-dimeth-
ylacetal (DMF-DMA); Enaminones; Structure–activity relationship
(SAR).
The 1H NMR spectrum of compound 3 displayed two sin-
glet signals at d 2.76 and at d 2.43 characteristics for two
methyl groups and broad D2O-exchangeable signal at d
9.01 characteristic for amide NH, in addition to multiplets
*
Corresponding author. Tel.: +20 12377 3794; fax: +20 23572
7556; e-mail: afarag49@yahoo.com
0968-0896/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2007.10.015

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A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
R
N
O
N
N
HN
O
N
O
HN
N
X
N
N
I
Cl
Cl
General structure of the newly
synthesized compounds
Canabenoid compound
Figure 1.
O
O
N
O
O
O
H
N
+
EtONa/ EtOH
N
N
N
NH
H
R.T., 1h
Cl
1
2
3
O
O
H3CO
H3CO
CH3
N
CH3
N
N
H
N
Dry xylene
Reflux, 4 h
N
4
5
Scheme 1.
at 7.12–7.70 due to aromatic protons. Whereas, its 13C
NMR spectrum revealed fifteen carbon types, the most
important signals being displayed at d 192 and d 154 char-
acteristics for acetyl and amide carbonyl carbons, respec-
tively. These two carbonyl groups have absorption bands
on the IR spectrum at 1751 and 1666 cmÀ1, respectively.
Another important band on IR spectrum appeared at
3259 cmÀ1 characteristic for amide NH.
paid to their utility as dienophiles in 1,3-dipolar cycload-
dition reactions.23,29 We report here on the 1,3-cycload-
ditions of some nitrilimines to the versatile, hitherto
unreported 4-[(E)-3-(dimethylamino)acryloyl]-5-methyl-
1-phenyl-3-phenyl-carbamoyl-1H-pyrazole (5).
The double bond in the enaminone 5 can be looked on
as an electron-rich one that may enter 1,3-dipolar cyclo-
addition reactions. Thus, reaction of nitrilimines 7a–d
[generated, in situ, by action of triethylamine on N-
aryl-2-oxo-N-arylpropanehydrazonyl chlorides 6a–d]
with the enaminone 5 in refluxing benzene afforded, in
each case, only one isolable product.
1
The H NMR spectrum of enaminone 5 displayed three
singlet signals at d 2.43, at d 2.88, and at d 3.11 character-
istics for three methyl groups, two doublets at d 5.55 and
at d 7.30 (J = 12.5 Hz) due to olefinic protons, in addition
to an aromatic multiplet in the region of d 7.25–7.45. The
value of the coupling constant for the ethylenic protons
indicates that the enaminone 5 exists exclusively in the
E-configuration. Its 13C NMR spectrum revealed 18 car-
bon types, the conjugation in enaminone 5 makes its car-
bonyl’s carbons displayed at d 186 (instead of 192 in
compound 3), the other important signals being displayed
at d 159, 45, and 37 corresponding to amide carbonyl car-
bon and two N-methyl carbons, respectively. IR spectrum
revealed three important bands at 3421, 1681, and
1627 cmÀ1 characteristics for amide NH, ketonic, and
amidic carbonyl groups, respectively.
The reaction products were assigned the pyrazole struc-
tures 9a–d which were assumed to be formed via 1,3-
dipolar cycloaddition of the nitrilimines 7a–d to the
activated double bond in the enaminone 5 to afford
the non-isolable dihydropyrazole intermediates 8a–d
which then lose dimethylamine yielding the correspond-
ing pyrazole derivatives 9a–d. The other possible iso-
meric structure 11 was excluded on the basis of
spectral data of the isolated products. For example, in
the pyrazole ring system C-4 is the most electron-rich
carbon, thus, H-4 is expected to appear at a higher field,
typically at d 6.31. On the other hand, H-5 is linked to
the carbon attached to the nitrogen atom and thus it is
deshielded to appear typically in the region d 7.5–8.5.
In spite of enormous literature on the uses of enaminones
in heterocyclic synthesis,23–28 a little attention has been

A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
883
1
The H NMR spectra of the isolated reaction products
In the same manner, the enaminone 5 reacts with C-1-
(ethoxycarbonyl)-N-4-arylnitrilimine 13a–c to afford
products that may be formulated as the pyrazole struc-
tures 15a–c or their regioisomers 17 (Scheme 3).
revealed, in each case, a singlet signal in the region of
7.68–8.87 which indicates the presence of the pyrazole
H-5 rather than H-4 in the structure of the isolated
products (Scheme 2).
Structure 17 was excluded on the basis of the spectro-
scopic data of the isolated products. For example, H
1
Aliphatic methyl groups of compounds 9a–d appear on
the H NMR spectra as singlet signals between d 2.35
1
NMR spectra of the reaction products revealed, in each
case, the pyrazole CH-5 in the region between d 8.96
and 9.15 which is in accordance with structures 15a–c.
Their IR spectra showed, in each case, a carbonyl
adsorption band around 1735 cmÀ1, due to carbonyl es-
ter, the latter structures were further established on the
and d 2.52. The ketonic carbonyl groups appear on
the IR spectra as absorption bands at frequencies lying
between 1670 and 1797 cmÀ1
.
The 13C NMR spectrum of compounds 9a–c revealed
two ketonic carbonyl carbons around d 183.71 and
192.97, amide carbonyl carbons were displayed down-
field at d 160.34–160.38. While the aliphatic methyl
groups appeared in the region between d 11.97 and d
27.39 (see Section 4).
1
basis of the H NMR spectra of the reaction products
which revealed, in each case, the presence of ethyl pro-
tons as triplet signals at d 1.16, quartet signals at d
4.212, and H-5 pyrazole protons at d 9.1. The 13C
NMR spectrum of compound, 15b and15c revealed
O
Cl
H3C
N
NH
6a-d
Ar
Et3N/
Dry benzene
O
O
O
N
N
+
H
H3C
N
N
N
+
-
N
Ar
7a-d
5
Reflux, 2h
O
O
O
NMe2
N
O
O
O
N
N
N
H
H
N
N
N
N
N
N
Ar
Me2N
Ar
8a-d
-Me2NH
10a-d
-Me2NH
O
O
O
O
O
O
N
N
N
H
H
Ar
N
6-9
a
N
N
N
N
N
N
C6H5
Ar
Ar
b
c
C6H4-p-CH3
C6H4-m-CH3
9a-d
11a-d
d
C6H4-p-Br
Scheme 2.

884
A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
O
Cl
EtO
N
NH
Ar
12a-c
Et3N/
Dry benzene
O
O
O
N
N
+
H
EtO
N
+
N
N
-
N
Ar
13a-c
5
Reflux, 2h
O
OEt
O
O
O
O
NMe2
N
O
N
N
N
N
H
H
N
OEt
N
N
N
Me2N
N
Ar
Ar
14a-c
-Me2NH
16a-c
-Me2NH
O
O
OEt
Ar
O
O
O
O
N
N
N
N
H
H
OEt
N
N
N
N
N
N
Ar
12-15
a
Ar
15a-c
17
C6H5
b
c
C6H4-p-NO2
C6H4-p-Br
Scheme 3.
twenty-four carbon types. Carbonyl carbons of ketonic,
ester, and amide groups are displayed at d 182.6, 160,
and 159.95, respectively. Other important signals are
displayed at d 13 and d 61 characteristics for ethyl car-
bons, while C-5 pyrazole was displayed downfield at d
147.5.
The 1H NMR spectrum of compound 20 revealed a sin-
glet signal at d 9.06 corresponding to pyrazole H-5 pro-
ton and two singlet signals at d 10.23 and at d 10.76
(D2O exchangeable) due to two NH protons. These
two amide NH groups have two bands on the IR spec-
trum at 3228 and 3386 cmÀ1. Its IR spectrum shows
an intense band at 1662 cmÀ1 which revealed overlap-
ping of the two carbonyl groups. These two carbonyl
carbons were displayed very closely on 13C NMR spec-
trum at d 159.837 and at d 159.395, other ketonic carbon
was displayed at d 184.05.
The enaminone 5 reacts also with C-phenylcarbamoyl-
N-phenylnitrilimine 18 under the same experimental
conditions to afford the corresponding pyrazole deriva-
tive 20 in a good yield (Scheme 4).

A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
885
Table 1. In vitro cytotoxic activity of newly synthesized compounds
and doxorubicin
O
Cl
IC50 (lg/ml)*
N
H
Compound
Non-viable cells (%)
N
Concentration (lg/ml)
NH
100
0
50
0
25
0
0
0
0
0
0
0
0
0
5
0
0
1
3
0
5
9a
10
20
10
20
25
10
0
5
>100
>100
>100
>100
>100
>100
0
Et3N/
Dry benzene
5
9b
9c
5
10
15
0
O
9d
O
O
15a
15b
15c
20
N
H
N
N
H
0
N
N
20
35
0
10
20
0
>100
70
N
N
24
Control
0
—
0
0
18
5
Doxorubicin
100
55
20
35
*IC50 > 100 (lg/ml) is considered to be inactive.
Reflux, 2h
ton. Its 13C NMR spectrum revealed twenty-five carbon
types. Carbonyl carbons of ketonic and amide are dis-
played at d 183.76 and 160.13, respectively. Other
important signals are displayed at d 152.50 and 11.53
characteristics for pyrazole C-5 and methyl attached to
position 5 in other pyrazole ring.
H
H
N
H
N
H
N
N
O
O
O
O
O
O
N
N
N
N
N
N
N
N
-HNMe2
Me2N
The antitumor screening result confirms our pervious
assumption, since compound 24 is devoid of any cyto-
toxic activity.
19
20
Scheme 4.
2.2. Pharmacology
Antitumor screening result showed a strong correlation
between cytotoxic activity and substituted carbonyl car-
bon which occupies position 3 from pyrazole ring B
(Fig. 2). The cytotoxic result showed that compound
20 that carries carboxamido group has the highest activ-
ity, while compounds 9 and 15 showed weak activities
(Table 1). In order to confirm this assumption, we syn-
thesized compound 24 which has no carbonyl carbon
at this position, that is, we removed the carboxamido
moiety occupying position 3 from pyrazole ring B.
2.2.1. Antitumor screening test. The cytotoxic effects of
the newly synthesized compounds and doxorubicin
(Adriablastina)ꢁ, as a reference drug, in three deferent
concentrations, were evaluated in the National Institute
of Cancer, Cairo, Egypt.
IC50 was calculated with regard to saline control group
and potency was calculated with regard to the percent-
age of the change of the doxorubicin and tested com-
pounds, as depicted in Table 1.
Compound 5 reacts with C-phenyl-N-phenylnitrilimine
19 under the same experimental conditions to afford
the pyrazole derivative 24 (Scheme 5).
3. Conclusions
1
The H NMR spectrum of the latter product revealed a
singlet signal at d 8.91 assignable to pyrazole CH-5 pro-
The results of antitumor activity study of the newly syn-
thesized compounds indicated that all compounds have
no or low antitumor activity except compound 24 which
was found to have moderate activity toward Ehrlich
Ascites Carcinoma tumor cells (in vitro) in relation to
the reference drug Doxorubicin (Table 1).
R
O
N
O
HN
B
N
Compounds carrying two carbamoyl moieties are more
active than those carrying one moiety. Moreover, com-
pounds carrying carboxamide moiety are more active
than those carrying acetyl or ester moieties. Also haloge-
nated derivatives are more active than non-halogenated
ones. m-alkyl substitution showed double the activity of
p-alkyl as in compounds 9b,c. Finally substitution with
N
X
A
N
Figure 2.

886
A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
chloro-N-phenylacetamide (1) (5.18 g, 20 mmol) and
pentan-2,4-dione (2) (2 ml, 20 mmol ) was added to
20 ml freshly prepared sodium ethoxide solution [pre-
pared by adding 460 mg sodium metal into absolute eth-
anol (20 mmol)] and the mixture was stirred for 1 h at
room temperature. The yellow precipitated product
was filtered off, washed with distilled water to get rid
of NaCl salt, and dried. Recrystallization from ethanol
afforded 5.1 g of 4-acetyl-5-methyl-1-phenyl-3-phenylc-
arbamoyl-1H-pyrazole (3) (80% yield), mp 141–142 ꢂC.
IR (KBr) tmax/cmÀ1: 3259 (NH), 1751 (C@O), 1666
Cl
N
NH
21
Et3N/
Dry benzene
1
(C@O), 1596 (C@N); H NMR (DMSO-d6): d 2.43 (s,
O
O
3H), 2.76 (s, 3H), 7.12–7.7 (m, 10H), 9.01 (s, br., D2O
exchangeable, NH); 13C NMR (DMSO-d6): d 7.167,
26.744 (2 CH3, aliphatic), 114.82, 119.25, 120.65,
123.87, 124.28, 124.32, 132.54, 132.99, 138.99, 139.85
(11 CH, aromatic carbons), 154.17 (C@O, amide), 192
(C@O, ketonic carbon); MS (m/z, %): 319 (M+, 100),
227 (99.5), 157 (26.5), 118 (22.9), 77 (54); analysis for
C19H17N3O2 (319.36), Calcd: C, 71.46; H, 5.37; N,
13.16%, found C, 71.61; H, 5.79; N, 13.23%.
N
N
H
N
N
N
N
5
22
Reflux, 2h
4.1.3. 4-[(E)-3-(Dimethylamino)acryloyl]-5-methyl-1-phe-
nyl-3- phenylcarbamoyl-1H-pyrazole (5). A mixture of 4-
acetyl-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-pyra-
zole (3) (6.38 g, 20 mmol) and dimethylformamide-
dimethylacetal (DMF-DMA) (4) (2.38 ml, 20 mmol)
was taken in dry xylene (20 ml) and the mixture was re-
fluxed for 4 h, then left to cool to room temperature.
The reddish-yellow precipitated product was filtered
off, washed with petroleum ether (60/80 ꢂC), and dried.
Recrystallization from benzene afforded 6.73 g of
4-((E)-3-(dimethylamino)acryloyl)-5-methyl-N-1-diphenyl-
1H-pyrazole-3-carboxamide (90% yield ), mp 169–
170 ꢂC. IR (KBr) tmax/cmÀ1: 3421 (NH), 1681 (C@O),
H
N
O
H
N
O
O
O
-HNMe2
N
N
N
N
N
N
N
N
Me2N
24
23
Scheme 5.
1
1627 (C@O), 1591 (C@N); H NMR (CDCl3): d 2.43
electron withdrawing group such as NO2 abolished the
activity as in compound 15c.
(s, 3 H), 2.88, 3.11 (s, 6H, N(CH3)2), 5.55 (d, 1H,
J = 12.5 Hz), 7.03–7.79 (m, 10H), 7.3 (d, 1H,
J = 12.5 Hz), 11 (s, br., D2O exchangeable NH); 13C
NMR (DMSO-d6): d 12.95 (CH3, aliphatic), 37.4, 43.6
(N(CH3)2), 97.74 (CH, aliphatic), 119.87, 122.73,
123.5, 125.66, 128.65, 128.7, 129.03, 138.64, 138.7,
140.48, 145.31 (11 CH, aromatic carbons), 154.55
(–CH@CH–N(CH3)2), 159.57 (amide), 187.5 (ketonic
carbon); MS (m/z, %): 374 (M+, 22.6), 330 (15.5), 304
(15.1), 282 (32.3), 118 (26.8), 98 (100), 77 (57), 70
(68.2); analysis for C22H22N4O2 (374.44), Calcd: C,
70.57; H, 5.92; N, 14.96%, found C, 70.61; H, 5.79; N,
14.93%.
4. Experimental
4.1. Chemistry
4.1.1. General. All melting points were measured on a
Gallenkamp melting point apparatus and are uncor-
rected. The infrared spectra were recorded in potassium
bromide disks on pye Unicam SP 3300 and Shimadzu
FT IR 8101 PC infrared spectrophotometers. The
NMR spectra were recorded on a Varian Mercury
VX-300 NMR spectrometer. 1H (300 MHz) and 13C
NMR (75.46 MHz) were run in deuterated chloroform
(CDCl3) or dimethylsulfoxide (DMSO-d6). Chemical
shifts were related to that of the solvent. Mass spectra
were recorded on a Shimadzu GCMS-QP 1000 EX mass
spectrometer at 70 eV. Elemental analyses were carried
out at the Microanalytical Center of Cairo University,
Giza, Egypt. Hydrazonoyl chlorides 1,30 6a–d,31 12a–
c,32 and 2133 were prepared following the procedures
reported in the literature.
4.1.4. 3-Acetyl-1-aryl-4-[(5-methyl-1-phenyl-3-phenylcar-
bamoyl)- 1H-pyrazol-4-yl]carbonylpyrazoles (9a–d): Gen-
eral procedure. To a mixture of enaminone 5 (0.748 g,
2 mmol) and the appropriate 2-oxo-N-arylpropanehyd-
razonyl chloride 6 (2 mmol), in benzene (10 ml), an
equivalent amount of triethylamine was added. The
reaction mixture was heated under reflux for 2 h and
the solvent was distilled off under reduced pressure.
The residual brown viscous liquid was taken in ethanol
and the resulting solid was collected by filtration,
washed thoroughly with ethanol, dried, and finally
recrystallized from ethanol/DMF to afford correspond-
ing pyrazole derivatives 9a–d in 70–80% yield. The phys-
4.1.2. 4-Acetyl-5-methyl-1-phenyl-3-phenylcarbamoyl-1H-
pyrazole (3). A mixture of 2-(2-phenylhydrazono)-2-

A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
887
1
ical and spectral data of compounds 9a–d are listed
below.
(C@O), 1529 (C@N); H NMR (DMSO-d6): d 2.45 (s,
3H, CH3), 2.52 (s, 3H, CH3), 6.97–7.66 (m, 14H, ArH’s),
8.87 (s, 1H, pyrazole-5-CH), 10.31 (s, br., D2O
exchangeable, NH); MS (m/z, %): 569 (M++2, 12.0),
567 (M+, 12.3), 526 (21.1), 524 (22.0), 477 (1.5), 475
(1.5), 435 (97.5), 433 (100), 407 (0.3), 405 (0.3), 304
(2.5), 276 (0.7), 118 (14.0), 77 (27.9); analysis for
C29H22BrN5O3 (568.42), Calcd: C, 61.28; H, 3.90; N,
12.32%, found C, 61.60; H, 3.92; N, 12.40%.
4.1.4.1. 3-Acetyl-1-phenyl-4-[(5-methyl-1-phenyl-3-phe-
nylcarbamoyl)-1H-pyrazol-4-yl]carbonylpyrazole
Yield (74%), mp 240–242 ꢂC (ethanol/DMF). IR (KBr)
max/cmÀ1: 3413 (NH), 1701 (C@O), 1670 (C@O),
(9a).
t
1635 (C@O), 1600 (C@N);1H NMR (DMSO-d6): d
2.46 (s, 3H, CH3), 2.52 (s, 3H, CH3CO), 6.97–7.83 (m,
15H, ArH’s), 8.84 (s, 1H, pyrazole-5-CH), 10.31 (s,
br., D2O exchangeable, NH);13C NMR (DMSO-d6): d
11.99, 27.35 (2 CH3, aliphatic), 119.59, 119.70, 120.35,
123.78, 125.18, 125.50, 127.94, 128.51, 129.13, 129.54,
129.60, 131.82, 137.94, 138.23, 138.49, 143.39, 148.24,
(17 aromatic carbons), 149.58 (pyrazole-5-CH), 160.34
(amide), 183.69, 192.96 (2 ketonic carbons); MS (m/z,
%): 489 (M+, 16.8), 446 (40.1), 355 (100), 327 (12.3),
118 (20.9), 77 (18.1). Analysis for C29H23N5O3
(489.52): Calcd: C, 71.15; H, 4.74; N, 14.31%; found
C, 71.39; H, 4.91; N, 14.36%.
4.1.5. Ethyl 1-aryl-4-(4[(5-methyl-1-phenyl-3-phenylcar-
bamoyl)-1H-pyrazolyl]carbon-yl)pyrazole-3-carboxylates
(15a–c): General procedure. To a mixture of enaminone
5 (0.748 g, 2 mmol) and the appropriate chloro(arylhyd-
razono)ethyl acetate 12a–c (2 mmol), in benzene (10 ml),
an equivalent amount of triethylamine was added. The
reaction mixture was heated under reflux for 2 h and
the solvent was distilled off at reduced pressure. The
residual viscous liquid was taken in ethanol then the
resulting solid was collected by filtration, washed thor-
oughly with ethanol, dried, and finally recrystallized
from ethanol/DMF to afford corresponding pyrazole
derivatives 15a–c in 70–80% yield. The physical and
spectral data of compounds 15a–c are listed below.
4.1.4.2. 3-Acetyl-1-(4-methylphenyl)-4-[(5-methyl-1-
phenyl-3-phenylcarbamoyl)pyrazol-4-yl]carbonyl-pyra-
zole (9b). Yield (76%), mp 205–207 ꢂC (ethanol/DMF).
IR (KBr) tmax/cmÀ1: 3417 (NH), 1797 (C@O), 1670 (2
1
C@O), 1596 (C@N); H NMR (DMSO-d6): d 2.35 (s,
4.1.5.1. Ethyl 4-(4[(5-methyl-1-phenyl-3-phenylcarba-
moyl)-1H-pyrazolyl]carbonyl)-1-phenylpyrazole-3-carbox-
ylate (15a). Yield (80%), mp 120–122 ꢂC (ethanol/
DMF). IR (KBr) tmax/cmÀ1: 3413 (NH), 1732 (C@O),
1639 (C@O), 1600 (C@O), 1531 (C@N); 1H NMR
(DMSO-d6): d 1.23 (t, 3H, CH3, J = 6.9), 2.49 (s, 3H,
CH3), 4.259 (q, 2H, CH2, J = 6.9), 6.97–7.74 (m, 15H,
ArH’s), 8.79 (s, 1H, pyrazole-5-CH), 11.2 (s, br., D2O
exchangeable, NH); MS (m/z, %): 519 (M+, 15.8), 427
(40.1), 355 (100), 118 (10.1), 77 (20.5); analysis for
C30H25N5O4 (519.6), Calcd: C, 69.35; H, 4.85; N,
13.48%, found C, 69.70; H, 4.93; N, 13.52%.
3H, CH3), 2.45 (s, 3H, CH3), 2.51 (s, 3H, CH3CO),
6.99-7.63 (m, 10H, ArH’s), 7.670 (d, 2H, J = 2.7 Hz),
7.677 (d, 2H, J = 2.7 Hz), 8.79 (s, 1H, pyrazole-5-CH),
10.32 (s, br., D2O exchangeable, NH); 13C NMR
(DMSO-d6): d 11.96, 20.55, 27.39 (3 CH3, aliphatic),
119.51, 119.76, 120.49, 123.78, 125.13, 125.50, 128.52,
129.10, 129.52, 129.96, 131.75, 136.32, 137.52, 137.98,
138.30, 143.36, 148.20, (17 CH, aromatic carbons),
149.49 (pyrazole-5-CH), 160.35 (amide), 183.74, 192.99
(2 ketonic carbons); MS (m/z, %): 503 (M+, 14.3), 460
(32.2), 369 (100), 118 (18.1), 77 (16.2); analysis for
C30H25N5O3 (503.55), Calcd: C, 71.56; H, 5.00; N,
13.91%, found C, 71.59; H, 5.01; N, 14.00%.
4.1.5.2. Ethyl 4-(4[(5-methyl-1-phenyl-3-phenylcarba-
moyl)-1H-pyrazolyl]carbonyl)-1-(4-nitrophenyl)-pyrazole-
3-carboxylate(15b). Yield (79%), mp 121–122 ꢂC (etha-
nol/DMF). IR (KBr) tmax/cmÀ1: 3413 (NH), 1739
(C@O), 1631 (2 C@O), 1596 (C@N); 1H NMR
(DMSO-d6): d 1.16 (t, 3H, CH3, J = 6.9), 2.45 (s, 3H,
CH3), 4.21 (q, 2H, CH2,J = 6.9), 6.97–7.64 (m, 10H,
ArH’s), 7.693 (d, 2H, J = 9), 7.723 (d, 2H, J = 9), 8.96
(s, 1H, pyrazole-5-CH), 10.26 (s, br., D2O exchangeable,
NH); 13C NMR (DMSO-d6): d 11.96, 13.72 (2 CH3, ali-
phatic), 61.34 (CH2), 119.89, 120.5, 123.76, 125.25,
125.48, 126.66, 128.45, 129.2, 129.54, 132.55, 137.89,
138.13, 142.69, 143.41, 144.28, 146.05 (17 CH, aromatic
carbons), 147.64 (pyrazole-5-CH), 159.95 (amide),
160.96, 182.59 (2 ketonic carbons); MS (m/z, %): 564
(M+, 35.4), 472 (75.8), 400 (100), 354 (37.6), 185
(16.2), 118 (49.5), 77 (62.3); analysis for C30H24N6O6
(519.6), Calcd: C, 62.82; H, 4.28; N, 14.89%, found C,
62.89; H, 4.33; N, 14.92%.
4.1.4.3. 3-Acetyl-1-(3-methylphenyl)-4-[(5-methyl-1-
phenyl-3-phenylcarbamoyl)pyrazol-4-yl]carbonyl-pyra-
zole (9c). Yield (71%), mp 208–209 ꢂC (ethanol/DMF).
IR (KBr) tmax/cmÀ1: 3433 (NH), 1790 (C@O), 1680
1
(C@O), 1616 (C@O), 1523 (C@N); H NMR (DMSO-
d6): d 2.36 (s, 3H, CH3), 2.46 (s, 3H, CH3), 2.52 (s,
3H, CH3CO), 6.96–7.68 (m, 14H, ArH’s), 8.78 (s, 1H,
pyrazole-5-CH), 10.33 (s, br., D2O exchangeable, NH);
13C NMR (DMSO-d6): d 11.97, 20.97, 27.41 (3 CH3, ali-
phatic), 116.79, 119.68, 120.12, 120.38, 123.75, 125.15,
125.50, 128.34, 128.5, 129.1, 129.38, 129.53, 131.84,
137.97, 138.3, 138.49, 139.31, 143.39, 148.32 (19 CH,
aromatic carbons), 149.57 (pyrazole-5-CH), 160.38
(amide), 183.69, 192.96 (2 ketonic carbons); MS (m/z,
%): 503 (M+, 13.9), 460 (30.4), 369 (100), 118 (16.1),
77 (23.2); analysis for C30H25N5O3 (503.55), Calcd: C,
71.56; H, 5.00; N, 13.91%, found C, 71.60; H, 5.08; N,
13.99%.
4.1.5.3. Ethyl 1-(4-bromophenyl)-4-{4[(5-methyl-1-
phenyl-3-phenylcarbamo-yl)-1H- pyrazolyl]carbonyl} pyr-
azole-3-carboxylate (15c). Yield (71%), mp 178–180 ꢂC
(ethanol/DMF). IR (KBr) tmax/cmÀ1: 3367 (NH), 1732
(C@O), 1681 (2 C@O), 1596 (C@N); 1H NMR
4.1.4.4. 3-Acetyl-1-(4-bromophenyl)-4-[(5-methyl-1-
phenyl-3-phenylcarbamoyl)pyrazol-4-yl]carbonyl-pyra-
zole (9d). Yield (80%), mp 258–259 ꢂC (ethanol/DMF).
IR (KBr) tmax/cmÀ1: 3431 (NH), 1670 (2C@O), 1596

888
A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
(DMSO-d6): d 1.17 (t, 3H, CH3, J = 7.2), 2.48 (s, 3H,
CH3), 4.235 (q, 2H, CH2, J = 7.2), 6.93–7.704 (m, 10H,
ArH’s), 8.098 (d, 2H, J = 9), 8.352 (d, 2H, J = 9), 9.15
(s, 1H, pyrazole-5-CH), 10.28 (s, br., D2O exchangeable,
NH); 13C NMR (DMSO-d6): d 11.89, 13.79 (2 CH3, ali-
phatic), 61.18 (CH2), 120.01, 120.54, 120.72, 121.45,
123.77, 125.53, 126.11, 128.5, 129.19, 129.55, 132.00,
132.48, 137.68, 137.99, 138.26, 143.19, 143.53 (17 CH,
ArC’s), 147.56 (pyrazole-5-CH), 159.95 (C@O, amide),
161.25 (C@O, ketonic carbon), 182.68 (C@O, ester car-
bonyl carbon); MS (m/z, %): 599 (M++2, 8.8), 597 (M+,
7.9), 507 (22.0), 505 (23.5), 479 (0.7), 477 (0.7), 435
(97.4), 433 (100), 354 (37.6), 157 (2.5), 185 (16.2), 118
(50.9), 77 (44.7); analysis for C30H24N6O6 (598.4),
Calcd: C, 60.21; H, 4.04; N, 11.70%, found C, 60.45;
H, 4.14; N, 11.72%.
120.11, 121.72, 123.47, 123.78, 125.57, 127.33, 127.88,
128.51, 128.56, 128.80, 129.05, 129.44, 129.56, 132.14,
133.38, 138.18, 138.36, 138.76, 141.82, 147.04, (21
CH, ArC’s), 152.48 (pyrazole-5-CH), 160.13 (C@O,
amide), 183.76 (C@O, ketonic carbon); MS (m/z): 523
(M+, 25.6), 431 (100%), 247 (24.5%), 118 (11%), 77
(35.1%); analysis for C33H25N5O2 (523.6), Calcd: C,
75.70; H, 4.81; N, 13.38%, found C, 75.75; H, 4.84;
N; 13.52%.
4.2. Pharmacology
4.2.1. Materials. RPMI 1640 medium (Sigma), Ehrlich
Ascites Carcinoma cells (EAC) suspension (2.5.105/
ml), and Trypan blue dye. A stock solution was pre-
pared by dissolving one gram of the dye in distilled
water (100 ml). The working solution was then prepared
by diluting (1 ml) the stock solution with 9 ml of dis-
tilled water. The stain was used then for staining the
dead EAC cells.
4.1.6. 4-[(5-Methyl-1-phenyl-3-phenylcarbamoyl-pyrazol-
4-yl)carbonyl]-1-phenyl-3-phenylcarbamoyl-1H-pyrazole
(20). To a mixture of 5 (0.748 g, 2 mmol) and 2-(2-phen-
ylhydrazono)-2-chloro-N-phenylacetamide (1) (0.518 g,
2 mmol) in benzene (10 ml), an equivalent amount of tri-
ethylamine was added. The reaction mixture was heated
under reflux for 2 h. The solvent was distilled off at re-
duced pressure and the residual viscous liquid was taken
in ethanol. The resulting solid was collected by filtration,
washed thoroughly with ethanol, dried, and finally
recrystallized from ethanol/DMF to afford the corre-
sponding pyrazole derivative 20 in 95% yield, mp 183–
184 ꢂC. IR (KBr) tmax /cmÀ1: 3386 (NH), 3228 (NH),
4.2.2. Antitumor activity of the E.A.C.34–36 A set of ster-
ile test tubes was used, where 2.5 · 105 tumor cells/ ml
were suspended in phosphate-buffered saline. Then 25,
50, 100 lg/ml from tested compound were added to
the suspension, kept at 37 ꢂC for 2 h. Trypan blue dye
exclusion test was then carried out to calculate the per-
centage of nonviable cells.
Doxorubicin (Adriablastina)ꢁ is taken as a positive con-
trol. The percentage of the non-viable cells is calculated
by the following equation; % of non-viable cells = N/
Nt · 100, where N is the number of non-viable cells
counted, Nt is the total number of cells. The test was re-
peated four times for each compound.
1
1662 (2 C@O), 1604 (C@O), 1527 (C@N); H NMR
(DMSO-d6): d 2.38 (s, 3H, CH3), 7.02–7.93 (m, 20H,
ArH’s), 8.06 (s, 1H, pyrazole-5-CH), 10.23 (s, br., D2O
exchangeable, NH), 10.76 (s, br., D2O exchangeable,
NH); 13C NMR (DMSO-d6): d 11.76 (CH3, aliphatic),
119.55, 119.83, 120.24, 121.27, 123.79, 123.90, 124.32,
125.61, 127.92, 128.54, 128.85, 129.10, 129.39, 129.66,
132.95, 138.10, 138.38, 138.51, 138.66, 142.33, 146.63
(21 ArC’s), 147.93 (pyrazole-5-CH), 159.39, 159.83 (2
C@O, amide), 184.05 (C@O, ketonic carbon); MS (m/
z): 566 (M+, 23.9), 446 (18.6), 355 (100), 118 (14.5), 77
(29.5); analysis for C34H26N6O3 (566.6), Calcd: C,
72.07; H, 4.64; N, 14.83%, found C, 72.45; H, 4.70; N,
14.92%.
4.2.3. Statistical analysis. Data are expressed as means
SE. Differences between control and treated tubes
were tested using one-way ANOVA followed by multi-
ple comparisons by the Duncan’s multiple rang test. A
probability value less than 0.05 was considered statisti-
cally significant.
References and notes
4.1.7. 1,3-Diphenyl-4-[(5-methyl-1-phenyl-3-phenylcar-
bamoylpyrazol-4-yl)carbonyl]-1H-pyrazole (24). To a
mixture of the enaminone 5 (0.748 g, 2 mmol) and
N-phenylbenzenecarbohydrazonoyl chloride (21)
(0.46 g, 2 mmol) in benzene (10 ml), an equivalent
amount of triethylamine was added. The reaction mix-
ture was heated under reflux for 2 h and the solvent
was removed under reduced pressure. The residual
viscous liquid was taken in ethanol and the resulting
solid was collected by filtration, washed thoroughly
with ethanol, dried, and finally recrystallized from
ethanol/DMF to afford compound 24. Yield (92%),
1. Abdel-Gawad, S. M.; Abdel-Aziem, A.; Ghorab, M. M.
Phosphorus Sulfur Silicon 2003, 178, 1795.
2. Maekawa, T.; Hara, R.; Odaka, H.; Kimura, H.; Mizu-
fune, H.; Fukatsu, K. PCT Int. Appl. WO 03 99,793.
[Chem.Abstr., 2004, 140, 16723h].
3. Mercep, M.; Mesic, M.; Pesic, D. PCT Int. Appl. WO 03
99,822. [Chem.Abstr., 2004, 140, 16724j].
4. Qiao, J. X.; Pinto, D. J.; Orwat, M. J.; Han, W.; Friedrich,
S. R. PCT Int. Appl. WO 03 99,276. [Chem.Abstr.,2004,
140, 16722g].
5. Baraldi, P. G.; Bovero, A.; Fruttarolo, F.; Romagnoli, R.;
Tabrizi, M. A.; Preti, D.; Varani, K.; Borea, P. A.;
Moorman, A. R. Bioorg. Med. Chem. 2003, 11, 4161.
6. Stamford, A. W.; Wu, Y., PCT Int. Appl. WO 2004 5,262.
[Chem.Abstr. 2004, 140, 111411p].
7. Brown, M. L.; Cheung, M.; Dickerson, S. H.; Drewry, D.
H.; Lackey, K. E.; Peat, A. J.; Thomson, S. A.; Veal, J.
M.; Wilson, J. L. R., PCT Int. Appl. WO 2004 9,596.
[Chem.Abstr. 2004, 140, 128436y].
mp 241–242 ꢂC (ethanol/DMF). IR (KBr) tmax/cmÀ1
:
3382 (NH), 1678 (2 C@O), 1596 (C@O), 1527
1
(C@N); H NMR (DMSO-d6): d 2.33 (s, 3H, CH3),
7.01–7.89 (m, 20H, ArH’s), 8.91 (s, 1H, pyrazole-5-
CH), 10.23 (s, br., D2O exchangeable, NH); 13C
NMR (DMSO-d6): d 11.53 (CH3, aliphatic), 119.14,

A. M. Farag et al. / Bioorg. Med. Chem. 16 (2008) 881–889
889
8. Stevensons, T. M.; Lahm, G. P.; Pasteris, R. J., PCT Int.
Appl. WO 03 106,427. [Chem.Abstr. 2004, 140, 42172x].
9. Heerding, D. A., PCT Int. Appl. WO 03 103,686.
[Chem.Abstr. 2004,140, 42170v].
10. Cardia, M. C.; Corda, L.; Fadda, A. M.; Maccioni, A. M.;
Maccioni, E.; Plumitallo, A. Farmaco 1998, 53, 698.
11. Mullican, M. D.; Wilson, M. W.; Cannor, D. T.; Kostlan,
C. R.; Dyer, R. D. J. Med. Chem. 1993, 36, 1090.
12. Kirkpatrick, W. E.; Okabe, T.; Hillyard, I.; Robins, R. K.;
Dren, A. T.; Novinson, T. J. Med. Chem. 1977, 20, 387.
13. Abadi, A. H.; Abdel-Haleem, E. A.; Hassan, G. S. Chem.
Pharm. Bull. 2003, 51, 838.
21. Foglia, S.; Nieri, P.; Chicca, A.; Adinolfi, B.; Mariotti, V.;
Iacopetti, P.; Breschi, M. C.; Pellegrini, S. FEBS Lett.
2006, 580, 1733.
22. Yoshida, M.; Hayakawa, I.; Hayashi, N.; Agatsuma, T.;
Oda, Y.; Tanzawa, F.; Iwasaki, S.; Koyama, K.; Furuk-
awa, H.; Kurakata, S.; Sugano, Y. Bioorg. Med. Chem.
Lett. 2005, 15, 3328.
23. Shaaban, R. M.; Saleh, T. S.; Osman, F. H.; Farag, A. M.
J. Heterocycl. Chem. 2007, 44, 177.
24. Shaaban, R. M.; Saleh, T. S.; Farag, A. M. Heterocycles
2007, 71, 1765.
25. Dawood, K. M.; Farag, A. M.; Abdel-Aziz, H. A. J. Chin.
Chem. Soc. 2006, 53, 873.
26. Dawood, K. M.; Farag, A. M.; Abdel-Aziz, H. A.
Heteroatom Chem. 2005, 17, 621.
14. Furet, P.; Imbach, P.; Ramsey, T. M.; Schlapbach, A.;
Scholz, D. and Caravatti, G., PCT Int. Appl. WO 2004
5,282. [Chem. Abstr. 2004, 140, 111424v].
15. Raffa, D.; Daidone, G.; Maggio, B.; Cascioferro, S.;
Plescia, F.; Schillaci, D. Farmaco 2004, 59, 215.
27. Dawood, K. M.; Farag, A. M.; Abdel-Aziz, H. A.
J. Chem. Res. (S) 2005, 378.
16. Sherif, A. F. R. Bioorg. Med. Chem. 2006, 14, 6475.
17. Cheung, K.-M.; Matthews, T. P.; James, K.; Rowlands,
M. G.; Boxall, K. J.; Sharp, S. Y.; Maloney, A.; Roe, S.
M.; Prodromou, C.; Pearl, L. H.; Aherne, G. W.;
McDonald, E.; Workman, P. Bioorg. Med. Chem. Lett.
2005, 15, 3338.
28. Dawood, K. M.; Ragab, E. A.; Farag, A. M. J. Chem.
Res. (S) 2003, 685M, 1151.
29. Al-Omran, F.; Al-Awadi, N.; Abau El-Khair, A.; Elnagdi,
M. H. Org. Prep. Proced. Int. 1997, 29, 285.
30. Shawali, A. S.; Osman, A. Tetrahedron 1971, 27,
2517.
18. Dymock, B. W.; Barril, X.; Brough, P. A.; Cansfield, J. E.;
Massey, A.; McDonald, E.; Hubbard, R. E.; Surgenor, A.;
Roughley, S. D.; Webb, P.; Workman, P.; Wright, L.;
Drysdale, M. J. J. Med. Chem. 2005, 48, 4212.
19. Barril, X.; Beswick, M. C.; Collier, A.; Drysdale, M. J.;
Dymock, B. W.; Fink, A.; Grant, K.; Howes, R.; Jordan,
A. M.; Massey, A.; Wayne, A. S.; Workman, J. P.;
Wright, L. Bioorg. Med. Chem. Lett. 2006, 16, 2543.
20. Allan, G. M.; Bubert, C.; Vicker, N.; Smith, A.; Tutill, H.
J.; Purohit, A.; Reed, M. J.; Potter, B. V. L. Molecul. Cell
Endocrin. 2006, 248, 204.
31. Dieckmann, W.; Platz, O. Chem. Ber. 1906, 38, 2989.
32. Hegarty, A. F.; Cashaman, M. P.; Scoti, F. L. Chem.
Commun. 1971, 13, 884.
33. Wolkoff, P. Can. J. Chem. 1975, 53, 1333.
34. El-Merzabani, M. M.; El-Aaser, A. A.; El-Dueini, A. K.;
EL-Masry, A. M. Planta Medica 1979, 36, 87–90.
35. Takemoto, D. J.; Dunford, C.; McMurray, M. M.
Toxicology 1982, 20, 593.
36. El-Merzabani, M. M.; El-Aaser, A. A.; Attia, M. A.; El-
Dueini, A. K.; Ghazal, A. M. Planta Medica 1979, 36,
150–155.