Synthesis and antimicrobial activity of some new heterocycles incorporating antipyrine moiety

Article abstract of DOI:10.1016/j.ejmech.2007.12.009

2-Cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide (1) was utilized as key intermediate for the synthesis of some new coumarin 2, pyridine 3, pyrrole 4, thiazole 7, pyrido[2′,3′:3,4][pyrazolo[5,1-c]triazine and aminopyrazole 9. Treatment of aminopyrazole 9 with nitrous acid, 1,3-dicarbonyl compounds, enaminone, and DMF-DMA led to the formation of pyrazolo[3,4-d]triazine 10, pyrazolo[1,5-a]pyrimidines 11, 12, 14, and pyrazolo[3,4-d]pyrimidine 13, respectively. Condensation of 9 with isatin afforded Schiff base 16. The newly synthesized compounds were characterized by IR, ¹H NMR and mass spectral studies. Representative compounds of the synthesized products were tested and evaluated as antimicrobial agents.

Full text of DOI:10.1016/j.ejmech.2007.12.009

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European Journal of Medicinal Chemistry 43 (2008) 2122e2129
http://www.elsevier.com/locate/ejmech
Original article
Synthesis and antimicrobial activity of some new heterocycles
incorporating antipyrine moiety
*
Samir Bondock , Ramy Rabie, Hassan A. Etman, Ahmed A. Fadda
Department of Chemistry, Faculty of Science, Mansoura University, El-gomhuria Street, ET-35516 Mansoura, Egypt
Received 5 September 2007; received in revised form 27 November 2007; accepted 6 December 2007
Available online 23 December 2007
Abstract
2-Cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide (1) was utilized as key intermediate for the synthesis of
some new coumarin 2, pyridine 3, pyrrole 4, thiazole 7, pyrido[20,30:3,4][pyrazolo[5,1-c]triazine and aminopyrazole 9. Treatment of aminopyr-
azole 9 with nitrous acid, 1,3-dicarbonyl compounds, enaminone, and DMFeDMA led to the formation of pyrazolo[3,4-d]triazine 10, pyra-
zolo[1,5-a]pyrimidines 11, 12, 14, and pyrazolo[3,4-d]pyrimidine 13, respectively. Condensation of 9 with isatin afforded Schiff base 16.
The newly synthesized compounds were characterized by IR, 1H NMR and mass spectral studies. Representative compounds of the synthesized
products were tested and evaluated as antimicrobial agents.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Antipyrine; Pyrazole; Pyrazolo[1,5-a]pyrimidine; Pyrazolo[3,4-d]triazine; Pyridine; Antimicrobial activity
1. Introduction
some new heterocycles incorporating antipyrine moiety start-
ing from N-antipyrinyl cyanoacetamide in order to investigate
their antimicrobial activity.
Antipyrine (2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) was
the first pyrazolone derivative used in the management of
pain and inflammation, and their derivatives have attracted
the attention of several research groups due to their potential
activities [1e5]. In this context, broad spectra of bioactive
antipyrine derivatives have been investigated and diversities
of bioactivities such as analgesic [6,7], anti-inflammatory
[8], antimicrobial [9e11], and anticancer activity [12] have
been reported. The antibacterial activity caught our attention
because antimicrobial resistance developed by important path-
ogens has increased in the last decade [13]. Besides, emerging
and re-emerging bacterial infectious diseases still cause death
and disability worldwide [14].
2. Results and discussion
2.1. Chemistry
The synthetic procedures adopted to obtain the target
compounds are depicted in Schemes 1 and 2. The starting
compound, 2-cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-di-
hydro-1H-pyrazol-4-yl)acetamide (1) was prepared according
to the previously reported procedure [21]. Thus, cycloconden-
sation of compound 1 with salicylaldehyde in boiling ethanol
containing a catalytic amount of piperidine afforded the cou-
marin derivative 2. The reaction of 1 with 1,3-dicarbonyl
compound was studied in the aim of formation of pyridine
derivatives with potential biological activities [22,23]. Thus,
it reacted with acetylacetone to give the pyridine derivative
3. Structure of the latter product was based on analytical and
spectral data. The IR spectrum showed three absorption bands
at 2217, 1662 and 1645 cmꢀ1 due to CN and two CO groups.
In view of the above mentioned findings and as continua-
tion of our effort [15e20] to identify new candidates that
may be of value in designing new, potent, selective and less
toxic antimicrobial agents, we report herein the synthesis of
* Corresponding author. Tel.: þ20 502369267; fax: þ20 502246781.
E-mail address: Bondock@mans.edu.eg (S. Bondock).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.12.009

S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
2123
CHO
N
H
N
OH
N
N
N
N
NH
N
H
N
H
N
N
AcOH/
N
H
An
H
N
An
CN
O
EtOH/Pip.
An
O
NH
O
O
NH
(6)
(5)
N2Cl
N
(2)
N
N
S
H
O
O
S
H
H
N
N
N
Ph-N=C=S / S
EtOH / TEA
Ph
An
CN
N
An
EtOH/Pip.
CN
An
O
O
NH2
O
(1)
(7)
(3)
i. PhNCS / KOH / DMF
ii. MeI
O
Ph
PhHN
N
PhHN
SMe
CN
Br
NH
CN
NH2NH2.H2O
EtOH
H
N
Ph
H
N
N
An
An
An
EtOH/TEA
O
O
NH2
O
(4)
(8)
(9)
An
=
O
N
N
Ph
Scheme 1.
1
Its H NMR spectrum revealed the appearance of three new
singlets at d 2.25, 2.36, and 6.15 ppm assigned to two methyl
protons and the pyridinone H-5.
compound 1 with 4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-
diazonium chloride [26] in pyridine at 0e5 ꢁC afforded the
corresponding hydrazono compound 5. When compound 5 is
refluxed in acetic acid, it can be cyclized to N-(1,5-dimethyl-
3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-4-imino-4,6-
dihydropyrido[20,30:3,4]pyrazolo[5,1-c][1,2,4]triazine-3-carbox-
amide (6). The formation of 6 may be interpreted through the
nucleophilic attack of ring nitrogen on cyano group. The IR
spectrum of compound 6 showed three absorption bands at
3406, 3288, and 3228 cmꢀ1 due to three NH groups besides
two carbonyl absorption bands at 1672 and 1641 cmꢀ1. Its
1H NMR spectrum revealed three D2O-exchangeable singlets
at d 9.12, 9.33, and 10.24 ppm due to three NH protons, in ad-
dition to four singlets at d 2.21, 3.18, 2.73, and 3.07 ppm as-
signable for two methyl protons of the pyridine ring and two
methyl protons of the antipyrine ring, respectively.
Recently, we have reported the reaction of cyanoacetamide
moiety with a-halocarbonyl compounds which represents
a new, simple and efficient synthetic route for the synthesis
of pyrrole derivatives [24]. Therefore, it was interesting to
study the reaction of 1 with phenacyl bromide. Cycloconden-
sation of 1 with phenacyl bromide in boiling ethanol using
triethylamine as a basic catalyst furnished the pyrrole deriva-
tive 4. The analytical and spectral data are in agreement
1
with the proposed structure. Thus, H NMR spectrum of the
reaction product showed two doublet signals at d 4.54 and
5.65 ppm corresponding to the two vicinal pyrroline protons
H-3 and H-4, respectively, two singlets at d 2.24, 3.24 ppm
corresponding to CH3, NCH3, and a multiplet at d 7.15e
7.67 ppm corresponding to aromatic protons. The IR spectrum
showed the presence of two C]O groups stretching at 1690,
The reaction of compound 1 with both elemental sulfur and
phenyl isothiocyanate in warming ethanol containing a cata-
lytic amount of triethylamine gave the thiazole derivative 7.
1645 cmꢀ1 and CN group at 2195 cmꢀ1
.
1
In continuation of our interest in the synthesis of bridged-
head nitrogen heterocyclic systems [25], we have found that
diazotized heterocyclic amine is an excellent building block
for the synthesis of the target compound. Thus, coupling of
Elemental analysis, IR, H NMR and 13C NMR are in agree-
ment with the proposed structure.
Treatment of compound 1 with phenyl isothiocyanate in
DMF, and in the presence of potassium hydroxide, at room

2124
S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
PhHN
PhHN
N
N
N
PhHN
N
N
NH
NH
H
N
AcOH/
-Me2NH
NaNO2 / HCl
0-5 °C
NH
O
An
O
N
O
N
(14)
N
N
An
N
An
(13)
O
(10)
N
O
PhHN
N
Ph
O
O
O
PhHN
N
N
PhHN
N
H
N
N
H
N
Ph
N
An
NH
H
N
An
AcOH
AcOH
O
An
N
O
N
O
NH2
(15)
O
(9)
O
N
H
PhHN
N
OH
PhHN
N
O
O
N
H
N
NH
N
O
An
PhHN
An
AcOH/
NHPh
AcOH
NH
H
N
O
N
NH
N
An
O
O
N
(12)
NH
NH
(16)
An
O
=
O
(17)
N
N
Ph
Scheme 2.
temperature, followed by treatment with methyl iodide af-
forded the novel ketene N,S-acetal 8. The structure of 8 was
established on the basis of its elemental analysis and spectral
data. Its IR spectrum showed absorption bands at 3350, 3268,
and 2190 cmꢀ1 due to two NH groups and nitrile functions,
respectively. The mass spectrum showed a molecular ion
peak at m/z 419 (Mþ) which agree with its molecular formula
C22H21N5O2S. Reaction of 8 with hydrazine in refluxing
ethanol gave the corresponding pyrazole derivative 9. The
chemical structure of 9 was established on the basis of its el-
emental analysis and spectral data. Its 1H NMR spectrum dis-
played a broad signal at d 6.05 ppm corresponding to the NH2
group, a multiplet signal at 6.92e7.45 ppm related to the ar-
omatic protons, and another three singlets at d 7.97, 8.92, and
11.35 ppm assignable to the three NH protons. The 13C NMR
spectrum was characterized by signals at 11.7, 31.2 ppm
assigned to the two methyl carbons, and signals at 123.8e
135.4 ppm assigned to aromatic carbons, and signals at
162.5, 164.2 ppm assigned to the two amidic carbonyl carbon
atoms.
pyrazolo[3,4-d]triazine derivative 10 in excellent yield. The
structure of compound 10 was established on the basis of
analytical and spectral data. The IR spectrum showed the dis-
appearance of the amino group and presence of a sharp intense
absorption band at 2182 cmꢀ1 indicating the cyclic diazo
group. The formation of compound 10 may be rationalized
via intramolecular attack of the electrophilic nitrogen of a di-
azo group on a carboxamide function [31,32].
Next, we moved on to investigate the applicability and syn-
thetic potency of 9 to develop a facile and convenient route to
polyfunctionally substituted pyrazolopyrimidine derivatives of
an expected wide spectrum of bioresponses [33e35]. Thus,
cyclocondensation reactions of compound 9 with some 1,3-
dicarbonyl compounds were also studied. The reaction of 9
with either acetylacetone or acetoacetanilide in boiling acetic
acid produced in each case a single product, as evidenced by
TLC. The reaction products can be formulated as pyra-
zolo[1,5-a]pyrimidine derivatives 11 and 12, evidence for
the assigned structures being provided by analytical and spec-
troscopic data.
5-Aminopyrazoles are versatile reagents and have been
extensively used as synthetic intermediates for the synthesis
of polysubstituted fused pyrazoles of potential biological ac-
tivity [27e30]. It was thus of interest to study the reactivity
of 5-aminopyrazole derivative 9 towards a variety of chemical
reagents. Diazotization of compound 9 with sodium nitrite and
hydrochloric acid at 0e5 ꢁC led to the formation of
Although one may argue that the reaction of 9 with acetoa-
cetanilide may lead to the other regioisomer, the regioselectiv-
ity of such reactions is well established [36]. The formation of
compounds 11 and 12 is, therefore, assumed to proceed via
initial attack of the exocyclic amino group of 9 on the keto
group of 1,3-dicarbonyls followed by intramolecular cycliza-
tion via elimination of water and aniline, respectively.

S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
2125
Table 1
Inhibition zone (mean diameter of inhibition in mm) as a criterion of antibac-
terial and antifungal activities of the newly synthesized compounds
The reaction of 9 with dimethylformamideedimethylacetal
(DMFeDMA) in dry dioxane afforded N,N-dimethylamino-
methyleneamino pyrazole derivative 13. Structure 13 was con-
firmed on the basis of elemental analysis and spectral studies.
The mass spectrum revealed a molecular ion peak at m/z 458
Compound
no.
Inhibition zone in mm
Bacteria
Fungi
1
corresponding to C24H26N8O2. Its H NMR spectrum showed
Gram positive Gram negative B. fabae F. oxysporum
bacteria bacteria
in addition to the expected signals three singlets at d 3.04,
3.11, 8.21 ppm assigned to dimethylamino group (N(CH3)2)
and azomethine proton (CH]N), respectively. Compound
13 could be transformed to pyrazolo[3,4-d]pyrimidine deriva-
tive 14 upon heating in glacial acetic acid. The IR and mass
spectra were consistent with the proposed structure.
B. thuringiensis K. pneumoniae
1
12
24
10
16
13
12
15
22
21
20
27
28
13
22
13
19
14
12
12
22
28
24
24
29
10
18
12
16
13
13
16
26
24
27
25
27
12
18
12
16
14
13
12
22
25
25
21
25
2
3
5
6
Furthermore, we also investigated the reactivity of aminopyr-
azole 9 towards enaminone with the aim of preparing
pyrazolo[1,5-a]pyrimidine. Thus, reaction of 9 with 3-(dimethy-
lamino)-1-phenylprop-2-en-1-one [37] in glacial acetic acid at
reflux afforded pyrazolo[1,5-a]pyrimidine derivative 15. Struc-
ture of the latter product was confirmed on the basis of its correct
elemental analysis and spectral data. The mass spectrum showed
a molecular ion peak at m/z 515 (Mþ) corresponding to a molec-
7
9
10
11
12
13
14
Reference drugs
Ampicillin
18
19
20
e
17
16
22
15
15
16
1
Chloramphenicol 23
Fluconazole
ular formula C30H25N7O2. Its H NMR spectrum showed in
e
addition to the expected signals two doublet signals at d 8.23
and 8.34 ppm with coupling constant (J ¼ 4.5 Hz) assigned to
two vicinal protons of the pyrimidine ring H-4 and H-5, respec-
tively. The formation of compound 15 is assumed to take place
via an initial Michael addition of the exocyclic amino group in 9
to the activated double bond in enaminone followed by cycliza-
tion and aromatization via loss of both dimethylamine and water
molecules. Although the endocyclic imino group in compound 9
is the most nucleophilic center [38e40], nevertheless, it is the
most sterically hindered site [41].
Condensation of 9 with isatin in boiling ethanol furnished
Schiff’s base 16 in excellent yield. The chemical structure of
16 was elucidated on the basis of elemental analysis and spec-
tral data. The IR spectrum indicated the presence of three
strong absorption bands at 1744, 1703, and 1640 cmꢀ1 due
to three carbonyl groups. In contrast to the behavior of com-
pound 13 towards acetic acid, compound 16 failed to give
the spiro derivative 17. This may be attributed to steric hin-
drance in compound 16 which restricted cyclization process.
market and used in a concentration of 25 mg/mL as references
for antibacterial and antifungal activities. The results for anti-
bacterial activities depicted in Table 1 revealed that compounds
2, 13 and 14 exhibited good activities. On the other hand, most of
the prepared compounds 2, 10e14, exhibited interesting high
antifungal activities against the reference chemotherapeutics.
It is worth mentioning that incorporation of antipyrine to the
coumarin nucleus at position 3 via a carboxamide linker 2 pro-
duced a high antimicrobial activity. Conversion of 5-aminopyr-
azole derivative 9 to pyrazolo[3,4-d]pyrimidine derivative 14
enhanced also the antimicrobial activity. On other hand, incor-
poration of the antipyrine nucleus to pyridine at position 1 in 3
unfortunately produced weak antimicrobial activity.
In conclusion, we reported herein a simple and convenient
route for the synthesis of some new heterocycles based on an-
tipyrine for antimicrobial evaluation.
4. Experimental
3. Pharmacology
Melting points were measured with a Gallenkamp appara-
tus and are uncorrected. IR spectra were recorded for KBr
disc on a Mattson 5000 FTIR spectrophotometer. H NMR
3.1. Antimicrobial evaluation
1
Twelve compounds were screened in vitro for their antimi-
crobial activities against two strains of bacteria Bacillus thurin-
giensis, Klebsiella pneumoniae, and two strains of fungi Botrytis
fabae and Fusarium oxysporum by the agar diffusion technique
[42]. A 0.15 mg/mL solution in DMSO was used. The bacteria
and fungi were maintained on nutrient agar and Czapek’s-Dox
agar media, respectively. DMSO showed no inhibition zones.
The agar media were incubated with different microorganism
cultures tested. After 24 h of incubation at 30 ꢁC for bacteria
and 72 h of incubation at 28 ꢁC for fungi, the diameter of inhibi-
tion zone (mm) was measured (Table 1). Ampicillin, Chloroam-
phenicol, and Fluconazole were purchased from Egyptian
and 13C NMR spectra were measured on a Bruker AC 300
(300 MHz) in CDCl3 or DMSO-d6 as solvent, using TMS as
an internal standard, and chemical shifts are expressed as
dppm. Mass spectra were determined on Finnigan Incos 500
(70 eV). Elemental analyses were carried out at the Microan-
alytical Center of Cairo University. All reactions were fol-
lowed by TLC (Silica gel, aluminum sheets 60 F254, Merck).
2-Cyano-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-
pyrazol-4-yl)acetamide
1 [21], 4,6-dimethyl-1H-pyrazolo
[3,4-b]pyridin-3-diazonium chloride [26], and 3-(dimethyla-
mino)-1-phenylprop-2-en-1-one [37] were prepared according
to the procedures reported in the literature.

2126
S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
4.1. Synthesis of N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-
dihydro-1H-pyrazol-4-yl)-2-imino-2H-chromene-3-
carboxamide (2)
4.4. Synthesis of 2-cyano-N-(1,5-dimethyl-3-oxo-2-
phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-[(4,6-
dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl)
hydrazono]acetamide (5)
To a solution of compound 1 (0.54 g, 2 mmol) in absolute
ethanol (20 mL) containing piperidine (0.5 mL), salicylalde-
hyde (0.3 g, 2 mmol) was added. The reaction mixture was
heated under reflux for 3 h, and then allowed to cool. The
precipitate that formed was filtered off, washed with ethanol,
dried and recrystallized from ethanol to afford 2.
To a cold (0e5 ꢁC) solution of compound 1 (0.54 g,
2 mmol) in pyridine (25 mL) was added the 4,6-dimethyl-
2H-pyrazolo[3,4-b]pyridine-3-yl diazonium salt [which was
prepared by dissolving sodium nitrite (0.14 g, 2 mmol) in water
(2 mL) and adding to a cold solution of 3-amino-4,6-dimethyl-
2H-pyrazolo[3,4-b]pyridine (0.32 g, 2 mmol) containing the
appropriate amount of hydrochloric acid with continuous stir-
ring] portionwise over a period of 30 min. The reaction mixture
was kept in an ice box overnight and then diluted with water.
The solid that precipitated was filtered off, washed with water
and dried, and recrystallized from a mixture of ethanol and
DMF (2:1) to give compound 5.
Pale yellow crystal; yield 90%; mp 225e227 ꢁC; IR (KBr):
1
n/cmꢀ1 ¼ 3223, 3431 (2NH), 1685, 1620 (2C]O). H NMR
(CDCl3): dppm ¼ 2.33 (s, 3H, CH3), 3.06 (s, 3H, NCH3),
7.03e7.48 (m, 9H, ArH), 7.77 (s, 1H, CH]), 8.43 (s, 1H,
NH]), 11.79 (s, 1H, NHCO). MS m/z (%): 375 (Mþ þ 1,
2.45), 374 (Mþ, 6.89), 307 (13.25), 270 (2.95), 255 (4.8),
230 (6.15), 203 (11.58), 56 (100). Anal. for C21H18N4O3
(374.14): calcd.: C 67.37, H 4.85, N 14.96%; found: C
67.28, H 4.81, N 15.00%.
Red powder; yield 75%; mp 198e200 ꢁC; IR (KBr):
1
n/cmꢀ1 ¼ 3392 (NH), 1660, 1645 (2C]O), 2197 (CN). H
NMR (DMSO-d6): dppm ¼ 2.23 (s, 3H, CH3), 2.71 (s, 3H,
CH3), 3.03 (s, 3H, CH3), 3.16 (s, 3H, NCH3), 7.11 (s, 1H, pyr-
idine H-5), 7.41e7.61 (m, 5H, ArH), 9.10 (s, 1H, NH), 9.31 (s,
1H, NH), 10.19 (s, H, NH). MS m/z (%): 443 (Mþ, 19.38), 413
(25), 375 (3.13), 291 (3.13), 269 (7.8), 202 (13.75), 56 (100).
Anal. for C22H21N9O2 (443.46): calcd.: C 59.58, H 4.77, N
28.43%; found: C 59.42, H 4.61, N 28.56%.
4.2. Synthesis of 1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-
dihydro-1H-pyrazol-4-yl)-4,6-dimethyl-2-oxo-1,2-
dihydropyridine-3-carbonitrile (3)
A mixture of compound 1 (0.54 g, 2 mmol) and acetylace-
tone (0.21 mL, 2 mmol) in ethanol (15 mL) containing a few
drops of piperidine (3 drops) was refluxed for 10 h. The reac-
tion mixture was cooled and the solid so obtained was filtered
off and recrystallized from ethanol to give 3.
Colorless crystals; yield 85%; mp 235e237 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 2217 (CN), 1662, 1645 (2C]O). 1H NMR (CDCl3):
dppm ¼ 2.16 (s, 3H, CH3-pyrazole), 2.25 (s, 3H, CH3), 2.36 (s,
3H, CH3), 3.23 (s, 3H, NCH3), 6.15 (s, 1H, pyridine H-5),
7.25e7.59 (m, 5H, ArH). 13C NMR (CDCl3): dppm ¼ 11.5 (q,
CH3), 20.9 (q, CH3), 21.3 (q, CH3), 35.5 (q, NCH3), 101.4,
106.2, 109.2, 115.3 (CN), 125.1, 127.7, 129.4, 134.0, 152.3,
152.8, 159.5 (C]O), 160.0 (C]O). Anal. for C19H18N4O2
(334.14): calcd.: C 68.25, H 5.43, N 16.76%; found: C 68.32,
H 5.31, N 16.56%.
4.5. Synthesis of N-(1,5-dimethyl-3-oxo-2-phenyl-2,
3-dihydro-1H-pyrazol-4-yl)-4-imino-8,10-dimethyl-4,
6-dihydropyrido[20,30:3,4]pyrazolo[5,1-c][1,2,4]-
triazine-3-carboxamide (6)
A solution of 5 (0.89 g, 2 mmol) in glacial acetic acid
(20 mL) was refluxed for 3 h, and then allowed to cool. The
precipitate that formed was filtered off, washed with ethanol
and recrystallized from a mixture of ethanol and DMF (1:1)
to give compound 6.
White powder; yield 80%; mp >300 ꢁC; IR (KBr): n/cmꢀ1
¼
3406, 3288, 3228 (3NH), 1672, 1641 (2C]O). 1H NMR
(DMSO-d6): dppm ¼ 2.21 (s, 3H, CH3-pyrazole), 2.73 (s, 3H,
CH3), 3.07 (s, 3H, CH3), 3.18 (s, 3H, NCH3), 6.98 (s, 1H, pyri-
dine H-5), 7.36e7.58 (m, 5H, ArH), 9.12 (s, 1H, NH), 9.33 (s,
1H, NH), 10.24 (s, H, NH). Anal. for C22H21N9O2 (443.46):
calcd.: C 59.58, H 4.77, N 28.43%; found: C 59.46, H 4.41, N
28.36%.
4.3. Synthesis of 1-(1,5-dimethyl-3-oxo-2-phenyl-2,3-
dihydro-1H-pyrazol-4-yl)-2-oxo-5-phenyl-2,3-dihydro-
1H-pyrrole-3-carbonitrile (4)
A mixture of compound 1 (0.54 g, 2 mmol) and phenacyl
bromide (0.389 g, 2 mmol) in ethanol (30 mL) containing trie-
thylamine (0.5 mL) was refluxed for 3 h. The formed solid
product was filtered off, dried and recrystallized from ethanol
to give compound 4.
4.6. Synthesis of 4-amino-N-(1,5-dimethyl-3-
oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-3-
phenyl-2-thioxo-2,3-dihydro-1,
Pale yellow powder; yield 45%; mp 140e142 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 2195 (CN), 1690, 1645 (2C]O). 1H NMR (CDCl3):
dppm ¼ 2.24 (s, 3H, CH3), 3.24 (s, 3H, NCH3), 4.54 (d,
J ¼ 2.5 Hz, 1H, pyrrole H-3), 5.65 (d, J ¼ 2.5 Hz, 1H, pyrrole
H-4), 7.15e7.67 (m, 10H, ArH). MS m/z (%): 371 (Mþ þ 1,
3.3), 370 (Mþ, 6.9), 229 (18.1), 142 (2.6), 119 (10.1), 56
(100). Anal. for C22H18N4O2 (370.40): calcd.: C 71. 34, H
4.90, N 15.13%; found: C 71.22, H 4.86, N 15.09%.
3-thiazole-5-carboxamide (7)
To a solution of compound 1 (0.54 g, 2 mmol) in ethanol
(20 mL) containing triethylamine (0.5 mL), elemental sulfur
(0.064 g, 2 mmol) and phenyl isothiocyanate (0.27 g, 2 mmol)
were added. The reaction mixture was heated at 60 ꢁC for 2 h
with continuous stirring and then poured into a beaker contain-
ing an ice/water mixture containing few drops of hydrochloric

S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
2127
acid. The formed solid product was collected by filtration,
dried, and recrystallized from DMF and ethanol (3:1) to give
compound 7.
4.9. Synthesis of 5-anilino-3-(1,5-dimethyl-3-oxo-2-
phenyl-2,3-dihydro-1H-pyrazol-4-yl)-3,7-dihydro-4H-
pyrazolo[3,4-d][1,2,3]triazin-4-one (10)
White powder; yield 65%; mp 236e238 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 3420 (NH2), 3345 (NH), 1693, 1670 (2C]O),
1210 (C]S). 1H NMR (DMSO-d6): dppm ¼ 2.13 (s, 3H,
CH3), 3.06 (s, 3H, NCH3), 6.82 (s, 2H, NH2), 7.21e7.63 (m,
10 H, ArH), 8.99 (s, 1H, NH). 13C NMR (DMSO-d6):
dppm ¼ 11.3, 36.3, 124.1, 126.8, 129.3, 129.5, 130.5, 135.3,
135.4, 153.9, 162.6, 186.1. Anal. for C21H19N5O2S2
(437.54): calcd.: C 57.65, H 4.38, N 16.01%; found: C
57.52, H 4.41, N 16.06%.
A well-stirred solution of compound 9 (0.403 g, 10 mmol)
in 3 mL concentrated hydrochloric acid and 3 mL water was
cooled in an ice-bath (0e5 ꢁC), then a cooled solution of
sodium nitrite (0.7 g) in 5 mL water was added dropwise to
the above solution. The reaction mixture was stirred for 2 h
and the separated solid was filtered off, dried well and recrys-
tallized from ethanol to give compound 10.
Pale yellow crystals; yield 90%; mp 198e200 ꢁC; IR
(KBr): n/cmꢀ1 ¼ 3423 (NH), 2182 (N]N), 1706, 1643
1
(2C]O). H NMR (CDCl3): dppm ¼ 2.42 (s, 3H, CH3), 3.31
4.7. Synthesis of 3-anilino-2-cyano-N-(1,5-dimethyl-3-
oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-3-
(methylthio)acrylamide (8)
(s, 3H, NCH3), 6.88e7.65 (m, 10H, ArH), 8.39 (s, 1H, NH),
14.22 (s, H, NH). MS m/z (%): 415 (Mþ þ 1, 2.2), 414 (Mþ,
6.7), 399 (0.75), 386 (9.47), 321 (0.75), 229 (100), 187
(5.13). Anal. for C21H18N8O2 (414.42): calcd.: C 60.86, H
4.38, N 27.04%; found: C 60.76, H 4.26, N 27.21%.
To a stirred solution of potassium hydroxide (0.11 g,
2 mmol) in dimethylformamide (20 mL) was added compound
1 (0.544 g, 2 mmol). After stirring for 30 min, phenyl isothio-
cyanate (0.27 g, 2 mmol) was added to the resulting mixture.
Stirring was continued for 6 h, and then methyl iodide (0.28 g,
2 mmol) was added. Stirring was continued for additional 3 h.
Then, the reaction mixture was poured onto ice water. The solid
product that formed was filtered off, dried and recrystallized
from ethanol to afford 8.
Yellow powder; yield 85%; mp 85e87 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 3350, 3268 (2NH), 2190 (CN), 1660, 1645
(2C]O), 1623 (C]C). 1H NMR (DMSO-d6): dppm ¼ 2.17
(s, 3H, CH3-pyrazole), 2.28 (s, 3H, SCH3), 3.18 (s, 3H,
NCH3), 7.07e7.64 (m, 10H, ArH), 9.12 (s, 1H, NH), 11.15
(s, 1H, NH). MS m/z (%): 419 (Mþ, 3.4), 372 (Mþ ꢀ SMe,
8.9), 230 (10.6), 229 (20.8), 203 (10.6), 189 (2.3), 171
(5.5), 169 (6.8), 119 (2.7), 102 (1.9), 56 (100). Anal. for
C22H21N5O2S (419.50): calcd.: C 62.99, H 5.05, N 16.69%;
found: C 62.86, H 4.98, N 16.61%.
4.10. General procedure for the reaction of 5-
aminopyrazole 9 with 1,3-dicarbonyl compounds
A mixture of compound 9 (0.81 g, 2 mmol) and an equimo-
lar amount of the appropriate 1,3-dicarbonyl compound (ace-
tylacetone or acetoacetanilide) in glacial acetic acid (20 mL)
was refluxed for 3 h, then the reaction mixture was poured
into crushed ice, and the separated solid was filtered off, dried
well and recrystallized from a suitable solvent to give com-
pounds 11 and 12.
4.10.1. 2-Anilino-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-
dihydro-1H-pyrazol-4-yl)-5,7-dimethylpyrazolo[1,5-
a]pyrimidine-3-carboxamide (11)
White crystals (EtOH:DMF); yield 85%; mp 255e257 ꢁC;
IR (KBr): n/cmꢀ1 ¼ 3432, 3280 (2NH), 1670, 1650 (2C]O).
1H NMR (CDCl3): dppm ¼ 1.93 (s, 3H, CH3-pyrazole), 2.62 (s,
3H, CH3), 2.83 (s, 3H, CH3), 3.37 (s, 3H, NMe), 6.93 (s, 1H,
pyrimidine H-6), 7.26e8.19 (m, 10H, ArH), 9.46 (s, 1H, NH),
9. 86 (s, 1H, NH). MS m/z (%): 467 (Mþ, 17), 413 (6.0), 265
(100), 238 (23.3), 202 (11.2), 119 (5.4), 56 (42.0). Anal. for
C26H25N7O2 (467.52): calcd.: C 66.79, H 5.39, N 20.97%;
found: C 66.81, H 5.46, N 20.89%.
4.8. Synthesis of 5-amino-3-anilino-N-(1,5-dimethyl-3-
oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-5,7-
dimethylpyrazolo[1,5-a]pyrimidine-3-carboxamide (9)
A mixture of compound 8 (0.9 g, 2 mmol) and hydrazine
hydrate 98% (0.5 mL, 5 mmol) was heated on a steam bath
for 1 h and then left to cool. The reaction mixture was tritu-
rated with ethanol and the resulting solid was filtered off
and recrystallized from ethanol to give compound 9.
4.10.2. 2-Anilino-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-
dihydro-1H-pyrazol-4-yl)-7-hydroxy-5-methylpyrazolo[1,5-
a]pyrimidine-3-carboxamide (12)
Colorless crystals; yield 85%; mp 243e245 ꢁC; IR (KBr):
White crystals (EtOH:CHCl3); yield 82%; mp 285e287 ꢁC;
IR (KBr): n/cmꢀ1 ¼ 3455 (OH), 3430, 3304 (2NH), 1695,
1
n/cmꢀ1 ¼ 1628 (C]O), 3240, 3355 (2NH), 3400 (NH2). H
1
NMR (DMSO-d6): dppm ¼ 2.21 (s, 3H, CH3), 3.23 (s, 3H,
NCH3), 6.05 (s, 2H, NH2), 6.92e7.45 (m, 10H, ArH), 7.97
(s, 1H, NH), 8.92 (s, 1H, NH), 11.35 (s, 1H, NH). 13C NMR
(DMSO-d6): dppm ¼ 11.7, 31.2, 107.9, 116.2, 119.3, 123.8,
126.5, 126.1, 129.1, 135.4, 143.3, 148.3, 151.2, 153, 162.5,
164.2. Anal. for C21H21N7O2 (403.44): calcd.: C 62.52, H
5.25, N 24.30%; found: C 62.61, H 5.16, N 24.41%.
1629 (2CO). H NMR (DMSO-d6): dppm ¼ 2.23 (s, 3H, CH3-
pyrazole), 2.39 (s, 3H, CH3), 3.14 (s, 3H, NMe), 5.84 (s,
1H, pyrimidine H-6), 6.91e7.72 (m, 10H, ArH), 8.87 (s, 1H,
NH), 9.34 (s, 1H, NH), 11.98 (br s, 1H, OH). MS m/z (%):
469 (Mþ, 10.6), 267 (25.8), 240 (100), 203 (40.6), 119
(36.5), 56 (73.6). Anal. for C25H23N7O3 (469.50): calcd.: C
63.96, H 4.94, N 20.88%; found: C 63.81, H 4.86, N 20.71%.

2128
S. Bondock et al. / European Journal of Medicinal Chemistry 43 (2008) 2122e2129
4.11. Synthesis of 3-anilino-5-{[1-
56 (65.2). Anal. for C30H25N7O2 (515.21): calcd.: C 69.89,
H 4.89, N 19.02%; found: C 69.86, H 4.79, N 19.11%.
(dimethylamino)methylene]amino}-N-(1,5-dimethyl-3-
oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-1H-
pyrazole-4-carboxamide (13)
4.14. Synthesis of 3-anilino-N-(1,5-dimethyl-3-oxo-2-
phenyl-2,3-dihydro-1H-pyrazol-4-yl)-5-{[2-oxo-1,2-
dihydro-3H-indol-3-ylidene]amino}-1H-pyrazole-4-
carboxamide (16)
A mixture of compound 9 (0.81 g, 2 mmol) and dimethyl-
formamideedimethylacetal (DMFeDMA) (0.24 g, 2 mmol)
in dry dioxane (30 mL) was refluxed for 4 h, then allowed to
cool. The precipitated product that formed was filtered off,
washed with petroleum ether (60e80 ꢁC), dried, and recrystal-
lized from a mixture of ethanol and DMF (2:1) to give com-
pound 13.
White crystals; yield 85%; mp 238e240 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 3405, 3325, 3233 (3NH), 1697, 1645 (2C]O),
1630 (C]N). 1H NMR (DMSO-d6): dppm ¼ 2.29 (s, 3H,
CH3), 3.02 (s, 3H, NCH3), 3.04 (s, 3H, NCH3), 3.11 (s, 3H,
NCH3), 8.21 (s, 1H, CH]N), 8.86 (s, 1H, NH), 9.41 (s, H,
NH), 11.83 (s, 1H, NH). MS m/z (%): 458 (Mþ, 13.7), 414
(25.4), 413 (100), 254 (6.9), 211 (29.0), 156 (18.9), 109
(80.4), 56 (90.4). Anal. for C24H26N8O2 (458.52): calcd.: C
62.87, H 5.72, N 24.44%; found: C 62.81, H 5.66, N 24.31%.
A mixture of compound 9 (0.8 g, 2 mmol) and isatin
(0.147 g, 1 mmol) in ethanol (30 mL) containing piperidine
(3 drops) was refluxed for 2 h. The precipitate obtained was
filtered off, dried well and recrystallized from a mixture of
ethanol and DMF (1:2) to give compound 16.
Reddish brown powder; yield 85%; mp 261e263 ꢁC; IR
(KBr): n/cmꢀ1 ¼ 3418, 3336, 3275 (3NH), 1744, 1703, 1640
(3C]O). 1H NMR (DMSO-d6): dppm ¼ 2.29 (s, 3H, CH3),
3.06 (s, 3H, NMe), 6.82e7.83 (m, 14H, ArH), 9.00 (s, 1H,
NH), 9.13 (s, 1H, NH), 10.99 (s, 1H, NH), 13.19 (s, 1H,
NH). Anal. for C29H24N8O3 (532.55): calcd.: C 65.40, H
4.54, N 21.04%; found: C 65.51, H 4.46, N 21.11%.
Acknowledgments
4.12. Synthesis of 3-anilino-5-(1,5-dimethyl-3-oxo-2-
phenyl-2,3-dihydro-1H-pyrazol-4-yl)-1,5-dihydro-4H-
pyrazolo[3,4-d]pyrimidin-4-one (14)
The authors are very grateful to Dr. Ahmed Shawkey, De-
partment of Botany, Faculty of Science, Mansoura University,
for performing the antimicrobial evaluation.
A solution of compound 13 (0.92 g, 2 mmol) in glacial ace-
tic acid (30 mL) was refluxed for 3 h, and then allowed to cool.
The precipitate that formed was filtered off, washed with eth-
anol, dried and recrystallized from a mixture of ethanol and
DMF (2:1) to give compound 14.
White crystals; yield 78%; mp 260e262 ꢁC; IR (KBr):
n/cmꢀ1 ¼ 1678, 1645 (2C]O), 1629 (CH]N). 1H NMR
(CDCl3): dppm ¼ 2.02 (s, 3H, CH3), 3.01 (s, 3H, NCH3),
6.63e7.32 (m, 10H, ArH), 7.37 (s, 1H, NH), 7.68 (s, 1H,
CH]N). Anal. for C22H19N7O2 (413.43): calcd.: C 63.91, H
4.63, N 23.72%; found: C 63.81, H 4.76, N 23.61%.
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