Synthesis and pharmacological properties of some novel pyrazolidine and pyrazole derivatives

Article abstract of DOI:10.1007/s00044-011-9687-0

Microwave synthesis technique opens new avenues for the synthesis of many compounds. A novel and simple method has been developed for the synthesis of 1-(2,4-dinitrophenyl) pyrazolidine-3,5-dione and 1-(2,4-dinitrophenyl)-3,5- dimethyl-1H-pyrazole derivatives under microwave irradiation. These compounds exhibit mild to moderate antimircrobial activity against different strains of bacteria (e.g. E. coli, P. aeruginosa, S. aureus and B subtilis) and fungi (e.g. C. albicans and A. niger). All these synthesised compounds have been characterised by employing various techniques like TLC, Elemental analysis, IR, NMR and MS spectra. In addition to this, the yields of these compounds have been compared with the same compounds, obtained by conventional heating procedures. And the results show that by microwave irradiation method, the product yield is either high or may be same but it takes a very short period of time for reaction. Moreover, this technique provides ecofriendly or green chemical pathway for the synthesis of these compounds. Thus, the microwave irradiation method is more useful than the conventional method because of the shorter reaction time, better yield, conservation of energy and ecofriendly nature. Springer Science+Business Media, LLC 2011.

Full text of DOI:10.1007/s00044-011-9687-0

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2012) 21:1692–1699
DOI 10.1007/s00044-011-9687-0
ORIGINAL RESEARCH
Synthesis and pharmacological properties of some novel
pyrazolidine and pyrazole derivatives
•
•
•
Bharat Parashar Abhilasha Jain Sudhir Bharadwaj
V. K. Sharma
Received: 11 October 2010 / Accepted: 26 May 2011 / Published online: 9 June 2011
Ó Springer Science+Business Media, LLC 2011
Abstract Microwave synthesis technique opens new
avenues for the synthesis of many compounds. A novel and
simple method has been developed for the synthesis of
1-(2,4-dinitrophenyl) pyrazolidine-3,5-dione and 1-(2,4-
dinitrophenyl)-3,5-dimethyl-1H-pyrazole derivatives under
microwave irradiation. These compounds exhibit mild to
moderate antimircrobial activity against different strains of
bacteria (e.g. E. coli, P. aeruginosa, S. aureus and B sub-
tilis) and fungi (e.g. C. albicans and A. niger). All these
synthesised compounds have been characterised by
employing various techniques like TLC, Elemental analy-
sis, IR, NMR and MS spectra. In addition to this, the yields
of these compounds have been compared with the same
compounds, obtained by conventional heating procedures.
And the results show that by microwave irradiation
method, the product yield is either high or may be same but
it takes a very short period of time for reaction. Moreover,
this technique provides ecofriendly or green chemical
pathway for the synthesis of these compounds. Thus, the
microwave irradiation method is more useful than the
conventional method because of the shorter reaction time,
better yield, conservation of energy and ecofriendly nature.
Keywords Synthesis Á Microwave irradiation Á
Conventional heating Á Isonicotinohydrazide Á
Ethyl 2-cyanoacetate Á Hexane-2 Á 4-Dione Á
Pyrazolidine and pyrazole
Introduction
Pyrazoline consist a unique class of five-member ring.
Pyrazoline (Kumar et al., 2009) shows various biological
and pharmacological activities such as antimicrobial,
(Venkataraman et al., 2010) and (Parashar et al., 2010a, b),
anti-inflammatory (Amir et al., 2008) and (Rathish et al.,
2009), antitumor (Stirrett et al., 2008), antidepressant
(Prasad et al., 2005), antamoebic (Abid et al., 2007),
insecticides (Silver and Soderlund, 2005) activities.
Whereas some of these show antidiabetic (Ahn et al.,
2004), analgesic (Karabasanagouda et al., 2009), antican-
cer (Ozdemir and Asim, 2008) and antiepileptic (Kelekci
et al., 2008), activities. The chemistry and antimicrobial
activity of some substituted pyrazolines have been inves-
tigated in recent years (Parshar et al., 2010a, b) and it was
thought world while to synthesis the some new pyrazolines
compounds (Revanasiddappa et al., 2010) from easily
available starting materials and evaluations of its possible
antimicrobial and anti-inflammatory activity.
B. Parashar
Geetanjali College of Pharmacy, Udaipur, Rajasthan, India
The microwave irradiations technique is employed for
carrying out chemical transformations, which are eco-
friendly. The basis of this synthesis techniques is the
empirical observation that some organic reactions proceed
much faster and with higher yields under microwave irra-
diation compared to conventional heating (Chawla et al.,
2010) and (Parashar et al., 2010a, b). Most of the organic
reactions have been heated using traditional heat transfer
equipments such as oil baths, sand baths or heating
A. Jain (&)
St. Xavier’s College, Mumbai, Maharastra, India
e-mail: jainabhilasha5@gmail.com
S. Bharadwaj
College of Pharmacy, Bamor, Gwalior, Madhya Pradesh, India
V. K. Sharma
Microwave Chemistry Laboratory, University College
of Science, Udaipur, Rajasthan, India
123

Med Chem Res (2012) 21:1692–1699
1693
mentales. These techniques are rather slow and create
temperature gradients within the sample.
Experimental
Synthesis of some new pyrazolines derivatives using
diethylmalonate, acetyl acetate, 1-chlorohexane-2-4-dione,
ethyl acetate, ethylcynoacetate by conventional and micro-
wave-assisted methods have been done. The reaction
carried out in absolute alcohol or DMF using conventional
method required about 4–12 h, while microwave irradia-
tion method required only 2 to 3.30 min. In conventional
method, the yields are lower as compared to microwave
irradiation. It should be mentioned here that the effect of
microwave irradiation is not purely thermal; microwave
irritation facilitates the polarisation of the molecules under
irradiation causing rapid reaction to occur. The synthetic
route of above mentioned compound is shown in
Scheme 1.
All the reactions were carried out in a domestic microwave
oven (Kenstar, model no. OM 26.EGO). Melting points of
synthesis compounds were determined in open capillaries
in liquid paraffin are uncorrected. Purity of the compounds
in addition to elemental analysis were verified by perco-
lated TLC using silica gel G as a adsorbent using ethyl
acetate: n-hexane (7:3) as a eluent and spot was detected by
using iodine vapours. The IR (KBr pellets) spectra were
recorded on a Perkin Elimer-1800-spectrophotometer and
1H NMR spectra were recorded on BRUKER DRX-
300 MHz spectrophotometer, (TMS as a internal reference)
and chemical shifts are expressed in d. Mass spectra were
recorded on Jeol D30 spectrophotometer. Elemental anal-
yses for C, H and N were conducted using a Perkin-Elmer
O
-O N+
O-
N+
O
N
H
O
O-
N+
O
N
O-
O
O
N+
O
N+
O-
HN
N
O
S
-O
N
O
N+
N
O
N
1-(2, 4-dinitrophenyl)
pyrazolidine-3, 5-dione
O
H3C
O
(E)-3-(2, 4-dinitrophenylamino)-2-
(phenylimino) thiazolidin-4-one
C
H
1-acetyl-2-(2, 4-dinitrophenyl)
pyrazolidine-3, 5-dione
(C
O
O
C
(i)Morpholine
(ii)ClCH2COOC2H5
H
)
2
1
5
)
H
8
2
C
O
O
-O
C
(
H
O
O
2
H
N+
O-
N+
O
H
C
O
C
N
3
H
N+
C
HN
-O
O
O
N
-O
2
C6H5NCS
N+
H3C
CH3COCH2COCH3
O-
N+
N
N
S
H
7
N+
HN NH2
O
-O
O
1-(3,5-dinitrophenyl)hydrazine
3
CH3
C
l
4-(2, 4-dinitrophenyl)-1-
phenylthiosemicarbazide
C
H
1-(2, 4-dinitrophenyl)-3, 5-
dimethyl-1H-pyrazole
2
C
O
C
O
-O N+
N
H
2
C
O
6
C
2
H2N
H
5
O
N+
O
N
-O
O-
N+
N
O
O-
N+
Cl
N
O
O
N
3-amino-1-(2, 4-dinitrophenyl)-
1H-pyrazol-5(4H)-one
H3C
N+ O-
O-
N+
N
O
O
3-(chloromethyl)-1-(2, 4-dinitrophenyl)-
1H-pyrazol-5(4H)-one
O
1-(2, 4-dinitrophenyl)-3-methyl-
1H-pyrazol-5(4H)-one
4
5
Scheme 1 The synthetic route of compounds (1–8)
123

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Med Chem Res (2012) 21:1692–1699
C, H, and N analyzer. The results were found to be an in
good agreement with the calculated values ( 0.4%).
Ar–H), 8.70 (s, H, NH), 3.45–3.40 (2H, d, CH2 of pyraz-
oline); MS: m/z [M]? 266.
Synthesis of 1-(2,4-dinitrophenyl) pyrazolidine-3,5-
Synthesis of 1-acetyl-2-(2,4-dinitrophenyl)
dione (1)
pyrazolidine-3,5-dione (2)
Conventional method
Conventional method
To a solution of 1.00 g of 1-(3, 5-dinitrophenyl) hydrazine
(0.005 mol), in 50 ml of absolute ethanol, 5 ml acetic acid
and 0.80 g of diethyl malonate (0.005 mol), were added in
a round bottom flask. The mixture was well stirred and
refluxed for about 12–14 h. The reaction was monitored by
TLC. When the reaction was complete, the reaction mix-
ture was cooled at room temperature and poured into a
beaker containing crushed ice. Solid was separated and
recrystallized from ethanol.
To a solution of 1.00 g of 1-(3, 5-dinitrophenyl) hydrazine
(0.005 mol), in 20 ml acetic acid, 0.80 g of diethyl mal-
onate (0.005 mol) was added in a round bottom flask. Then
the well-stirred mixture was refluxed for 11–12 h. The
completion of the reaction was monitored by TLC. The
reaction mixture was then cooled at room temperatures and
poured into crushed ice. The solid obtained was filtered,
washed with water, and recrystallized from ethanol to give
product 2.
Microwave method
Microwave method
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol), 5 ml acetic acid and 0.80 g of diethyl mal-
onate (0.005 mol) were taken in an Erlenmeyer flask and
stirred. Then this well-stirred mixture was irradiated in
microwave oven for 3 min at 480 W (i.e., 40% microwave
power). The completion of the reaction was monitored by
TLC. The brown coloured oily mass obtained was cooled
and the crude product was recrystallized from ethanol to
give compound 1. Spectral and analytical data were found
to be similar for compounds obtained by conventional and
microwave methods. The physical data and Rf value are
reported in Table 1.
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol), 10 ml acetic acid, 0.80 g of diethyl malonate
(0.005 mol) were taken in Erlenmeyer flask. Then the well-
stirred mixture was irradiated in microwave oven for
3.00 min at 480 W (i.e., 40% microwave power). The
completion of the reaction was monitored by TLC. The
solid reaction mixture was cooled and poured into a beaker
containing crushed ice. The solid obtained was recrystal-
lized from ethanol to give product 2. Spectral and analyt-
ical data were found to similar as reported for conventional
method. The physical data and Rf values are recorded in
Table 1. Spectral and analytical data were found to similar
as reported for conventional method.
Elemental analysis (found)
Elemental analysis (found)
C, 40.35; H, 2.54; N, 20.70; (Calculated): C, 40.61 H, 2.27;
N, 21.05, Mol. Formula: C9H6N4O6; IR (cm-1): 3303
(–NH), 1660, 1640 (C=O), 1525 (–NO2), 1230 (N–N);
1HNMR (d, ppm DMSO-d6): 7.20, 8.50, 9.00 (m, 3H,
C, 42.35; H, 2.44; N, 18.38; (Calculated): C, 42.87 H, 2.62;
N, 18.18, Mol. Formula: C11H8N4O7; IR (cm-1): 1710,
1668, 1650 (C=O), 1538 (–NO2) 1230 (N–N); 1HNMR
Table 1 The physical data and Rf value of the synthesised compounds (1–8)
Com.
Condition
Molecular formula
M. wt
Convention method
Microwave method
m.p. °C
2
Rf
Yield%
R time (h)
Yield %
R time (min)
1
2
3
4
5
6
7
8
Acetic acid
–
C9H6N4O6
266
308
262
298
264
265
333
373
48
52
51
57
55
49
52
46
12–14
11–12
15–16
12–14
10–11
10–11
14–15
16–17
82
88
88
86
87
88
75
84
3.00
3.00
3.30
3.30
3.00
2.00
3.00
2.30
185
205
168
222
167
188
238
268
0.53
0.55
0.54
0.58
0.54
0.51
0.53
0.61
C
C
C
C
11H8N4O7
11H10N4O4
10H7ClN4O5
10H8N4O5
Acetic acid
Morpholine
C9H7N5O5
C
C
13H11N5O4S
15H11N5O5S
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Med Chem Res (2012) 21:1692–1699
1695
(d, ppm DMSO-d6): 7.22, 8.40, 8.98 (m, 3H, Ar–H),
3.40–3.32 (2H, d, CH2 of pyrazoline,); 2.40 (s, 3H, CH3);
MS: m/z [M]? 308.
was filtered, dried, and recrystallized from alcohol to
give 4.
Microwave method
Synthesis of 1-(2,4-dinitrophenyl)-3,5-dimethyl-1H-
pyrazole (3)
Mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and 1-chloro-hexane 2-4-dione (0.80 g, 0.005
mol) was taken in an Erlenmeyer flask and stirred vigor-
ously. The well-stirred mixture was irradiated in micro-
wave oven for 3.30 min at 480 W (i.e., 40% microwave
power) with intermitted irradiation for 30 s interval. The
reaction was monitored by TLC and after completion of the
reaction; the contents were poured onto the crushed ice.
The solid obtained was filtered off, washed with cold
water, and purified by recrystallization from ethanol to get
product 4. The physical data and Rf value are reported in
Table 1. Spectral and analytical data were found to similar
as reported for conventional method.
Conventional method
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and acetyl acetone (0.50 g, 0.005 mol) in
absolute alcohol (20.0 ml) was warmed on a water bath for
15–16 h with stirring. The completion of the reaction was
monitored by TLC. The reaction mixture was cooled at
room temperature and treated with ice-cold water. The
solid product obtained was filtered off, washed with water
and recrystallized from methanol to give product 3.
Microwave method
Elemental analysis (found)
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and acetyl acetone (0.50 g, 0.005 mol) were
taken in Erlenmeyer flask. The mixture was well stirred
and irradiated in microwave oven for a period 3.30 min at
480 W (i.e., 40% microwave power) with intermitted
irradiation for 30 s interval. The reaction mixture was then
allowed to stand at room temperatures. The solid product
obtained was filtered off, washed with water and dissolved
in methanol then filtered, dried and recrystallized from
ethanol to afford compound 3. The physical data and Rf
value are recorded in Table 1. Spectral and analytical data
were found to similar as reported for conventional method.
C, 40.24; H, 2.59; N, 18.58; (Calculated): C, 40.42; H,
2.36; N, 18.76; Mol. Formula: C10H7ClN4O5; IR (cm-1):
1
1666 (C=O), 1606 (C=N), 1239 (N–N); H NMR (d, ppm
DMSO-d6): 8.12, 8.56, 9.08 (m, 3H, Ar–H), 3.34–3.26 (2H,
d, CH2 of pyrazoline,) 2.30 (s, 2H, CH2); MS: m/z [M]?
298.
Synthesis of 1-(2,4-dinitrophenyl)-3-methyl-1H-
pyrazol-5(4H)-one (5)
Conventional method
Elemental analysis (found)
To a solution of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) in 25.00 ml of absolute ethanol, 5.00 mL
acetic acid and hexane-2,4-dione (0.55 g, 0.005 mol) was
added in a round bottom flask. The mixture was well stirred
and refluxed for about 12–14 h. The reaction was moni-
tored by TLC and after completion of the reaction; the
contents were poured onto the crushed ice. The solid
obtained was filtered off, washed with cold water and
purified by recrystallization from ethanol to get product 5.
The physical data and Rf value are reported in Table 1.
Spectral and analytical data were found to similar as
reported for conventional method.
C, 50.66; H, 3.51; N, 21.08; (Calculated): C, 50.38; H,
3.84; N, 21.37; Mol. Formula: C11H10N4O4; IR (cm-1):,
1
1553 (C=N), 1530 (-NO2) 1234 (N–N); H NMR (d, ppm
DMSO-d6): 7.82, 8.60, 9.10 (m, 3H, Ar–H), 6.20 (s, 1H,
CH), 2.20 (s, 3H, CH3) 2.30 (s, 3H, CH3); MS: m/z [M]?
262.
Synthesis of 3-(chloromethyl)-1-(2,4-dinitrophenyl)-
1H-pyrazol-5(4H)-one (4)
Conventional method
Microwave method
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and 1-chloro-hexane 2-4-dione (0.80 g, 0.005
mol) was taken in absolute alcohol (25.00 ml). The mixture
was well stirred and refluxed for 12–14 h. Then the reac-
tion mixture was kept overnight and the solution was
poured into ice-cold water. The resulting solid compound
To a solution of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) in 25.00 ml of absolute ethanol, 5.00 ml acetic
acid and hexane-2,4-dione (0.55 g, 0.005 mol) was taken
in an Erlenmeyer flask and stirred vigorously. The mixture
was then irradiated under microwave oven for 3.00 min at
123

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Med Chem Res (2012) 21:1692–1699
480 W (i.e. 40% microwave power) with intermitted irra-
diation for 30 s interval. Upon completion of the reaction
(monitored by TLC), the reaction mixture was poured onto
the crushed ice. The solid mass obtained was filtered and
washed several times with water. Purification by recrys-
tallization with alcohol gave product 5. The physical data
and Rf values are reported in Table 1. Spectral and ana-
lytical data were found to similar as reported for conven-
tional method.
(m, 3H, Ar–H); 5.10 (s, 2H, NH2), 3.51–3.44 (2H, d, CH2
of pyrazoline); MS: m/z [M]? 265.
Synthesis of 4-(2,4-dinitrophenyl)-1-
phenylthiosemicarbazide (7)
Conventional method
A mixture of 1-(3,5-dinitrophenyl) hydrazine (1.00 g,
0.005 mol) and phenyl isothiocynate (0.70 g, 0.005 mol)
was dissolved in 20 ml of DMF in a round bottom flask.
Then the well-stirred mixture was refluxed 14–15 h. The
TLC monitored the completion of the reaction. The reac-
tion mixture was then allowed to stand at room tempera-
ture, after that the mixture was poured in ice-cold water.
The resulting solid was filtered, dried, and recrystallized
from benzene.
Elemental analysis (found)
C, 45.14; H, 2.75; N, 21.42; (Calculated): C, 45.46; H,
3.05; N, 21.21; Mol. Formula: C10H8N4O5; IR (cm-1):
1
1660 (C=O), 1520 (C=N), 1301 (N=N); H NMR(d, ppm
DMSO-d6): 7.80, 810, 8.60 (m, 4H, Ar–H),), 3.41–3.34
(2H, d, CH2 of pyrazoline,) MS: m/z [M]? 264.
Synthesis of 3-amino-1-(2,4-dinitrophenyl)-1H-
Microwave method
pyrazol-5(4H)-one (6)
A mixture of 1-(3,5-dinitrophenyl) hydrazine (1.00 g,
0.005 mol), phenyl isothiocynate (0.70 g, 0.005 mol) and
20 ml DMF was taken in Erlenmeyer flask. The mixture
was irradiated under microwave for 3.00 min at 400 W
powers with intermittent radiation of 15 s interval. TLC
examined the progress of the reaction. The mixture was
poured into ice-cold water. The resulting solid was filtered,
dried, and recrystallized from benzene to give product 7.
The physical data and Rf value are recorded in Table 1.
Spectral and analytical data were found to be similar for
compounds obtained by both reported methods for con-
ventional and microwave methods.
Conventional method
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and ethyl 2-cyanoacetate (0.60 g, 0.005 mol)
was taken 20.0 ml of DMF and the mixture was refluxed
for 10–11 h. The progress of the reaction was monitored by
the TLC. The reaction mixture was allowed to attain the
room temperature. The mixture was then poured into the
ice-cold water. The resulting solid product 6 was filtered,
dried, and recrystallized from methanol.
Microwave method
Elemental analysis (found)
A mixture of 1.00 g of 1-(3,5-dinitrophenyl) hydrazine
(0.005 mol) and ethyl 2-cyanoacetate (0.60 g, 0.005 mol)
was taken in an Erlenmeyer flask and mixed thoroughly.
The mixture was irradiated under microwave for 2.00 min
at 600 W (i.e., 50% microwave power) power with inter-
mittent radiation of 30 s interval. The progress of the
reaction was monitored by the TLC. The mixture was then
poured into the ice-cold water, filtered, dried, and recrys-
tallized from methanol to give product 6. The physical data
and Rf values are reported in Table 1. Spectral and ana-
lytical data were found to similar as reported for conven-
tional method.
C, 57.55; H, 4.24; N, 20.70, S; 9.40 (Calculated): C, 46.84;
H, 3.33; N, 21.01, S, 9.62; Mol. Formula: C13H11N5O4S;
IR (cm-1): 3410, 3362, 3342 (–NH), 1530 (–NO2), 1110
1
(C=S), H NMR (d, ppm DMSO-d6): 6.66–7.10. (m, 5H,
Ar–H) 6.98, 8.23, 8.60 (m, 3H, Ar–H), 3.64 (s, H, HN–Ph),
3.84 (s, H, HN–dinitrophenyl hydrazine), 2.20 (s, H, HN–
N); MS: m/z [M]? 333.
Synthesis of (E)-3-(2,4-dinitrophenylamino)-2-
(phenylimino) thiazolidin-4-one (8)
Conventional method
Elemental analysis (found)
A mixture of compound 7 (1.00 g, 0.003 mol), ethylchlo-
roacetate (0.40 g, 0.003 mol) and 2-3 drops of morpholine
was taken in a round bottom flask and dissolved in 25 mL
ethanol. After then reaction mixture was refluxed for
16–17 h. The TLC monitored the progress of the reaction.
C, 40.52; H, 2.80; N, 26.72; (Calculated): C, 40.76; H,
2.66; N, 26.41, Mol. Formula: C9H7N5O5; IR (cm-1):
3334, 3218 (–NH2), 1670 (C=O), 1554 (C=N), 1311
(N=N); 1HNMR (d, ppm DMSO-d6): 8.02, 8.16, 8.40
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Med Chem Res (2012) 21:1692–1699
1697
The reaction mixture was allowed to attain the room
temperature. After that the mixture was poured into the ice-
cold water. The resulting solid product 8 was filtered, dried,
and recrystallized from methanol.
active against E. coli, P. aeruginosa, and S. aureus,
whereas compound 4 is active on E. coli, P. aeruginosa and
B subtilis. It has also been observed that compound 6
showed activity against S. aureus whereas 8 is active on
E. coli, S. aureus and B. subtilis.
Microwave method
The antifungal activity of the compounds was studied
for the two pathogenic fungi. It was observed that com-
pounds 2 and 4 have highest activity against C. albicans
and A. niger, whereas compound 3 is active against A.
niger. It has also been observed that compound 8 showed
good activity against C. albicans.
A mixture of 7 (1.00 g, 0.003 mol), ethylchloroacetate
(0.40 g, 0.003 mol) and in presence of catalytic amount of
morpholine were taken in Erlenmeyer flask and mixed
thoroughly. Then the mixture was irradiated under micro-
wave oven for 2.30 min at 480 W (i.e. 40% microwave
power) with an intermitted irradiation for 30 s interval. The
TLC monitored the progress of the reaction. The product
was cooled and poured into ice-cold water and recrystal-
lized from ethanol to give product 8. The physical data and
Rf value are recorded in Table 1. Spectral and analytical
data were found to be similar for compounds obtained by
both reported methods for conventional and microwave
methods.
Results and discussion
In conventional method, the yield of all these products is
lower as compared to the yield obtained by microwave
irradiation technique. Microwave irradiation method
facilitates the polarization of the reacting molecule causing
reactions to occur at higher rate. A comparative study in
terms of yield and reaction time is shown in Table 1. The
compounds (1–7) have been synthesised by condensation
of isonicotinohydrazide and diethyl malonate (in glacial
acetic acid) or acetyl acetone or 1-chloro-hexane-2,4-dione
or hexane-2, 4-dione and acetic acid or ethyl 2-cyanoace-
tateor phenyl isothiocynate, respectively. Compound (8)
has synthesised by the condensation reaction of (7) and
ethylchloroacetate in presence of morpholine. These com-
pounds have also been synthesised by the conventional
method. It is noteworthy that the reaction, which required
5–12 h in conventional method, was completed within
2.00–3.30 min in microwave system at power level of
480–600 W. Yields have been remarkably improved from
46–57% to 75–88%.
Elemental analysis (found)
C, 57.35; H, 4.14; N, 18.20, S, 8.28; (Calculated): C, 48.26;
H, 2.97; N, 18.76 S, 8.59; Mol. Formula: C15H11N5O5S; IR
(cm-1): 3362 (–NH), 1649 (C=O), 1554 (C=N), 1235
1
(N–N) 742 (C–S–C); H NMR (d, ppm DMSO-d6): 9.60
(s, H, HN) 7.6–7.8 (m, 5H, Ar–H), 7.18, 8.43, 8.68 (m, 3H,
Ar–H), 4.10 (s, 2H, CH2) MS: m/z [M]? 373.
Antimicrobial activity
All the synthesis compounds 1–8 have been screened for
In vitro antimicrobial study. It was carried out on Muller
Hinton agar (Hi-media) plates (37°C, 24 h) by agar diffu-
sion cup plate method (Kelekci et al., 2008). These were
screened for antimicrobial activity at 200, 100 and 50 lg/
ml concentration against the bacterial strains: Escherichia
coli, Staphylococcus aureus, Pseudomonas eruginosa, and
Staphylococcous aureus. Antifungal activity was tested
on Sabouraud dextrose agar (Hi-media) plates (26°C,
48–72 h) by cup plate method against Candida albicans
and Aspergillus niger at the concentration level of 200,
100, and 50 lg/ml, ciprofloxacin and griseofulvin were
used as a standards for comparison of antibacterial and
antifungal activity under the similar conditions. DMSO
was used as a solvent control for both antibacterial and anti
fungal activities. The results are summarised in Tables 2
and 3, which include the activity of reference compound
ciprofloxacin and griseofulvin, respectively. The tested
compounds exhibit mild to moderate antibacterial activity
against all four strains of bacteria. The compound 2 is
The structures of the synthesised compounds (1–8) have
been confirmed on the basis of spectral and elemental
analysis. The IR spectra of compounds 1 and 2 exhibit
bands at 1660, 1640 (C=O), 1230 (N–N) cm-1. Further, in
1
their H NMR (d, ppm DMSO-d6) spectrum, the appear-
ance of a signal at d 3.45-3.40 (2H, d, CH2 of pyrazoline)
confirms the presence of the pyrazolidine-3, 5-Dione. The
IR spectra of compounds (3–6) exhibited the stretching
vibration band at 1606–1520 cm-1 due to (C=N, pyrazo-
line ring) and 1311–1234 (N–N), 1670–1660 (C=O),
which indicate the presence of the pyrazol-5(4H)-one and
-1H-pyrazole ring. Further, in their 1H NMR (d, ppm
DMSO-d6) spectrum the appearance of a signal at d
3.51–3.26 (2H, d, CH2 of pyrazoline), 6.20 (s, 1H, CH),
confirms the presence of pyrazol-5(4H)-one and -1H-pyr-
azole ring. Similarly, the structures of compounds 7 and 8
were confirmed on the basis of spectral and elemental
analysis. The IR spectrum of 7 exhibited a band due to
3410, 3362, 3342 (–NH), 1110 (C=S), their 1H NMR
123

1698
Med Chem Res (2012) 21:1692–1699
Table 2 In vitro antibacterial activity of compounds
Compd.
Inhibition zone diameter in mm
E. coli
P. aeruginosa
S. aureus
B. subtilis
50 lg/ml 100 lg/ml 200 lg/ml 50 lg/ml 100 lg/ml 200 lg/ml 50 lg/ml 100 lg/ml 200 lg/ml 50 lg/ml 100 lg/ml 200 lg/ml
1
2
3
4
5
6
7
8
16.20
13.20
14.30
14.20
12.00
12.30
10.20
18.20
18.10
15.20
23.00
23.00
16.00
16.00
14.10
26.10
35.42
20.20
30.60
28.50
30.40
20.40
20.60
18.60
30.10
35.53
12.10
18.20
10.20
14.00
12.20
08.40
12.00
10.20
31.11
13.20
22.80
18.60
22.10
16.00
12.10
14.20
10.30
31.11
16.10
28.00
25.00
28.60.
22.00
16.30
20.20
12.00
31.11
08.40
10.00
14.00
15.00
14.20
14.00
10.00
16.20
30.45
12.00
22.00
23.00
20.00
18.00
20.00
14.00
22.20
30.45
18.10
26.10
24.00
28.10
24.10
26.00
18.00
30.40
30.45
10.20
10.20
10.40
12.20
10.20
10.40
10.20
12.00
31.34
12.00
18.90
18.50
20.10
10.10
08.10
14.10
20.80
31.34
16.00
25.10
22.90
28.00
12.00
12.00
18.40
26.40
31.34
Norfloxacin 35.43
Table 3 In vitro antifungal activity of compounds
Compound
Inhibition zone diameter in mm
C. albicans
A. niger
50 lg/ml
100 lg/ml
200 lg/ml
50 lg/ml
100 lg/ml
200 lg/ml
1
06.20
13.20
14.30
14.20
10.00
12.30
11.50
11.10
28.40
10.10
18.20
20.00
23.00
14.00
14.00
14.10
18.40
28.40
10.20
24.20
24.50
26.40
20.40
20.80
18.40
24.20
28.40
10.10
12.20
10.20
14.00
12.20
08.40
10.00
10.20
28.40
12.20
16.80
18.60
22.10
14.00
10.10
14.20
14.50
28.40
14.10
24.00
25.00
26.60.
18.00
14.30
16.20
16.60
28.40
2
3
4
5
6
7
8
Clotrimazole
(d, ppm DMSO-d6) spectrum, appearance of a signal at d
3.64 (s, H, HN–Ph), 3.84 (s, H, HN-dinitrophenyl hydra-
zine), 2.20 (s, H, HN–N); confirms the structure of 7
compound. The IR spectrum of 8 shows a band due to 3362
(–NH), 1649 (C=O), 1554 (C=N), 1235 (N–N) 742 (C–S–
A. niger, where as compound 3 is active against A. niger. It
has also been observed that compound 8 showed good
activity against C. albicans.
Thus, from these studies it can also be concluded that
microwave technique is one of the promising technique of
synthesis with better yield, less time consuming and pro-
vides green chemical pathway for the synthesis of various
organic compounds. It is an eco-friendly technique.
1
C); their H NMR (d, ppm DMSO-d6) spectrum, appear-
ance of a signal at 9.60(s, H, HN), 4.10 (s, 2H, CH2)
confirms the presence thiazolidin-4-one ring. The yields
and the physical constants of the compounds synthesised
by the conventional and microwave irradiation methods are
given in Table 1.
Acknowledgements The authors are thankful to HOD, Department
of Chemistry, University College of Science, M. L. Sukhadia
University, Udaipur (Rajasthan) for providing laboratory facilities.
Authors are also thankful to Director, CDRI Lucknow, India for
providing spectral and analytical data. Special thanks to Dr. Ashok
Kumar Sharma (A.D.) Regional Disease Diagnostic Center, Kota
(Rajasthan) for antimicrobial screening.
The tested compounds exhibited mild to moderate
antibacterial activity against all four strains of bacteria. The
compound, 2 is active on E. coli, P. aeruginosa S. aureus,
where as 4 is active on E. coli, P. aeruginosa, B. subtilis. It
has also been observed that compounds 6 showed activity
against S. aureus, and 8 is active on E. coli, S. aureus and
B. subtilis.
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