1,4-Diazabicyclo[2.2.2]octane-catalyzed one-pot synthesis of pyrazolo[1,2-a][1,2,4]triazole-1,3-diones under ultrasound acceleration

Article abstract of DOI:10.1002/jhet.1706

1,4-Diazabicyclo[2.2.2]octane has been explored as an efficient catalyst to effect the three-component condensation reactions between malononitrile, 4-arylurazoles, and aromatic aldehydes in ethanol under ultrasound irradiation conditions. The reactions proceeded very rapidly under mild conditions to furnish the corresponding pyrazolo[1,2-a][1,2,4]triazole-1,3-dione derivatives in excellent yields.

Full text of DOI:10.1002/jhet.1706

Month 2013
1,4-Diazabicyclo[2.2.2]octane-Catalyzed One-Pot Synthesis of Pyrazolo
[1,2-a][1,2,4]triazole-1,3-diones under Ultrasound Acceleration
,*
Davood Azarifar Razieh Nejat-Yami, and Mohammad Ali Zolfigol
Faculty of Chemistry, University of Bu-Ali Sina, 65178, Hamedan, Iran
*
E-mail: azarifar@basu.ac.ir
Received August 27, 2011
DOI 10.1002/jhet.1706
Published online 00 Month 2013 in Wiley Online Library (wileyonlinelibrary.com).
1,4-Diazabicyclo[2.2.2]octane has been explored as an efficient catalyst to effect the three-component
condensation reactions between malononitrile, 4-arylurazoles, and aromatic aldehydes in ethanol under
ultrasound irradiation conditions. The reactions proceeded very rapidly under mild conditions to furnish the
corresponding pyrazolo[1,2-a][1,2,4]triazole-1,3-dione derivatives in excellent yields.
J. Heterocyclic Chem., 00, 00 (2013).
INTRODUCTION
temperature of roughly 5000ꢀC, pressures of about
1000 atm, and heating and cooling rates above 10 billion
ꢀC per second [32]. Such localized hot spots can be consid-
ered as microreactors in which the energy of sound is
transformed into a useful chemical form.
Moreover, one-pot multicomponent reactions have
proven to be more advantageous over conventional
linear-type synthesis [33], because the multistep reac-
tions usually suffer from complex isolation procedures
and produce significant amounts of waste products. In
addition, one-pot processes provide rapid and efficient
approach to organic transformations including diverse
synthesis of polyfunctionalized heterocycles of synthetic
importance [5].
As mentioned previously, among the important hetero-
cyclic compounds, pyrazolo-fused heterocycles such as
pyrazolo[1,2-a][1,2,4]triazole-1,3-dione derivatives are of
synthetic and biological importance, and a number of
methods have been previously reported for their synthesis
[34–40]. Bazgir et al. [41] have recently reported the
triethylamine-catalyzed synthesis of 1H-pyrazolo[1,2-b]
phthalazine-5,10-diones.
A wide range of naturally occurring compounds belongs
to nitrogen-containing heterocyclic compounds. Many of
these heterocycles are of significant biological and synthetic
importance, which act as pharmaceuticals, agrochemicals,
and polyfunctionalized fragments [1–10]. Among these
heterocyclic compounds, 1,2,4-triazolidine-3,5-dione contain-
ing heterocycles, so-called urazoles, have received consider-
able interest in synthetic and industrial chemistry. Also,
these compounds have found immense technological applica-
tions in the manufacture of herbicides and antifungal com-
pounds, and in the production of plastics such as automobile
air bags and blowing agents [11,12]. Also, pyrazolourazoles
as their fused derivatives with diverse structures have attracted
much interest because of their wide range of biological prop-
erties such as analgesic, antibacterial, anti-inflammatory, anti-
diabetic, and psychoanaleptic activities [13–18]. Regarding
the vital importance of these urazole derivatives, many novel
methods have been reported for their synthesis in recent years
[19–24], and development of new approaches for their synthe-
sis seems to be interesting challenge.
On the other hand, application of ultrasound [25–30] in a
so-called “sonochemistry” has received enormous interest as
a versatile and challenging technique in organic synthesis
[31]. It is a known fact that ultrasonic irradiation technique
can not only enhance the reaction rates but also have
profound effect on the yields of various organic reactions
[25–30]. The phenomenon called “acoustic cavitations” is
responsible for the beneficial effects of ultrasound on
chemical reactions. Namely, the molecules of the liquid are
separated during the rarefaction cycle of the wave, generat-
ing bubbles that undergo subsequent implosive collapse in
a liquid, which produces unusual chemical and physical
environments. These rapid and violent implosions of the
bubbles generate localized “hot spots” with a transient
RESULTS AND DISCUSSION
In connection with our continuing interest in the synthesis
of pyrazoles [42–44] and also regarding the efficiency of
one-pot processes joined with ultrasonic irradiation tech-
nique in organic reactions [45,46], we were encouraged to
examine a one-pot three-component condensation among
malononitrile, 4-arylurazoles, and aromatic and aliphatic
aldehydes under the catalytic effect of 1,4-diazabicyclo
[2.2.2]octane (DABCO) and ultrasonic irradiation condi-
tions as a new approach for the synthesis of new derivatives
of pyrazolo[1,2-a][1,2,4]triazole-1,3-diones (Scheme 1).
© 2013 HeteroCorporation

D. Azarifar, R. Nejat-Yami, and M. A. Zolfigol
Vol 000
Scheme 1
To establish the conditions for the titled reactions, we
preliminary examined the model condensation reaction
among malononitrile (1 mmol), benzaldehyde (1mmol),
and 4-(4-chlorophenyl)urazole (1 mmol) as test compounds.
The effects of solvent, catalyst, and other conditions on
the reaction were studied using various solvents such as
EtOH, MeCN, CH2Cl2, and H2O with a variety of basic
and acidic catalysts (Table 1). As seen in Table 1, it was
observed that the reaction worked out best at 50ꢀC under
ultrasonication in terms of reaction time (35 min) and the
yield (95%, entry 9) in the presence of 20 mol% DABCO
catalyst. Ethanol was found to be the solvent of choice.
Also, among the basic catalysts DABCO, Et3N, and DBU
employed in this reaction, DABCO was proved to be the
most effective catalyst to provide the highest possible yield
(95%) in shortest reaction time (35 min). To substantiate
the catalytic effect of DABCO, the reaction was performed
in the absence of the catalyst. As a result, no detectable
amount of respective product was formed after a long
(300 min) ultrasonication in EtOH (entry 1). Also, using
lower or higher amounts of the catalyst did not have any
significant effect on the yield of the product (entries 7
Table 1
Optimization of the reaction conditions.a
Entry
Condition
Method
Ultrasound
Catalyst (mol%)
None
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
EtOH/50 ꢀC
EtOH /80 ꢀC
EtOH/rt
120
90
90
90
60
45
40
35
35
35
50
50
120
60
120
120
120
120
120
120
60
300
70
70
–
Trace
Trace
Trace
<30
82
90
93
95
93
82
83
Trace
<20
Trace
–
–
–
–
–
Reflux
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (10)
DABCO (20)
DABCO (20)
DABCO (30)
Et3N (20)
Et3N (30)
Et3N (30)
DBU (20)
DBU (20)
HClO4.SiO2 (1)
HClO4.SiO2 (1)
SSA(1)
SSA (1)
LiBr (10)
High speed stirring
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Ultrasound
Reflux
Ultrasound
Reflux
Ultrasound
Reflux
Ultrasound
Reflux
EtOH/rt
EtOH/30ꢀC
EtOH/40ꢀC
EtOH/50ꢀC
EtOH/60ꢀC
EtOH/50ꢀC
EtOH/50ꢀC
EtOH/50ꢀC
EtOH/50ꢀC
EtOH/80ꢀC
EtOH/50ꢀC
EtOH/80ꢀC
EtOH/50ꢀC
EtOH/80ꢀC
EtOH/50ꢀC
EtOH/80ꢀC
EtOH/50ꢀC
EtOH/50ꢀC
EtOH/50ꢀC
H2O/50ꢀC
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Ultrasound
MW (100 W)
Solvent free (80ꢀC)
Ultrasound
Ultrasound
Reflux
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
DABCO (20)
<20
<20
35
CH3CN/50ꢀC
CH3CN
45
70
70
70
Trace
Trace
<20
CH3CN/50ꢀC
CH2Cl2/40ꢀC
High speed stirring
Ultrasound
aConditions: malononitrile (1 mmol), 4-(4-chlorophenyl)urazole (1 mmol), and benzaldehyde (1 mmol).
bIsolated yield.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2013
1,4-Diazabicyclo[2.2.2]octane-Catalyzed One-Pot Synthesis of Pyrazolo[1,2-a]
[1,2,4]triazole-1,3-diones under Ultrasound Acceleration
and 10). Also, the role of ultrasound irradiation in the reac-
tion was evaluated by conducting the reaction under
conventional heating at room temperature and reflux point
(~80ꢀC), which resulted in the formation of only trace
amounts of the product (entries 2 and 3). Application of
microwave irradiation (100 W) was also examined in this
reaction, which resulted in a very low yield (<20%) of
the product (entry 21). It is interesting to note that when
acid catalysts such as silica-supported HClO4, silica sulfu-
ric acid, and LiBr were employed in this reaction either
under sonication or conventional reflux condition in EtOH,
no respective product was detected (entries 16–20).
it appears that this method is unsuitable for the synthesis
of pyrazolo[1,2-a][1,2,4]triazole-1,3-diones derived from
aliphatic aldehydes (entries p–r).
A possible mechanism to explain the formation of pyrazolo
[1,2-a][1,2,4]triazole-1,3-diones 4a–4o is depicted in
Scheme 2. As shown in this scheme, it seems likely that the
reaction initiates with a Knoevenagel-type condensation reac-
tion of malononitrile 1 with aromatic aldehyde 2 under the
catalytic effect of DABCO to yield a dehydrated condensed
malononitrile derivative (A). The subsequent Michael-type
addition of intermediate (A) to 4-arylurazole 3 provides a
second intermediate (B), which undergoes successive cycliza-
tion to (C) and DABCO-catalyzed tautomerization to afford
the expected product.
In summary, we have developed a rapid and reliable
synthetic procedure that provides easy access to hitherto
unknown pyrazolo[1,2-a][1,2,4]triazole-1,3-diones in rela-
tively excellent yields and short reaction times via a three-
component cyclo-condensation reaction of aromatic aldehydes,
malononitrile, and 4-arylurazoles catalyzed by DABCO as a
cost-effective and readily available nontoxic compound under
ultrasound irradiation conditions.
To develop the scope of these reactions, a series of
aromatic aldehydes 2a–2o as well as aliphatic ones 2p–2r
were subjected to condensation with various 4-arylurazoles
3a–3r in the presence of malononitrile 1 under the opti-
mized conditions (ultrasonication at 50ꢀC in EtOH using
20 mol% DABCO catalyst). As evident from the experi-
mental results (Table 2), almost all the aromatic aldehydes
reacted in relatively short reaction times (30–55 min) to
afford the corresponding pyrazolo[1,2-a][1,2,4]triazole-1,
3-diones 4a–4o in excellent yields (85–98%). The structures
of the products were fully characterized on the basis of their
1
elemental and spectral (IR, H NMR, 13C NMR, and MS)
EXPERIMENTAL
analysis. It is interesting to note that essential improvements
in the yields and also in the rates of the titled reactions occur
with using DABCO in comparison with triethylamine,
which was used as the catalyst to affect the same type of
reactions in our previously reported work [45]. However,
Chemicals used in this work were purchased from Fluka
(Muenchen, Germany) and Merck (Buchs, Switzerland) chemical
companies and used without purification. IR spectra were recorded
on a Shimadzu 435-U-04 FT spectrophotometer from KBr pellets.
1H and 13C NMR spectra were measured for samples in DMSO-
d6 with the use of a Bruker DRX-300 AVANCE instrument at
300.13 and 75.47 MHz, respectively, using Me4Si as internal stan-
dard. Mass spectra were recorded with a Finnigan-MAT 8430 spec-
trometer operating at an ionization potential of 70ev. Melting points
were measured on an SMPI apparatus. Elemental analysis for C, H,
and N atoms were performed using a PerkinElmer 2400 series ana-
lyzer. Ultrasonication was performed in a TRANSSONI 660/H ul-
trasound cleaner with a frequency of 35kHz and an output power
of 70W. The reactions were performed in open vessels. Urazoles
were synthesized according to the reported procedures [47–51].
Table 2
Ultrasonic-accelerated synthesis of pyrazolo[1,2-a][1,2,4]triazole-1,
3-diones 4a–4r catalyzed by DABCO.a
Entry
Ar1
Ar2
Time (min) Yield (%)b
a
b
c
d
e
C6H5
C6H5
C6H5
4-ClC6H4
C6H5
C6H5
4-ClC6H4
C6H5
4-ClC6H4
2,4-Cl2C6H3
4-NO2C6H4
4-MeOC6H4
C6H5
4-MeOC6H4
4-Me3CC6H4
4-Me3CC6H4
C6H5
30
35
40
20
40
45
45
45
55
50
45
45
50
50
30
120
120
120
98 [45]
95
95 [45]
95 [45]
98
90 [45]
98
96
85
92
95 [45]
94
90
4-MeC6H4
4-ClC6H4
4-ClC6H4
4-FC6H4
4-NO2C6H4
4-NO2C6H4
4-NO2C6H4
C6H5
4-CNC6H4
4-NO2C6H4
C6H5
4-NO2C6H4
Pyridin-4-yl
C2H5
General procedure for the synthesis of pyrazolo[1,2-a]
[1,2,4]triazole-1,3-diones (4). A mixture of malononitrile
1 (0.07 g, 1 mmol), aldehyde 2 (1 mmol), 4-arylurazole 3
(1 mmol), and DABCO (0.023 g, 0.2 mmol) in EtOH
(10 mL) was sonicated at 50ꢀC for an appropriate time
(Table 2). After completion of the reaction as monitored by
TLC analysis, the reaction mixture was filtered, and the
separated solid was washed with ethanol (2Â 3 mL) to
afford almost pure products 4. The structures of the
f
g
h
i
j
k
l
m
n
o
p
q
r
92
94 [45]
–
–
–
1
products were fully established on the basis of their H
NMR, 13C NMR, and IR spectra as well as the elemental
and MS spectral analysis for the new compounds as given
C6H5
C6H5
C6H5
b-PhC2H4
n-C6H13
in the succeeding text.
7-Amino-2-(4-chlorophenyl)-1,2,3,5-tetrahydro-1,3-dioxo-5-
aConditions: aldehyde (1 mmol), malononitrile (1 mmol), 4-arylurazole
(1 mmol), DABCO catalyst (20 mol%), ultrasonication at 50ꢀC, in EtOH.
bIsolated yield.
phenylpyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4b). White
powder; mp > 300ꢀC; FTIR (KBr): 3441 (NH2), 3314
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

D. Azarifar, R. Nejat-Yami, and M. A. Zolfigol
Vol 000
Scheme 2
1
(NH2), 2193 (CN), 1769 (C═O), 1714 (C═O) cmÀ1; H
NMR (300 MHz, DMSO-d6): d 5.85 (s, 1H, CH), 7.20–7.72
(m, 11H, Ar–H and NH2); 13C NMR (75 MHz, DMSO-d6):
d 61.9 (C-aliphatic), 64.5 (═C–CN) , 116.8 (CN), 127.5
(Ar), 128.9 (Ar), 129.2 (Ar), 129.5 (Ar), 130.1 (Ar), 134.6
(Ar), 137.9 (Ar), 145.7 (Ar), 150.4 (C═O), 150.6 (C═O),
153.8 (═C–NH2); MS (EI, 70 ev): m/z (%) = 365 (M+);
Anal. Calcd for C18H12ClN5O2: C, 59.11; H, 3.31; N,
1
1653 (NO2), 1348 (NO2), 845 (C–NO2) cmÀ1; H NMR
(300 MHz, DMSO-d6): d 7.01 (s, 1H, CH), 7.50–8.33 (m,
9H, Ar–H and NH2); 13C NMR (75 MHz, DMSO-d6): d
61.2 (C-aliphatic), 63.5 (═C–CN), 116.7 (CN), 124.6 (Ar),
127.5 (Ar), 128.7 (Ar), 129.0 (Ar), 130.5 (Ar), 131.6 (Ar),
131.7 (Ar), 146.5 (Ar), 150.4 (C═O), 150.6 (C═O), 153.5
(═C–NH2); MS (EI, 70 ev): m/z (%) = 444 (M+); Anal. Calcd
for C18H10Cl2N6O4: C, 48.56; H, 2.26; N, 18.88%. Found:
19.15%. Found: C, 59.02; H, 3.14; N, 19.06%.
C, 48.42; H, 2.18; N, 18.76%.
7-Amino-2,5-bis(4-chlorophenyl)-1,2,3,5-tetrahydro-1,3-
dioxo-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4e). White
7-Amino-1,2,3,5-tetrahydro-2,5-bis(4-nitrophenyl)-1,3-dioxo-
pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4i).
White
powder; mp> 300ꢀC; FTIR (KBr): 3401 (NH2), 3317
powder; mp > 300ꢀC; FTIR (KBr): 3442 (NH2), 3327
(NH2), 2201 (CN), 1775 (C═O), 1725 (C═O), 1682
(NO2), 1664 (NO2), 1372 (NO2), 1351 (NO2), 847 (C–
(NH2), 2198 (CN), 1774 (C═O), 1715 (C═O) cmÀ1; H
1
NMR (300 MHz, DMSO-d6): d 5.86 (s, 1H, CH), 7.49–
7.68 (m, 10H, Ar–H and NH2); 13C NMR (75 MHz,
DMSO-d6): d 61.5 (C-aliphatic), 63.9 (═C–CN), 116.9
(CN), 129.0 (Ar), 129.3 (Ar), 129.5 (Ar), 129.6 (Ar), 130.0
(Ar), 130.3 (Ar), 133.7 (Ar), 138.5 (Ar), 150.4 (C═O),
150.7 (C═O), 153.9 (═C–NH2); MS (EI, 70ev): m/z
(%) = 399 (M+); Anal. Calcd for C18H11Cl2N5O2: C, 54.02;
1
NO2) cmÀ1; H NMR (300 MHz, DMSO-d6): d 6.13 (s,
1H, CH); 7.61–8.43 (m, 10H, Ar–H and NH2); 13C NMR
(75 MHz, DMSO-d6): d 61.8 (C-aliphatic), 63.9 (═C–
CN), 116.9 (CN), 124.6 (Ar), 128.7 (Ar), 129.0 (Ar),
129.6 (Ar), 131.0 (Ar), 133.6 (Ar), 146.8 (Ar), 148.9 (Ar),
150.6 (C═O), 150.9 (C═O), 153.9 (═C–NH2); MS (EI,
70 ev): m/z (%) = 421 (M+); Anal. Calcd for C18H11N7O6:
C, 51.32; H, 2.63; N, 23.27%. Found: C, 51.23; H, 2.54;
H, 2.77; N, 17.50%. Found: C, 53.92; H, 2.68; N, 17.43%.
7-Amino-2-(4-chlorophenyl)-1,2,3,5-tetrahydro-5-(4-nitrophenyl)-
1,3-dioxo-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4g). White
N, 23.22%.
powder; mp > 300ꢀC; FTIR (KBr): 3405 (NH2), 3311 (NH2),
2192 (CN), 1763 (C═O), 1713 (C═O), 1608 (NO2), 1348
(NO2), 852 (C–NO2) cmÀ1; 1H NMR (300 MHz, DMSO-d6):
7-Amino-1,2,3,5-tetrahydro-2-(4-methoxyphenyl)-1,3-dioxo-
5-phenylpyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4j). Yellow
powder; mp > 300ꢀC; FTIR (KBr): 3422 (NH2), 3307 (NH2),
d 6.01 (s, 1H, CH), 7.71–8.33 (m, 10H, Ar–H and NH2); 13
C
2191 (CN), 1763 (C═O), 1724 (C═O) cmÀ1 1H NMR
;
NMR (75 MHz, DMSO-d6): d 61.2 (C-aliphatic), 63.5 (═C–
CN), 116.8 (CN), 124.6 (Ar), 128.8 (Ar), 129.0 (Ar), 129.6
(Ar), 130.2 (Ar), 133.7 (Ar), 146.6 (Ar), 148.0 (Ar), 150.6
(C═O), 150.8 (C═O), 153.9 (═C–NH2); MS (EI, 70 ev): m/z
(%) = 410 (M+); Anal. Calcd for C18H11ClN6O4: C, 52.64; H,
(300 MHz, DMSO-d6): d 3.83 (s, 3H, OCH3), 5.86 (s, 1H,
CH), 7.05–7.62 (m, 11H, Ar–H and NH2); 13C NMR
(75 MHz, DMSO-d6): d 55.9 (OCH3), 61.9 (C-aliphatic), 64.5
(═C–CN), 114.7 (Ar), 117.1(CN), 123.9 (Ar), 127.5 (Ar),
128.8 (Ar), 129.0 (Ar), 129.2 (Ar), 139.6 (Ar), 150.5 (Ar),
151.4 (C═O), 154.4 (C═O), 159.7 (═C–NH2); MS (EI,
70 ev): m/z (%) = 361 (M+); Anal. Calcd for C19H15N5O3: C,
63.16; H, 4.18; N, 19.38%. Found: C, 63.04; H, 4.12; N,
19.34%.
2.70; N, 20.46%. Found: C, 52.56; H, 2.64; N, 20.42%.
7-Amino-2-(2,4-dichlorophenyl)-1,2,3,5-tetrahydro-5-(4-
nitrophenyl)-1,3-dioxo-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile
(4h).
White powder; mp > 300 ꢀC; FTIR (KBr): 3473
(NH2), 3332 (NH2), 2205 (CN), 1782 (C═O), 1743 (C═O),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

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1,4-Diazabicyclo[2.2.2]octane-Catalyzed One-Pot Synthesis of Pyrazolo[1,2-a]
[1,2,4]triazole-1,3-diones under Ultrasound Acceleration
[12] Mallakpour, S.; Rafiee, Z. Polym Bull 2006, 56, 293.
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7-Amino-1,2,3,5-tetrahydro-2-(4-methoxyphenyl)-5-(4-
nitrophenyl)-1,3-dioxo-pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile
(4l). White powder; mp > 300ꢀC; FTIR (KBr): 3383 (NH2),
3322 (NH2), 2206 (CN), 1776 (C═O), 1732 (C═O), 1583
;
(NO2), 1346 (NO2), 848 (C–NO2) cmÀ1 1H NMR
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(300 MHz, DMSO-d6): d 3.82 (s, 3H, OCH3), 5.89 (s, 1H,
CH), 7.05–7.63 (m, 10H, Ar–H and NH2); 13C NMR
(75 MHz, DMSO-d6): d 55.8 (OCH3), 61.9 (C-aliphatic),
64.6 (═C–CN), 114.7 (Ar), 117.3 (CN), 123.9 (Ar), 127.5
(Ar), 128.9 (Ar), 129.1(Ar), 139.6 (Ar), 146.3 (Ar), 150.5
(Ar), 151.4 (C═O), 154.5 (C═O), 159.7 (═C–NH2); MS
(EI, 70 ev): m/z (%) = 406 (M+); Anal. Calcd for
C19H14N6O5: C, 56.17; H, 3.47; N, 20.68%. Found: C,
56.07; H, 3.38; N, 20.58%.
7-Amino-1,2,3,5-tetrahydro-1,3-dioxo-5-phenyl-2-(4-t-butylphenyl)
pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile (4m).
Yellow
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Lett 1998, 39, 4561.
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2003, 44, 6591.
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Encyclopedia of Physical Science and Technology; Academic Press:
San Diego, 2001.
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Horwood Limited: New York, 1991.
powder; mp> 300ꢀC; FTIR (KBr): 3358 (NH2), 3316
(NH2), 2183 (CN), 1764 (C═O), 1725 (C═O) cmÀ1; H
1
NMR (300 MHz, DMSO-d6): d 1.34 (s, 9H, C(CH3)3),
6.21 (s, 1H, CH), 7.31–8.03 (m, 11H, Ar–H and NH2);
13C NMR (75 MHz, DMSO-d6): d 31.2 (CH3), 34.3 (C
(CH3)3), 61.1 (C-aliphatic), 63.4 (═C–CN), 116.3 (CN),
124.3 (Ar), 126.6 (Ar), 127.8 (Ar), 128.6 (Ar), 133.4 (Ar),
146.6 (Ar), 148.1 (Ar), 150.6 (Ar), 151.3 (C═O), 151.7
(C═O), 153.3 (═C–NH2); MS (EI, 70 ev): m/z (%) = 387
(M+); Anal. Calcd for C22H21N5O2: C, 68.21; H, 5.46; N,
[27] Luche, J. L. Synthetic Organic Sonochemistry; Plenum:
New York, 1998.
[28] Mason, T. J. Ultrason Sonochem 2007, 14, 476.
[29] Suslick, K. S. Sonochemistry in Comprehensive Coordination
Chemistry; Elsevier Science: New York, 2003, Vol. 2, p.731.
[30] Putterman, S. J.; Weninger, K. R. Ann Rev Fluid Mech
2000, 32, 445.
[31] Lim, H. J.; Keum, G.; Kang, S. B.; Chung, B. Y.; Kim, Y.
Tetrahedron Lett 1998, 39, 4367.
[32] Martins, M. A. P.; Pereira, C. M. P.; Cunico, W.; Moura, S.;
Rosa, F.; Peres, R. L.; Machado, P.; Zanatta, N.; Bonacorso, H. G.
Ultrason Sonochem 2006, 13, 364.
[33] Ugi, I.; Dömling, A. Endeavor 1994, 18, 115.
[34] Adib, M.; Sayahi, M. H.; Mahmoodi, N.; Bijanzadeh, H. R.
Helv Chim Acta 2006, 89, 1176.
[35] Ghahremanzadeh, R.; Imani Shakibaei, G.; Bazgir, A. Synlett
2008, 1129.
[36] Teimouri, M. B. Tetrahedron 2006, 62, 10849.
[37] Shaterian, H. R.; Hosseinian, A.; Ghashang, M. Arkivoc
2009, 2, 59.
[38] Aziz Elassar, A. Z. A.; Elkholy, Y. M.; Elnagdi, M. H.
Pharmazie 1996, 51, 714.
18.08%. Found: C, 68.17; H, 5.38; N, 18.03%.
7-Amino-1,2,3,5-tetrahydro-5-(4-nitrophenyl)-1,3-dioxo-2-
(4-t-butylphenyl)pyrazolo[1,2-a][1,2,4]triazole-6-carbonitrile
(4n).
White powder; mp> 300ꢀC; FTIR (KBr): 3368
(NH2), 3318 (NH2), 2187 (CN), 1766 (C═O), 1711
(C═O), 1597 (NO2), 1363 (NO2), 854 (C–N) cmÀ1; H
1
NMR (300 MHz, DMSO-d6): d 1.30 (s, 9H, C(CH3)3),
6.02 (s, 1H, CH), 7.38–8.33 (m, 10H, Ar–H and NH2); 13
C
NMR (75 MHz, DMSO-d6): d 31.4 (CH3), 34.9 (C(CH3)3),
61.3 (C-aliphatic), 63.6 (═C–CN), 116.8 (CN), 124.6 (Ar),
124.8 (Ar), 126.3 (Ar), 126.9 (Ar), 128.7 (Ar), 133.1 (Ar),
148.0 (Ar), 150.7 (Ar), 151.2 (C═O), 151.8 (C═O), 154.4
(═C–NH2); MS (EI, 70 ev): m/z (%) = 432 (M+); Anal.
Calcd for C22H20N6O4: C, 61.11; H, 4.66, N, 19.43%.
Found: C, 61.02; H, 4.57; N, 19.38%.
[39] Shaterian, H. R.; Ghashang, M.; Feyzi, M. Appl Catal A Gen
2008, 345, 128.
[40] Al-Assar, F.; Zelenin, K. N.; Lesiovskaya, E. E.; Bezhan, I. P.;
Chakchir, B. A. Pharm Chem J 2002, 36, 598.
REFERENCES AND NOTES
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet