Synthesis of pyrano[2,3-c]pyrazole derivatives using Fe3O4@SiO2@piperidinium benzene-1,3-disulfonate (Fe3O4@SiO2 nanoparticle-supported IL) as a novel, green and heterogeneous catalyst

Article abstract of DOI:10.1002/aoc.3816

A simple, green and efficient protocol for the one-pot four-component synthesis of pyrano[2,3-c]pyrazole derivatives produced from reaction between aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of nano magnetic piperidinium benzene-1,3-disulfonate was synthesized in water at 60 °C. The Fe₃O₄@SiO₂ nanoparticle-supported IL was designed and synthesized. The present process offers advantages such as clean reaction, short reaction time, good to excellent yield, easy purification and easy recoverable catalyst.

Full text of DOI:10.1002/aoc.3816

Received: 10 November 2016
DOI: 10.1002/aoc.3816
Revised: 9 January 2017
Accepted: 4 March 2017
F U L L PA P E R
Synthesis of pyrano[2,3‐c]pyrazole derivatives using
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
(Fe3O4@SiO2 nanoparticle‐supported IL) as a novel, green and
heterogeneous catalyst
Ramin Ghorbani‐Vaghei
| Jafar Mahmoodi | Azadeh Shahriari | Yaser Maghbooli
Faculty of Chemistry, Bu‐Ali Sina
University, Hamedan 6517838683, Iran
A simple, green and efficient protocol for the one‐pot four‐component synthesis of
pyrano[2,3‐c]pyrazole derivatives produced from reaction between aryl aldehydes,
ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of nano
magnetic piperidinium benzene‐1,3‐disulfonate was synthesized in water at 60°C.
The Fe3O4@SiO2 nanoparticle‐supported IL was designed and synthesized. The
present process offers advantages such as clean reaction, short reaction time, good
to excellent yield, easy purification and easy recoverable catalyst.
Correspondence
Ramin Ghorbani‐Vaghei, Faculty of
Chemistry, Bu‐Ali Sina University, Hamedan
6517838683, Iran.
Email: rgvaghei@yahoo.com
KEYWORDS
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate, pyrano[2,3‐c]pyrazole, water solvent
1 | INTRODUCTION
Multi‐component reactions (MCRs) play an important
part in combinatorial chemistry because of the ability to
Green chemistry methods continue to progress in important
and alternative procedures which aim to conserve resources
and reduce costs.[1–3] The focus on green chemistry using
environmentally benign mixtures and conditions is one of
the most appealing developments in the synthesis of gener-
ally used organic compounds.[4] Catalysts supported on
magnetic nanoparticles (MNPs), usually iron oxides, can be
quickly and easily recovered by external magnetic fields for
recycling.[5] The method of magnetic separation, taking
advantage of magnetic nano particles, is generally more effi-
cient than filtration or centrifugation as it inhibits loss of the
catalyst. The magnetic separation of MNPs is cost‐effective
and favourable for industrial applications.[6] Presently, abun-
dant investigation is focused on the synthesis of magnetic
core‐shell structures using coating a SiO2 shell around pre‐
formed NPs.[7] Moreover, the rational design and combina-
tion of ionic liquids and magnetic nano particles affords
new ionic liquid stabilized on magnetic nano particles
(MNPs@ILs) with desirable properties. Therefore, knowl-
edge‐based and multifunctional systems can be prepared in
good accordance with green chemistry disciplines.[8]
synthesize compounds purposefully with higher productiv-
ity and atom economy by generating structural complexity
in a single step from four reactants.[9–11] In addition,
MCRs offer the advantage of simplicity and synthetic
efficacy over typical chemical reactions. Moreover, the
magnetic properties completely recover catalysts by means
of an external magnetic field. These advantages become
greater if such reactions can be conducted in aqueous
media.[12] Pyrano[2,3‐c]pyrazoles are joined to heterocyclic
compounds that possess many biological properties such
as fungicidal,[13] bactericidal,[14] vasodilator activities[15]
and act as anticancer agents.[16] They also find application
as pharmaceutical ingredients and biodegradable agro-
chemicals.[17,18] Pyrano[2,3‐c]pyrazoles were first synthe-
sized by a reaction between 3‐methyl‐5‐pyrazolone with
tetracyanoethylene.[19]
Herein, we have designed, synthesized and character-
ized a green Fe3O4@SiO2@piperidinium benzene‐1,3‐
disulfonate and we used it for the synthesis of
6‐amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐
1,4‐dihydropyrano[2,3‐c]pyrazoles via the one‐pot four
Appl Organometal Chem. 2017;e3816.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.3816

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GHORBANI‐VAGHEI ET AL.
component condensation reaction between aryl aldehydes,
ethyl acetoacetate, malononitrile and hydrazine hydrate in
water solvent at 60°C and employed it for the synthesis of
pyrano[2,3‐c]pyrazole derivatives in water solvent at 60°C
(Scheme 1).
2 | RESULTS AND DISCUSSION
2.1 | Application of
Fe3O4@SiO2@piperidinium benzene‐1,3‐
disulfonate
The Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
was produced as reported in our previous research.[20]
To optimize the reaction conditions, the condensation
reaction of 4‐chlorobenzaldehyde with ethyl acetoacetate,
malononitrile and hydrazine hydrate was selected as a typ-
ical and different amount of Fe3O4@SiO2 nanoparticle‐
supported IL in a range of 25–90°C and the optimization
was confirmed in water solvent (Table 1). As exposed in
Table 1, the best results were obtained when the reaction
was achieved using 20 mg of nano magnetic catalyst at
60°C (Table 1, entry 9). No improvement was detected
in the yield of reaction via increasing the amount of the
catalyst and temperature (Table 1, entries 10–12). Table 1
obviously shows that in the absence of Fe3O4@SiO2 nano-
particle‐supported IL, the product was made in low effi-
ciency (Table 1, entries 1 and 2).
To compare the result of the solution with that of water
solvent, a mixture of 4‐chlorobenzaldehyde with ethyl
acetoacetate, hydrazine hydrate and malononitrile as a model
using 20 mg of Fe3O4@SiO2 nanoparticle‐supported IL in
numerous solvents such as H2O, C2H5OH, CH3CN,
CH3CO2Et, CH2Cl2 and toluene was studied at 60°C. The
results are presented in Table 3. As it can be seen in
Table 2, water is clearly the best selection for this reaction.
Another purpose for choosing water as a solvent for this
SCHEME 1 Synthesis of 6‐amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐
methyl‐1‐phenyl‐1,4‐dihydropyrano[2,3‐c]pyrazoles using
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate as a catalyst
TABLE 1 The effect of quantity of the catalyst and temperature on the synthesis of 6‐amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐
dihydropyrano[2,3‐c]pyrazoles in water solventa
Entry
Catalyst loading (mg)
Reaction temperature (°C)
Reaction time (min)
Yieldb (%)
1
2
—
—
5
r.t.
90
r.t.
90
r.t.
60
90
r.t.
60
90
r.t.
60
60
60
10
10
10
8
10
15
60
65
65
70
75
82
98
98
85
98
3
4
5
5
10
10
10
20
20
20
30
30
6
7
8
8
8
9
8
10
11
12
8
8
8
Reaction conditions:
a4‐Chlorobenzaldehyde (1 mmol), ethyl acetoacetate (1 mmol), hydrazine hydrate (1 mmol), malononitrile (1 mmol);
bIsolated yield.

GHORBANI‐VAGHEI ET AL.
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TABLE 2 The effect of numerous solvents on the synthesis of
6‐amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐
dihydropyrano[2,3‐c]pyrazoles at 60oCa
reaction is that water is a safe, cheap, benign and green
solvent in comparison with organic solvents. In addition, a
mixture of piperidine and benzene‐1,3‐disulfonic acid was
prepared to obtain a free catalyst of piperidinium benzene‐
1,3‐disulfonate. Then, it was used in the model reaction and
15 mol% of this catalyst gave the best results which obtained
by the nanocatalyst. Due to the high amount requirement of
free catalyst in addition to this fact that it is a homogeneous
and non‐recyclable catalyst, it is better to use the heteroge-
neous nanocatalyst.
Entry
Solvent
H2O
Reaction time (min)
Yieldb (%)
1
2
3
4
5
6
7
8
10
10
15
15
45
60
98
94
92
70
70
25
10
Solvent‐free
C2H5OH
CH3CN
CH3CO2Et
CH2Cl2
Stimulated by the significant results, and with the inten-
tion of displaying the overview and scope of this new
Toluene
approach,
a range of 6‐amino‐4‐(4‐methoxyphenyl)‐5‐
cyano‐3‐methyl‐1‐phenyl‐1,4‐dihydropyrano[2,3‐c]pyrazoles
derivatives were produced from the one‐pot four‐component
reaction of ethyl acetoacetate, hydrazine hydrate, vari-
ous aldehydes and malononitrile using a catalytic amount
Reaction conditions:
a4‐Chlorobenzaldehyde (1 mmol), ethylacetoacetate (1 mmol), hydrazine hydrate
(1 mmol), malononitrile (1 mmol);
bIsolated yield.
TABLE 3 The synthesis of 6‐amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐dihydropyrano[2,3‐c]pyrazoles derivatives using 20 mg
of Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonatea
Entry
Aldehyde
R
Reaction time (min)
Yieldb (%)
M.p (°C)[Ref.]
1
2‐Hydroxy‐3‐methoxybenzaldehyde
Naphtalene‐2‐carbaldehyde
Biphenyl‐4‐carbaldehyde
Benzaldehyde
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
14
10
12
11
14
14
10
8
90
92
92
92
90
91
96
98
93
92
90
91
97
96
94
98
240–242
226–228[21]
2
3
252–254
4
232–234[22]
247–249[23]
262–264[22]
243–245[23]
243–245[23]
240–242[24]
247–249[23]
262–264[22]
247–249[23]
258–260[24]
244–246[23]
243–245[23]
244–246[23]
5
2‐Hydroxybenzaldehyde
4‐Methoxybenzaldehyde
3‐Chlorobenzaldehyde
4‐Chlorobenzaldehyde
Furfural
6
7
8
9
10
12
15
15
10
8
10
11
12
13
14
15
16
3‐Hydroxybenzaldehyde
2‐Methoxybenzaldehyde
4‐Hydroxybenzaldehyde
3‐Bromobenzaldehyde
3‐Nitrobenzaldehyde
2‐Chlorobenzaldehyde
4‐Nitrobenzaldehyde
10
8
Reaction conditions:
aAldehyde (1 mmol), malonitrile (1 mmol), ethylacetoacetate (1 mmol), hydrazine hydrate (1 mmol); water solvent, 60 °C;
bIsolated yield

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GHORBANI‐VAGHEI ET AL.
of Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
(20 mg) in water solvent at 60 °C. The results are briefly
shown in Table 3. The reaction time of aromatic aldehydes
having electron withdrawing groups was rather faster than
that of electron donating groups. However meta‐ and para‐
substituted aromatic aldehydes produced excellent results,
but ortho‐substituted aromatic aldehydes produced rather
lower yields due to the steric effects.
In another study, recyclability and reusability of the
Fe3O4@SiO2 nanoparticle‐supported IL was confirmed on
the condensation of between 4‐chlorobenzaldehyde with
malonitrile, ethyl acetoacetate and hydrazine hydrate. At the
end of the reaction, Fe3O4@SiO2 nanoparticle‐supported IL
was separated by magnets then the reaction mixture was
decanted and washed with water. The nano magnetic ionic
liquid was used without further cleansing after Isolation.
Afterwards the recycled catalyst was applied for alternative
reaction. Dynamic light scattering (DLS) was applied for
definition of particle size in colloidal solution. According to
Figure 1, the DLS analysis performed on the freshly prepared
catalyst revealed that the average size of the
Fe3O4@SiO2@piperidinium
benzene‐1,3‐disulfonate
(Fe3O4@SiO2 nanoparticle‐supported IL) is 86 nm. The
distribution of nanoparticles is about 60 to 100 nm which
indicates modest distribution of the nanoparticles. We
detected that the catalytic activity of the catalyst was main-
tained within the limits of the experimental errors for seven
continuous runs (Figure 2). Also, comparison of TGA analy-
sis of Fe3O4@SiO2 nanoparticle‐supported IL before and
after recycling showed the thermal stability of catalyst.
Furthermore, FT‐IR spectrum of the recycled catalyst
(Figure 3) shows the main absorbance bands as mentioned
before (for the initial catalyst) in Figure 4e. This confirms
that the organic functional groups on the surface of the cata-
lyst were not leached to the reaction solution and grafting
process was well done during preparation of the catalyst.
A probable mechanism for the synthesis of the 6‐
amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐
dihydropyrano[2,3‐c]pyrazoles (5) is presented in Scheme 3.[22]
Firstly, Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
activates the carbonyl group of the ethyl acetoacetate (1)
and hydrazine attacks the carbonyl group of the activated
ethyl acetoacetate. Then it loses one molecule H2O, and
intramolecular nucleophilic attacks by another NH2 group
of hydrazine to the following carbonyl group of ethyl
acetoacetate affords 5‐methyl‐2,4‐dihydro‐pyrazol‐3‐one
(6) and removes ethanol. In the next step, the aromatic
aldehyde which is activated by nano magnetic catalyst
and 5‐methyl‐2,4‐dihydro‐pyrazol‐3‐one (6), attacks to
the carbonyl group of the activated aldehyde and removes
H2O,
gives
4‐benzylidene‐5‐methyl‐2,4‐dihydro‐3H‐
pyrazol‐3‐one (7). Then, malononitrile after rearrange-
ment in (8) form, attacks to the double bond in the
FIGURE 1 Dynamic light scattering size distribution graph of the
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
FIGURE
2
Study of the reusability of Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate in 8 minutes (a) and TGA of
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate after recycling (b)

GHORBANI‐VAGHEI ET AL.
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FIGURE 3 FT‐IR spectrum of the recycled Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate
FIGURE 4 The IR spectrum of Fe3O4 (a); Fe3O4@SiO2 (b);
Fe3O4@SiO2@(CH2)3Cl (c); Fe3O4@SiO2@(CH2)3‐piperidine (d);
{Fe3O4@SiO2@(CH2)3‐piperidinium}2Benzene‐1,3‐disulfonate (e)
4‐benzylidene‐5‐methyl‐2,4‐dihydro‐3H‐pyrazol‐3‐one (7),
and
provides
6‐imino‐3‐methyl‐4‐phenyl‐2,4,5,6‐
tetrahydropyrano[2,3‐c]pyrazole‐5‐carbonitrile (9). Finally, 6‐
imino‐3‐methyl‐4‐phenyl‐2,4,5,6‐tetrahydropyrano[2,3‐c]
pyrazole‐5‐carbonitrile (9) after rearrangement, can afford the
expected pyrano[2,3‐c]pyrazole (5) as shown in Scheme 2.
The reaction occurs by primary formation of arylidene
malononitrile (7) in quantitative yield via the Knoevenagel
addition of activated malononitrile (2) to the activated
aromatic aldehyde (6) and followed by loss of magnetite
nanoparticles tag: piperidinium hydroxide ionic liquid.
The creation of the 1,4‐dihydropyrano‐[2,3‐c]‐pyrazole (5)
is suggested to include the following tandem reactions:
pyrazolone (8) formation using reaction between activated
ethyl acetoacetate (3) and hydrazine Hydrate 4), Michael
addition of pyrazolone (8) to arylidene malononitrile (7),
followed by cyclization and tautomerization (Scheme 2).31
To compare the efficiency of {Fe3O4@SiO2@(CH2)3‐
SCHEME 2 The proposed mechanism for the synthesis of 6‐amino‐
4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐1,4‐dihydropyrano
[2,3‐c]pyrazoles using Fe3O4@SiO2@piperidinium benzene‐1,3‐
disulfonate
amino‐4‐(4‐methoxyphenyl)‐5‐cyano‐3‐methyl‐1‐phenyl‐
1,4‐dihydropyrano[2,3‐c]pyrazoles, we have tabulated the
results of these catalysts to achieve the condensation of 4‐
chlorobenzaldehyde, ethyl acetoacetate, malononitrile and
hydrazine hydrate, in Table 4. As Table 4 displays, magnetic
piperidinium}2Benzene‐1,3‐disulfonate
catalyst
with
Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@(CH2)3Cl and
Fe3O4@SiO2@(CH2)3‐piperidine for the synthesis of 6‐

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GHORBANI‐VAGHEI ET AL.
TABLE 4 Compare the efficiency of MNPs catalyst with other catalysts in the reaction between 4‐chlorobenzaldehyde, ethyl acetoacetate,
malononitrile and hydrazine hydratea
Entry
Catalyst
MNPs catalyst
Catalyst loading
Time (min)
Yield (%)b
1
2
3
4
5
20 mg
20 mg
20 mg
20 mg
20 mg
8
60
60
60
60
98
45
35
5
Fe3O4
Fe3O4@SiO2
Fe3O4@SiO2@(CH2)3Cl
Fe3O4@SiO2@(CH2)3‐piperidine
5
Reaction conditions:
a4‐Chlorobenzaldehyde (1 mmol), ethylacetoacetate (1 mmol), hydrazine hydrate (1 mmol), malononitrile (1 mmol), H2O solvent, 60 °C;
bIsolated yield.
nanoparticles tag: piperidinium benzene‐1,3‐disulfonate
ionic liquid catalyst has strangely improved the synthesis
of dihydropyrano[2,3‐c]pyrazoles in different terms (reaction
time and yield). The reaction time were shorter and the
yields were higher when MNPs catalyst was used.
treated Fe3O4@SiO2@(CH2)3 was filtered, washed twice
with dry toluene and anhydrous diethyl ether, and dried at
80°C for 6 h in vacuum. To prepare piperidine modified
magnetic nanoparticles (pi‐SCMNPs), 1.0 g silica coated
magnetic nanoparticles was added to 50 ml of dry toluene
and 3 ml piperidine. The reaction mixture was dispersed
for 30 min, and then refluxed with stirring for 72 h.
The solid phase was filtered, washed with toluene and
ethanol, and dried at 60°C in vacuum. 1.0 g of pi‐
SCMNPs was suspended in 50 ml of acetonitrile and
3 ml of benzene‐1,3‐disulfonic acid was added to this
suspension. The mixture was stirred at room temperature
for 24 h, then filtered and washed twice with acetonitrile
and further washed with deionized water and dried at
60°C in vacuum.
3 | CONCLUSION
In summary, we have developed an efficient, green and envi-
ronmental friendly process for the synthesis of pyrano[2,3‐c]
pyrazole derivatives by four component cyclocondensation
reaction in the presence of Fe3O4@SiO2@piperidinium
benzene‐1,3‐disulfonate as a novel and powerful catalyst in
water solvent at 60°C with good to excellent yields. We sug-
gest that the method has also various advantages such as low
loading of catalyst, clean reaction, mild reaction conditions,
short reaction time, ease of workup, high yields and general
applicability for the synthesis of pyrano[2,3‐c]pyrazole.
3.1.2 | General procedure for the preparation
of 6‐amino‐3‐methyl‐4‐phenyl‐2,4‐
dihydropyrano[2,3‐c]pyrazole‐5‐carbonitrile
derivatives
3.1 | Experimental
To a mixture of aldehydes (1 mmol), malononitrile
(1 mmol), ethyl acetoacetate (1 mmol) and hydrazine
hydrate (1 mmol) in a round bottom flask, 20 mg of
Fe3O4@SiO2@piperidinium benzene‐1,3‐disulfonate was
added as a Fe3O4@SiO2 nanoparticle‐supported IL and
the resulting mixture was vigorously stirred long enough
in water solvent at 60°C (Table 3). After completion of
the reaction as observed by TLC (n‐hexane/ethyl acetate:
7/3), the catalyst was separated magnetically. The magnetic
Fe3O4 nanoparticles were washed three to four times with
ethanol and then dried at 50°C for 3 h in order to preserve
catalyst and it was used for alternative reaction. The prod-
uct obtained was pure by TLC and NMR spectroscopy.
Subsequently, the products in the aqueous layer was fil-
tered, separated and then the crude product was purified
by washing with acetone. In this study, nano magnetic
ionic liquid as a catalyst was recycled and reused for seven
times without any loss of catalytic activity.
3.1.1 | Preparation of
Fe3O4@SiO2@piperidinium benzene‐1,3‐
disulfonate
In the beginning, magnetite phase Fe3O4 was synthesized
via adding 3 ml FeCl3 (2 M dissolved in 2 M HCl) to
10.33 mL double distilled water followed using drop wise
addition of 2 ml Na2SO3 (1 M) for 3 min under magnetic
stirring. In the solution color changed from red to light
yellow, 80 ml of an NH3·H2O solution (0.85 M) were
added under severe stirring. After 30 min, the magnetite
precipitate Fe3O4 was washed to pH < 7.5 by distilled water
and separated with amagnet. To a mixture containing 1 g of
Fe3O4, 20 ml water, 80 ml ethanol, 3 ml ammonia and 3 ml
tetraethylorthosilicate were added under reflux to attain
Fe3O4@SiO2.[25–32] Consequently, 3 g of Fe3O4@SiO2
and (3‐chloropropyl) triethoxysilane (10 mmol) in 80 ml
of dry toluene were refluxed under nitrogen for 12 h. The

GHORBANI‐VAGHEI ET AL.
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3.2 | Spectral data analysis for compounds
3.2.3 | 4‐([1,1′‐Biphenyl]‐4‐yl)‐6‐amino‐3‐
methyl‐2,4‐dihydropyrano[2,3‐c]pyrazole‐5‐
carbonitrile (table 4, entry 3):
3.2.1 | 6‐Amino‐4‐(2‐hydroxy‐3‐
methoxyphenyl)‐3‐methyl‐2,4‐dihydropyrano
[2,3‐c]pyrazole‐5‐carbonitrile (table 4, entry 1):
White solid; M.p: 252–254°C; Yield; 90%; IR (KBr): υ
White solid; M.p: 240–242 °C; Yield; 88%; IR (KBr): υ
1
3342, 3376, 3160, 2935, 2837, 2194, 1656, 1612 cm−1, H
1
3468, 3382, 2975, 2845, 2185, 1651, 1617 cm−1, H NMR
NMR (400 MHz, DMSO‐d6): δppm 1.84 (s, 3H, H—C20),
4.66 (s, 1H, H—C13), 6.91 (s, 2H—NH2), 7.25 (dd, 2H,
J = 8 Hz and J = 8 Hz, H—C7,9), 7.35 (t, 1H, J = 8 Hz,
H—C8), 7.45 (d, 2H, J = 8 Hz, H—C6,10), 7.64 (m, 4H,
J = 10 Hz, H—C2,3,12,11), 12.13 (s, 1H, —NH); 13C
NMR (100 MHz, DMSO‐d6): δppm 10.2 (C20), 36.3 (C13),
57.5 (C18), 98 (C14), 121.3 (C19), 127 (C8), 127.2
(C3,11), 127.8 (C6,10), 128.5 (C7,9), 129.3 (C2,12), 136.1
(C1), 139.0 (C4), 140.2 (C15), 144.2 (C5), 155.2 (C16),
161.4 (C17); Anal. Calc.: C: 73.42, H: 5.18, N: 17.32.
(400 MHz, DMSO‐d6): δppm 1.96 (s, 3H, H—C14), 3.79 (s,
3H, H—C7 aliphatic), 4.60 (s, 1H, H—C8), 6.50 (d, 1H,
J = 8 Hz, H—C4), 6.68 (s, 2H, —NH2), 6.86 (d, 1H,
J = 8 Hz, H—C6), 6.95 (dd, 1H, J = 8 Hz and J = 8.0 Hz,
H—C5), 10.39 (s, 2H, —NH, OH); 13C NMR (100 MHz,
DMSO‐d6): δppm 10.3 (C14), 29.2 (C8), 56 (C7), 55 (C13),
105.4 (C4), 110.5 (C9), 120.5 (C1), 121.3 (C15), 124.3
(C5), 124.7 (C6), 136.9 (C10), 138.3 (C2), 147.1 (C3),
159.5 (C1), 160.5 (C12); Anal. Calc.: C: 60.22, H: 4.97, N:
18.99.
ACKNOWLEDGEMENTS
3.2.2 | 6‐Amino‐3‐methyl‐4‐(naphthalen‐2‐yl)‐
2,4‐dihydropyrano[2,3‐c]pyrazole‐5‐
carbonitrile (table 4, entry 2):
We are thankful to Bu‐Ali Sina University, Center of Excel-
lence in Development of Environmentally Friendly Methods
for Chemical Synthesis (CEDEFMCS), for financial support.
REFERENCES
[1] C. J. Li, T. H. Chan, Comprehensive Organic Reactions in Aqueous
Media, John Wiley & Sons, Chicago 2007.
[2] M. A. Zolfigol, A. Khazaei, A. R. Moosavi‐Zare, A. Zare, V.
Khakyzadeh, Appl. Catal A. 2011, 400, 70.
White solid; M.p: 226–228 °C; Yield; 90%; IR (KBr): υ
[3] M. A. Zolfigol, A. Khazaei, A. R. Moosavi‐Zare, A. Zare, Org.
Prep. Proced. Int. 2010, 42, 95.
1
3373, 3311, 3022, 2877, 2192, 1649, 1611 cm−1, H NMR
(400 MHz, DMSO‐d6): δppm 1.76 (s, 3H, H—C18), 4.78 (s,
1H, H—C11), 6.9 (s, 2H, —NH2), 7.2 (d, 1H, J = 8 Hz, H
—C4), 7.4 (d, 1H, J = 8 Hz, H—C7), 7.7 (dd, 2H,
J = 8 Hz and J = 8 Hz, H—C5,6), 7.8 (m, 3H, J = 12 Hz,
H—C2,9,10), 12.1 (s, 1H, —NH); 13C NMR (100 MHz,
DMSO‐d6): δppm 10.1 (C18), 36.9 (C11), 57.5 (C16), 97.8
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