Green Synthesis of Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] Using Nano-silica Supported 1,4-Diazabicyclo[2.2.2]octane as a Novel Catalyst

Full text of DOI:10.1080/00304948.2018.1537748

Organic Preparations and Procedures International
The New Journal for Organic Synthesis
ISSN: 0030-4948 (Print) 1945-5453 (Online) Journal homepage: https://www.tandfonline.com/loi/uopp20
Green Synthesis of Pyrano[2,3-c]pyrazoles and
Spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles]
Using Nano-silica Supported 1,4-
Diazabicyclo[2.2.2]octane as a Novel Catalyst
Naeimeh Salehi & Bi Bi Fatemeh Mirjalili
To cite this article: Naeimeh Salehi & Bi Bi Fatemeh Mirjalili (2018) Green Synthesis of
Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,4′-pyrano[2,3-c]pyrazoles] Using Nano-silica
Supported 1,4-Diazabicyclo[2.2.2]octane as a Novel Catalyst, Organic Preparations and
Procedures International, 50:6, 578-587, DOI: 10.1080/00304948.2018.1537748
To link to this article: https://doi.org/10.1080/00304948.2018.1537748
Published online: 08 Feb 2019.
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Organic Preparations and Procedures International, 50:578–587, 2018
# 2018 Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2018.1537748
OPPI BRIEF
Green Synthesis of Pyrano[2,3-c]pyrazoles and
Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles] Using
Nano-silica Supported 1,4-
Diazabicyclo[2.2.2]octane as a Novel Catalyst
Naeimeh Salehi and Bi Bi Fatemeh Mirjalili
Department of Chemistry, College of Science, Yazd University, P.O. Box
89195-741, Yazd, Iran
Multi-component reactions (MCRs) play an essential role in developing molecular
design and combinatorial chemistry due to their pot-, atom- and step-economy
(PASE).1 Combining synthetic potentialities of MCRs and principles of green chemistry
can provide efficient ways to develop new eco-compatible methodologies.
Pyrano[2,3-c]pyrazoles have attracted considerable interest in organic synthesis
because of their wide application in medicinal and pharmaceutical chemistry.2 Many of
these moieties are known for their antimicrobial,3 anti-inflammatory,4 anticancer,5 mol-
luscicidal6 and kinase inhibitory7 activities. In addition, spirooxindoles are unique core
structures found in pharmaceuticals8 and natural products such as Spirotryprostatin (A
& B), Pteropodine, Marcfortine B and Glesemine.9 Furthermore, it has been reported
that the spiro-carbon atom in position 3 of 2-oxoindoles considerably enhances bio-
logical activity.10 Considering the biological significance of these structural motifs,
many efforts have been undertaken to develop their synthetic methods, from multi-step
reactions11–14 to one-pot 4-component reactions.15–34 All the reported methods have
their own merits along with some disadvantages.
1,4-Diazabicyclo[2.2.2]octane (DABCO) has been widely applied as a convenient,
inexpensive and environmentally benign base catalyst for different kinds of organic
reactions such as the Baylis-Hillman reaction,35 Henry reaction,36 [2 þ 2] cycloaddition
reactions,37 sp3 C-H activation reactions,38 synthesis of fused imidazo-heterocycles39
and synthesis of dihydropyrano[3,2-c]chromenes.40 Nevertheless, in many of these
cases, the catalytic system has not been recycled, and DABCO has been eliminated as a
residue. Therefore, replacement of DABCO with a corresponding retrievable solid-sup-
ported alternative is in demand.
Received November 24, 2017; in final form August 7, 2018.
Address correspondence to Bi Bi Fatemeh Mirjalili, Department of Chemistry, College of
Science, Yazd University, P.O. Box 89195-741, Yazd, Iran. E-mail: fmirjalili@yazd.ac.ir
Color versions of one or more figures in this article can be found online at www.tandfonline.
com/uopp.
578

Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles]
579
In continuation of our research in the area of green chemistry, particularly in develop-
ing solid-supported catalysts,41 we describe here a convenient procedure to prepare dihydro-
pyrano [2,3-c]pyrazoles (5a-p) and spiro[indoline-3,40-pyrano[2,3-c]pyrazole] (7a-g)
derivatives. We use a one-pot four-component reaction with nano-silica supported DABCO
(nano-SiO2/DABCO) as a reusable and efficient heterogeneous catalyst (Scheme 1).
Scheme 1. Synthesis of compounds (5a-p) and (7a-g) using nano-SiO2/DABCO as a catalyst.
Nano-SiO2/DABCO was prepared as a new basic catalyst in two steps. Initially, a
mixture of commercial nano silica gel and thionyl chloride was put under reflux condi-
tions for 48 h to produce nano silica chloride by replacement of the OH functional
groups of silica gel with Cl atoms. In the next step, the dried silica-chloride reacted
with DABCO in EtOH at reflux temperature. The chlorine atoms of the silica-chloride
were substituted with the N-nucleophiles in DABCO (Scheme 2). The characterization
of the nano-SiO2/DABCO structure was performed by FT-IR, field emission scanning
electron microscopy (FESEM), transmission electron microscopey (TEM), energy-dis-
persive X-ray spectroscopy (EDX), thermo gravimetric analysis/differential thermal
analysis (TGA/DTA), X-ray diffraction (XRD), brunauer-emmett-teller (BET) analysis
and elemental analysis.
Scheme 2. Preparation of nano-SiO2/DABCO.
The elemental composition of nano-SiO2/DABCO was analyzed by EDX. The ele-
ments C, N, O, Si and Cl were found in the catalyst. Quantitative elemental analysis of
the catalyst shows C, 13.11%; H, 3.17%; N, 4.38%; which suggests the loading of
DABCO on silica gel.
The catalytic activity of nano-SiO2/DABCO was investigated for the synthesis of
different derivatives (5a-p) and (7a-g) by means of a one-pot four-component reaction.
For initial optimization studies, the reaction among 4-chlorobenzaldehyde, hydrazine
hydrate, ethyl acetoacetate and malononitrile in the molar ratio 1:1.5:1:1 in the presence
of nano-SiO2/DABCO was selected as a model and conducted under different condi-
tions (Table 1). The best result was obtained using a solvent-free grinding technique at
room temperature with 0.05 g of catalyst (Table 1, entry 11). A similar reaction was
studied in the absence of catalyst (Table 1, entry 9), and results suggested the useful
performance of the catalyst in this reaction.

580
Mirjalili and Salehi
Table 1
Synthesis of 6-amino-4-(4-chlorophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-
carbonitrile under various conditions.a
Entry
Solvent
Conditions
Catalystb (g) Time (min) Yieldc (%)
1
2
3
4
5
6
7
8
H2O
EtOH
H2O:EtOH (1:1)
r.t.
r.t.
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
–
30
30
30
30
30
30
30
30
8
55
50
79
88
80
89
88
93
29
90
93
91
r.t.
H2O
EtOH
65 ꢀC
65 ꢀC
–
–
–
–
–
-
65 ꢀC
90 ꢀC
r.t./grinding
r.t./grinding
r.t./grinding
r.t./grinding
r.t./grinding
9
10
11
12
0.03
0.05
0.07
8
8
8
–
aReaction conditions: hydrazine (1.5 mmol), ethyl acetoacetate (1 mmol), 4-chlorobenzaldehyde
(1 mmol) and malononitrile (1 mmol).
bNano-SiO2/DABCO.
cIsolated yields.
After optimizing the reaction conditions, the generality was examined using alde-
hydes, including heteroaryl aldehydes and arylaldehydes possessing electron-releasing
and electron-withdrawing substituents, with malononitrile, hydrazine hydrate and ethyl
acetoacetate (Table 2). Reaction times were quite short, and yields were uniformly high
(mean 88%).
The useful catalytic efficiency of nano-SiO2/DABCO in the synthesis of pyr-
ano[2,3-c]pyrazoles prompted us to investigate their efficacy for the synthesis of com-
pounds (7a-g) (Table 3). The desired products (7a–g) were again obtained in high
yields (mean 91%).
Scheme 3 presents a plausible mechanism for the synthesis of compounds (5a-p)
using our catalyst. First, the condensation of hydrazine hydrate and diethyl acetoacetate
affords pyrazolone A that is converted to anion B in the presence of nano-SiO2/
DABCO. The Knoevenagal reaction between the aldehyde and malononitrile in the
presence of the basic catalyst forms the intermediate C. The Michael addition between
B and C, followed by cyclization and tautomerization gives the final product 5.
In order to investigate the reusability of the catalyst, after completion of the reaction,
the nano-SiO2/DABCO was isolated by adding ethanol to reaction mixture and then filter-
ing. The recovered catalyst was washed with hot EtOH and then acetone, followed by dry-
ing at room temperature. It was observed that the recovered nanocatalyst could be used at
least five times with only a slight decrease in its catalytic activity (Figure 1).

Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles]
581
Table 2
Synthesis of compounds (5a-p) in the presence of nano-SiO2/DABCOa
M.P. (ꢀC)
Time Yieldb
Entry
Aldehyde
Benzaldehyde
2-Methoxybenzaldehyde
3-Nitrobenzaldehyde
3-Bromobenzaldehyde
4-Methylbenzaldehyde
4-Hydroxybenzaldehyde
4-Nitrobenzaldehyde
4-fluorobenzaldehyde
4-Chlorobenzaldehyde
4-Bromobenzaldehyde
2,4-Dichlorobenzaldehyde
3,4-Dihydroxybenzaldehyde
Product (min) (%) Foundc ReportedLit
1
2
3
4
5
6
7
8
5a
5b
5c
5d
5e
5f
5g
5h
5i
12
10
10
15
15
10
8
91 242-244 241-24314
80 226-228 220-22217
89 210-211 212-21417
83 223-224 221-22315
87 204-206 204-20515
94 222-224 220–22115
92 242-244 242-24417
95 212-214 216-21817
93 230-231 226-22814
91 178-180 179-18017
85 223-225 222-22315
94 225-227 221-22448
93 234-236 233-23515
8
8
9
10
11
12
13
14
15
16
5j
5k
5l
10
20
8
10
30
20
25
3-Methoxy-4-hydroxybenzaldehyde 5m
Pyrrole-2-carbaldehyde
Furan-2-carbaldehyde
1-Naphthaldehyde
5n
5o
5p
83 212-213
–
84 228-230 234-23550
83 206-208 200-20216
aReaction conditions:1 (1 mmol), 2 (1 mmol), 3 (1 mmol) and 4 (1.5 mmol), under grinding and
solvent-free conditions at room temperature.
bIsolated yields.
cRecrystallized form.
Finally, the catalytic performance of nano-SiO2/DABCO was compared with that
of other previously reported catalysts for the synthesis of 5a and 7a (Table 4). From the
viewpoints of green chemistry and simplicity, our method is among the best.
In summary, nano-SiO2/DABCO was found to be a useful heterogeneous catalyst
for synthesis of dihydropyrano[2,3-c]pyrazoles and spiro[indoline-3,40-pyrano[2,3-
c]pyrazoles] employing a multicomponent-grinding strategy. Simplicity, easy work-up,
high yields, short reaction times, ease of recovery of the catalyst and green nature of
this protocol make it appealing.
Experimental Section
All compounds were purchased from Merck and Fluka Chemical Company and used
without any additional purification. The hydrazine hydrate was reagent grade, contain-
ing 50-60% hydrazine. FT-IR spectra were run on a Bruker, Eqinox 55 spectrometer.
Thin-layer chromatography (TLC) was done on silica gel 60 F254 plates (Merck). A
1
Bruker (DRX-400 Avance) NMR was used to record the H-NMR spectra. FESEM was
obtained on a Mira 3-XMU, and TEM photographs were prepared on a Leo 912AB
OMEGA instrument. EDS was recorded using a Phenom pro X instrument and TGA

582
Mirjalili and Salehi
Table 3
Synthesis of compounds (7a-g) in the presence of nano-SiO2/DABCOa
M.P. (ꢀC)
Foundc ReportedLit
R2
(3a)
R3
(3b)
Time Yieldb
Product (min) (%)
Entry
R1
1
2
3
4
5
6
7
H
H
H
CH3
–
7a
7b
7c
7d
7e
7f
10
10
10
35
30
15
10
94
93
93
87
88
93
92
284-285 284-28643
268-270 273-27445
274-276 268-27043
230-232 227-22943
268-270 270-27243
274-276 281-28450
260-262 257-25849
C2H5
C3H7
CH3
–
–
C6H5
4-OMeC6H4 CH3
–
–
H
H
–
CO2C2H5
CO2CH3
–
7g
aReaction conditions: 2 (1.5 mmol), 3 (1 mmol), 4 (1 mmol) and 6 (1 mmol), under grinding and
solvent-free conditions at room temperature.
bIsolated yields.
cRecrystallized form.
Scheme 3. Plausible mechanism for the synthesis of compounds (5a-p) in the presence of nano-
SiO2/DABCO.

Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles]
583
Figure 1. Catalyst recycling experiments.
was conducted with an STA 504 instrument. The XRD pattern was obtained on a
Philips Xpert MPD diffractometer (Cu Ka, radiation, k¼ 0.154056 nm). BET surface
area analysis of catalyst was conducted with Micromeritics, Tristar II 3020 analyzer.
Melting points were determined by a Buchi B-540 B.V.CHI apparatus, and were uncor-
1
rected. The products were characterized by FT-IR, H-NMR, 13CNMR, and a compari-
son of their physical properties with those reported in the literature was performed.
Elemental analysis (C, H, N) was conducted using a Vario EL analyzer. Data for com-
plete characterization of the catalyst are available from the corresponding author upon
request. The data were submitted for review by the editor and reviewers.
Preparation of Silica Chloride
In a round bottomed flask (250 mL) equipped with a condenser, nano silicagel (10 g) and thi-
onyl chloride (40 mL) were charged and refluxed for 48 h. After cooling the reaction mix-
ture, it was filtered through a Buchner funnel, and the residue was washed thoroughly with
dichloromethane. The resulting silica chloride was dried in the air at room temperature.
Safety Notes: The use of thionyl chloride requires a well-ventilated hood, eye pro-
tection and gloves. All workers should be thoroughly drained on the use of this reagent
prior to doing an experiment.
Preparation of Nano-SiO2/DABCO
Silica chloride (1 g), DABCO (1 g) and EtOH (20 mL) were charged in a round bot-
tomed flask (100 mL) equipped with a condenser and refluxed for 15 h. The reaction
mixture was cooled, filtered and washed with EtOH to obtain nano-SiO2/DABCO. The
resulted catalyst was dried at room temperature and stored under ambient conditions.
General Procedure for Synthesis of Pyrano[2,3-c]pyrazole and Spiro[indoline-3,40-
pyrano[2,3-c] pyrazole] Derivatives
In a mortar, a mixture of b-keto ester or dialkyl acetylenedicarboxylate (1 mmol) and
hydrazine hydrate 50-60% (0.1 ml) was ground with a pestle at room temperature for

584
Mirjalili and Salehi
Table 4
Catalytic performances of nano-SiO2/DABCO versus some other catalysts for synthesis
of 5a and 7aa
Catalyst
Entry (g/ml/ mol%/mmol)
Time
Yieldb
(%)Ref
Solvent
Product Conditions (min)
1
2
3
4
I2 (5 mol%)
H2O
H2O
EtOH
5a
5a
5a
5a
r.t.
r.t.
10
5–10
15
9012
8942
7220
9451
piperidine (5 mol%)
Et3N (20 mol%)
Fe3O4@SiO2 (0.2 g)
reflux
EtOH/H2O
(1:1)
EtOH/H2O
(9:1)
70 ꢀC
25
5
6
BSA (0.05 g)
5a
5a
45 ꢀC
80 ꢀC
45
10
9515
9252
isonicotinic acid
(10 mol%)
[Dsim]AlCl4 (7 mol%)
ChCl–Urea DES
(1 ml)
–
7
8
–
–
5a
5a
80 ꢀC
80 ꢀC
1
15
9218
8619
9
10
11
DES (5 ml)
–
5a
5a
5a
80 ꢀC
100 ꢀC
r.t.
20
4
8
8953
[cmpy]I (10 mol%)
nano-SiO2/DABCO
(0.05 g)
4-DMAP (0.1 mmol)
Magnetic-Guanidine
(0.03g)
Carbon-SO3H
Fe3O4@SiO2–NH2
(0.035 g)
piperdine (20 mol %)
b-cyclodextrin
(0.2 mmol)
–
9417
this work
- (grinding)
93
12
13
EtOH
EtOH
7a
7a
60 ꢀC
reflux
60
25
8044
9348
14
15
EtOH
EtOH
7a
7a
80 ꢀC
60 ꢀC
300
20
9045
9446
16
17
EtOH
EtOH/H2O
(1:9)
7a
7a
US
60
15
9243
9047
80 ꢀC
this work
18
nano-SiO2/DABCO
(0.05 g)
- (grinding)
7a
r.t.
10 94
aBSA: Bovine serum albumin, [Dsim]AlCl4: Disulfonic acid imidazolium chloroaluminate,
ChCl–Urea DES: Choline Chloride/Urea Deep Eutectic Solvent, [cmpy]I: 1-(carboxymethyl)pyri-
dinium iodide, 4-DMAP: 4-Dimethylaminopyridine.
bIsolated yields.
1 min. Then, the aldehyde or isatin (1 mmol), malononitrile (1 mmol) and nano-SiO2/
DABCO (0.05 g) were added to the reaction mixture and it was ground continuously at
room temperature for the times shown in Table 2. After completion of reaction (as indi-
cated by TLC, ethyl acetate: n-hexane, 20:80), the mixture was dissolved in EtOH.
Then, the catalyst was filtered off and the obtained solution was poured into cold water.
The obtained solid product was filtered and purified by re-crystallization from EtOH
and water. The structures of the compounds were confirmed by physical and spectro-
1
scopic data: m.p., FT-IR, H NMR, 13C NMR and elemental analysis. Safety Note: The
use of hydrazine requires a hood and personal protection gear including gloves and
eye protection.

Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles]
585
Typical Procedure for Preparation of 6-Amino-3-methyl-4-(1H-pyrrol-2-yl)-1,4-
dihydropyrano[2,3-c]pyrazole-5-carbonitrile (5n)
A mixture of ethyl acetoacetate (1 mmol, 0.13 mL) and hydrazine hydrate 50-60%
(0.1 mL) was ground at room temperature for 1 minute in a mortar. Then, pyrrol-2-car-
baldehyde (1 mmol, 0.095 g), malononitrile (1 mmol, 0.066 g) and nano-SiO2/DABCO
(0.05 g) were added to the reaction mixture. The obtained mixture was ground continu-
ously at room temperature for 30 minutes. After completion of the reaction (as indicated
by TLC), the mixture was dissolved in EtOH, filtered off and poured into cold water.
The solid product was filtered and re-crystallized in EtOH and water: Brown solid, m.p.
212-213 ꢀC. FT-IR (ATR) ꢀ (cmꢁ1): 3360, 3308, 3171, 2187, 1637, 1591, 1490, 1403,
1
1028, 744. H NMR (400 MHz, DMSO-d6)/d ppm: 12.04 (s, NH, 1H), 10.52 (s, NH,
1H), 6.78 (s, NH, 2H), 6.57 (d, J ¼ 1.6, 1H), 5.88-5.90 (m, 1H), 5.85 (br s, 1H), 4.64
(s, 1H), 1.84 (s, 3H). 13C NMR (100 MHz, DMSO-d6,)/d ppm: 161.24, 155.16, 136.16,
133.98, 121.44, 117.61, 107.26, 105.62, 97.39, 57.03, 30.02, 9.98.
Anal. Calcd for C12H11N5O: C, 59.74; H, 4.60; N, 29.03. Found: C, 59.53; H, 4.32;
N, 29.25.
Acknowledgment
The Research Council of Yazd University is gratefully acknowledged for the financial
support for this work.
References
1. A. Domling, W. Wang and K. Wang, Chem. Rev., 112, 3083 (2012).
2. D. Das, R. Banerjee and A. Mitra, J. Chem. Pharmaceut. Res., 6, 108 (2014).
3. A.H. Mandour, E.R. El-Sawy, M.S. Ebaid and S.M. Hassan, Acta Pharm., 62, 15 (2012).
4. M.E.A. Zaki, H.A. Soliman, O.A. Hiekal and A.E. Rashad, Z. Naturforsch., C 61, 1 (2006).
5. Nadia R. Mohamed, Nahed Y. Khaireldin, Amin F. Fahmy and A.A. El-Sayed, Der Pharma
Chem., 2, 400 (2010).
6. F.M. Abdelrazek, P. Metz, N.H. Metwally, and S.F. El-Mahrouky, Arch. Pharm.
(Weinheim), 339, 456 (2006).
7. N. Foloppe, L.M. Fisher, R. Howes, A. Potter, A.G. Robertson and A.E. Surgenor, Bioorg.
Med. Chem., 14, 4792 (2006).
8. A. Dandia, R. Singh, S. Khaturia, C. Merienne, G. Morgant and A. Loupy, Bioorg. Med.
Chem., 14, 2409 (2006).
9. T.-H. Kang, K. Matsumoto, M. Tohda, Y. Murakami, H. Takayama, M. Kitajima, N. Aimi
and H. Watanabe, Eur. J. Pharmacol., 444, 39 (2002).
10. A.H. Abdel-Rahman, E.M. Keshk, M.A. Hanna and M. Bady Sh, Bioorg. Med. Chem., 12,
2483 (2004).
11. H. Junek and H. Aigner, Chem. Ber., 106, 914 (1973).
12. S. Muramulla and C.-G. Zhao, Tetrahedron Lett., 52, 3905 (2011).

586
Mirjalili and Salehi
13. N.J. Parmar, H.A. Barad, B.R. Pansuriya and N.P. Talpada, RSC Adv., 3, 8064 (2013).
14. R.S. Aliabadi and N.O. Mahmoodi, RSC Adv., 6, 85877 (2016).
15. X. Huang, Z. Li, D. Wang and Y. Li, Chin. J. Catal., 37, 1461 (2016).
16. H. Mecadon, M.R. Rohman, M. Rajbangshi and B. Myrboh, Tetrahedron Lett., 52, 2523
(2011).
17. A.R. Moosavi-Zare, M.A. Zolfigol, R. Salehi-Moratab and E. Noroozizadeh, J. Mol. Catal.
A Chem., 415, 144 (2016).
18. A.R. Moosavi-Zare, M.A. Zolfigol, E. Noroozizadeh, M. Tavasoli, V. Khakyzadeh and A.
Zare, New J. Chem., 37, 4089 (2013).
19. A. Moshtaghi Zonouz and D. Moghani, Synth. Commun., 46, 220 (2015).
20. Y.M. Litvinov, A.A. Shestopalov, L.A. Rodinovskaya and A.M. Shestopalov, J. Comb.
Chem., 11, 914 (2009).
21. R.H.Vekariya, K.D. Patel, H.D. Patel, Indian J. Chem. 57B, 576 (2018).
22. H. Kiani, H.A. Samimi, F. Ghorbani, S. Esmaieli, Curr. Chem. Lett. 2, 197 (2013).
23. A. I. Ilovaisky, M.G. Medvedev, V.M. Merkulova, M.N. Elison, G.I. Nikishin, J. Heterocycl.
Chem. 51, 523 (2014).
24. A.A. Hamid, M. Abd-Elmonem, A. M. Hayallah, F.A. Abo Elsoud, K.U. Sadek, Chemistry
Select. 2, 10689 (2017).
25. R.Y. Guo, Z-M. An, L-P. Mo, S-T. Yang, H-X. Liu, S-X. Wang, Z-H. Zhang, Tetrahedron,
69, 9931 (2013).
26. M. Fatahpour, F. Noori Sadeh, N. Hazeri, M. T. Maghsoodlou, M. Lashkari, J. Iran. Chem.
Soc. 14, 1945 (2017).
27. D. Survase, B. Bandgar, V. Helavi, Synth. Commun. 47, 680 (2017).
28. R.H. Vekariya, K.D. Patel, H.D. Patel, Res. Chem. Inter. 42, 4683 (2016).
29. R.H. Vekariya, K.D. Patel, H.D. Patel, Res. Chem. Inter. 42, 7559 (2016).
30. K.G. Patel, N.M. Misra, r.h. Vekariya, R.R. Shettigar, Res. Chem. Inter. 44, 289 (2018).
31. H.K. Munira, T. Muhamma, J.J.A. Khan, S.S. Rasheed, A. Khan, S. Perveen, K. Javaid, A.
Wahab, K.M. Khan, M.I. Choudhary, Bioorgan. Chem. 65, 61 (2016).
32. F. Rigi, H. R. Shaterian, Polycycl. Arom. Comp. 37, 314 (2017).
33. B. Myrboh, H. Mecadon, M. R. Rohman, M. Rajbangshi, I. Kharkongor, B. M. Laloo, I.
Kharbangar, B. Kshiar, Org. Prep. Proced. Int. 45, 253 (2013).
34. M. A. Chaudhari, J. B. Gujar, D. S. Kawade, N. R. Jogdand, M. S. Shingare, Cogent Chem.
1, 1063830 (2015).
35. J.-F. Pan and K. Chen, Tetrahedron Lett., 45, 2541 (2004).
36. H.M. Meshram, P. Ramesh, A. Sanjeeva Kumar and A. Swetha, Tetrahedron Lett., 52, 5862
(2011).
37. T. Wang, X.-Y. Chen, and S. Ye, Tetrahedron Lett., 52, 5488 (2011).
38. X.-L. Liu, D.-H. Jing, Z. Yao, W.-H. Zhang, X.-W. Liu, Z.-J. Yang, Z. Zhao, Y. Zhou and
X.-N. Li, Tetrahedron Lett., 56, 5637 (2015).

Pyrano[2,3-c]pyrazoles and Spiro[indoline-3,40-pyrano[2,3-c]pyrazoles]
587
39. V.M. Bangade, B.C. Reddy, P.B. Thakur, B. Madhu Babu and H.M. Meshram, Tetrahedron
Lett., 54, 4767 (2013).
40. S. Vodnala, A.K. Bhavani, R. Kamutam, V.G. Naidu, Promila and C. Prabhakar, Bioorg.
Med. Chem. Lett., 26, 3973 (2016).
41. N. Salehi and B.B. Fatameh Mirjalili, RSC Adv., 7, 30303 (2017).
42. G. Vasuki and K. Kumaravel, Tetrahedron Lett., 49, 5636 (2008).
43. Y. Zou, Y. Hu, H. Liu and D. Shi, ACS Comb. Sci., 14, 38 (2012).
44. J. Feng, K. Ablajan and A. Sali, Tetrahedron, 70, 484 (2014).
45. B. Maheshwar Rao, G.N. Reddy, T.V. Reddy, B.L.A.P. Devi, R.B.N. Prasad, J.S. Yadav and
B.V.S. Reddy, Tetrahedron Lett., 54, 2466 (2013).
46. F. Alemi-Tameh, J. Safaei-Ghomi, M. Mahmoudi-Hashemi and M. Monajjemi, Polycycl.
Aromat. Compd., 1 (2016).
47. Y.A. Tayade, S.A. Padvi, Y.B. Wagh and D.S. Dalal, Tetrahedron Lett., 56, 2441 (2015).
48. F.A. Tameh, J. Safaei-Ghomi, M. Mahmoudi-Hashemi and H. Shahbazi-Alavi, RSC Adv., 6,
74802 (2016).
49. G. Brahmachari and B. Banerjee, Asian J. Org. Chem., 5, 271 (2016).
50. D.M. Pore, P.B. Patil, D.S. Gaikwad, P.G. Hegade, J.D. Patil and K.A. Undale, Tetrahedron
Lett., 54, 5876 (2013).
51. E. Soleimani, M. Jafarzadeh, P. Norouzi, J. Dayou, C.S. Sipaut, R.F. Mansa and P. Saei, J.
Chin. Chem. Soc., 62, 1155 (2015).
52. M.A. Zolfigol, M. Tavasoli, A.R. Moosavi-Zare, P. Moosavi, H.G. Kruger, M. Shiri and V.
Khakyzadeh, RSC Adv., 3, 25681 (2013).
53. M.R. Bhosle, L.D. Khillare, S.T. Dhumal and R.A. Mane, Chin. Chem. Lett., 27, 370 (2016).