Visible-light-induced radical cascade cyclization of pyrazoles bearing a coumarin unit

Article abstract of DOI:10.1039/d0nj02714f

Herein, we have described an efficient, eco-friendly, metal free, visible light catalysed synthesis of coumarin based pyrazoles under an open atmosphere involving a photoredox catalyst, which is an inexpensive organic dye. The present strategy is the firs

Full text of DOI:10.1039/d0nj02714f

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DOI: 10.1039/D0NJ02714F
Visible-Light-Induced Radical Cascade Cyclization of Pyrazoles
bearing a coumarin unit
Amit Kumar Sharma,a Anjali Jaiswal,a Anu Mishra,a Jyoti Tiwari,a Deepali Jaiswal,a Shailesh
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Singh,a Jaya Singhb and Jagdamba Singha*
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aEnvironmentally Benign Synthesis Lab, Department of Chemistry, University of Allahabad, Allahabad-211002
(India); Tel: +919415218507; E-mail: dr.jdsau@gmail.com
bDepartment of Chemistry, LRPG College, Sahibabad, Ghaziabad-201005 (India)
Abstract
Herein, we have described an efficient, eco-friendly, metal free, visible light catalysed
synthesis of coumarin based pyrazoles under an open atmosphere condition involving a
photoredox catalyst, which is an inexpensive organic dye. The present strategy is the first
example of visible light promoted, aerobic, oxidative cyclization of pyrazoles bearing a
coumarin unit via the formation of C–C, C–O and C-N bonds to afford excellent yield of the
products in a simple one-pot operation under mild reaction conditions. The major advantages
of the present methodology include short reaction time, cost effectiveness, easy work-up, broad
substrate scope and high atom economy.
Keywords: Visible Light, Photoredox Catalysis, Multicomponent, Pyrazoles bearing a
coumarin unit.
Introduction
In the last few era, visible-light-mediated photoredox catalysis,1-3 for single electron transfer
(SET) has been arisen as a substitute, versatile, economical and green implement for imperative
organic transformations such as oxidation/reduction, C-C/ C-X bond formation in the
heterocyclic compounds.4-6 Organo-photoredox catalyst has an unique characteristic as it can
stimulate atmospheric oxygen, a green and natural oxidizing agent, in presence of visible-light
for organic transformations involving SET.7,8 In contrast, the transition metal based
photocatalysts such as iridium, ruthenium and polypyridyl complexes have been associated
with many drawbacks such as being highly expensive, low sustainability, low toughness,
potential toxicity and being problematic during separation.9-11 Metal-free organic dye,
primarily Eosin Y has been utilized as it is an economically and environmentally better option
than metal-based photo-redox catalyst.12,13 The photochemistry of Eosin Y has been very much

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analyzed upon excitation by visible light and it has been shown that Eosin Y experiDeOnIc: 1e0s.10q3u9/iDc0kNJ02714F
intersystem crossing to the lowest energy triplet state.14,15
6
Now a days, multicomponent reactions (MCRs) are turning out to be an influential and
competent strategies for the development of heterocycles in modern organic and medicinal
chemistry since they permit multistep synthesis to be led in a single procedural step to give
novel and highly functionalized biologically active heterocyclic compound from conveniently
available starting materials. Multicomponent reactions (MCRs) have been linked to remarkable
synthetic efficiency, reduce the generation of chemical waste, Easy purification and high atom
economy.16-18
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Pyrazole nucleus is a well-recognized to be an essential core of numerous agrochemicals and
pharmaceuticals. They demonstrate wide spectrum of biological activities for example,
antitubercular,19 anti-hyperglycemic,20 antioxidant,21 Pharmacological Activities,22 kinase
inhibitors,23 anti-AIDS,24 anti-anxiety,25 corrosion inhibition,26 insecticidal agents,27 and
Antimicrobial.28 Coumarin also constitute another essential nucleus frequently occurring in
various natural products, pharmaceuticals, agrochemicals, dyes and functional materials.29-32
Due to the significance of these two auxiliary structures, the development of a basic
methodology for the synthesis of the target compound containing both the pyrazole and
coumarin nucleus by utilizing biodegradable material as a catalyst and green solvent is still
desirable and challenging task (Figure 1).33,34

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DOI: 10.1039/D0NJ02714F
O
O
N
Cl
N
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Ulcerogenic activity 35
O
O
N
O
O
N
OMe
OH
O
O
N
N
HN
N
Anti-inflammatory activity 35
Antibacterial activity 36
O
O
N
OMe
N
Antioxidant activity 35
Figure 1. Examples of some biologically active pyrazoles bearing a coumarin unit
Previous Work
O
OH
O
Various Catalyst and
Solvent, High Temp
R1
R2
O
O
N
R1
R2
H
R3NHNH2
OH
O
Meglumine
EtOH-H2O reflux 37
N
R3
Piperidine
reflux 38
This Work
O
OH
R1
R2
O
O
N
R1
H
Eosin-Y
CH3CN
Visible Light, O2
R3NHNH2
R2
OH
O
2
O
3a-d
1a-f
4a-l
N
R3

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DOI: 10.1039/D0NJ02714F
Scheme 1. Comparison of proposed protocol with previously reported methods
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Evidently this moiety has never been synthesized via visible-light pathway initiated by
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photoredox catalyst. Therefore, visible light was chosen as an efficient promoter for the
synthesis of coumarin containing pyrazoles using Eosin-Y as a photoredox catalyst at room
temperature (Scheme 1). This new approach for the synthesis of coumarin based pyrazole and
its derivatives is mechanistically attractive because it involves through visible light photoredox
catalysis.
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Results and discussion
In order to check the credibility of our proposed protocol, we instigated our study by utilizing
4-Nitrosalicylaldehyde (1a), 1,4-hydroxy-6-methyl-2H-pyran-2-one (2) and phenylhydrazine
(3a) as model substrates for the synthesis of target compound. We commenced with the
optimisation of the reaction conditions by using varied catalyst (Table 1). To begin with,
reaction is carried out in the absence of photocatalyst at room temperature under CFL (23W)
irradiation, product could not be obtained even after 24 h of irradiation (Table 1, entry 1).
Subsequently, we performed our reaction in the presence of photocatalysts. We used Eosin Y
(2 mol%) as a catalyst which afforded 84 % yield of the product within 24 h (Table 1, entry 4).
A series of other organic photocatalysts such as Methylene Blue, Rose-Bengal and Rhodamine-
B, and (Table 1, entries 6−8) were explored. Although, Rhodamine-B gave good yield but
amongst all the catalysts screened, Eosin Y was outstanding. In the case of methylene blue, no
product was formed and Rose-Bengal gives trace in yield. Decreasing the amount of Eosin Y
had a significant effect on the yield of the product, whereas increasing the amount of Eosin Y
did not affect the yield of product (Table 1, entries 3 and 5). Repeated experiments led to the
conclusion that organic dye and visible light are obligatory components for this novel
transformation (Table 1, entries 1 and 2).
Table 1. Optimization of organic photoredox catalystsa
O
OH
O
O
N
H
CH3CN
Ph-NHNH2
O2N
Visible Light, O2
O2N
OH
O
2
O
3a
4a
N
1a
Ph

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Entry
Photocatalyst (mol %)
Time (hour)
Yield (%)bDOI: 10.1039/D0NJ02714F
Nonec
24
24
24
24
24
24
24
24
NRd
NRd
64
5
6
7
8
1
2
3
4
5
6
7
8
Eosin Y (2)e
Eosin Y (1)
Eosin Y (2)
Eosin Y (4)
Methylene Blue
Rose Bengal
Rhodamine B
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84
84
NRd
Trace
75
a Reaction conditions: 1a (1.0 mmol), 2 (1.0 mmol), 3a (1.0 mmol), CH3CN (3 mL), 23W CFL irradiation under
an open atmosphere at room temperature; b Isolated yield of product; Without catalyst; d NR = no reaction;
c
e
Without irradiation.
Encouraged by favourable results, we performed our model reaction with different intensities
of light source (CFL 18W, 23W, 27W, Green LED, blue LED and white LED) (Table 2, entries
1-6) and observed that CFL (23W) is the ideal source of visible light for the present protocol
(Table 2, entry 2). Moreover, the reaction was quenched with 2,2,6,6-tetramethylpiperidyl-1-
oxyl (TEMPO) (2.0 mmol), clearly indicate that reaction proceed through a free radical
pathway (Table 2, entry 9).39, 40
Table 2. Optimization of visible-light sourcea
O
OH
O
O
N
H
Eosin-Y
CH3CN
Ph-NHNH2
O2N
O2N
OH
O
2
O
3a
4a
N
1a
Ph
Entry
Visible - light source
CFL (18 W)
Time (h)
Yield (%)b
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2
3
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8
24
24
24
36
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24
24
70
CFL (23 W)
84
CFL (27 W)
84
Green LED (2.5W)
Blue LED (6W)
White LED (9W)
CFL (23 W) TEMPO
Daylight
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15
10
NRc, d
NRd

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9
Dark
24
24
NRd
10
Nitrogen atm
NRd
a Reaction conditions: 1a (1.0 mmol), 2 (1.0 mmol), 3a (1.0 mmol), CH3CN (3 mL), in different light source under
an open atmosphere at room temperature; b Isolated yield of product; c Reaction was quenched with TEMPO
(2,2,6,6-Tetramethyl-piperidin-1-yl)oxyl) (2.0 equiv.); d NR = no reaction.
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After the finalization of the best photocatalyst and light source, we next screened different
solvent to further optimize the reaction conditions (Table 3). Firstly, we used 2 mL of
tetrahydrofuran (THF) or in 2 ml of dimethyl sulfoxide (DMSO), separately and the reaction
mixture was irradiated under compact florescent lamp (CFL) with 2 mol% Eosin Y for 24 h in
an open pot at room temperature. The expected product could not be detected and the substrate
was recovered completely unreacted (Table 3, entries 1 and 2). Next, we carried the reaction
in various solvents and neat condition (Table 3, entries 3-8) and observed that the acetonitrile
has been found to be most impressive, convenient and efficient for the desired transformation.
Table 3. Optimization of solvents.a
O
OH
O
O
N
H
Eosin-Y
Ph-NHNH2
O2N
Visible Light, O2
O2N
OH
O
2
O
3a
4a
N
1a
Ph
Entry
Solvent
THF
Time (hour)
Yield (%)b
NRc
NRc
84
1
2
3
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8
24
24
24
24
24
24
24
24
DMSO
CH3CN
DMF
NRc
52
DCE
EtOH
40
Toluene
Neat
25
10
a Reaction conditions: 1a (1.0 mmol), 2 (1.0 mmol), 3a (1.0 mmol), in different solvent using 23W CFL irradiation
b
c
under an open atmosphere at room temperature; Isolated yield of product; NR = no reaction. DMF=
DiMethylFormamide, DCE= DiChloroEthane
Under the established reaction conditions, we next explored the substrate scope of the present
strategy. The results of our investigation are listed in (Table 4). Explicitly, salicylaldehyde

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bearing either electron-withdrawing or electron-donating groups (such as -OMe, -OH, -Cl, -Br,
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-NO2) are well tolerated and furnished the target compound and its derivatives afforded
excellent (4a-4f) 92−75% yields.
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Inspired by these results, we next explored the other substrate, arylhydrazine containing
electron-withdrawing and electron-releasing group and observed that all afforded excellent
(4g−4i) 83−73% yields. However, it was established that arylhydrazine containing electron-
releasing group is more efficient product formation.
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Table 4. Substrate scope.a,b
O
OH
R1
R2
O
O
N
R1
R2
H
Eosin-Y
CH3CN
Visible Light, O2
R3NHNH2
OH
O
2
O
3a-d
1a-f
4a-l
N
R3
R1 = H, OH, OMe
12-Molecules
73-92%
R2 = H, Cl, Br, NO2
R3 = Ph, 2-OMe-Ph, 4-Br-Ph, 3,4-(F)2-Ph
O
O
N
MeO
O
O
N
HO
O
O
O2N
N
N
N
N
4a 84%
O
4b 77%
4c 75 %
O
O
O
N
O
O
N
Br
Cl
N
N
N
N
4d 78 %
4e 88%
4f 92%

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O
O
N
O
O
N
O
ODOI: 10.1039/D0NJ02714F
N
N
N
N
F
9
OMe
4g 83 %
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Br
F
4h 74%
O
4i 73%
O
MeO
O
N
O
N
O
O
Cl
Cl
N
N
N
N
F
F
F
OMe
F
4l 80%
4j 87%
4k 76%
a Reaction conditions: 1a-f (1.0 mmol), 2 (1.0 mmol), 3a-d (1.0 mmol), CH3CN (3 mL), 23W CFL irradiation
under an open atmosphere at room temperature; b Isolated yield of product.
Mechanism
Examine by the control experiments and literature reports,41-45 the following plausible
mechanism using the model substrates has been suggested (Figure 2 and 3). The pyrone radical
(5) is generated smoothly by the HAT through light-activated *Eosin Y (I) and pyrone (2).44
Pyrone radical (5) react with salicylaldehyde (1) to produce another radical (6). Now the
reverse hydrogen atom transfer (RHAT) between radical 6 and eosin Y-H (II) regenerates
ground state Eosin Y and intermediate (8). Similarly, in the same way, HAT between light-
activated *Eosin Y (I) and intermediate (8) to produce radical (9). In this step, eosin Y-H
•
undergoes aerial oxidation to regenerate the ground state Eosin Y and forms a HO2 radical,
which further undergoes disproportionation to give oxygen and hydrogen peroxide.46,47 Thus,
formed H2O2 was distinguished by starch and potassium iodide as indicator.48 After that radical
(9) undergoes an intramolecular cyclization by free radical addition of enolate oxygen to
carbonyl group as well as ring opening to afford the compound (10) and then compound (11)
by abstraction of H• radical from water molecule. A homolytic cleavage of compound (11) and
phenyl-hydrazine (3) followed by free radical addition between compound (12) and phenyl-
hydrazine radical (3) gives compound (13). After that compound (13) undergoes dehydration
to form the compound (14). Finally, homolytic cleavage of N-H bond and carbonyl carbon
followed by radical coupling of the compound (14) gives the desired product (4).

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DOI: 10.1039/D0NJ02714F
O
O
O
OH
O
R1
R2
R1
R2
H
H
A
T
O
HO
O
OHO
O
O
E
Y
-H
E
O
5
Y
*
1
6
(II)
(I)
CFL
2
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E
Y
-H
E
Y
*
(II)
(I)
E
Y
T
A
H
E
R
Y
O
O
N-NH-R3
1
)
C
l
O
R1
R2
H
HO
o
m
o
e
l
y
R1
R2
a
t
v
2
i
c
a
)
g
O
14
R
e
O
a
d
c
R3
N
N
i
c
o
a
u
OHO
7
l
p
-H2O
l
i
n
g
R1
R2
OH NH-NH-R3
-H2O
O
R1
R2
OH
O
4
O
O
13
O
R1
R2
O
O
OH
8
OH O
H
H
A
T
R1
R2
E
Y
(II)
-H
E
(I)
Y
*
H
R3 N NH
O
12
O
3
O2
R3-NH-NH-H
E
Y
3
O
HO2
O
O
OH O
O
R1
R2
R1
R2
R1
R2
H2O
H2O2
O2
O
O O
O
10
O
O
11
9
Figure 2. Probable mechanism

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DOI: 10.1039/D0NJ02714F
X2-H
5
6
X2
7
8
9
Reverse Hydrogen
Atom Transfer
(RHAT)
COOH
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Br
Br
COOH
Br
HO
O
O
Br
Br
Br
EY
HO
O
OH
Photoredox
cycle
Br
Br
EY-H
n
e
g
o
r
X1
d
y
m
COOH
r
o
t
e
H
f
A
s
Br
HO
Br
n
)
a
r
T
T
A
H
(
O
O
X1-H
Br
Br
EY*
X1 = 2,8
X2 = 6,10
Figure 3. Photoredox cycle of Eosin Y44
Conclusions
In conclusion, we have successfully developed a novel and an effective synthetic pathway for
coumarin based pyrazole and its derivatives via one-pot-three-component reaction of
salicylaldehydes (1), 4-hydroxy-6-methyl-2H-pyran-2-one (2) and phenylhydrazines (3) in
acetonitrile by utilizing air and Eosin Y as an inexpensive, biodegradable photoredox catalyst.
The present method incorporates broad range of substrate scope applicability. Most important
highlights of the proposed protocol are that it is accessible, greener, experimentally feasible,
cost-effective and during the product formation air is used as a sole green oxidant.
Experimental Section
General Remarks
All chemicals were reagent grade and purchased from Aldrich, Alfa Aesar, Merck,
Spectrochem and Qualigens and were used without purification. The reactions were monitored
using pre-coated TLC plates of silica gel G/UV-254 of 0.25 mm thickness (Merck 60 F-254).
NMR spectra were recorded on a Bruker Avance Neo 500FT spectrometer at 500 MHz (1H)
and 125 MHz (13C) in CDCl3 using TMS as an internal reference. Mass spectra were recorded
on a JEOL SX-102 (FAB) mass spectrometer at 70 eV. Mass Spectra (ESIMS) were obtained

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on Micromassquadro II spectrometer. Melting points were determined by open glass capiVlileawrAyrticle Online
DOI: 10.1039/D0NJ02714F
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method and were uncorrected.
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General Experimental Procedure
9
In a tube equipped with a magnetic stirrer bar salicylaldehyde (1, 1 mmol), 1,4-hydroxy-6-
methyl-2H-pyran-2-one (2, 1 mmol) and phenylhydrazine (3, 1 mmol), were added in 3 mL
acetonitrile and Eosin Y (2 mol%). The resulting mixture was stirred under irradiation with
23W CFL at room temperature. After the completion of the reaction (monitored by TLC), the
reaction mixture was quenched with cold water (3 ml) and compound was dissolved in EtOAc.
The EtOAc layer was separated and the aqueous fraction was extracted with EtOAc (3X3 mL).
The combined organic layers were dried over Na2SO4 and concentrated in vacuo and the crude
product was purified by silica gel chromatography (100-200 mesh silica gel; EtOAc/Hexane)
to obtain the pure product 4a-l. All the products are well known which were characterized by
the comparison of their spectra and melting point with those reported in the literature.37,38
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Supporting Information Summary
General experimental, General procedure for the synthesis of pyrazoles bearing a coumarin
derivatives and Characterization data of products.
Acknowledgements
The authors are thankful to SAIF, PU, Chandigarh for spectral data. The authors Amit Kumar
Sharma, Anu Mishra and Anjali Jaiswal thanks to UGC, New Delhi for the award of SRF and
JRF respectively. Prof. Jagdamba Singh acknowledges the financial support from UGC, New
Delhi in the form of BSR Faculty Fellowship (Fellowship No. 201819-BSRFACULTY-10074-
3). We are also thanks to Dr. Anil K. Singh, Associate Prof. department of physics, ECC PG
college, University of Allahabad, for their valuable support.
References
1 N. A. Romero and D. A. Nicewicz, Chem. Rev., 2016, 116, 10075-10166.
2 A. Savateev, I. Ghosh, B. Konig and M. Antonietti, Angew. Chem. Int.,
Ed.,10.1002/anie.201802472.
3 I. Ghosh, R. S. Shaikh and B. Konig, Angew. Chem. Int. Ed., 2017, 56, 1-7.
4 M. A. Ansari, D. Yadav, S. Soni, A. Srivastava and M. S. Singh, J. Org. Chem., 2019, 84,
5404-5412.
5 K. Wang, L. Meng and L. Wang, J. Org. Chem., 2016, 81, 7080-7087.

New Journal of Chemistry
Page 12 of 14
1
2
3
4
5
6 K. Muralirajan, R. Kancherla and M. Rueping, Angew. Chem. Int. Ed., 2018,D5O7I:,101.1403V79ie8/wD7A0r-NticJle02O7n1li4nFe
14791.
6
7 X. Lang, J. Zhao, and X. Chen, Angew. Chem. Int. Ed., 2016, 55, 4697-4700.
8 R. S. Rohokale B. Koenig and D. D. Dhavale, J. Org. Chem., 2016, 81, 7121-7126.
9 S. D. Tambe, M. S. Jadhav, R. S. Rohokale and U. A. Kshirsagar, Eur. J. Org. Chem., 2018,
4867-4873.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
10 Y. Zhou, J. Wang, Z. Gu, S. Wang, W. Zhu, J. L. Acenã, V. A. Soloshonok, K. Izawa and
H. Liu, Chem. Rev., 2016, 116, 422.
11 T. Xu, C. W. Cheung and X. Hu, Angew. Chem. Int. Ed., 2014, 53, 4910.
12 L. Lin, X. Bai, X. Ye, X. Zhao, C. Tan and Z. Jiang, Angew. Chem. Int. Ed., 2017, 56,
13842-13846.
13 M. Majek and A. J. V. Wangelin, Angew. Chem. Int. Ed., 2014, 53, 1-6.
14 L. Buzzetti, G. E. M. Crisenza and P. Melchiorre, Angew. Chem. Int. Ed.,
10.1002/anie.201809984.
15 A. A. Soto, K. Kaastrup, S. Kim, K. Ugo-Beke and H. D. Sikes, ACS Catal., 2018, 8,
6394−6400.
16 Q. Xiong, S. Dong, Y. Chen, X. Liu and X. Feng, Nat. Commun., 2019, 10, 2116.
17 J. Tian, Z. Chen, R. Jiang, L. Mao, M. Liu, F. Deng, H. Huang, L. Liu, X. Zhang and Y.
Wei, Dyes and Pigments., 2019, 171, 107673.
18 M. Loubidi, J. Jouha, I. Hdoufane, M. E. Hafi, Z. Tber, D. Cherqaoui and J. T. Mague, J.
Mol. Struct., 2020, 1201, 127178.
19 A. A. Bekhit, A. M. M. Hassan, H. A. A. E. Razik, M. M. M. El-Miligy, E. J. El-Agroudy
and A. E. A. Bekhit, Eur. J. Med. Chem., 10.1016/j.ejmech.2015.02.038.
20 K. L. Kees, J. J. Fitzgerald, K. E. Steiner, J. F. Mattes, B. Mihan, T. Tosi, D. Mondoro and
M. L. McCaleb, J. Med. Chem.,1996, 39, 3920-3928.
21 S. Durgamma, A. Muralikrishna, V. Padmavathi and A. Padmaja, Med. Chem. Res., 2014,
23, 2916–2929.
22 K. Karrouchi, S. Radi, Y. Ramli, J. Taoufik, Y. N. Mabkhot, F. A. Al-aizari and M. Ansar,
Molecules., 2018, 23, 134.
23 A. Dore, B. Asproni, A. Scampuddu, G. A. Pinna, C. T. Christoffersen, M. Langgard and J.
Kehler, Eur. J. Med. Chem., 2014, 84, 181-193.
24 S. Jacob K. and S. Ganguly, Int. J. Pham Pharm. Sci., 2016, 8, 75-79.
25 A. Jamwal, A Javed and V. Bhardwaj, J. Pharm. Bio Sci., 2013, 3, 114-123.

Page 13 of 14
New Journal of Chemistry
1
2
3
4
View Article Online
26 F. Boudjellal, H. B. Ouici, A. Guendouzi, O. Benali and A. Sehmi, J. Mol. StDrOuIc: 1t0.,.102309/2D00,NJ02714F
5
6
1199, 127051.
27 S. T. Heller and S. R. Natarajan. Org. Lett., 2006, 8, 2675-2678.
28 Bayu Ardiansah, Asian J Pharm Clin Res., 2018, 11, 88-94.
29 F. G. Medina, J. G. Marrero, M. M. Alonso, M. C. Gonzalez, I. C. Guerrero, A. G. T.
Garcia and S. O. Robles, J. Name., 2012, 00, 1-3.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
30 E. C. Gaudinoa, S. Tagliapietraa, K. Martinaa, G. Palmisanob and G. Cravotto, J. Name.,
2013, 00, 1-3.
31 A. K. Mourad, F. K. Mohamed and A. Y. Soliman, Heterocycles., 2018, 96, 1.
32 Y. Zhao, N. Wang, H. Wu, Y. Zhou, C. Huang, J. Luo, Z. Zeng, and L. Kong, J. Adv. Res.,
2020, 21 57-64.
33 A. S. Al-Ayed, Int. J. Org. Chem., 2011, 1, 87-96.
34 M. K. Bashir, N. A. W. Al-Omari and A. O. Omar, International Journal of Enhanced
Research in Science, Technology & Engineering., 2018, 7, 2319-7463.
35 P. Aragade, R. Venkatnarayanan and P. Patil, Drug Res., 2013, 63, 28–33.
36 P. Aragade, R. V. Narayanan, V. Maddi, P. Patil, P. Shinde and M. Agrawal, J. Enzyme
Inhib. Med. Chem., 2012, 27, 849–853.
37 X. T. Li, Y. H. Liu, X. L. and Z. H. Zhang, RSC Adv., 2015, 5, 25625-25633.
38 A. Alizadeh and R. Ghanbaripour, Synth. Commun., 2014, 44, 1635-1640.
39 A. K. Yadav and L. D. S. Yadav, Green Chem., 2015, 17, 3515.
40 A. K. Yadav and L. D. S. Yadav, Org Biomol Chem., 2015, 13, 2606.
41 W. Xiao, X. Yu, Q. Zhao, J. Chen, and J Chen, Angew. Chem. Int. Ed.,
10.1002/anie.201809820.
42 M. A. Ansari, D. Yadav, S. Soni, A. Srivastava and M. S. Singh, J. Org. Chem., 2019, 84,
5404-5412.
43 Nathan A. Romero and David A. Nicewicz, Chem. Rev., 2016, 116, 10075-10166.
44 X. Fan, P. Xiao, Z. Jiao, T. Yang, X. Dai, W. Xu, J. D. Tan, G. Cui, H. Su, W. Fang and
J. Wu, Angew. Chem. Int. Ed.,10.1002/anie.201908556.
45 J. Zhu, W. Cui, S. Wang and Z. Yao, Org. Lett., 2018, 20, 3174-3178.
46 K. Ohkubo, K. Mizushima, R. Iwata, K. Souma, N. Suzuki and S. Fukuzumi, Chem.
Commun. 2010, 46, 601−603.
47 D. Ravelli, M. Fagnoni and A. Albini, Chem. Soc. Rev. 2013, 42, 97−113.
48 L. Revathi, L. Ravindar, W.-Y. Fang, K. P. Rakesh and H.-L. Qin, Adv. Synth. Catal.
2018, 360, 4652−4698.

New Journal of Chemistry
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DOI: 10.1039/D0NJ02714F
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A visible light facilitated protocol for the synthesis of pyrazole and its derivatives bearing a
coumarin unit in presence of Eosin Y.