Chitosan-SO3H (CTSA) an efficient and biodegradable polymeric catalyst for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s

Article abstract of DOI:10.1080/00397911.2020.1753078

An efficient, green procedure for the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s using biodegradable polymeric catalyst chitosan-SO₃H (CTSA), is operationally easy to prepare by mixing chitosan and chlor

Full text of DOI:10.1080/00397911.2020.1753078

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Chitosan-SO3H (CTSA) an efficient and
biodegradable polymeric catalyst for the synthesis
of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol) and α-
amidoalkyl-β-naphthol’s
Paresh G. Patil, Suman Sehlangia & Dhananjay H. More
To cite this article: Paresh G. Patil, Suman Sehlangia & Dhananjay H. More (2020): Chitosan-
SO3H (CTSA) an efficient and biodegradable polymeric catalyst for the synthesis of 4,4′-
(arylmethylene)bis(1H-pyrazol-5-ol) and α-amidoalkyl-β-naphthol’s, Synthetic Communications,
DOI: 10.1080/00397911.2020.1753078
To link to this article: https://doi.org/10.1080/00397911.2020.1753078
View supplementary material
Published online: 24 Apr 2020.
Submit your article to this journal
View related articles
View Crossmark data
Full Terms & Conditions of access and use can be found at
https://www.tandfonline.com/action/journalInformation?journalCode=lsyc20

R
SYNTHETIC COMMUNICATIONSV
https://doi.org/10.1080/00397911.2020.1753078
Chitosan-SO3H (CTSA) an efficient and biodegradable
polymeric catalyst for the synthesis of 4,40-(arylmethylene)
bis(1H-pyrazol-5-ol) and a-amidoalkyl-b-naphthol’s
Paresh G. Patila , Suman Sehlangiab, and Dhananjay H. Morec
b
aDepartment of Chemistry, S.P.D.M. College Shirpur, Shirpur, MS, India; School of Basic Sciences,
c
Indian Institute of Technology, Mandi, HP, India; School of Chemical Sciences, Kavayitri Bahinabai
Chaudhari North Maharashtra University Jalgaon, Jalgaon, MS, India
ABSTRACT
ARTICLE HISTORY
An efficient, green procedure for the synthesis of 4,40-(arylmethylene)
bis(1H-pyrazol-5-ol) and a-amidoalkyl-b-naphthol’s using biodegrad-
able polymeric catalyst chitosan-SO3H (CTSA), is operationally easy to
prepare by mixing chitosan and chlorosulfonic acid. This catalyst dis-
plays excellent catalytic activity and reusable for five subsequent
reactions without significant loss of catalytic activity. This protocol
proceeds with short reaction times, at mild temperatures, in a solv-
ent-free reaction, and generally with high yields. We present herein
a practical, efficient and simple procedure with a broad substrate
scope that allows access to two different reactions 1H-pyrazole-5-ol
and a-amidoalkyl-b-naphthol’s core unit.
Received 19 January 2020
KEYWORDS
4,40-(arylmethylene)bis(1H-
pyrazol-5-ol) arens;
a-amidoalkyl-b-naphthol’s
arens; biodegradable
polymeric catalyst; CS-SO3H;
solid acid catalyst
GRAPHICAL ABSTRACT
Introduction
In recent years direction of researcher is shifted more toward sulfonic acid functional-
ized heterogeneous catalysts instead of homogeneous catalyst due to many advantages
such as ease of product separation, simplicity in handling, reduced reactor and plant
corrosion problems, and cost-effective, they can be easily recovered and reused many
times without loss of their efficiency.[1] Sulfonic acid-functionalized catalyst is a current
ongoing area in organic research. Owing to numerous advantages associated with this
sulfonic acid-functionalized heterogeneous catalyst, CS-SO3H has been explored as a
powerful solid acid catalyst for the synthesis of a variety of organic and
CONTACT Dhananjay H. More
dhmore@rediffmail.com
School of Chemical Sciences, Kavayitri Bahinabai
Chaudhari North Maharashtra University Jalgaon, Jalgaon, MS, India.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2020 Taylor & Francis Group, LLC

2
P. G. PATIL ET AL.
Polymeric chitosan
Polymeric chitosan-SO3H
Scheme 1. Synthesis of chitosan-SO3H.
heterocyclic compounds.[2] Chitosan is a biopolymer that is the ideal support for cata-
lysts. Chitosan is a good candidate it is a natural, biocompatible, biodegradable, and
biopolymer is perfect for catalyst. Chitosan possesses exclusive property such as avail-
ability, non-toxicity, biocompatibility, safety, stability, and insolubility mainly in an
organic solvent. Chitosan is stable in acidic and basic solutions. Due to all those proper-
ties, it has been used as good support for the preparation of heterogeneous catalysts.[3]
For chemical modification, one primary amine and two hydroxyl groups are active cen-
ters present in chitosan which on sulfonation leads to the formation of chitosan-SO3H
(CTSA) as a solid acid catalyst for the synthesis of a variety of organic and heterocyclic
compounds.[4] Considering high importance of heterogeneous catalyst, we have synthe-
sized CTSA by reaction of Chitosan and chlorosulfonic acid (Scheme 1).
A synthesis of pyrazole and their derivatives has emerged as powerful tool in organic
synthesis due to many pharmacological properties and plays extensive roles in biological
process such as antipyretic, analgesic and ani-inflammatory,[5] antiviral,[6] antidepres-
sant,[7] anticancer,[8] antiproliferative,[9] antioxidant,[10] antifungal, and antibacterial.[11]
Because of their broad range of biological and chemical importance. Synthesis of pyra-
zole has received sustainable attraction of many organic chemists. Therefore, for the
preparation of the important pyrazoles and their derivatives large assays have been
occurred (Figure 1).
In past synthesis of pyrazoles has been carried out by number of catalyst these
include 3-aminopropylated silica gel,[12] silica-bonded S-sulfonic acid,[13] xanthan sul-
furic acid,[14] phosphomolybdic acid,[15] lithium hydroxide monohydrate,[16] PEG-
SO3H,[17] cellulose sulfuric acid,[18] 2-hydroxyethylammonium acetate (HEAA),[19]
[Et3NH][HSO4],[20] pyridinium salt (1-carboxymethyl) pyridinium chloride
f[cmpy]Clgac),[21] 1-sulfopyridinium chloride,[22] and THBS.[23]
The a- amidoalkyl naphthol and its derivatives seem to be an important class of
organic compounds because of their easy transformation and biological important in
amide hydrolysis reaction that exhibits hypotensive and bradycardic activities.[24]
Furthermore, a amidoalkyl naphthol also converted into1,3-oxazine derivatives via the
Vilsmeier–Haack reactions.[25] 1,3-Oxazines possesses potentially different biological
activities including antibiotic,[26] antitumor,[27] analgesic,[28] anticonvulsant,[29] anti-
psychotic,[30] and antianginal.[31] Consequently, for efficient synthesis of a amidoalkyl
naphthol many efforts have been made. There are several catalysts found in the litera-
ture for the synthesis of a aminoalkyl naphthol, such as Montmorillonite K10 clay,[32]
[37]
Ce(SO4)2,[33] Tritylchloride,[34] H3Mo12O40P,[35] SSA,[36] HClO4-SiO2,
zwitterionic
salt,[38] silica gel-supported dual acidic ionic liquid,[39] Graphene oxide,[40] Brønsted
acidic ionic liquid ([TEA][HSO4]),[41] and 2-HSBA.[42]

R
SYNTHETIC COMMUNICATIONSV
3
O
N
O
NC
NH
N
N
N
N
O
S
N
N
N
N
H
O
Br
JHU75575
O
Sildenafil
HO
OH
Me
NH
NH
N
H
N
H
Vibrindole
HIV-1 integrase
inhibitor
Figure 1. Some biologically active pyrazole skeleton and bis-methane derivatives core.
Although these reported methods provide improvements, many of these reported
methods suffer from one or more drawbacks, such as unsatisfactory yield, long reaction
time, toxic and corrosive solvents, and using an expensive and excess amount of cata-
lyst. For these purposes here we describe a practical, efficient method for synthesis of
4,40-(arylmethylene) bis(1H-pyrazol-5-ol) and a-amidoalkyl-b-naphthol’s in the presence
of CTSA as a heterogeneous catalyst.
Previous Work
This work
R
CHO
DCDBTSD43, 2-HEAP44
,
Me
Me
ionic liquid45, SSA46,,
R
N
N
Ph
N
N
Ph
OH
HO
Montmorillonite K1032
MoO3/SiO2 50,, Polymer-SA51
,
ionic liquid52, S-PNP53
.
Me
O
R
NH
OH
Results and discussion
The aim of this research to develop a green, eco-friendly and efficient methodology to
decrease the use of hazardous material. At first, we focused our attention on the synthe-
sis of 4,40-(arylmethylene)bis(1H-pyrazol-5-ol). To search optimal reaction conditions,
the condensation of 4-chlorobenzaldehyde (1 mmol) with 5-methyl-2-phenyl-2,4-dihy-
dro-3H-pyrazol-3-one (2 mmol) was selected as a model reaction and the optimization

4
P. G. PATIL ET AL.
Table 1. Optimization of reaction condition for synthesis of 4-((4-chlorophenyl)5-hydroxy-3-methyl-1-
phenyl-1H-pyrazol-4-yl)-3-methyl-1-phenyl-1H-pyrazol-5-ol catalyzed by CTSA.
Entry
Catalyst (mg)
Solvent
Temperature ꢀC
Time (min)
Yield (%)a
1
2
3
4
5
6
7
8
–
–
Solvent free
H2O
70
70
rt
12 h
12 h
6h
40
30
15
15
15
15
15
60
60
15
20
25
25
40
<20
<20
40
65
85
88
86
92
96
96
65
70
92
88
86
85
82
50
50
50
50
50
40
30
20
10
30
30
30
30
30
30
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
Solvent free
H2O
EtOH
MeOH
DCM
Chloroform
40
60
70
80
70
70
70
70
70
70
70
70
70
70
9
10
11
12
13
14
15
16
17
Toluene
n.r: no reaction observed.
aIsolated yield.
assay including the amount of catalyst, solvent, and temperature were examined, the
results of which are tabulated in (Table 1).
Initially, the reaction was carried out in the absence of CTSA catalyst under solvent-
free and using polar protic solvent as a water condition at 70 ꢀC in 12 h, which gave a
product 7 in yield (<20%) (entries 1 and 2). Those initial reaction inspired us fathered
continuous optimization. After deep previous literature investigation, we have analyzed
that the reaction medium needs organocatalyst. We were decided to use CTSA (50 mg)
under the solvent-free condition at room temperature which gave product 7 yields in
40% (entries 3). These experiments validated our hypothesis and confirmed CTSA was
able to increase yield. In further optimization assay, we used CTSA (50 mg) under the
solvent-free condition and slowly increase the temperature product 7 yield in 65%
(entries 4). However (entries 4) conclude that the effect of temperature increases prod-
uct yield and decreased the time for reaction. We have increased the temperature slowly
from 60, 70, and 80 ꢀC with 50 mg of catalyst, under the solvent-free condition in 30
and 15 min we got excellent yield product 7 in 85, 88, and 86%, respectively (entries 5,
6, and 7).
After finding catalyst and temperature conditions we were decided to be decreased
catalyst lodging using (40 mg) of catalyst under the solvent-free condition at 70 ꢀC

R
SYNTHETIC COMMUNICATIONSV
5
in 15 min yield product 7 in 92% (entries 8). We have analyzed the model reaction at
lower amounts of a catalyst under the solvent-free condition at temperature 70 ꢀC,
increased the yield compared to previous entries. In furthered optimization, we were
decreased catalyst lodging (30 mg), (20 mg), and (10 mg), product 7 yield in 96, 96, and
65%, respectively (entries 9, 10, and 11). With decreasing, catalyst lodging (20 mg) in
(entries 10) obtained the optimized condition for catalyst lodging. In fathered optimiza-
tion, we were carried out with different polar and nonpolar solvent H2O, EtOH,
MeOH, DCM, CHCl3, and Toluene with (30 mg of catalyst) product 7 yield in 70, 92,
88, 86, 85, and 82%, respectively (entries 12–17). Using different solvents, we cannot
find any change in increasing product yield. Among the tested conditions results shows
that 20 mg of CTSA and solvent-free condition in 15 min is the more appropriate condi-
tion for this reaction (entries 10).
This set of experiments allowed reliable determination of the optimal reaction conditions;
thus, we proceeded to explore the scope of the new procedure with respect to changes in the
aryl unit with 3-methyl-1-phenyl-5-pyrazolone and it is shown in Scheme 2.
A range of electron-rich and electron-poor aromatic aldehyde substrates was tested,
as well as some of their heterocyclic derivatives. Thus, benzaldehyde treated with 3-
methyl-1-phenyl-5-pyrazolone in standard condition to lead 1 in 93% yield. This reac-
tion also gave an excellent 91% yield when performed on a gram-scale. This experiment
demonstrated the scalability and efficiency of our procedure. 4-Methylbenzaldehyde and
2,4-dimethylbenzaldehyde treated with 3-methyl-1-phenyl-5-pyrazolone 92 and 86%
yields were obtained for 2 and 3, respectively. The sterically hindered methyl group in
2,4-dimethylbenzaldehyde it slightly affects the yield in 3 as compared to 4-methylben-
zaldehyde product 2. The [1,10-biphenyl]-4-carbaldehyde in an excellent 90% yield
to get 4. In the same way, the 4-methoxybenzaldehyde treated with 3-methyl-1-phenyl-
5-pyrazolone in standard condition to result in product 5. This set of experiments high-
light the efficacy of our protocol applied to electron-rich aromatic aldehyde
derivatives. The further scope of the reaction was tested with different electron-with-
drawing aromatic aldehyde derivatives. 2-Chlorobenzaldehyde treated with 3-methyl-1-
phenyl-5-pyrazolone in standard condition to lead 6 in 93% yield. The 4-chlorobenzal-
dehyde and 4-bromobenzaldehyde treated with 3-methyl-1-phenyl-5-pyrazolone 96 and
89% yields were obtained for 7 and 8, respectively. Aryl aldehyde at the free –OH,
highly sterically hindered and heterocyclic aryl aldehyde groups were explored. Thereby,
the –OH, derivative yielded the corresponding product 9 in 82% yield. The presence of
a free –OH group allowed the reaction. 2,4,6-Trichlorobenzaldehyde treated with 3-
methyl-1-phenyl-5-pyrazolone in standard condition to lead 10 in 85% yield. The prod-
uct is obtained highly sterically with good yield. The presence of a heterocyclic group
allowed the reaction to obtain 11 to proceed in 79% yield. These tests demonstrate the
excellent reactivity of CTSA which provided good yields for electron windrowing,
donating, sterically hindered, and heterocyclic aryl aldehyde led into the product cor-
roborating our hypothesis. Thus, we denied that electron-withdrawing substituents at
the para and ortho position concerning the electron-donating also not affect the yield.
These results clearly outline the scope and limitations of our protocol. Also, all com-
pounds, we were recrystallized in ethanol and recovered the catalyst while filtration and
reused for the next reactions.

6
P. G. PATIL ET AL.
Ph
Me
Me
Me
Me
Me
Me
Me
Me
N
N
Me
Me
Me
N
N
N
N
N
N
N
N
N
N
N
N
N
N
OH
HO
OH
HO
OH
HO
OH
HO
b, c
4, 25 min (90%)
b, c
b
b
3, 40 min (88%)
1, 25 min (93%)
2, 30 min (92%)
(91%) gram scalea
Cl
Br
OMe
Cl
Me
Me
Me
Me
Me
Me
N
Me
Me
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
OH
OH
HO
OH
HO
HO
OH
HO
b
b
b
b
6, 20 min (93%)
8, 20 min (89%)
7, 15 min (96%)
5, 35 min (90%)
OH
Cl
S
Me
Me
Cl
N
Cl
Me
Me
Me
N
Me
N
N
N
N
N
N
N
N
N
OH
HO
N
OH
HO
OH
HO
b
11, 70 min (79%)
b
b,c
9, 40 min (82%)
10, 20 min (85%)
Scheme 2. Synthesis of 4,40-(arylmethylene)bis(1H-pyrazol-5-ol) derivatives under optimized condi-
tionsa. aReaction conditions: aromatic aldehyde (1 mmol), 3-methyl-l-phenyl-2-pyrazolin-5-one
b
c
(2 mmol), solvent-free conditions. Isolated yield. Novel compound.
After our first successful we were inspired to achieve an advantage for our second
reaction CTSA to use in the synthesis of 1-amidoalkyl-2-naphthols derivative from the
reaction of 2-naphthol, aromatic aldehyde, and acetamide. For optimization of reaction
conditions, the reaction 4-chlorobenzaldehyde, 2-naphthol, and acetamide in presence of
CTSA were studied as a model reaction and the various conditions including the amount
of the catalyst, solvent and temperature were examined and results are shown in Table 2.
The previous optimization conditions give an initial idea from Table 1. The initial
optimization reaction was carried out in the absence of CTSA catalyst under solvent-
free at 80 ꢀC for 24 h no reaction observed (entry 1). Then we have carried out the reac-
tion with CTSA (20 mg), under the solvent-free condition to obtained product 17 in
45% yield (entry 2). Subsequently, the effect of the amount of CTSA on the reaction
was investigated the lower amount of catalyst improve the yield 85% of product 17
(entry 3). It was observed that (20 mg) of catalyst enough to achieve a high yield 94% of
product 17 while increasing temperature and reduced reaction time and a higher
amount of catalyst did not improve the yield 90 and 88%, respectively, of the product

R
SYNTHETIC COMMUNICATIONSV
7
Table 2. Optimization of reaction condition for the synthesis of N-((4-chlorophenyl)(2-hydroxynap-
thalen-1-yl)methyl)acetamide catalyzed by CTSAa.
Entry
Catalyst (mg)
Solvent
Temperature ꢀC
Time (min)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
–
Solvent free
Solvent-free
Solvent free
Solvent free
Solvent free
Solvent free
H2O
EtOH
MeOH
CH3CN
80
40
80
80
80
80
80
80
80
80
24 h
2h
15
10
10
10
60
60
60
60
n.r
45
85
94
90
88
<20
75
68
20
10
20
30
40
20
20
20
20
42
aReaction conditions: 4-chloro benzaldehyde (1 mmol), 2- naphthol (1 mmol), acetamide (1.2 mmol), solvent (0.15 M),
open flask. n.r: no reaction observed.
bIsolated yield.
17 to a greater extent (entries 5 and 6). In fathered optimization, we were carried out
with different solvents H2O, EtOH, MeOH, and CH3CN with (20 mg of catalyst) prod-
uct 17 yield in <20, 75, 68, and 68%, respectively (entries 7–10). Using different sol-
vents, we cannot find any change in increasing product yield. Among the tested
conditions results show that (20 mg) of CTSA and solvent-free condition in 10 min is
the more appropriate condition for this reaction (entries 4).
After established the optimal reaction conditions, we explored the scope of our protocol
(entries 4) for the synthesis of a-amidoalkyl-b-naphthol’s catalyzed by (20 mg) of CTSA
(Scheme 3). A variety of electron-rich, electron-poor aromatic aldehyde and hetero-
aromatic aldehyde substrates was tested, in this way, benzaldehyde was trite with standard
reaction condition 12 in 90% yield. This reaction also imparted an excellent 86% yield
when did on a gram-scale. This experiment proved the scalability and effectiveness of our
procedure. The 4-methylbenzaldehyde and [1,10-biphenyl]-4-carbaldehyde giving rise 13
and 14, respectively, in 87–85% yields in 20 min. 4-Hydroxybenzaldehyde also produced
their corresponding derivatives 15 in 87% yields. It shows that the free –OH group did not
influence the corresponding production, in reaction electron-donating groups (13, 14, and
15) were isolated in high yields (85–78%), which demonstrated the excellent efficiency of
our protocol. In fact, our protocol resulted in a general improvement of the previous
report for the synthesis of 1-amidoalkyl-2-naphthols derivatives.
In further scope, some electron withdrawing aldehyde was tested, with the electron-
attracting 3-chlorobenzaldehyde, 4-chlorobenzaldehyde and 4-bromobenzaldehyde, 16,
17, and 18, respectively, in 92, 94, and 92% yields in 10–14 min. Chloride and bromide
groups were tolerated very well, guiding to the totally controlled introduction withdrawing
groups more favorable in high to excellent yields in less time. Even the strongly deacti-
vated group like –NO2 and –CN lead 1-amidoalkyl-2-naphthols derivatives 19, 20, and 21,
respectively, in 86, 88, and 89% yields in 8–12 min which demonstrated the excellent

8
P. G. PATIL ET AL.
a
Scheme 3. Synthesis of 1-amidoalkyl-2-naphthols derivatives under optimized conditionsa. Reaction
conditions: aromatic aldehyde (1 mmol), 2- naphthol (1 mmol), and acetamide (1.2 mmol), solvent-free
b
conditions, and open flask. Isolated yield.
efficiency of our protocol toward the strongly deactivated group. Also, the heteroaromatic
aldehyde substrates thiophene-2-carbaldehyde give rise corresponding 1-amidoalkyl-2-
naphthols derivatives 22 in 86% yield in 25 min. It accomplished that our protocol also
efficient for heteroaromatic aldehyde substrates. After all, those set of an experiment for
the synthesis of 1-amidoalkyl-2-naphthols derivatives for electron-donating and electron-
withdrawing aromatic aldehyde were reacted smoothly to offered corresponding product.
Furthermore, heteroaromatic aldehyde also provided the desired product in very good
yield with (20 mg) of CTSA catalyst in the solvent-free condition in short reaction time.
However, the benefits of our protocol for the Synthesis of 4,40-(arylmethylene)bis(1H-
pyrazol-5-ol) and 1-amidoalkyl-2-naphthols derivatives important to notes following
points: (1) high yielding, (2) solvent-free, (3) the absence of an inert atmosphere, (4) easily
recovered catalyst while filtration (5) catalyst are biodegradable polymeric catalyst, (6) no
need column purification easily recrystallized in ethanol, and (7) in short reaction time.
To gain extra understanding toward the chemoselectivity of our protocol we decided
to carry out the synthesis with ketone functional group to corresponding derivatives for
synthesis of 4,40-(arylmethylene)bis(1H-pyrazol-5-ol) and 1-amidoalkyl-2-naphthols in
order to determine if a carbonyl function group pathway was operating (Equations (1)
and (2)). The acetophenone treated with 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-
one with standard reaction conditions we have not observed any reaction.

R
SYNTHETIC COMMUNICATIONSV
9
Also, acetophenone reacted with 2-naphthol and acetamide with standard reaction
conditions for corresponding 1-amidoalkyl-2-naphthols derivatives but we cannot
observe any reaction only starting material isolated after the reaction. This experi-
ment proved the chemoselectivity of our protocol toward the aldehyde func-
tional group.
Finally, one of the important characteristics in organic synthesis reusability of cat-
alysts for commercial and industrial applications. The recyclability of the catalyst was
investigated from the model reaction of 4-chlorobenzaldehyde with 3-methyl-
1Hpyrazol-5(4H)-one. After completion of the reaction, the catalyst was easily recov-
ered by filtration, washed with acetone, and air-dried. It is shown in Figure 2. The
catalyst could be reused for the next five runs without any appreciable loss of
its activity.
The different reported catalysts used in the literature for the synthesis of products 7
and 17 are charted in Table 3. After a deep analysis of previous literature, we have ana-
lyzed the following limitation for the previous report, long reaction time, harsh reaction
Figure 2. Reusability of catalysts for the synthesis of product 7.

10
P. G. PATIL ET AL.
Table 3. Comparison of the results obtained from the synthesis of 4,40-
(arylmethylene)bis(1H-pyrazol-5-ol) and a-amidoalkyl-b-naphthol’s.
Product
Catalyst
Time
Yield
References
Product 7
DCDBTSD
2-HEAP
Ionic liquid
SSA
40 min
40 min
25 min
70 min
60 min
45
1.5 h
6.5 h
3
6 h
27
30
27
80
89
94
90
90
90
89
82
94
87
94
90
95
[43]ab
[44]a
[45]c
[13]a
[46]ac
[47]d
[32]a
[48]a
[49]a
[50]a
[51]c
[52]c
[53]a
([Sipmim]HSO4)
([HMIM]HSO4)
Montmorillonite K10
HClO4–SiO2
Product 17
(MoO3/SiO2)
Polymer-supported sulfonic Acid
Benzimidazolium Ionic liquids
S-PNP
Adipic acid
Literature limitations:
aLong reaction time.
bLow yields.
cHard conditions for the catalyst preparation.
dUltrasonication.
Scheme 4. Plausible mechanistic pathway for Scheme 2.
condition, low yield, and a long step required for preparation of catalyst using harsh
conditions. Also, many protocols do not have good tolerance with electron-withdrawing,
donating and heteroaromatics groups.
However, we were overcome many limitations of the previous report. Our protocol is
recyclable, a biodegradable polymeric catalyst of CTSA, solvent-free, high yielding,
eco-friendly and good tolerance electron-withdrawing, donating, and heteroaromatic
aldehyde for synthesis corresponding product derivatives product 7 and 17 which sum-
marized in Schemes 3 and 4.
Plausible mechanism
A plausible reaction mechanism for these reactions is shown in Schemes 2 and 3. It can
be assumed that the reaction starts with the activation of an oxygen atom of the car-
bonyl group of the aldehydes using acidic using CTSA catalyst, followed by the nucleo-
philic attack of heterocyclic compounds or 2-napthol on activated aldehydes and
departure of water which led to the formation of alkene intermediates.

R
SYNTHETIC COMMUNICATIONSV
11
Scheme 5. Plausible mechanistic pathway for Scheme 3.
The condensation of the second molecule of with the alkene intermediates and then
elimination of proton from bis-heterocyclic intermediates or ortho-quinone methide (o-
QMs), leads to the formation of the desired bis-heterocycles or corresponding a-ami-
doalkyl-b-naphthol’s. Similar mechanisms are represented in different acid catalyst in
different some literature.[42,53–55]
Here, we propose a plausible mechanistic path for our protocols which represented in
Schemes 4 and 5 respectively. For the formation of bis(pyrazolyl)-methanes using chito-
san sulfonic acid. CTSA act as proton donor it increases the electrophilic character of
aldehyde in reaction. Initially in first step 1-phenyl-3-methyl-5-pyrazolone undergo tau-
tomerism which is converted in respective tautomeric for keto–enol the electrophilic
aldehyde easily goes aldol condensation the formation of benzylidene [I]. In the final
step, second equivalent of an enolic form of 1-phenyl-3-methyl-5-pyrazolone added to
II in Michael addition fashion to form 4,40-(arylmethylene)bis(1H-pyrazol-5-ol) (III).
Also, for the possible mechanism for Scheme 4 formation of a-amidoalkyl-b-naphthol’s
using CTSA. Initially, electrophilic activation of aromatic aldehyde takes place using CTSA
which triggered a nucleophilic attack of 2-Napthol to generate o-QMs, (IV). In the next
step, CTSA facilitates 1–4 nucleophilic addition on o-QMs of the amide to form correspond-
ing a-amidoalkyl-b-naphthol’s (V).
Conclusions
In summary, we have reported CTSA shown to be a recyclable, biodegradable polymeric
catalyst of CTSA, effective, chemoselective and its application as a heterogeneous solid acid
catalyst in the synthesis of 4,40-(arylmethylene)bis(1H-pyrazol-5-ol) and a-amidoalkyl-
b-naphthol’s and its different derivatives. This protocol was applied to a broad range of dif-
ferent arenas including aromatic and heteroaromatic derivatives. The simplicity of this novel
procedure takes place operationally simple reaction conditions, excellent yield, high reaction
rate, recyclability of catalyst and, eco-friendly, good tolerance electron-withdrawing, donat-
ing, and heteroaromatic aldehyde with short reaction times (10ꢁ40min), methodology are
clean and high yields this procedure have a remarkable advantage.
Experimental
Synthesis of 4,40-(arylmethylene)bis(1H-pyrazol-5-ol)
Procedure
A 25 ml oven-dried round-bottom flask equipped with a magnetic stirrer bar was charged
with the corresponding aldehyde (1 mmol), 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-
one (2 mmol), and CTSA (20 mg) was magnetically stirred at 70 ꢀC on preheated oil bath

12
P. G. PATIL ET AL.
until fully consumption of the starting material (usually 15–40 min). After completion of
the reaction, the reaction mixture was cooled to room temperature slowly and 25 ml hot
ethanol was added. The catalyst was filtered, and the solution was concentrated, and the
product was recrystallized from ethanol to give the desired product.
Synthesis of a-amidoalkyl-b-naphthol’s
Procedure
A 25 ml oven-dried round-bottom flask equipped with a magnetic stirrer bar was
charged with the corresponding aldehyde (1 mmol), 2-naphthol (1 mmol), acetamide
(1.2 mmol), and CTSA (20 mg) was magnetically stirred at 80 ꢀC on preheated oil bath
until fully consumption of the starting material (usually 10–40 min). After completion
of the reaction, the reaction mixture was cooled to room temperature slowly and 25 ml
hot ethanol was added. The catalyst was filtered, and the solution was concentrated to
obtain the product. The product was recrystallized from ethanol to give the
desired product.
The Supporting Information is available on the Publications website. Synthesis, IR
1
and SEM of Chitosan-SO3H and Copies of H NMR, m.p, IR and HRMS spectra of
compounds 1–22.
Acknowledgments
The authors are thankful to IIT Mandi Himachal Pradesh for providing analytical facilities. We
also gratefully acknowledge the School of chemical Science K.B.C.N.M.U for providing all neces-
sary facilities.
Disclosure statement
No conflict of interest was reported by the author(s).
ORCID
Paresh G. Patil
http://orcid.org/0000-0002-8030-3209
References
[1] (a) Hara, M.; Yoshida, T.; Takagaki, A.; Takata, T.; Kondo, J. N.; Hayashi, S.; Domen, K.
A Carbon Material as a Strong Protonic Acid. Angew. Chem. Int. Ed. 2004, 43,
2955–2958. DOI: 10.1002/anie.200453947. (b) Nakajima, K.; Tomita, I.; Hara, M.; Hayashi,
S.; Domen, K.; Kondo, J. N. Development of Highly Active SO3H-Modified Hybrid
Mesoporous Catalyst. Catal. Today. 2006, 116, 151–156. DOI: 10.1016/j.cattod.2006.01.
022.(c) Prabhavathi Devi, B. L. A.; Gangadhar, K. N.; Sai Prasad, P. S.; Jagannadh, B.;
Prasad, R. B. N. A Glycerol-Based Carbon Catalyst for the Preparation of Biodiesel. Chem.
Sus. Chem. 2009, 2, 617–620. DOI: 10.1002/cssc.200900097.(d) Shaabani, A.; Maleki, A.
Cellulose Sulfuric Acid as a Bio-Supported and Recyclable Solid Acid Catalyst for the
One-Pot Three-Component Synthesis of a-Amino Nitriles. Appl. Catal. A Gen. 2007, 331,
149–151. DOI: 10.1016/j.apcata.2007.07.021.(e) Shaabani, A.; Rahmati, A.; Badri, Z.

R
SYNTHETIC COMMUNICATIONSV
13
Sulfonated Cellulose and Starch: New Biodegradable and Renewable Solid Acid Catalysts
for Efficient Synthesis of Quinolines. Catal. Commun. 2008, 9, 13–16. DOI: 10.1016/j.cat-
com.2007.05.021.(f) Kumar, A.; Gupta, G.; Srivastava, S. Diversity Oriented Synthesis of
Pyrrolidines via Natural Carbohydrate Solid Acid Catalyst. J. Comb. Chem. 2010, 12,
458–462. DOI: 10.1021/cc100007a.
[2] (a) Perumal, R.; Bathrinarayanan, B.; Ghashang, M.; Mansoor, S. An Efficient One-Pot
Synthesis
of
7,7-Dimethyl-2-(2-Oxo-2H-Chromen-3-yl)-4-Aryl-7,8-Dihydroquinolin-
5(6H)-One Derivatives Using Chitosan–so 3 H as Biodegradable Organocatalyst. J.
Heterocyclic Chem. 2019, 56, 947–955. DOI: 10.1002/jhet.3473. (b) Safari, J.; Zarnegar, Z.;
Sadeghi, M.; Azizi, F. Chitosan-SO3H: An Efficient and Biodegradable Catalyst for the
Green Syntheses of 1,4-Dihydropyridines. Curr. Org. Chem. 2016, 20, 2926–2932. DOI: 10.
2174/1385272820666160805112208.(c) Reddy, B. V. S.; Venkateswarlu, A.; Reddy, G. N.;
Reddy, Y. V. R. Chitosan-SO 3 H: An Efficient, Biodegradable, and Recyclable Solid Acid
€
for the Synthesis of Quinoline Derivatives via Friedlander Annulation. Tetrahedron Lett.
2013, 54, 5767–5770. DOI: 10.1016/j.tetlet.2013.07.165.
[3] (a) Lim, S. H.; Hudson, S. M. Synthesis and Antimicrobial Activity of a Water-Soluble
Chitosan Derivative with a Fiber-Reactive Group. Carbohydr. Res. 2004, 339, 313–319.
DOI: 10.1016/j.carres.2003.10.024. (b) Bodnar, M.; Hartmann, J. F.; Borbely, J. Preparation
and Characterization of Chitosan-Based Nanoparticles. Biomacromolecules 2005, 6,
2521–2527. DOI: 10.1021/bm0502258.(c) Guibal, E. Heterogeneous Catalysis on Chitosan-
Based Materials: A Review. Prog. Polym. Sci. 2005, 30, 71–109. DOI: 10.1016/j.progpo-
lymsci.2004.12.001.(d) Sinha, V. R.; Singla, A. K.; Wadhawan, S.; Kaushik, R.; Kumria, R.;
Bansal, K.; Dhawan, S. Chitosan Microspheres as a Potential Carrier for Drugs. Int. J.
Pharm. 2004, 274, 1–33. DOI: 10.1016/j.ijpharm.2003.12.026.
[4] Mohammadi, R.; Kassaee, M. Z. Sulfochitosan Encapsulated nano-Fe3O4 as an
Efficient and Reusable Magnetic Catalyst for Green Synthesis of 2-Amino-4H-Chromen-4-
yl Phosphonates. J. Mol. Catal. A Chem. 2013, 380, 152–158. DOI: 10.1016/j.molcata.2013.
09.027.
[5] (a) Mariappan, G.; Saha, B. P.; Sutharson, L.; Singh, Ankit.; Garg, S.; Pandey, L.;
Kumar, D. Analgesic, anti-Inflammatory, Antipyretic and Toxicological Evaluation of
Some Newer 3-Methyl Pyrazolone Derivatives. Saudi Pharm. J. 2011, 19, 115–122. DOI:
10.1016/j.jsps.2011.01.003. (b) Uramaru, N.; Shigematsu, H.; Toda, A.; Eyanagi, R.;
Kitamura, S.; Ohta, S. Design, Synthesis, and Pharmacological Activity of Nonallergenic
Pyrazolone-Type Antipyretic Analgesics. J. Med. Chem. 2010, 53, 8727–8733. DOI: 10.
1021/jm101208x.
[6] Sujatha, K.; Shanthi, G.; Selvam, N. P.; Manoharan, S.; Perumal, P. T.; Rajendran, M.
Synthesis and Antiviral Activity of 4,40-(Arylmethylene)Bis(1H-Pyrazol-5-Ols) against
Peste Des Petits Ruminant Virus (PPRV). Bioorganic Med. Chem. Lett. 2009, 19,
4501–4503. DOI: 10.1016/j.bmcl.2009.02.113.
[7] Bailey, D. M.; Hansen, P. E.; Hlavac, A. G.; Baizman, E. R.; Pearl, J.; DeFelice, A. F.;
Feigenson, M. E. 3, 4-Diphenyl-1H-Pyrazole-1-Propanamine Antidepressants. J. Med.
Chem. 1985, 28, 256–260. DOI: 10.1021/jm00380a020.
~
ꢀ
[8] Brana, M.; Gradillas, A.; Ovalles, A. G.; Lopez, B.; Acero, N.; Llinares, F.; Mingarro, D. M.
Synthesis and Biological Activity of N,N-Dialkylaminoalkyl-Substituted Bisindolyl and
Diphenyl Pyrazolone Derivatives. Bioorganic Med. Chem. 2006, 14, 9–16. DOI: 10.1016/j.
bmc.2005.09.059.
[9] Kim, K. R.; Kwon, J. L.; Kim, J. S.; No, Z.; Kim, H. R.; Cheon, H. G. EK-6136 (3-Methyl-
4-(O-Methyl-Oximino)-1-Phenylpyrazolin-5-One):
A
Novel Cdc25B Inhibitor with
Antiproliferative Activity. Eur. J. Pharmacol. 2005, 528, 37–42. DOI: 10.1016/j.ejphar.2005.
10.027.
[10] (a) Manojkumar, P.; Ravi, T. K.; Gopalakrishnan, S. Antioxidant and Antibacterial Studies
of Arylazopyrazoles and Arylhydrazonopyrazolones Containing Coumarin Moiety. Eur. J.
Med. Chem. 2009, 44, 4690–4694. DOI: 10.1016/j.ejmech.2009.07.004. (b) Parmar, N.;
Teraiya, S.; Patel, R.; Barad, H.; Jajda, H.; Thakkar, V. Synthesis, Antimicrobial and

14
P. G. PATIL ET AL.
Antioxidant Activities of Some 5-Pyrazolone Based Schiff Bases. J. Saudi Chem. Soc. 2015,
19, 36–41. DOI: 10.1016/j.jscs.2011.12.014.
[11] (a) Venkat Ragavan, R.; Vijayakumar, V.; Suchetha Kumari, N. Synthesis of Some Novel
Bioactive 4-Oxy/Thio Substituted-1H-Pyrazol-5(4H)-Ones via Efficient Cross-Claisen
Condensation. Eur. J. Med. Chem. 2009, 44, 3852–3857. DOI: 10.1016/j.ejmech.2009.04.
010. (b) Liu, Y.; He, G.; Kai, C.; Li, Y.; Zhu, H. Synthesis, Crystal Structure, and
Fungicidal Activity of Novel 1,5-Diaryl-1H-Pyrazol-3-Oxy Derivatives Containing
Oxyacetic Acid or Oxy(2-Thioxothiazolidin-3-yl)Ethanone Moieties. J. Heterocyclic Chem.
2012, 49, 1370–1375. DOI: 10.1002/jhet.1045.
[12] Sobhani, S.; Hasaninejad, A. R.; Maleki, M. F.; Parizi, Z. P. Tandem Knoevenagel-Michael
Reaction of 1-Phenyl-3-Methyl-5-Pyrazolone with Aldehydes Using 3-Aminopropylated
Silica Gel as an Efficient and Reusable Heterogeneous Catalyst. Synth. Commun. 2012, 42,
2245–2255. DOI: 10.1080/00397911.2011.555589.
[13] Niknam, K.; Saberi, D.; Sadegheyan, M.; Deris, A. Silica-Bonded S-Sulfonic Acid: An
Efficient and Recyclable Solid Acid Catalyst for the Synthesis of 4,40-
(Arylmethylene)Bis(1H-Pyrazol-5-Ols). Tetrahedron Lett. 2010, 51, 692–694. DOI: 10.
1016/j.tetlet.2009.11.114.
[14] Kuarm, B. S.; B. Xanthan Sulfuric Acid, R. An Efficient, Biosupported, and Recyclable
Solid Acid Catalyst for the Synthesis of 4,4-(arylmethylene)bis(1H-pyrazol-5-ols). Synth.
Commun. 2012, 42, 2382. DOI: 10.1080/00397911.2011.557516.
[15] Phatangare, K.; Padalkar, V.; Gupta, V.; Patil, V.; Umape, P. G.; Sekar, N.
Phosphomolybdic Acid: An Efficient and Recyclable Solid Acid Catalyst for the Synthesis
of 4,40-(Arylmethylene)Bis(1hpyrazol-5-Ols). Synth. Commun. 2012, 42, 1349–1358. DOI:
10.1080/00397911.2010.539759.
[16] Gouda, M. A.; Abu-Hashem, A. A. An Eco-Friendly Procedure for the Efficient Synthesis
of Arylidinemalononitriles and 4,40-(Arylmethylene)Bis(3-Methyl-1-Phenyl-1H-Pyrazol-5-
Ols) in Aqueous Media. Green Chem. Lett. Rev. 2012, 5, 203–209. DOI: 10.1080/17518253.
2011.613858.
[17] Hasaninejad, A.; Shekouhy, M.; Zare, A.; Hoseini Ghattali, S. M. S.; Golzar, N. Iranian
Chemical Society PEG-SO 3 H as a New, Highly Efficient and Homogeneous Polymeric
Catalyst for the Synthesis of Bis (Indolyl) Methanes and 4, 40-(Arylmethylene) -Bis (3-
Methyl-1-Phenyl-1 H-Pyrazol-5-ol) s in Water. JICS. 2011, 8, 411–423. DOI: 10.1007/
BF03249075.
[18] Mosaddegh, E. L. A. H. E. H.; Hassankhani, A. S. A. D. O. L. L. A. H.; Baghizadeh, A. M.
I. N. Cellulose Sulfuric Acid as a New, Biodegradable and Environmentally Friendly
Biopolymer for Synthesis of 4,40-(Arylmethylene)Bis(3-Methyl-1-Phenyl-1H-Pyrazol-5-
Ols). J. Chil. Chem. Soc. 2010, 55, 419–420. DOI: 10.4067/S0717-97072010000400001.
[19] Sobhani, S.; Nasseri, R.; Honarmand, M. 2-Hydroxyethylammonium Acetate as a Reusable
and Cost-Effective Ionic Liquid for the Efficient Synthesis of Bis(Pyrazolyl)Methanes and
2-Pyrazolyl-1-Nitroalkanes. Can. J. Chem. 2012, 90, 798–804. DOI: 10.1139/v2012-059.
[20] Zhou, Z.; Zhang, Y. An Eco-Friendly One-Pot Synthesis of 4,40-(Arylmethylene)Bis(1H-
Pyrazol-5-Ols) Using [Et3NH][HSO4] as a Recyclable Catalyst. J. Chil. Chem. Soc. 2015,
60, 2992–2996. DOI: 10.4067/S0717-97072015000300003.
[21] Moosavi-Zare, A. R.; Zolfigol, M. A.; Noroozizadeh, E.; Khaledian, O.; Shaghasemi, B. S.
Cyclocondensation-Knoevenagel–MichaelDomino Reaction of Phenyl Hydrazine,
Acetoacetate Derivatives and Aryl Aldehydes over Acetic Acid Functionalized Ionic
Liquid. Res. Chem. Intermed. 2016, 42, 4759–4772. DOI: 10.1007/s11164-015-2317-6.
[22] Moosavi-Zare, A. R.; Zolfigol, M. A.; Zarei, M.; Zare, A.; Khakyzadeh, V.; Hasaninejad, A.
Design, Characterization and Application of New Ionic Liquid 1-Sulfopyridinium Chloride
as an Efficient Catalyst for Tandem Knoevenagel – Michael Reaction of 3-Methyl-1-
Phenyl-1H-Pyrazol-5(4H)-One with Aldehydes. Appl. Catal. A Gen. 2013, 467, 61–68.
DOI: 10.1016/j.apcata.2013.07.004.
[23] Karimi-Jaberi, Z.; Pooladian, B.; Moradi, M.; Ghasemi, E. 1, 3, 5-tris(Hydrogensulfato)
Benzene:
A
New and Efficient Catalyst for Synthesis of 4,40-(Arylmethylene)

R
SYNTHETIC COMMUNICATIONSV
15
Bis(1H-Pyrazol-5-ol) Derivatives. Chin. J. Catal. 2012, 33, 1945–1949. DOI: 10.1016/
S1872-2067(11)60477-4.
[24] Shen, A. Y.; Tsai, C. T.; Chen, C. L. Synthesis and Cardiovascular Evaluation of
N-Substituted 1- Aminomethyl-2-Naphthols. Eur. J. Med. Chem. 1999, 34, 877–882. DOI:
10.1016/S0223-5234(99)00204-4.
[25] Damodiran, M.; Panneer Selvam, N.; Perumal, P. T. Synthesis of Highly Functionalized
Oxazines by Vilsmeier Cyclization of Amidoalkyl Naphthols. Tetrahedron Lett. 2009, 50,
5474–5478. DOI: 10.1016/j.tetlet.2009.07.051.
[26] (a) Haneishi, T.; Okazaki, T.; Hata, T.; Tamura, C.; Nomura, M.; Naito, N.; Seki, I.; Arai,
M. Oxazinomycin, a New Carbon-Linked Nugleoside Antibiotic. J. Antibiot. 1971, 24,
797–799. DOI: 10.7164/antibiotics.24.797. (b) Sasaki, K.; Kusakabe, Y.; Esumi, S. The
Structure of Minimycin, a Novel Carbon-Linked Nucleoside Antibiotic Related to b
Pseudouridine. J. Antibiot. 1972, 25, 151–154. DOI: 10.7164/antibiotics.25.151.
[27] Johnson, P. Y.; Silver, R. B. The Synthesis and Antitumor Properties of
a
6-Alkoxytetrahydrooxazine. J. Heterocyclic Chem. 1973, 10, 1029–1030. DOI: 10.1002/jhet.
5570100628.
[28] Lesher, G. Y.; Surrey, A. R. A New Method for the Preparation of 3-Substituted-2-
Oxazolidones. J. Am. Chem. Soc. 1955, 77, 636–641. DOI: 10.1021/ja01608a032.
[29] Mosher, H. S.; Frankel, M. B.; Gregory, M. Heterocyclic Diphenylmethane Derivatives.
J. Am. Chem. Soc. 1953, 75, 5326–5328. DOI: 10.1021/ja01117a054.
[30] Peglion, J. L.; Vian, J.; Goument, B.; Despaux, N.; Audinot, V.; Millan, M. J. Tetraqcyclic
Analogues of [þ]-S 14297: Synthesis and Determination of Affinity and Selectivity at
Cloned Human Dopamine D3VsD2 Receptor. Bioorg. Med. Chem. Lett. 1997, 7, 881–886.
DOI: 10.1016/S0960-894X(97)00126-1.
[31] Benedini, F.; Bertolini, G.; Cereda, R.; Dona, G.; Gromo, G.; Levi, S.; Mizrahi, J.; Sala, A.
New Antianginal Nitro Esters with Reduced Hypotensive Activity. Synthesis and
Pharmacological Evaluation of 3-[(Nitrooxy)Alkyl]-2H-1,3-Benzoxazin-4(3H)-Ones.
J. Med. Chem. 1995, 38, 130–136. DOI: 10.1021/jm00001a018.
[32] Kantevari, S.; Vuppalapati, S. V. N.; Nagarapu, L. Montmorillonite K10 Catalyzed Efficient
Synthesis of Amidoalkyl Naphthols under Solvent Free Conditions. Catal. Commun. 2007,
8, 1857–1862. DOI: 10.1016/j.catcom.2007.02.022.
[33] Selvam, N. P.; Perumal, P. T. A New Synthesis of Acetamido Phenols Promoted by
Ce(SO4)2. Tetrahedron Lett. 2006, 47, 7481–7483. DOI: 10.1016/j.tetlet.2006.08.038.
[34] Khazaei, A.; Zolfigol, M. A.; Moosavi-Zare, A. R.; Zare, A.; Parhami, A.; Khalafi-Nezhad,
A. Trityl Chloride as an Efficient Organic Catalyst for the Synthesis of 1-Amidoalkyl-2-
Naphtols in Neutral Media at Room Temperature. Appl. Catal. A Gen. 2010, 386,
179–187. DOI: 10.1016/j.apcata.2010.07.057.
[35] Gawand, P.; Deokar, H.; Langi, B.; Yadav, A.; Chaskar, A. H3Mo12O40P-Catalyzed OnePot
Synthesis of Amidoalkyl Naphthols. Synth. Commun. 2009, 39, 4171–4179. DOI: 10.1080/
00397910902885541.
[36] Srihari, G.; Nagaraju, M.; Murthy, M. M. Solvent-Free One-Pot Synthesis of Amidoalkyl
Naphthols Catalyzed by Silica Sulfuric Acid. Helvet. Chim. Acta. 2007, 90, 1497–1504.
DOI: 10.1002/hlca.200790156.
[37] Mahdavinia, G. H.; Bigdeli, M. A.; Heravi, M. M. Silica Supported Perchloric Acid
(HClO4 -SiO2): A Mild, Reusable and Highly Efficient Heterogeneous Catalyst for the
Synthesis of Amidoalkyl Naphthols. Chinese Chem. Lett. 2008, 19, 1171–1174. DOI: 10.
1016/j.cclet.2008.06.048.
[38] Kundu, D.; Majee, A.; Hajra, A. Zwitterionic-Type Molten Salt: An Efficient Mild
Organocatalyst for Synthesis of 2-Amidoalkyl and 2-Carbamatoalkyl Naphthols. Catal.
Commun. 2010, 11, 1157–1159. DOI: 10.1016/j.catcom.2010.06.001.
[39] Zhang, Q.; Luo, J.; Wei, Y. A Silica Gel Supported Dual Acidic Ionic Liquid: An Efficient
and Recyclable Heterogeneous Catalyst for the One-Pot Synthesis of Amidoalkyl
Naphthols. Green Chem. 2010, 12, 2246. DOI: 10.1039/c0gc00472c.

16
P. G. PATIL ET AL.
[40] Gupta, A.; Kour, D.; Gupta, V.; Kapoor, K. Graphene Oxide Mediated Solvent-Free Three
Component Reaction for the Synthesis of 1-Amidoalkyl-2-Naphthols and 1,2-Dihydro-1-
Arylnaphth[1,2-e][1,3]Oxazin-3-Ones. Tetrahedron Lett. 2016, 57, 4869–4872. DOI: 10.
1016/j.tetlet.2016.09.067.
[41] Suryawanshi, N. S.; Jain, P. Bronsted Acidic Ionic Liquid as an Efficient and Reusable
Catalyst for One-Pot Synthesis of 1-Amidoalkyl 2-Naphthols under Solvent-Free
Conditions. Orient. J. Chem. 2010, 26, 1525.
[42] Kiyani, H.; Darbandi, H.; Mosallanezhad, A.; Ghorbani, F. 2-Hydroxy-5- Sulphonic Acid:
An Efficient Organo Catalyst for Three Component Synthesis of 1-Amidoalkyl
2-Naphthols and 3,4-di Substituted Isoxal-5(4H)-One. Res. Chem. Intermed. 2015, 41,
7561–7579. DOI: 10.1007/s11164-014-1844-x.
[43] Khazaei, A.; Abbasi, F.; Moosavi-Zare, A. R. Moosavi-Zare, AR. Tandem cyclocondensa-
tion-Knoevenagel-Michael Reaction of Phenyl Hydrazine, Acetoacetate Derivatives and
Arylaldehydes. New J. Chem. 2014, 38, 5287–5292. DOI: 10.1039/C4NJ01079E.
[44] Zhou, Z.; Zhang, Y. An Efficient and Green One-Pot Three-Component Synthesis of 4,40-
(Arylmethylene)Bis(1H-Pyrazol-5-ol)s Catalyzed by 2-Hydroxy Ethylammonium
Propionate. Green Chem. Lett. Rev. 2014, 7, 18–23. DOI: 10.1080/17518253.2014.894142.
[45] Khaligh, N. G.; Hamid, S. B. A.; Titinchi, S. J. J. N-Methylimidazolium Perchlorate as a
New Ionic Liquid for the Synthesis of Bis(Pyrazol-5-ol)s under Solvent-Free Conditions.
Chinese Chem. Lett. 2016, 27, 104–108. DOI: 10.1016/j.cclet.2015.07.027.
[46] Baghernejad, M.; Niknam, K. Synthesis of 4,40-(Arylmethylene)Bis(1H-Pyrazol-5-Ols)
Using Silica-Bonded Ionic Liquid as Recyclable Catalyst. Int. J. Chem. 2012, 4, 52. DOI:
10.5539/ijc.v4n3p52.
[47] Zang, H.; Su, Q.; Mo, Y.; Cheng, B. Ionic Liquid under Ultrasonic Irradiation towards a
Facile Synthesis of Pyrazolonederivatives. Ultrason. Sonochem. 2011, 18, 68–72. DOI: 10.
1016/j.ultsonch.2010.08.001.
[48] Das, B.; Kumar, D. N.; Laxminarayana, K.; Ravikanth, B. Perchloric Acid – Silica (HClO4
ꢂ SiO2) -Catalyzed Synthesis of 14-Alkyl- or 14-Aryl-14H-Dibenzo [a, j] Xanthenes and N-
[(2-Hydroxynaphthalen-1- yl)Methyl]Amides.). HCA. 2007, 90, 1330–1334. DOI: 10.1002/
hlca.200790134.
[49] Moeinpour, F.; Dorostkar-Ahmadi, N.; Sardashti-Birjandi, A.; Khojastehnezhad, A.; Vafaei,
M. Multicomponent Preparation of 1-Amidoalkyl-2-Naphthols Using Silica-Supported
Molybdenum Oxide (MoO3/SiO2) as a Mild and Recyclable Catalyst. Res. Chem. Intermed.
2014, 40, 3145–3152. DOI: 10.1007/s11164-013-1160-x.
[50] An, L. T.; Lu, X. H.; Ding, F. Q.; Jiang, W. Q.; Zou, J. P. Polymer-Supported Sulphonic
Acid Catalyzed Three-Component One-Pot Synthesis of a-Amidoalkyl-b-Naphthols. Chin.
J. Chem. 2008, 26, 2117–2119. DOI: 10.1002/cjoc.200890378.
[51] Muskawar, P. N.; Senthil Kumar, S.; Bhagat, P. R. Carboxyl-Functionalized Ionic Liquids
Based on Benzimidazolium Cation: Study of Hammett Values and Catalytic Activity
towards One-Pot Synthesis of 1-Amidoalkyl Naphthols. J. Mol. Catal. A Chem. 2013, 380,
112–117. DOI: 10.1002/cjoc.200890378.
[52] Pourmousavi, S. A.; Moghimi, P.; Ghorbani, F.; Zamani, M. Sulfonated Polynaphthalene
as an Effective and Reusable Catalyst for the One-Pot Preparation of Amidoalkyl
Naphthols: DFT and Spectroscopic Studies. J. Mol. Struct. 2017, 1144, 87–102. DOI: 10.
1016/j.molstruc.2017.05.010.
[53] Darbandi, H.; Kiyani, H. Adipic Acid as a Biodegradable Solid Acid Catalyst for One-Pot,
Three Component Synthesis of 1-Amidoalkyl-2-Napthols. Curr. Organocatal. 2019, 7,
34–43. DOI: 10.2174/2213337206666190515091358.
[54] Kiyani, H.; Darbandi, H. One-Pot Three-Component Synthesis of 1-Amidoalkyl-2-
Naphthols in the Presence of phthalimide-N-Sulfonic Acid. Bul Chem. Commun. 2017, 49,
562.
[55] Kiyani, H.; Pourali, A.; Banari, H. Efficient Synthesis of Bis (Indolyl)Methane, Bis
Pyrazoles and Biscoumarin Using 4-Sulphopthalic Acid. Res. Chem. Intermed. 2017, 43,
1635–1649. DOI: 10.1007/s11164-016-2720-7.