Br?nsted acid hydrotrope combined catalysis in water: a green approach for the synthesis of indoloquinoxalines and bis-tetronic acids

Article abstract of DOI:10.1007/s11164-021-04430-w

The present work describes the applications of Br?nsted acid hydrotrope combined catalyst (BAHC) as a mild, efficient and reusable catalyst for synthesis of indoloquinoxalines and bis-tetronic acids in water. Using BAHC, we synthesized many indoloquinoxal

Full text of DOI:10.1007/s11164-021-04430-w

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-021-04430-w
Brönsted acid hydrotrope combined catalysis in water:
a green approach for the synthesis of indoloquinoxalines
and bis‑tetronic acids
Arjun Kumbhar1 · Dhanaji Kanase2 · Suhas Mohite3 · Rajshri Salunkhe4 ·
Trushant Lohar2
Received: 17 December 2020 / Accepted: 27 February 2021
© The Author(s), under exclusive licence to Springer Nature B.V. 2021
Abstract
The present work describes the applications of Brönsted acid hydrotrope combined
catalyst (BAHC) as a mild, efcient and reusable catalyst for synthesis of indolo-
quinoxalines and bis-tetronic acids in water. Using BAHC, we synthesized many
indoloquinoxaline derivatives from isatins and o-phenylene diamine using 10 mol%
PTSA in 40% aqueous hydrotropic (NaPTS) solution at room temperature with
83–90% yields. On the other hand, the reaction of tetronic acid with the aldehydes/
isatins forms bis-tetronic acids with 83–88% yields through Knoevengel conden-
sation-Michael addition pathway in same BHAC. Moreover, the BAHC can be
recycled upto 5th cycles with slight decrease in product yields. The extremely sim-
ple operational methodology, green solvent, ambient reaction conditions and high
yields render this approach extremely appealing for the synthesis of diferent hetero-
cyclic compounds.
Keywords Brönsted acid hydrotrope combined catalyst (BAHC) · Water ·
Indoloquinoxalines · Bis-tetronic acids
*
Trushant Lohar
trushantlohar@gmail.com
1
2
3
Padmabhushan Dr. Vasantraodada Patil Mahavidyalaya, Tasgaon, Maharashtra 416 312, India
Bharati Vidyapeeth’s Dr. Patangrao Kadam Mahavidyalaya, Sangli, Maharashtra 416 416, India
Bharati Vidyapeeth’s Yashwantrao Mohite College of Arts, Science and Commerce, Pune,
Maharashtra 411 038, India
4
Department of Chemistry, Shivaji University, Kolhapur, Maharashtra 416 004, India
Vol.:(0123456789)
1 3

A. Kumbhar et al.
Introduction
Environmental benign organic transformations have attracted much interest in
organic chemistry by using renewable resources and reduction of waste materials.
A streamline approach emerged out in this context is use of aqueous medium as a
reaction solvent, which signifcantly provides platform for eco-friendly organic syn-
thesis [1]. Though, the use of aqueous condition ofers many advantages, the major
problem associated with the use of water as a reaction medium is less solubility of
organic reactants with decreased selectivity of reaction. To alleviate these draw-
backs, several strategies like use of ultrasonication, use of co-solvents like DMF,
DMSO and surfactants, supercritical fuids have been employed [2]. Among these
strategies, use of hydrotropes (surface-active compounds), which was introduced by
Carl Neuberg [3], exhibited more opportunity to solubilize many reactants in water
through phenomenon called ‘hydrotropy.’ Hydrotropes enhance the solubility of
many organic compounds in water up to 200 fold by associative mechanism [3, 4].
The salient features of hydrotrope include stack-like arrangement of molecules and
amphiphilic molecular structure. The key use of hydrotropes as a reaction media
depends on the nature of hydrotrope used and its minimum hydrotropic concentra-
tion (MHC). MHC is a concentration, above which there is maximum solubility of
reactants in aqueous phase [5, 6]. Hydrotropes has attractive advantages such as it
is non-toxic, inexpensive, and readily available. It has good solubilizing power and
can be recyclable [7]. In addition, hydrotropes are also suitable under microwave
and ultrasonic conditions [8, 9]. These promising properties of hydotropes make
it a privileged reaction medium for various organic transformations such as multi-
component synthesis of pyrazole derivatives [10], the coupling reactions [11], regi-
oselective synthesis of β-hydroxytriazoles [12] and diversity-oriented synthesis of
quinazolinone derivatives [13].
The chemistry of heterocyclic compounds has remarkable importance in organic
chemistry [14], as a wide range of heterocyclic compounds have diferent pharmaco-
logical properties and clinical applications [15–18]. In addition, some heterocycles
fnd application in the feld of material chemistry [19–24]. Heterocyclic biorelevant
scafolds such as quinoxalines and tetronic acids represent an interesting template in
organic and medicinal chemistry (Fig. 1). Quinoxaline moiety is frequently found
as core nucleus in natural products particularly in alkaloids, as well as in diverse
bioactive compounds [25, 26]. Some derivatives of quinoxalines have signifcant
applications in agrochemicals and material sciences [27–30]. Tetronic acids are a
subclass of β-hydroxy butenolides that have received great attention in the synthetic
chemistry [31–33], as well as they play an essential role in the feld of medicinal
chemistry, especially as antibiotic [34], HIV-1 protese inhibitors [35], anticoagulant
[36], antifungal [37], antibacterial [38], analgesic [39], anti-infammatory [40] and
anticancer agent [41].
Considering the importance of all the above compounds and our previous work
for the synthesis of quinoxalines and pyrido[2,3-b]pyrazines [42], we report herein a
Brönsted acid hydrotrope combined catalyst (BAHC) for the synthesis of indoloqui-
noxaline and bis-tetronic acid derivatives in water at room temperature (Scheme 1).
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
Fig. 1 Bioactive quinoxaline and tetronic acid scafolds
Scheme 1 Synthesis of indoloquinoxalines and bis-tetronic acids using BAHC in water
1 3

A. Kumbhar et al.
Experimental
General
All the chemicals were obtained from Sigma Aldrich/Spectrochem and used with-
out further purifcation. Sodium p-toluene sulphonate (NaPTS hydrotrope) was
purchased from Alfa-Aesar company. TLC was carried out using silica gel G 60
F254 Plates (Merck). IR spectra were recorded on a Perkin–Elmer FT-IR 783 spec-
1
trophotometer. H NMR, and 13C NMR spectra were recorded on a Bruker AC
1
(300 MHz for H NMR and 75 MHz for 13C NMR) spectrometer using CDCl3
or DMSO-d6 as solvent and tetramethylsilane (TMS) as an internal standard.
Melting points were determined using DBK melting point apparatus and are
uncorrected.
Typical procedure for the synthesis of indoloquinoxalines
Isatins/ninhydrine/acenaphthoquinone (1.0 mmol), o-phenylene diamine (1.0 mmol)
and PTSA (10 mol %) were added in a round bottom fask, containing 40% aq
NaPTS (5 mL) and the reaction mixture was stirred at room temperature. The reac-
tion progress was monitored by thin-layer chromatography (TLC). After completion
of the reaction, the mixture was diluted with water (20 mL). The fltrate was washed
with water and dried afording the corresponding crude products, which on recrys-
tallization using ethanol gave pure products.
Typical procedure for the synthesis of bis‑tetronic acids
Tetronic acid (2.0 mmol), aldehydes/isatins (1.0 mmol) and PTSA (10 mol %) were
added in a round bottom fask, containing 40% aq NaPTS (5 mL) and the resulting
reaction mixture was stirred at room temperature. After completion of the reaction,
as monitored by TLC, the mixture was diluted with water (20 mL). The fltrate was
washed with water and dried afording the corresponding crude products, which on
recrystallization using ethanol gave pure products.
Spectral data of representative compounds
Compound 3a
Solid; M.P.: 285–287 °C; IR (KBr): 3452 (N–H stretching), 3134, 3034, 2857,
1621 (C=N stretching), 1589 (C=C Stretching), 1414, 1342, 1262, 1206, 1124,
1
778, 730 cm−1; H-NMR (300 MHz, DMSO-d6): δ 7.20–7.25 (t, 1H, J=15 Hz),
7.52–7.79 (m, 4H), 7.98–8.00 (d, 1H, J=6 Hz), 8.17–8.20 (d, 1H, J=9 Hz),
8.32–8.35 (d, 1H, J=9 Hz), 11.46 (s, 1H); 13C NMR (75 MHz, DMSO-d6): δ
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
111.88, 119.02, 120.66, 122.16, 125.50, 127.62, 128.31, 129.81, 131.21, 139.01,
140.68, 141.11, 144.39, 147.08 ppm.
Compound 5b
Solid; M.P.: 240–242 °C; IR (KBr): 3018, 1624 (C=N stretching), 1503 (C=C
Stretching), 1434, 1302, 1240 (C–C stretching), 1086 (C–N stretching), 1018,
1
842, 764 cm−1; H-NMR (300 MHz, DMSO-d6): δ 7.79–7.82 (dd, 2H, J=3.6 Hz,
J=6 Hz), 7.90–7.95 (dd, 2H, J=9 Hz, J=8.1 Hz), 8.17–8.20 (dd, 2H, J=3 Hz,
J=6 Hz), 8.32–8.35 (d, 2H, J=6 Hz), 8.43–8.46 (d, 2H, J=7.2 Hz); 13C NMR
(75 MHz, DMSO-d6): δ 121.10, 128.41, 129.16, 130.03, 130.21, 130.50, 131.72,
140.98, 154.05 ppm.
Compound 8h
Solid; M.P.: 174–176 °C; IR (KBr): 3494 (–OH stretching), 1750 (C=O Stretching),
1
1622 (C=C Stretching), 1490, 1398, 1164, 1066 (C–O Stretching) cm−1; H-NMR:
(300 MHz, DMSO- d6): δ 2.16 (s, 6H), 4.57–4.64 (m, 4H), 4.74 (s, 1H), 6.88 (d, 2H,
J=3.2 Hz), 6.97 (d, 1H, J=7.6 Hz), 7.94 (brs, 2H); 13C NMR (75 MHz, DMSO-
d6): δ 19.12, 20.38, 33.02, 68.14, 98.97, 125.26, 128.40, 129.89, 134.08, 136.60,
138.61, 176.08, 176.20 ppm.
Compound 9a
Solid; M.P.: 169–171 °C; IR (KBr): 3408 (-OH stretching), 3160 (N–H stretching),
3078, 1744 (lactone C=O Stretching), 1561 (lactum C=O Stretching), 1326, 924,
731 cm−1; 1H-NMR (300 MHz, DMSO-d6): δ 4.60 (s, 4H), 6.74 (d, 1H, J=7.8 Hz),
6.86 (t, 1H, J=7.6 Hz), 7.08 (t, 1H, J=7.5 Hz), 7.46 (d, 1H, J=7.5 Hz), 10.68
(s, 1H), 10.82 (brs, 2H); 13C NMR (75 MHz, DMSO-d6): δ 48.24, 67.02, 109.21,
122.02, 127.12, 128.60, 131.06, 142.05, 172.54, 174.85, 178.12 ppm.
Results and discussion
In order to optimize the reaction conditions, we carried out the condensation of isat-
ins and o-phenylene diamine at ambient temperature (Table 1). Previously, very few
catalytic systems, such as tetrabutylammonium bromide (TBAB) [43], glacial acetic
acid [44] and sulfamic acid [45] have been reported to be efective for the synthesis
of indoloquinoxaline derivatives. However, these methods have much or less short-
comings which limit their use under the aspect of environmentally benign processes.
To show the efcacy of Brönsted acid hydrotrope combined catalyst (BAHC),
we initially studied the synthesis of indoloquinoxaline by reacting isatin (1a) and
o-phenylene diamine (2). At room temperature in the absence of catalyst in water,
above reaction did not furnish the desired indoloquinoxaline 3a (Table 1, entry 1).
When the model reaction was carried out in the presence of p-Toluene Sulfonic Acid
(PTSA) (10 mol %), the reaction gave 3a with 40% yield in 6.0 h (Table 1, entry
1 3

A. Kumbhar et al.
Table 1 Screening of various reaction conditions for the synthesis of indoloquinoxalinea
O
O
N
H
NH2
NH2
N
N
1a
N
H
RT
2
3a
Entry
Hydrotrope
Aqueous hydrotrope
PTSA (mol %)
Time (h)
Yieldb (%)
concentration (% w/v)
1
2
3
4
5
6
7
8
H2O
H2O
–
–
–
10
–
6.0
6.0
3.0
2.5
2.5
2.0
100 min
100 min
100 min
100 min
110 min
110 min
00
40
55
71
61
82
89
89
87
86
85
86
NaPTS
NaPTS
NaPTS
NaPTS
NaPTS
NaPTS
NaXS
NaBS
NaCuS
NaSaI
20
20
10
30
40
50
40
40
40
40
10
10
10
10
10
10
10
10
10
9
10
11
12
aReaction conditions: Isatin (1 mmol), o-phenylene diamine (1 mmol), PTSA (10 mol%), aqueous hydro-
tropic solution (5 mL), RT
bIsolated yields
2). However, the addition of NaPTS (sodium p-toluene sulfonate) hydrotrope in the
presence of 10 mol % PTSA aforded a 71% product yield within 2.5 h in 20% w/v
hydrotropic concentration (Table 1, entry 4). On the completion of the reaction mon-
itored by TLC, the reaction mixture was diluted with cold water and product was
separated out. From this optimization study, we concluded that hydrotrope aided
acid catalysis showed signifcant progress in product yield at room temperature.
Next, the model reaction was performed with various concentrations of NaPTS
including 10–50% w/v in water (Table 1, entries 5–8). By changing the hydrotropic
concentration, a dramatic efect on the yield of product was observed. As shown in
Table 1, product yield changes linearly with concentration. The yield of the prod-
uct was highest at 40% of hydrotropic concentration, since this concentration may
be optimum for the maximum solubilization of organic reactants (Table 1, entry 7).
On further increasing hydrotropic concentration up to 50% w/v, the isolated product
remains as usual as 89% yield. (Table 1, entry 8). Subsequently, in order to examine
the efectiveness of the NaPTS, we used various hydrotropes such as NaXS (sodium
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
xylene sulfonate), NaBS (sodium benzene sulfonate), NaCuS (sodium cumene sul-
phonate) and NaSaI (sodium salicylate) with 10 mol % PTSA. The reaction results
revealed that compared to NaXS, NaBS, NaCuS and NaSaI, the reaction proceeds
with high efciency when PTSA was combined with NaPTS (Table 1, entries 9–12).
Thus, it is worth noting that the reaction gave 89% yield of product within 100 min
reaction time. The higher activity of NaPTS observed due to its overall planar struc-
ture and presence of more balanced hydrophobic and hydrophilic regions that ofer
a good micro-environment of lower polarity and stabilizes the reactants through a
cooperative binding mechanism [42].
With the optimized reaction condition in hand, we expanded the scope and gener-
ality of reaction by reacting o-phenylene diamine (2) with various substituted isatins
(1a-f) containing electron-withdrawing or electron-donating groups (Table 2). It was
observed that the isatin with electron-donating groups reacted faster and gave higher
yields (Table 2, entries 2, 3 and 5) as compared to isatin with electron-withdrawing
groups (Table 2, entries 4 and 6).
Further, under the similar reaction conditions, ninhydrine (4a) and acenaphtho-
quinone (4b) also underwent smooth condensation with o-phenylene diamine (2)
to furnish the corresponding quinoxaline derivatives (5a and 5b) in good yields
(Scheme 2).
Encouraged by the above-mentioned results, we decided to carry out the synthe-
sis of bis-tetronic acids using BAHC in water under similar reaction condition. The
detailed literature survey showed that there are only few reports available for the
synthesis of bis-tetronic acids. Zhang et al. [46] described the preparation of bis-
tetronic acids using aldehydes as starting compounds and diethylamine as well as an
electrochemically generated base (EGB) as the catalysts. Daribi and coworkers [47]
reported the synthesis of bis-tetronic acids using isatin as starting compounds, while
Desai et al. [48] synthesized bis-tetronic acids by condensation reaction of alde-
hydes/isatins and tetronic acid using sulfamic acid as a solid acid catalyst. In our ini-
tial endeavor to synthesize bis-tetronic acids (8a), we carried out the condensation
of benzaldehyde (6) (1 mmol) with tetronic acid (7) (2 mmol) in a freshly prepared
BAHC (10 mol % PTSA and 5 mL 40% w/v NaPTS) in water at room temperature.
The complete transformation of the desired product 8a was observed in 3.5 h, as
monitored by TLC with isolated 88% yield (Table 3, entry 1). We also investigated
the substrate scope by reacting diferent aldehydes and isatins with tetronic acid. It
was observed that all the aromatic aldehydes and isatins furnished corresponding
products (8a-h and 9a-f) in excellent yields (Table 3, entries 1–14).
Reaction mechanism for synthesis of bis‑tetronic acids
A mechanistic rationale portraying the plausible progress of events is briefy
outlined in Scheme 3. PTSA probably activates the carbonyl carbon of aldehyde
(6), which undergoes the nucleophilic attack of tetronic acid (7) via Knoeve-
nagel condensation to give α,β-unsaturated dicarbonyl intermediate (A). Sub-
sequently, another tetronic acid (7) molecule attack intermediate (A), giving
Michael adducts (B) which upon tautomerization yields the desired product (8).
1 3

A. Kumbhar et al.
Table 2 Synthesis of quinoxalines in BAHCa
Entry
1
Product
Time (min)
100
Yieldb (%)
89
Melting point (°C)
Obs
Lit.[Ref.]
285–287
290–292 [45]
N
N
N
H
3a
2
3
4
5
6
90
90
89
90
84
89
83
291–292
302–304
220–222
301–303
>300
>293 [45]
>300 [45]
222–224 [45]
>300 [45]
>300 [45]
Me
OMe
Cl
N
N
N
H
3b
N
N
N
H
3c
120
90
N
N
N
H
3d
Me
N
N
Me
N
H
3e
120
Br
N
N
N
H
3f
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
Table 2 (continued)
aReaction conditions: Isatins (1 mmol), o-phenylenediamine (1 mmol), PTSA (10 mol %), 40% aqueous
NaPTS hydrotropic solution (5 mL), RT
Scheme 2 Synthesis of quinoxaline of ninhydrine / acenaphthoquinone in BAHC
In this reaction, the eliminated water molecules get easily absorbed by hydro-
philic head groups of hydrotrope. As a result of the overall efect, there is rate
enhancement of reaction.
Recyclability study of BAHC
Hydrotropes being a novel class of reaction media which is widely used to develop
a highly efcient protocol for the preparation of various heterocyclic compounds. In
addition, BAHC could be easily reused many times. Thus, the recyclability of the
BAHC was studied for two reactions. After the completion of the reaction, water
was added to the reaction mixture and the precipitated product was simply separated
by fltration. The aqueous solution of BAHC was recovered by fltration, washed
thoroughly with diethyl ether, concentrated and then used for the next reaction cycle.
As shown in Fig. 2, the BAHC could be recycled up to fve times without a signif-
cant decrease in catalytic properties for both the reactions.
Conclusion
In summary, we have synthesized indoloquinoxaline and bis-tetronic acid deriva-
tives by a simple and sustainable one-pot approach using Brönsted acid hydrotrope
combined catalyst (BAHC) in water at room temperature. The developed method
provides several advantages like clean reaction profles, water as a reaction medium,
reactions at ambient temperature, easy isolation of product and high yield of prod-
ucts. Moreover, the BAHC could be recycled at least fve times.
1 3

A. Kumbhar et al.
Table 3 Synthesis of bis-tetronic acids in BAHCa
Entry
1
Product
Time (h)
3.5
Yieldb (%)
88
Melting point (°C)
Obs
Lit.[Ref.]
131–133
132–135 [48]
2
3
4
3.0
3.0
3.0
84
89
83
213–215
170–172
232–234
210–212 [48]
174–178 [48]
232–234 [48]
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
Table 3 (continued)
Entry
5
Product
Time (h)
3.0
Yieldb (%)
83
Melting point (°C)
Obs
Lit.[Ref.]
190–192
187–190 [48]
6
3.5
84
191–193
190–192 [48]
7
8
2.5
3.0
86
87
240–242
174–176
235–237 [48]
175–178 [48]
1 3

A. Kumbhar et al.
Table 3 (continued)
Entry
9
Product
Time (h)
4.0
Yieldb (%)
88
Melting point (°C)
Obs
Lit.[Ref.]
169–171
168–170 [48]
10
11
12
3.5
3.5
4.0
85
84
85
178–180
180–182
160–162
175–178 [48]
182–184 [48]
158–161 [48]
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
Table 3 (continued)
Entry
13
Product
Time (h)
4.0
Yieldb (%)
85
Melting point (°C)
Obs
Lit.[Ref.]
162–164
162–164 [48]
14
4.0
86
170–172
177–179 [48]
aReaction conditions: Aldehydes/isatins (1 mmol), tetronic acid (2 mmol), PTSA (10 mol%), 40% aque-
ous NaPTS hydrotropic solution (5 mL), RT
bIsolated yields
1 3

A. Kumbhar et al.
Scheme 3 Plausible mechanistic pathway for synthesis of bis-tetronic acids in BAHC
Fig. 2 Recyclability study of BAHC catalyst
1 3

Brönsted acid hydrotrope combined catalysis in water: a green…
Acknowledgements We like to show our appreciation to the University Grants Commission, Govern-
ment of India, New Delhi, for enduring this work under the scheme of Major Research Project [F.No.41-
182/2014 (SR)]. We also thankful to the Department of Chemistry, Shivaji University, Kolhapur for pro-
viding IR, 1H and 13C NMR Spectral analytical facilities.
References
1. C.-J. Li, L. Chen, Chem. Soc. Rev. 35, 68 (2006)
2. V.R. Vemula, V. Lagishetty, S. Lingala, Int. J. Pharm. Sci. Rev. Res. 5, 41 (2010)
3. C. Neuberg, Biochem. Z. 76, 107 (1916)
4. N.S. Tavare, V.K. Jadhav, J. Chem. Eng. Data. 41, 1196 (1996)
5. V. Srinivas, D. Balasubramanian, Langmuir 14(23), 6658 (1998)
6. V. Srinivas, G.A. Rodley, K. Ravikumar, W.T. Robinson, M.M. Turnbull, Langmuir 13(12), 3235
(1997)
7. A. Sapkal, S. Kamble, J. Heterocycl. Chem. 57(10), 3597 (2020)
8. G. Rashinkar, S. Kamble, A. Kumbhar, R. Salunkhe, Trans. Met. Chem. 35, 185 (2010)
9. S. Kamble, A. Kumbhar, G. Rashinkar, M. Barge, R. Salunkhe, Ultrason Sonochem. 19(4), 812
(2012)
10. M. Barge, S. Kamble, A. Kumbhar, G. Rashinkar, R. Salunkhe, Monatsh. Chem. 144(8), 1213
(2013)
11. S. Jadhav, A. Kumbhar, C. Rode, R. Salunkhe, Green Chem. 18, 1898 (2016)
12. A. Patil, R. Salunkhe, Res. Chem. Intermed. 43, 4175 (2017)
13. A. Patil, M. Barge, G. Rashinkar, R. Salunkhe, Mol. Divers. 19(3), 435 (2015)
14. R. Pratap, V.J. Ram, Chem. Rev. 114(20), 10476 (2014)
15. C.H. Jin, M. Krishnaiah, D. Sreenu, V.B. Subrahmanyam, H.-J. Park, S.-J. Park, Y.Y. Sheen, D.-K.
Kim, Bioorg. Med. Chem. 22(9), 2724 (2014)
16. D. Zych, A. Slodek, S. Krompiec, K. Malarz, A. Mrozek-Wilczkiewicz, R. Musiol, Chem. Select
3(24), 7009 (2018)
17. P.K. Paliwal, S.R. Jetti, S. Jain, Med. Chem. Res. 22(6), 2984 (2013)
18. Q. Li, S. He, Y. Chen, F. Feng, W. Qu, H. Sun, Eur. J. Med. Chem. 158, 463 (2018)
19. X. Wan, C. Li, M. Zhang, Y. Chen, Chem. Soc. Rev. 49, 2828 (2020)
20. A. Slodek, D. Zych, A. Maroń, S. Golba, E. Schab-Balcerzak, H. Janeczek, M. Siwy, S. Maćkowski,
Dyes Pigm. 166, 98 (2019)
21. H. Lai, J. Hong, P. Liu, C. Yuan, Y. Li, Q. Fang, RSC Adv. 2, 2427 (2012)
22. Y. Feng, D. Li, Q. Wang, S. Wang, X. Meng, Z. Shao, M. Zhu, X. Wang, Sens. Actuators B Chem.
225, 572 (2016)
23. A. Slodek, D. Zych, S. Golba, S. Zimosz, P. Gnida, E. Schab-Balcerzak, J. Mat. Chem. C. 7, 5830
(2019)
24. M. Judith Percino, M. Cerón, P. Venkatesan, E. Pérez-Gutiérrez, P. Santos, P. Ceballos et al., RSC
Adv. 9, 28704 (2019)
25. M.S. Abdelfattah, T. Kazufumi, M. Ishibashi, J. Nat. Prod. 73(12), 1999 (2010)
26. P.S. Chandrachood, A.R. Jadhav, D.R. Garud, N.R. Deshpande, V.G. Puranik, R.V. Kashalkar, Res.
Chem. Intermed. 46, 5219 (2020)
27. G. Sakata, K. Makino, Y. Kurasawa, Heterocycles 27, 2481 (1988)
28. K.R. Justin Thomas, M. Velusamy, J.T. Lin, C.H. Chuen, Y.T. Tao, Chem. Mater. 17(7), 1860
(2005)
29. S. Dailey, J.W. Feast, R.J. Peace, I.C. Sage, S.Till, E.L.Wood, J. Mater. Chem. 11, 2238 (2001)
30. M.J. Crossley, L.A. Johnston, Chem. Commun. 1122 (2002)
31. M.M. Abdou, R.A. El-Saeed, M.A. Abozeid, M.G. Sadek, E. Zaki, Y. Barakat, H. Ibrahim, M.
Fathy, S. Shabana, M. Amine, S. Bondock, Arab. J. Chem. 12(4), 464 (2019)
32. A.L. Zografos, D. Georgiadis, Synthesis 3157 (2006)
33. D. Tejedor, F. García-Tellado, Org. Prep. Proced. Int. 36(1), 33 (2004)
34. L. Vieweg, S. Reichau, R. Schobert, P.F. Leadlay, R.D. Süssmuth. Nat. Prod. Rep. 31(11), 1554
(2014)
1 3

A. Kumbhar et al.
35. B.E. Roggo, F. Petersen, R. Delmendo, H.B. Jenny, H.H. Peter, J. Roesel, J. Antibiot. 47(2), 136
(1994)
36. K. Rehse, U. Emisch, Arch. Pharm. 316(2), 115 (1983)
37. K. Luk, S.A. Readshaw, J. Chem. Soc. Perkin Trans. 1(7), 1641 (1991)
38. E.J. Murray, R.C. Crowley, A. Truman, S.R. Clarke, J.A. Cottam, G.P. Jadhav, V.R. Steele, P.
O’Shea, C. Lindholm, A. Cockayne, S.R. Chhabra, W.C. Chan, P. Williams, J. Med. Chem. 57(6),
2813 (2014)
39. A. Dal Pozzo, A. Dansi, E. Neneghini, Bull. Chim. Farm. 113(5), 280 (1974)
40. F.R. Foden, J. McCormick, D.M. O’Mant, J. Med. Chem. 18(2), 199 (1975)
41. M. Andreoli, M. Persico, A. Kumar, N. Orteca, V. Kumar, A. Pepe, C. Fattorusso, et al., J. Med.
Chem. 57(19), 7916 (2014)
42. A. Kumbhar, S. Kamble, M. Barge, G. Rashinkar, R. Salunkhe, Tetrahedron Lett. 53(22), 2756
(2012)
43. R. Jain, K. Sharma, D. Kumar, Tetrahedron Lett. 53(46), 6236 (2012)
44. R. Dowlatabadi, A. Khalaj, S. Rahimian, M. Montazeri, M. Amini, A. Shahverdi, E. Mahjub, Synth.
Commun. 41, 1650 (2011)
45. P.G. Hegade, M.M. Mane, J.D. Patil, D.M. Pore, Syn. Commun. 44(23), 3384 (2014)
46. Z.Z. Zhang, H. Zhang, W.Z.-Q. Li, C.C. Zeng, R.-G. Zhong, Y.-B. She, RSC Adv. 1, 583 (2011)
47. M. Dabiri, Z.N. Tisseh, M. Bahramnejad, A. Bazgir, Ultrason. Sonochem. 18, 353 (2011)
48. K.S. Pandit, U.V. Desai, P.P. Wadgaonkar, K.M. Kodam, Res. Chem. Intermed. 43, 141 (2016)
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional afliations.
1 3