A novel synthesis of 3-((benzo[d]thiazol-2-ylamino)(phenyl)methyl)-4-hydroxy-1-methylquinolin-2(1H)-one via consecutive C–C and C–N bond formation in water

Article abstract of DOI:10.1007/s11164-020-04173-0

Abstract: A simple, efficient, and eco-friendly protocol has been developed for the synthesis of novel 3-((benzo[d]thiazol-2-ylamino)(4-methoxyphenyl)methyl)-4-hydroxy-1-methylquinolin-2(1H)-one derivatives using a one-pot C–C and C–N bond forming strategy from the reaction of 4-hydroxy-1-methylquinolin-2(1H)-one, 2-aminobenzothiazole and aromatic aldehydes in aqueous solvent without using any metal catalyst. Several advantages of this protocol include its operational simplicity, short reaction time, mild reaction condition, efficient utilization of all the reactants, wide functional group tolerance, using water as an environmentally friendly solvent and non-chromatographic purification procedure. Graphic abstract: [Figure not available: see fulltext.].

Full text of DOI:10.1007/s11164-020-04173-0

Research on Chemical Intermediates
https://doi.org/10.1007/s11164-020-04173-0
A novel synthesis of 3‑((benzo[d]thiazol‑2‑ylamino)
(
phenyl)methyl)‑4‑hydroxy‑1‑methylquinolin‑2(1H)‑one
via consecutive C–C and C–N bond formation in water
1
2
1
Maruti B. Yadav · Sandip S. Vagh · Yeon Tae Jeong
Received: 12 February 2020 / Accepted: 6 May 2020
©
Springer Nature B.V. 2020
Abstract
A simple, efcient, and eco-ꢀriendly protocol has been developed ꢀor the synthesis oꢀ
novel 3-((benzo[d]thiazol-2-ylamino)(4-methoxyphenyl)methyl)-4-hydroxy-1-meth-
ylquinolin-2(1H)-one derivatives using a one-pot C–C and C–N bond ꢀorming strat-
egy ꢀrom the reaction oꢀ 4-hydroxy-1-methylquinolin-2(1H)-one, 2-aminobenzothia-
zole and aromatic aldehydes in aqueous solvent without using any metal catalyst.
Several advantages oꢀ this protocol include its operational simplicity, short reaction
time, mild reaction condition, efcient utilization oꢀ all the reactants, wide ꢀunc-
tional group tolerance, using water as an environmentally ꢀriendly solvent and non-
chromatographic puriꢁcation procedure.
Graphic abstract
Keywords Green solvent · Quinolines · Thiazole · 4-Hydroxy-1-methylquinolin-
2
(1H)-one · Multicomponent reactions (MCRs)
Electronic supplementary material The online version oꢀ this article (https://doi.org/10.1007/s1116
-020-04173-0) contains supplementary material, which is available to authorized users.
4
Extended author inꢀormation available on the last page oꢀ the article
Vol.:(012
1
3456789)
3

M. B. Yadav et al.
Introduction
The combination oꢀ two or more pharmacophores in a single molecule is a well-
established assumption ꢀor the development oꢀ more eꢂective drugs. Many literature
reports have highlighted the enhanced bioactive properties oꢀ the combination and
ꢀ
used heterocycles [1–4]. Thiazole and quinoline are a key heterocyclic molecule
prevalent in many bioactive compounds as well as in synthetic drugs [5, 6]. Particu-
larly, benzothiazole and ꢀunctionalized quinoline are ꢀound in the core oꢀ various
drug as well as natural products [7, 8]. Compound such as 6-ꢃuoroquinolin-3-yl)
benzo[d]imidazo[2,1-b]thiazol-3-amine (A) displayed strong antiꢀungal activity
compare to standard ꢃuconazole (Fig. 1) [9]. N′-(4-argiothiazol-2-yl)-2-(thiophen-
2
-yl)quinoline-4-carbohydrazide (B) demonstrate to be a potent anti-Inꢃammatory
[
10]. Compound (C) is considered to be potent anti-HIV activity and tipiꢀarnib (D)
as potential anticancer agents [11, 12]. Thiazole moiety is an omnipresent scaꢂold
and has involved in many natural and synthetic molecules having interesting activi-
ties, such as anticancer, antiviral, antiparkison, antimicrobial, and anti-inꢃammatory
activities [13–21]. Similarly, ꢀunctionalized quinoline are attractive target in organic
synthesis because oꢀ their highly prominent biological activities [22–25], including
anticancer [26], anti-inꢃammatory [27], anti-tuberculosis [28], anticonvulsant [29],
antimalarial [30], antihypertensive [31], antidiabetic [32] and so on.
Multicomponent reactions (MCRs) being efcient methods ꢀor the sustainable
and diversity oriented synthesis oꢀ heterocycles [33–40], it provides one oꢀ the most
powerꢀul platꢀorms to access diversity as well as complexity ꢀrom simple and inex-
pensive starting materials via the generation oꢀ several bonds in a single synthetic
operation. And also a great relevance to green chemistry because oꢀ the waste ꢀrom
organic solvents and chromatographic stationary phases associated with a reduced
number oꢀ intermediate puriꢁcation steps [41–46]. Water is a non-toxic, nonꢃam-
mable, non-hazardous, inexpensive, uniquely redox-stable solvent that the additional
advantage oꢀ being non-exhaustible resource. Consequently, water is close to being
Fig. 1 Some biological active molecules containing the thiazole and quinoline motiꢀ
1
3

A novel synthesis of…
an ideal green solvent, preꢀerable to alternatives such as ionic liquid [47, 48] ꢀor this
reasons the development oꢀ synthetically useꢀul reactions using water as the reaction
medium has gained considerable interest.
In continuation oꢀ our consistent eꢂorts in the development oꢀ novel synthetic
methodologies [49–55], using 4-hydroxy-1-methylquinoline derivatives as a key sub-
strate, we report a convenient synthesis oꢀ 3-((benzo[d]thiazol-2-ylamino)(phenyl)
methyl)-4-hydroxy-1-methylquinolin-2(1H)-one via p-toluenesulꢀonic acid mediated
one-pot MCRs condensation oꢀ 4-hydroxy-1-methylquinoline (1a), 2-aminobenzo-
thiazole (2a), aromatic aldehyde (3a) under water and Ethanol solvent (Scheme 1).
To the best oꢀ our knowledge, this is the ꢁrst reported synthesis oꢀ 3-((benzo[d]thia-
zol-2-ylamino) (phenyl) methyl)-4-hydroxy-1-methylquinolin-2(1H)-ones.
Result and discussion
For preliminary investigation, the reaction oꢀ 4-hydroxy-1-methylquinolin-2(1H)-
one (1a), 2-aminobenzothiazole (2a) and 4-Methoxybenzaldehyde (3a) has chosen
as a modal reaction. In the absence oꢀ any catalyst and solvent, we could not observe
the desired three component product, even aꢀter 12 h oꢀ stirring at reꢃux condition
with ethanol. Under the reꢃux and catalyst-ꢀree conditions, however, the same com-
bination provided 93% oꢀ bis-1-methylequinoline (5a) within 12 h ꢀrom the conden-
sation oꢀ two molecules oꢀ 4-hydroxy-1-methylquinolin-2(1H)-one (1a) with the
aldehyde (3a). The use oꢀ p-TSA (10 mol%) in reaction model provides the desired
three component product in 14% yield, along with a 53% yield oꢀ bis-1-methyle-
quinoline. Both the isolated compounds 4a and 5a are characterized by 1H-NMR
and 13C-NMR spectroscopy, and elemental analysis. Then, our attention is turned to
explore the various catalysts to achieve the optimum yield ꢀor 4a by minimizing the
Scheme 1 Synthesis oꢀ 3-((benzo[d]thiazol-2-ylamino) (phenyl) methyl)-4-hydroxy-1-methylquinolin-
2
(1H)-ones 4a and 3, 3′-(phenylmethylene) bis (4-hydroxy-1-methylquinolin-2(1H)-one) 5a
1
3

M. B. Yadav et al.
ꢀ
ormation oꢀ the bis-1-methylequinoline. Using AcOH and H2SO4 as the catalyst
the yield oꢀ 4a is unsatisꢀactory, similar to that obtained using TEA, Piperidine, and
L-proline. Thereꢀore, our attention is being ꢀocused on the other Lewis acids, such
as InCl3, FeCl3, InBr3 and the results are summarized in Table 1.
We have also investigated various solvent in the presence oꢀ p-TSA (Table 1,
entry 13–16) as the catalyst at reꢃux temperatures. To our surprise, we observed that
the reaction predominantly gives bis-1-methylequinoline (5a) along with traces oꢀ 4a
in organic solvents such as Acetonitrile, Toluene, Dimethylꢀormamide, Methanol,
(
Table 1, entry 13–16). As a ꢀurther investigation, we have screened the eꢂect oꢀ
temperature ꢀor this reaction (Table 1, entries 17–20). Interestingly, when we con-
duct reaction at lower temperature in the presence oꢀ p-TSA, the desire product 4a
is ꢀound 82% yield in 3 h (Table 1, entry 17). The best result is obtained in terms
oꢀ yield 96% and reaction time 2 h. When the reaction is perꢀormed using p-TSA in
5
0 °C (Table 1 entry 19). However, ꢀrom the environmental and economical point
oꢀ view, we have carried out the reaction in water, which aꢂorded the desire prod-
uct 88% yield within 4 h. (Table 1, entry 22). We are pleased to achieve complete
conversion oꢀ reactant and high yield oꢀ 4a using 20 mol% p-TSA in water at 60 °C
ꢀor 2 h. ꢀortunately, since the product are solid so they could be collected by simple
ꢁ
ltration.
Having optimized the reaction conditions, we proceed to expand the scope oꢀ the
reaction oꢀ 4-hydroxy-1-methylquinolin-2(1H)-one (1a), 2-aminobenzothiazole (2a)
with various substituted aldehydes (3a). A variety oꢀ ꢀunctional groups substituted at
the aromatic ring oꢀ the aldehyde substrate, including electron donating (methoxy,
ethoxy, methyl and isopropyl) and electron-withdrawing (i.e., chloro, ꢃuoro, bromo
and nitro) groups, are tolerated, thereꢀore we conclude that the electronic nature oꢀ
the substituents at the aldehyde does not signiꢁcantly aꢂect the reaction. Thereꢀore,
the present protocol has general applicability and accommodates a variety oꢀ substi-
tution patterns. However, hetero-aromatic aldehydes such as ꢀuran-2-carbaldehyde
and thiophene-2-carbaldehyde did not aꢂord the desired product under the opti-
mized reaction conditions (4w, 4x). In this procedure, the pure products are isolated
by recrystallization ꢀrom ethanol without any chromatogram phic or other unwieldy
work-up procedure. All the newly synthesized compounds (4a–4v) are ꢀully charac-
terized using 1H-NMR, 13C-NMR spectroscopy and elemental analysis. The struc-
ture oꢀ this 3-((benzo[d]thiazol-2-ylamino) (4-chlorophenyl) methyl)-4-hydroxy-
1
-methylquinolin-2(1H)-one (4i) are ꢀurther conꢁrmed by X-ray crystallography
spectrum (Fig. 2).
A plausible mechanism ꢀor the synthesis oꢀ 3-((benzo[d]thiazol-2-ylamino)
(
4-methoxyphenyl) methyl)-4-hydroxy-1-methylquinolin-2(1H)-one (4a) is shown
in Fig. 3. Initially, knoevenagel condensation oꢀ the 4-hydroxy-1-methylquinolin-
(1H)-one (1a) and aromatic aldehyde (3a) to generate an intermediate A. This is
2
ꢀ
ollowed by Michael addition oꢀ 2-aminobenzothiazole (2a) in presence oꢀ p-Tolue-
nesulꢀonic acid (p-TsOH) to ꢀorm intermediate B. The intermediate B goes a keto-
enol tautomerization (KET) to aꢂord the desired product 4a. We believe that the
catalyst enhances the electrophilicity oꢀ the carbonyl groups in Michael addition oꢀ
compound 4a.
1
3

A novel synthesis of…
Table 1 Optimization oꢀ reaction conditions . (Color table online)
a
Entry
Promoter (10 mol %)
Reaction condition
Time (h)
Yield (%)b
4
a
5a
93
92
53
71
61
98
95
82
84
79
82
96
83
91
88
59
1
2
3
4
5
6
7
8
9
–
–
–, 100 °C
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
12
03
03
02
02
12
04
02
06
06
–
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
EtOH, 80 °C
MeCN, 82 °C
Toluene, 110 °C
DMF, 120 °C
MeOH, 70 °C
EtOH, 60 °C
EtOH, 60 °C
EtOH, 50 °C
EtOH, 40 °C
p-TSA
H SO
AcOH
14
08
11
–
–
–
08
06
13
–
2
4
TEA
Piperidine
L-proline
InCl3
FeCl3
InBr3
CaCl2
p-TSA
p-TSA
p-TSA
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
12
p-TSA
p-TSA
18
82
86
96
87
–
88
94
22
–
P-TSA (15%)
P-TSA (20%)
P-TSA (30%)
P-TSA (20%)
P-TSA (20%)
P-TSA (20%)
P-TSA (20%)
P-TSA (20%)
–
–
–
–
–
–
56
98
H O, 25 °C
2
H O, 50 °C
2
H O, 60 °C
2
H O, 80 °C
2
H O, 100 °C
2
a
Reaction conditions: 4-hydroxy-1-methylquinolin-2(1H)-one (1 mmol, 1a), 4-Methoxybenzaldehyde
1 mmol, 3a), 2-aminobenzothiazole (1 mmol, 2a), and solvent 4 mL stirred at diꢂerent temperatures
Isolated yield
(
b
In addition, our attempt ꢀor the synthesized pyrimidine ꢀused ring system through
cyclisation oꢀ 3-((benzo[d]thiazol-2-ylamino)(4-methoxyphenyl)methyl)-4-hydroxy-
1
-methylquinolin-2(1H)-one (4a) as shows in Scheme 1, under solvent and catalytic
1
3

M. B. Yadav et al.
Fig. 2 X-ray crystal structure oꢀ
compound 4i. CCDC-1974973
Fig. 3 A plausible mechanism ꢀor the 3-((benzo[d]thiazol-2-ylamino) (4-methoxyphenyl) methyl)-4-hy-
droxy-1-methylquinolin-2(1H)-one (4a)
1
3

A novel synthesis of…
domino conditions have ꢀailed even at high temperature (up to 150 °C). This may be
attributed to the resonance-stabilized structures oꢀ 4a with vinylic-OH resisting con-
densative cyclisation under the present reaction condition (Table 2).
Conclusion
In conclusion, we have developed efcient methodology ꢀor the synthesis oꢀ
3
-((benzo[d]thiazol-2-ylamino) (4-methoxyphenyl) methyl)-4-hydroxy-1-meth-
ylquinolin-2(1H)-one derivatives by multicomponent reaction oꢀ 4-hydroxy-1-meth-
ylquinolin-2(1H)-one, 2-aminobenzothiazole and aromatic aldehydes. The present
methods are efcient and versatile method ꢀor the synthesis oꢀ diverse 3-((benzo[d]
thiazol-2-ylamino) (4-methoxyphenyl) methyl)-4-hydroxy-1-methylquinolin-2(1H)-
one. Considering the presence oꢀ bioactive 4-hydroxy-1-methylquinolin-2(1H)-
one and aminobenzothiazole moiety in the entire newly synthesized product, it
is expected that these molecules will ꢁnd applications in organic and medicinal
chemistry.
Experimental
Material and methods
Chemical has purchased ꢀrom Sigma-Aldrich and Alꢀa Aesar chemical companies
and used without ꢀurther puriꢁcation. NMR spectra are recorded in parts per million
(
ppm) in CDCl3 on a Jeol JNM ECP 400 NMR instrument using TMS as internal
standard abbreviation are used to denote signals multiplicities (s=singlet, d=dou-
blet, t=triplet, q=quartet, m=multiplate). HRMS were obtained by EI on a double-
ꢀ
ocusing mass analyser, ESI (positive ion mode) on TOF mass analyser. All melt-
ing points are determined using open capillaries on an Electro thermal-9100(Japan)
instrument and are uncorrected.
General procedure of the synthesis of 3‑((benzo[d]thiazol‑2‑ylamino)
(4‑methoxyphenyl) methyl) ‑4‑hydroxy ‑1‑methylquinolin‑2(1H)‑one (4a)
To a mixture oꢀ 4-hydroxy-1-methylquinolin-2(1H)-one (1 mmol), 2-aminobenzo-
thiazole (1 mmol) and 4-methoxybenzaldehyde (1 mmol) in 4 ml oꢀ H O or EtOH
2
was magnetically stirred at 50–60 °C ꢀor 2.0 h. Reaction was monitored by thin layer
chromatography (TLC). Aꢀter completion oꢀ the reaction, a solid product was ꢁl-
tered under the vacuum, air-dried, recrystallize with Ethanol, and obtain the analyti-
cally pure products. The compounds 4a–4v were also synthesized by adopting this
procedure.
3
‑((benzo[d]thiazol‑2‑ylamino)(4‑methoxyphenyl)methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4a) Yield: 96%; white solid; MP 174–176 °C; 1H NMR (400 MHz,
CDCl ) δ 8.22 (d, J=7.7 Hz, 1H), 7.55 (d, J=8.1 Hz, 2H), 7.51 (d, J=7.8 Hz, 1H),
3
1
3

M. B. Yadav et al.
Table 2 Substrate Scope. (Color table online)
1
3

A novel synthesis of…
Table 2 (continued)
a
Reaction conditions: 4-hydroxy-1-methylquinolin-2(1H)-one (1 mmol, 1a), 2-aminobenzothiazole (1
0
mmol, 2a), Aromatic aldehyde (1 mmol, 3a) and solvent 4mL stirred at 60 C
b
Isolated yield
7
3
1
1
.33–7.24 (m, 5H), 7.09 (t, J=7.5 Hz, 1H), 6.76 (d, J=8.5 Hz, 2H), 6.62 (s, 1H),
.69 (s, 3H), 3.63 (s, 3H). 13C NMR (100 MHz,) δ 168.28, 161.03, 158.57, 149.63,
39.76, 131.37, 129.99, 127.09, 126.44, 125.25, 122.79, 122.19, 121.39, 118.50,
14.15, 113.93, 55.41, 54.17, 29.76. HRMS (ESI, m/z): calcd ꢀor C25H21N3O3S
(
M+Na+) 467.1337, ꢀound: 467.1772.
3
‑((benzo[d]thiazol‑2‑ylamino) (3‑methoxyphenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4b) Yield: 92%; white solid; MP 178–180 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=8.0 Hz, 1H), 7.57 (d, J=8.1 Hz, 2H), 7.49 (d, J=7.8 Hz, 1H),
3
7
.34–7.23 (m, 3H), 7.11 (dt, J=15.4, 7.8 Hz, 2H), 6.94 (d, J=6.9 Hz, 2H), 6.66
(
s, 1H), 6.63 (s, 1H), 3.64 (s, 3H), 3.60 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
1
1
5
68.30, 161.42, 159.80, 149.51, 141.21, 139.76, 131.29, 130.04, 129.40, 126.37,
25.28, 122.60, 122.19, 121.33, 118.64, 118.46,118.30, 114.18, 112.57, 111.55,
5.25, 54.47, 29.87.
3
‑((benzo[d]thiazol‑2‑ylamino) (2‑methoxyphenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4c) Yield: 88%; white solid; MP:190–192 °C; 1H NMR (400 MHz,
CDCl ) δ 8.16 (d, J=7.9 Hz, 1H), 7.73 (d, J=7.6 Hz, 1H), 7.58–7.45 (m, 3H), 7.24
3
(
dd, J=13.3, 8.0 Hz, 4H), 7.07 (t, J=7.6 Hz, 1H), 6.98 (t, J=7.4 Hz, 1H), 6.87
(
d, J=8.1 Hz, 1H), 6.78 (s, 1H), 3.89 (s, 3H), 3.59 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 167.50, 163.26, 159.02, 156.26, 139.51, 131.27, 128.68, 128.03, 126.32,
1
2
24.99, 122.52, 122.14, 121.34, 117.71, 114.07, 111.32, 110.89, 56.55, 51.04,
9.51.
3‑((benzo[d]thiazol‑2‑ylamino) (p‑tolyl) methyl)‑4‑hydroxy‑1‑methylquinolin‑2(1H)‑one
(
4d) Yield: 93%; white solid; MP: 182–184 °C; 1H NMR (400 MHz, CDCl ) δ
3
8
.23 (d, J=7.8 Hz, 1H), 7.60–7.47 (m, 3H), 7.35–7.21 (m, 5H), 7.09 (t, J=7.4 Hz,
H), 7.01 (d, J=7.3 Hz, 2H), 6.64 (s, 1H), 3.65 (s, 3H), 2.21 (s, 3). 13C NMR NMR
1
(
100 MHz, CDCl3) δ 168.37, 163.74, 161.34, 149.71, 139.90, 136.39, 131.49,
1
30.08, 129.23, 126.51, 125.95, 125.38, 122.78, 122.25, 121.42, 118.74, 118.46,
14.22, 54.43, 30.02, 21.37.
1
3‑((benzo[d]thiazol‑2‑ylamino) (o‑tolyl) methyl)‑4‑hydroxy‑1‑methylquinolin‑2(1H)‑one
(
(
4e) Yield: 87%; white solid; MP:190–192 °C; 1H NMR (400 MHz, CDCl ) δ 8.22
3
d, J=7.4 Hz, 1H), 7.77 (d, J=7.2 Hz, 1H), 7.61 (d, J=7.7 Hz, 1H), 7.54–7.45 (m,
2
1
1
1
H), 7.34–7.23 (m, 3H), 7.18–7.07 (m, 4H), 6.59 (s,1H), 3.54 (s, 3H), 2.21 (s, 3H).
3C NMR (100 MHz, CDCl3) δ 168.62, 163.14, 160.44, 149.59, 139.79, 136.98,
35.79, 131.36, 130.87, 127.60, 127.39, 126.52, 125.73, 125.26, 122.93, 122.18,
21.49, 118.66, 118.22, 114.15, 111.40, 53.57, 29.59, 19.84.
1
3

M. B. Yadav et al.
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑ethoxyphenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4f) Yield: 88%; white solid; MP:180–182 °C; 1H NMR (400 MHz,
CDCl ) δ 8.21 (d, J=7.9 Hz, 1H), 7.53 (d, J=8.2 Hz, 2H), 7.48 (d, J=7.8 Hz, 1H),
3
7
6
1
1
1
.27 (dd, J=17.0, 8.2 Hz, 5H), 7.06 (t, J=7.4 Hz, 1H), 6.70 (d, J=8.6 Hz, 1H),
.61 (s, 1H), 3.84 (dt, J=17.0, 8.5 Hz, 2H), 3.63 (s, 3H), 1.30 (t, J=7.0 Hz, 3H).
3C NMR (100 MHz, CDCl3) δ 168.31, 161.12, 158.01, 149.74, 139.78, 131.35,
30.08, 127.88, 127.13, 126.41, 125.29, 122.71, 122.19, 121.39, 119.44, 118.54,
14.43, 114.16, 63.53, 54.21, 29.79, 15.20.
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑isopropylphenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4g) Yield: 87%; white solid; MP:174–176 °C; 1H NMR (400 MHz,
CDCl ) δ 8.21 (d, J=8.0 Hz, 1H), 7.55 (d, J=8.5 Hz, 2H), 7.50 (d, J=7.8 Hz, 1H),
3
7
.33–7.27 (m, 4H), 7.26 (s, 1H), 7.10 (dd, J=7.7, 3.1 Hz, 3H), 6.64 (s, 1H), 3.62 (s,
3
H), 2.84–2.76 (m, 1H), 1.17 (s, 3H), 1.16 (s, 3H). 13C NMR (100 MHz, CDCl3)
δ 168.29, 163.59, 161.16, 149.62, 147.31, 139.76, 136.71, 131.34, 130.37, 129.99,
1
5
4
26.60, 126.37, 126.02, 125.29, 122.64, 122.18, 121.36, 118.59, 118.37, 114.16,
4.55, 33.82, 29.81, 24.19. HRMS (ESI, m/z): calcd ꢀor C27H25N3O2S (M+Na+)
79.5713, ꢀound: 479.2032.
3‑((benzo[d]thiazol‑2‑ylamino) (phenyl) methyl)‑4‑hydroxy‑1‑methylquinolin‑2(1H)‑one
(
4h) Yield: 94%; white solid; MP:176–178 °C; δ 8.22 (d, J=7.9 Hz, 1H), 7.55 (d,
J=8.1 Hz, 2H), 7.51 (d, J=7.8 Hz, 1H), 7.37 (d, J=7.7 Hz, 2H), 7.33–7.22 (m,
H), 7.16 (t, J=7.2 Hz, 1H), 7.10 (t, J=7.5 Hz, 1H), 6.67 (s, 1H), 3.63 (s, 3H). 13C
5
NMR (100 MHz, CDCl3) δ 168.30, 163.58, 161.31, 149.52, 139.58, 131.41, 129.99,
1
28.51, 126.97, 126.59, 126.55, 125.27, 124.92, 122.74, 122.22, 121.38, 119.06,
18.50, 114.17, 112.01, 54.59, 29.89.
1
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑chlorophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4i) . Yield: 95%; white solid; MP:180–182 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=8.0 Hz, 1H), 7.50 (d, J=8.4 Hz, 2H), 7.51 (d, J=7.9 Hz, 1H),
3
7
.35–7.26 (m, 5H), 7.17 (d, J=8.6 Hz, 2H), 7.12–7.07 (m, 1H), 6.62 (s, 1H), 3.66
(
s, 3H). 13C NMR (100 MHz, CDCl3) δ 168.21, 161.53, 149.49, 139.76, 132.73,
1
1
4
31.59, 129.98, 128.68, 127.39, 126.50, 125.37, 122.91, 122.36, 121.42, 118.52,
14.22, 54.02, 29.88. HRMS (ESI, m/z): calcd ꢀor C24H18ClN3O2S (M+H+)
48.0808, ꢀound: 448.0888.
3
‑((benzo[d]thiazol‑2‑ylamino) (3‑chlorophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4j) Yield: 86%; white solid; MP: 184–186 °C; 1H NMR (400 MHz,
CDCl ) δ 8.22 (d, J=8.0 Hz, 1H), 7.58 (t, J=7.8 Hz, 2H), 7.53 (d, J=7.7 Hz,
3
1
H), 7.39–7.25 (m, 5H), 7.19–7.08 (m, 3H), 6.61 (s, 1H), 3.64 (s, 3H). 13C NMR
(
100 MHz, CDCl3) δ 164.47, 162.04, 161.80, 149.31, 139.79, 131.59, 129.95,
1
5
26.54, 125.34, 122.93, 122.33, 121.42, 118.49, 114.23, 113.93, 113.72, 113.32,
4.12, 29.89.
1
3

A novel synthesis of…
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑fuorophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4k) Yield: 88%; white solid; MP:174–178 °C; 1H NMR (400 MHz,
CDCl ) δ 8.22 (d, J=8.0 Hz, 1H), 7.60–7.55 (m, 2H), 7.51 (d, J=7.8 Hz, 1H), 7.37–
3
7
2
1
1
.27 (m, 3H), 7.28 (d, J=7.9 Hz, 2H), 7.10 (t, J=7.5 Hz, 1H), 6.92 (t, J=8.6 Hz,
H), 6.63 (s, 1H), 3.64 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 168.28, 163.17,
60.74, 149.54, 139.79, 131.57, 129.98, 127.63, 126.52, 125.36, 122.91, 122.35,
21.45, 118.53, 115.40, 115.12, 114.23, 77.71, 77.07, 54.05, 29.87.
3
‑((benzo[d]thiazol‑2‑ylamino) (3‑fuorophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4l) Yield: 83%; white solid; MP:182–184 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=7.9 Hz, 1H), 7.62–7.47 (m, 2H),7.51 (d, J=7.8 Hz, 1H), 7.36–
3
7
6
1
1
.25 (m, 3H), 7.15 (t, J=8.2 Hz, 2H), 7.12–7.04 (m, 2H), 6.82 (t, J=7.3 Hz, 1H),
1
.63 (s, 1H), 3.67 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 163.05 ( J =292 Hz),
C-F
3
62.08, 149.36, 139.83, 131.63, 129.99 ( J =8 Hz), 126.54, 125.38, 122.97,
C-F
2
2
22.37, 121.46, 118.48, 114.27, 114.27, 113.86 ( J =21 Hz), 113.24 (
J
C-F
1
9
=
23 Hz), 54.16, 29.89. F NMR δ (− 114.54).
C-F
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑bromophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4m) Yield: 89%; white solid; MP: 186–188 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=7.6 Hz, 1H), 7.62–7.47 (m, 3H), 7.30 (m, 7H), 7.10 (t,
3
J=7.3 Hz, 1H), 6.61 (s, 1H), 3.67 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 168.24,
1
1
63.58, 161.61, 149.41, 139.79, 131.63, 129.96, 127.81, 126.54, 125.41, 122.94,
22.40, 121.46, 120.93, 118.53, 114.26, 54.14, 29.96. HRMS (ESI, m/z): calcd ꢀor
C24H18BrN3O2S4 (M+H+) 492.0303, ꢀound: 492.0382.
3
‑((benzo[d]thiazol‑2‑ylamino) (3‑bromophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4n) Yield: 83%; white solid; MP: 190–192 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=7.8 Hz, 1H), 7.58 (t, J=8.1 Hz, 2H), 7.52 (d, J=8.7 Hz, 2H),
3
7
.34 (d, J=8.6 Hz, 1H), 7.31–7.26 (m, 3H), 7.23 (s, 1H), 7.14–7.01 (m, 2H), 6.61
(
s, 1H), 3.66 (S, 3H). 13 CNMR (100 MHz, CDCl3) δ 161.58, 154.49, 149.47,
1
1
42.26, 140.00, 131.70, 130.13, 129.15, 126.62, 125.48, 124.68, 123.04, 123.00,
22.45, 121.56, 118.64, 114.37, 54.08, 29.90.
3
‑((benzo[d]thiazol‑2‑ylamino) (4‑nitrophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4o) Yield: 91%; white solid; MP:178–180 °C; 1H NMR (400 MHz,
CDCl ) δ 8.24 (d, J=7.7 Hz, 1H), 8.03 (d, J=8.5 Hz, 2H), 7.62 (t, J=7.6 Hz, 1H),
3
7
.52 (d, J=8.0 Hz, 4H), 7.37 (d, J=8.4 Hz, 1H), 7.30 (t, J=7.4 Hz, 2H), 7.13 (t,
J=7.5 Hz, 1H), 6.68 (s, 1H), 3.69 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 163.43,
1
1
62.06, 146.97, 139.81, 132.00, 129.77, 126.80, 126.73, 125.51, 123.82, 123.30,
22.67, 121.43, 118.55, 118.47, 114.38, 54.40, 30.07. HRMS (ESI, m/z): calcd ꢀor
C24H18N4O4S (M+H+) 459.1049, ꢀound: 459.1130.
3
‑((benzo[d]thiazol‑2‑ylamino) (3‑nitrophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4p) Yield: 87%; white solid; MP:182–184 °C; 1H NMR (400 MHz,
CDCl ) δ 8.22 (d, J=8.0 Hz, 1H), 7.58 (d, J=8.1 Hz, 2H), 7.53 (d, J=7.7 Hz, 1H),
3
1
3

M. B. Yadav et al.
7
.38–7.25 (m, 5H), 7.15 (dd, J=17.5, 7.4 Hz, 3H), 6. 61 (s, 1H), 3.64 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 161.54, 156.62, 149.39, 139.88, 131.62, 130.05, 129.08,
1
5
26.54, 125.40, 124.59, 123.00, 122.94, 122.37, 121.48, 118.58, 118.52, 114.29,
4.01, 29.82.
3
‑((benzo[d]thiazol‑2‑ylamino) (2‑nitrophenyl) methyl)‑4‑hydroxy‑1‑methylquino‑
lin‑2(1H)‑one (4q) Yield: 84%; white solid; MP: 172–174 °C; 1H NMR (400 MHz,
CDCl ) δ 8.20 (d, J=7.9 Hz, 1H), 7.91 (d, J=7.8 Hz, 1H), 7.68 (d, J=7.9 Hz, 1H),
3
7
.61–7.48 (m, 4H), 7.37–7.24 (m, 5H), 7.12 (t, J=7.5 Hz, 1H), 3.61 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 163.25, 161.26, 148.66, 139.67, 134.34, 132.25, 131.64,
1
5
29.39, 128.05, 126.46, 125.42, 124.47, 122.96, 122.30, 121.37, 114.11, 110.34,
4.55, 29.65.
4
‑hydroxy‑1‑methyl‑3‑(((4‑methylbenzo[d]thiazol‑2‑yl) amino) (p‑tolyl) methyl) quino‑
lin‑2(1H)‑one (4r) Yield: 91%; white solid; MP: 190–192 °C; 1H NMR (400 MHz,
CDCl ) δ 8.22 (d, J=8.0 Hz, 1H), 7.56 (t, J=8.6 Hz, 1H), 7.43 (d, J=8.2 Hz, 1H),
3
7
2
.32–7.29 (m, 2H), 7.26–7.22 (m, 3H), 7.09 (d, J=9.1 Hz, 1H), 7.03 (d, J=7.9 Hz,
H), 6.61 (s, 1H), 3.62 (s, 3H), 2.36 (s, 3H), 2.24 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 167.48, 163.40, 160.76, 147.12, 139.48, 136.21, 132.38, 131.07, 129.06,
1
1
27.28, 125.45, 125.00, 121.90 121.20, 118.29, 117.85, 113.67, 54.08, 29.50, 21.11,
8.48.
3
‑((4‑chlorophenyl) ((4‑methylbenzo[d]thiazol‑2‑yl) amino) methyl)‑4‑hydroxy‑1‑meth‑
ylquinolin ‑2(1H)‑one (4s) Yield: 90%; white solid; MP: 188–190 °C; H1 NMR
(
400 MHz, CDCl ) δ 8.22 (d, J=8.0 Hz), 7.57 (t, J=7.8 Hz), 7.43 (d, J=8.2 Hz),
3
7
.30 (dd, J=17.3, 8.3 Hz), 7.18 (dd, J=8.6, 2.2 Hz), 7.10 (d, J=8.8 Hz), 6.59
(
s), 3.64 (s), 2.36 (s)0.13C NMR (100 MHz, CDCl3) δ NMR (100 MHz, CDCl3)
δ 161.10, 154.74, 146.92, 139.53, 132.66, 132.49, 131.31, 128.46, 127.43, 127.10,
1
25.10, 122.07, 121.25, 117.91, 113.97, 53.74, 29.55, 18.50.
4
‑hydroxy‑1‑methyl‑3‑(((4‑methylbenzo[d]thiazol‑2‑yl)amino)(phenyl)methyl)quino‑
lin‑2(1H)‑one (4t) Yield: 90%; white solid; MP: 184–186 °C; 1H NMR (400 MHz,
CDCl ) δ 8.23 (d, J=9.5 Hz, 1H), 7.56 (t, J=7.0 Hz, 1H), 7.43 (d, J=8.2 Hz, 1H),
3
7
1
.38 (d, J=7.5 Hz, 2H), 7.26 (ddd, J=18.2, 15.2, 7.7 Hz, 5H), 7.14 (t, J=7.3 Hz,
H), 7.08 (d, J=8.3 Hz, 1H), 6.67 (s, 1H), 3.64 (s, 3H), 2.36 (s, 3H). 13C NMR
(
100 MHz, CDCl3) δ 167.72, 163.54, 161.21, 147.34, 139.70, 132.53, 131.33,
1
1
29.94, 128.47, 127.51, 126.93, 125.94, 125.28, 122.15, 121.41, 118.56, 117.97,
14.12, 101.84, 54.43, 29.77, 18.67.
4
‑hydrox y‑3‑((4‑isopropylphenyl)((4‑methylbenzo[d]thiazol‑2‑yl)amino)
methyl)‑1‑methylquinolin‑2(1H)‑one (4u) Yield: 88%; white solid; MP: 182–184 °C;
1
7
1
H NMR (400 MHz, CDCl ) δ 8.21 (d, J=7.6 Hz, 1H), 7.55 (t, J=7.3 Hz, 1H),
3
.42 (d, J=7.9 Hz, 1H), 7.28 (t, J=13.8 Hz, 5H), 7.07 (d, J=7.2 Hz, 3H), 6.63 (s,
H), 3.62 (s, 3H), 2.85–2.70 (m, 1H), 2.35 (s, 3H), 1.15 (d, J=6.4 Hz, 6H). 13C
NMR (100 MHz, CDCl3) δ 167.77, 160.96, 147.35, 139.74, 136.75, 132.71, 131.30,
1
3

A novel synthesis of…
1
3
27.60, 126.64, 125.95, 125.24, 122.13, 121.46, 118.51, 118.03, 114.13, 54.53,
3.85, 29.70, 24.24, 24.17, 21.56.
3
‑((4‑bromophenyl) ((4‑methylbenzo[d]thiazol‑2‑yl) amino) methyl)‑4‑hydroxy‑1‑meth‑
ylquinolin‑2(1H)‑one (4v) yYield: 92%; white solid; MP: 196–198 °C; 1H NMR
(
400 MHz, CDCl ) δ 8.23 (d, J=8.0 Hz, 1H), 7.62–7.52 (m, 1H), 7.42 (d, J=8.3 Hz,
3
1
H), 7.34–7.22 (m, 7H), 7.09 (d, J=8.2 Hz, 1H), 6.59 (s, 1H), 3.66 (s, 3H), 2.36 (s,
3
H). 13C NMR (100 MHz, CDCl3) δ NMR (100 MHz, CDCl3) δ NMR (101 MHz,)
δ 161.53, 147.08, 139.71, 132.72, 131.55, 129.88, 127.77, 127.59, 125.36, 122.30,
1
21.46, 120.83, 118.55, 117.99, 114.19, 54.03, 29.87, 18.69.
3
, 3′‑((4‑methoxyphenyl) methylene) bis (4‑hydroxy‑1‑methylquinolin‑2(1H)‑one)
(
5a) Yield: 98%; white solid; MP: 236–238 °C; 1H NMR (400 MHz, CDCl ) δ
3
1
7
6
2.86 (s, 1H), 12.47 (s, 1H), 8.23 (dd, J=18.3, 7.3 Hz, 2H), 7.61 (t, J=7.7 Hz, 2H),
.41 (d, J=8.5 Hz, 2H), 7.32 (dt, J=12.4, 7.6 Hz, 2H), 7.09 (d, J=8.4 Hz, 2H),
.80 (d, J=8.7 Hz, 2H), 6.39 (s, 1H), 3.82 (s, 3H), 3.77 (s, 3H), 3.72 (s, 3H). 13C
NMR (100 MHz, CDCl ) δ 167.13, 165.26, 162.39, 161.40, 158.06, 138.88, 138.73,
3
1
1
31.54, 131.50, 129.98, 127.88, 125.23, 125.13, 122.96, 122.88, 118.45, 118.13,
14.54, 114.45, 113.89, 111.95, 110.33, 55.49, 36.86, 30.84, 30.38. HRMS (ESI,
m/z): calcd ꢀor C H N O (M+H+) 468.1685, ꢀound: 469.9.
2
8
24
2
5
Supporting Information
Experimental details, H NMR & 13C NMR spectra ꢀor all compounds were pro-
1
vided as Supplementary material.
References
1
.
T.C. Küehler, J. Fryklund, N.-K. Bergman, J. Weilitz, A. Lee, H. Larsson, J. Med. Chem. 38, 4906
(
1995)
2
3
.
.
P. Madsen, L.B. Knudsen, F.C. Wiberg, R.D. Carr, J. Med. Chem. 41, 5150 (1998)
L. Llauger, H.Z. He, J. Kim, J. Aguirre, Z. Rosen, U. Peters, P. Davies, G. Chiosis, J. Med. Chem.
4
8, 2892 (2005)
4
5
.
.
N. Pietrancosta, A. Moumen, R. Dono, P. Lingor, V. Planchamp, F. Lamballe, M. Bahr, J.L. Kraus,
F. Maina, J. Med. Chem. 49, 3645 (2006)
R. Gali, J. Banothu, M. Porika, R. Velpula, S. Hnamte, Bioorg. Med. Chem. Lett. 24(17), 4242
(
2014)
6
7
.
.
R. Gupta, R.P. Chaudhary, J. Mol. Struct. 189, 1049 (2013)
N. Pietrancosta, A. Moumen, R. Dono, P. Lingor, V. Planchamp, M. Lamballe, M. Ba¨hr, J.-L.
Kraus and F. Maina. J. Med. Chem. 12, 3645, (2006)
8
.
A. Patel, S.Y. Sharp, K. Hall, W. Lewis, M.F. Stevens, P. Workman, C.J. Moody, Org. Biomol.
Chem. 14, 3889 (2016)
9
.
T.H. Al-Tel, R.A. Al-Qawasmeh, R. Zaarour, Eur. J. Med. Chem. 46, 1881 (2011)
1
1
1
0. S.B. Srinivasa, B. Poojary, U. Brahmavara, A.J. Das, S.K. Middha, Chem. Sel. 3, 12485 (2018)
1. J. Zhao, H. Huang, W. Wu, H. Chen, H. Jiang, Org. Lett. 15, 2604 (2013)
2. O. Aꢀzal, S. Kumar, M.R. Haider, M.R. Ali, R. Kumar, M. Jaggi, S. Bawa, Eur. J. Med. Chem. 07,
0
44 (2014)
1
3

M. B. Yadav et al.
1
1
1
3. O.I. El-Sabbagh, M.M. Baraka, S.M. Ibrahim, C. Pannecouque, G. Andrei, R. Snoeck, J. Balzarini,
A.A. Rashad, Eur. J. Med. Chem. 44, 3753 (2009)
4. V. Zaharia, A. Ignat, N. Palibroda, B. Ngameni, V. Kuete, C.N. Fokunang, M.L. Moungang, B.T.
Ngadjui, Eur. J. Med. Chem. 45, 5085 (2010)
5. I. Hutchinson, S.A. Jennings, B.R. Vishnuvajjala, A.D. Westwell, M.F.G. Stevens, J. Med. Chem.
4
5, 747 (2002)
1
1
1
1
2
2
2
6. A. Kamal, M.N.A. Khan, K.S. Reddy, K. Rohini, Bioorg. Med. Chem. 15, 1013 (2007)
7. R.B. Pathak, B. Jahan, S.C. Bahel, Bokin Bobai. 9, 480 (1981)
8. D.D. Erol, U. Çaliş, R. Demirdamar, N. Yuluĝ, M. Ertan, J. Pharm. Sci. 84, 465 (1995)
9. F. Azam, B.A. El-gnidi, I.A. Alkskas, M.A. Ahmed, Med. Chem. 25, 826 (2010)
0. Y. Kumar, R. Green, D.S. Wise, L.L. Wotring, L.B. Townsend, J. Med. Chem. 36, 3852 (1993)
1. R.N. Sharma, F.P. Xavier, K.K. Vasu, S.C. Chaturvedi, S.S. Pancholi, Med. Chem. 24, 897 (2009)
2. M.U. Rahman, G. Jeyabalan, P. Saraswat, G. Parveen, S. Khan, M.S. Yar, Synth. Commun. 47(5),
4
08 (2016)
2
2
2
2
2
2
2
3
3
3. D. Monchaud, C. Allain, M.P. Teulade-Fichou, Bioorg. Med. Chem. Lett. 26(18), 4845 (2016)
4. X. Chen, Y. Du, H. Sun, F. Wang, L. Kong, M. Sun, Bioorg. Med. Chem. Lett. 24(3), 887 (2014)
5. M. Zahediꢀard, F.L. Faraj, M. Paydar et al., Curr. Pharm. Des. 21(23), 3426 (2015)
6. V. Chandregowda, AK. Kush, G. Chandrasekara Reddy. Eur. J. Med. Chem. 44 (7), 3055, (2014).
7. V. Alagarsamy, V. Raja Solomon, K. Dhanabal. Bioorg. Med. Chem. 15(1), 241, (2007).
8. P. Nandy, M.T. Vishalakshi, A.R. Bhat, Indian. J. Heterocycl. Chem. 15(3), 294 (2006)
9. H. Georgey, N. Abdel-Gawad, S. Abbas, Molecules 13(10), 2569 (2008)
0. P. Verhaeghe, N. Azas, M. Gasquet, Bioorg. Med. Chem. Lett. 18(1), 401 (2008)
1. M, A. Ismail, S. Barker, D. A. Abau el-Ella, K. A. Abouzid, R. A. Toubar, M. H. Todd. J. Med.
Chem. 49 (5), 1535, (2006).
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
2. M.S. Malamas, J. Millen, J. Med. Chem. 34(4), 1503 (1991)
3. M.P.D. Mahindaratne, K. Wimalsena, J. Org. Chem. 3, 2866 (1998)
4. M. Zhang, Y.H. Liua, Z.R. Shanga, H.C. Hu, Z.H. Zhang, Catal. Commun. 88, 44 (2017)
5. M.N. Chen, L.P. Mo, Z.S. Cui, Z.H. Zhang, Curr. Opin. Green Sustain. Chem. 15, 37 (2019)
6. A. R. Khosropour, M. M. Khodaei, H. Moghannian, Synlett, 955, (2005).
7. V. Anuradha, P.V. Srinivas, P. Aparna, M.J. Rao, Tetrahedron Lett. 47, 4935 (2006)
8. T. Li, Y. Souma, O. Xu, Catal. Today 111, 291 (2006)
9. K.B. Wang, G.Y. Wang, Chin. Chem. Lett. 18, 813 (2007)
0. J.D. Mosely, Tetrahedron Lett. 46, 3181 (2005)
1. B.B. Thompson, M.J. Enone, Org. Lett. 13, 3289 (2011)
2. B.M. Trost, A.J. Frontier, J. Am. Chem. Soc. 122, 11727 (2000)
3. B.M. Trost, A.C. Gutierrez, R.C. Livingston, Org. Lett. 11, 2539 (2009)
4. B. Jiang, S.J. Tu, P. Kaur, W. Wever, G. Li, J. Am. Chem. Soc. 131, 11660 (2009)
5. B. Jiang, M.S. Yi, F. Shi, S.J. Tu, S. Pindi, P. McDowell, G. Li, Chem. Commun. 48, 808 (2012)
6. M. Li, H. Cao, Y. Wang, X.L. Lv, L.R. Wen, Org. Lett. 14, 3470 (2012)
7. Y. Coquerel, T. Boddaert, M. Presset, D. Mailhol, J. Rodriguez, Wiley-VCH. Weinheim, Germany
9
, 187 (2010)
4
4
5
5
5
5
5
5
8. S. Tiwariand, A. Kumar, Angew. Chem. Int. Ed. 45, 4824 (2006)
9. S.G. Balwe, Y.T. Jeong, RSC Adv. 6, 107232 (2016)
0. S.G. Balwe, K.T. Lim, B.G. Cho, Y.T. Jeong, Tetrahedron 73, 3564 (2017)
1. S.G. Balwe, V.V. Shinde, A.A. Rokade, S.S. Park, Y.T. Jeong, Catal. Commun. 99, 126 (2017)
2. Y.T. Jeong, S.G. Balwe, Org. Chem. Front. 5, 1632 (2018)
3. A.M. Jadhav, S.G. Balwe, K.T. Lim, Y.T. Jeong, Tetrahedron 73, 2813 (2017)
4. A.M. Jadhav, S.G. Balwe, J.S. Kim, K.T. Lim, Y.T. Jeong, Tetrahedron Lett. 60, 565 (2019)
5. S.G. Balwe, A.A. Rokade, S.S. Park, Y.T. Jeong, Catal. Commun. 128, 105703 (2019)
Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional afliations.
1
3

A novel synthesis of…
Aꢀliations
1
2
1
Maruti B. Yadav · Sandip S. Vagh · Yeon Tae Jeong
*
Yeon Tae Jeong
ytjeong@pknu.ac.kr
1
2
Department oꢀ Image Science and Engineering, Pukyong National University, Busan 608-737,
Republic oꢀ Korea
Organic Chemistry Division, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road,
Pashan, Pune 411 008, India
1
3