Applying green and highly efficient approach for a facile synthesis of new thiazoloquinoline, thiazolopyridine, and thiazolonaphthyridine derivatives

Article abstract of DOI:10.1007/s13738-018-01579-x

Abstract: An eco-friendly approach for the synthesis of new thiazoloquinolines, thiazolopyridines, and thiazolonaphthyridines scaffolds has been achieved using α-enolicdithioesters, cysteamine, arylglyoxal monohydrate, and cyclic 1,3-diketones (dimedone,

Full text of DOI:10.1007/s13738-018-01579-x

Journal of the Iranian Chemical Society
https://doi.org/10.1007/s13738-018-01579-x
ORIGINAL PAPER
Applying green and highly efficient approach for a facile synthesis
of new thiazoloquinoline, thiazolopyridine, and thiazolonaphthyridine
derivatives
Zahra Arabpoor1 · Hamid Reza Shaterian1
Received: 19 May 2018 / Accepted: 24 December 2018
© Iranian Chemical Society 2019
Abstract
An eco-friendly approach for the synthesis of new thiazoloquinolines, thiazolopyridines, and thiazolonaphthyridines scaffolds
has been achieved using α-enolicdithioesters, cysteamine, arylglyoxal monohydrate, and cyclic 1,3-diketones (dimedone,
4-hydroxycoumarin, and 4-hydroxy-1-methyl-2(1H)-quinolone) under thermal solvent-free conditions. The highlight of this
protocol is the generation of two heterocyclic rings, using a domino, one-pot, four-component reaction. In producing het-
erocyclic rings first, a thiazole ring generated from the reaction of α-enolicdithioesters and cysteamine is achieved. Second
heterocyclic ring formed by the condensation of conjugated thiazole with the Knoevenagel product achieved from arylglyoxal
monohydrate and 1,3-diketones followed by an N-cyclization. Catalyst- and solvent-free, short reaction times, high yields
and a simple work-up make it an attractive protocol for the preparation of diversified thiazoloquinoline, thiazolopyridine,
and thiazolonaphthyridine derivatives.
Graphical abstract
Keywords Multi-component reaction · Heterocycles · Solvent-free · Thiazoloquinoline · Thiazolopyridine ·
Thiazolonaphthyridine
Introduction
* Hamid Reza Shaterian
hrshaterian@chem.usb.ac.ir
The organic synthesis field has achieved many inventive
technical developments in designing environmental proto-
1
Department of Chemistry, Faculty of Sciences, University
cols that reduce toxic reagents [1]. Increasing detrimental
of Sistan and Baluchestan, Zahedan 98135-674, Iran
Vol.:(0123456789)
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Journal of the Iranian Chemical Society
effects of chemicals on the environment has made more
researchers devote significant efforts to protect it. The ideal
synthesis in organic chemistry should be a composition of
environmentally acceptable, atom efficient, safe, one-step,
simple reactions. Green chemical syntheses include design-
ing processes that can facilitate operations of products and
work-up, avoiding the employment of catalysts and/or sol-
vents or using green catalysts and/or solvents with the goal
of preserving the environment [2, 3]. In the last decade, cat-
alyst-free and solvent-free reactions were developed eschew-
ing the use of catalyst and hazardous solvents in organic
reactions. By synthesis protocols improvement, the use of
hazardous solvents is prevented and these milieus are better
to be removed or replaced by green solvents [4]. In other
words, catalyst- and solvent-free reactions significantly sim-
plify the procedures by reducing waste and its impact on the
environment [5].
frameworks are also important structures that have various
applications in many fields. Pyridine-attached thiazoles
exhibit antimicrobial [13] and antifungal activities [14].
Besides, thiazolo[3,2-a]pyridines, have shown many signif-
icant bioactivities [15] such as 6-substituted-5-aryl-7-im-
ino-3-phenyl-7H-thiazolo[3,2-a]pyridine-8-carbonitriles
(Fig. 1d), and 5-amino-2-(1,3-diphenylpyrazol-4-yl)methyl-
idene-3-oxo-6,8-dicyano-2,3,7-trihydro-7-aryl-thiazolo[3,2-
a]pyridines (Fig. 1e). Another important class of heterocy-
cles is the naphthyridines which can have biological and
pharmacological activities [16]. Its derivatives have antibac-
terial activities and they also are employed as diverse kinds
of inhibitors [17] such as 8-alkyl(or aryl)thiazolo[4,5-b] [1,
6] naphthyridin-2(3H)-ones (Fig. 1f). Literature procedures,
which have been used for preparation of the thiazoloqui-
nolines, thiazolopyridines, and thiazolonaphthyridines,
suffer from multi-linear steps, harsh conditions, long reac-
tion times, low yields, and expensive reagents [10, 12, 13,
16, 18–22]. We attempted to explore an efficient procedure
that resolves these problems to synthesize compounds of
the same scope. Among various methods of synthesizing
these compounds, the multi-component reaction is the best
to be used in our study. Instead of synthesizing by means of
multi-steps, we used a one-pot, multi-component reaction in
which instead of using different benzaldehyde derivatives,
we applied more active derivatives of arylglyoxals. Thus,
without any catalyst or additives, it succeeded in preparing
new derivatives from the family of these compounds for the
first time with short reaction times and good efficiency under
very simple green conditions.
Through multi-component reactions (MCRs), diverse
complex molecules are generated in one-pot reaction from
simple substances, without isolation and purification of
intermediates [6]. MCRs technology has largely impacted
drug synthesis processes and is endorsed by academia and
industry [7]. Besides, MCRs are an important source of
molecular diversity consuming less time and reducing costs
[8].
Quinolone derivatives have drawn researchers’ atten-
tion, because these structures are found in natural alkaloids
and are precursors of some compounds with pharmaco-
logical features [9, 10]. Furthermore, quinolones are strong
antagonists of many receptors, and when they fuse to sul-
fur-containing heterocycles can exhibit cytostatic activity
versus a wide domain of malignant cell lines [11]. In the
literature, these heterocyclic compounds are introduced as
strong antibacterial [12] and mycobacterial [10] agents such
as 5H-thiazolo[3,2-a]quinoline-4-carboxylic acid derivatives
(Fig. 1a), benzothiazolo[3,2-a]quinolones (Fig. 1b), and
2-arylthiazolo[4,5-c]quinoline-5H-ones (Fig. 1c). Pyridine
Herein, we represent a facile green synthesis of novel
series of thiazoloquinoline, thiazolopyridine, and thiazol-
onaphthyridine under solvent-free conditions. In this work,
we described a one-pot four-component reaction involving
α-enolicdithioesters, cysteamine, arylglyoxal monohydrate
and cyclic 1,3-diketones (dimedone, 4-hydroxycoumarin,
and 4-hydroxy-1-methyl-2(1H)-quinolone) as reactants for
Fig. 1 Examples of thiazolo-
quinoline, thiazolopyridine, and
thiazolonaphthyridine deriva-
tives having biological activities
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synthesis of thiazoloquinoline, thiazolopyridine, and thia-
zolonaphthyridine derivatives (Scheme 1). The merit of this
approach includes simplicity, short reaction time, easy work-
up, catalyst-free, solvent-free, one-step process.
arylglyoxal monohydrate (3) (1 mmol) and cyclic 1,3-dik-
etones (4, 6, 8) (1 mmol) under solvent-free conditions at
90 °C (Scheme 1, Tables 2, 3, 4). The corresponding thia-
zoloquinolines (5, Table 2), thiazolopyridines (7, Table 3),
and thiazolonaphthyridines (9, Table 4) were produced
within 20–70 min in good-to-excellent yields. The desired
products were collected and purified by crystallization with
H2O–EtOH.
Results and discussion
First, we initiated the synthesis of α-enolicdithioester (1)
with the reaction of aromatic methylketones (10) and trithi-
ocarbonate (11) (Table 1) [23, 24]. The α-enolicdithioester
(1) is an ideal starting material that can bear different func-
tional groups, such as the aromatic and heteroaromatic rings
for synthesis of diverse products.
In exploring electronic effects of arylglyoxal monohy-
drate, we employed compounds with electron-donating and
electron-withdrawing groups on the phenyl ring. The elec-
tron-poor arylglyoxal monohydrate gave higher yields than
electron-rich compounds, because the arylglyoxal monohy-
drate plays an electrophilic role in the reaction. It must be
taken into consideration that electron-withdrawing groups,
increase electrophilic properties and electron-donating
groups decrease its activity.
In continuation of our studies on MCRs reactions [25],
we started the synthesis of diverse thiazoloquinoline deriva-
tives as novel products, with the domino one-pot four-com-
ponent reaction of the α-enolicdithioesters (1) (1 mmol)
and cysteamine (2) (1 mmol) that followed by addition of
The proposed mechanism for generation of thiazoloquino-
line, thiazolopyridine, and thiazolonaphthyridine derivatives
Scheme 1 Green synthesis of thiazoloquinoline, thiazolopyridine, and thiazolonaphthyridine derivatives via one-pot four-component reaction
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Journal of the Iranian Chemical Society
Table 1 Synthesis of α-enolicdithioester derivatives
Entry
1
Carbonyl compound
Product
Yield a (%)
72
2
3
78
78
70
4
5
6
76
80
aIsolated yield after purification using crystallization, and drying
is represented in Scheme 2. According to literature [21, 25]
and our procedure, first thiazole ring (I) formed through the
reaction of α-enolicdithioester and cysteamine. Second, the
conjugated thiazole (I) formed in previous step, attacked to
Knoevenagel product (II) formed from arylglyoxal monohy-
drate and 1,3-diketone (dimedone, 4-hydroxycoumarin, and
4-hydroxy-1-methyl-2(1H)-quinolone) and produced inter-
mediate (III), which is in balance with intermediate (IV).
Finally, intramolecular N-cyclization of intermediate (IV),
which followed by dehydration, the desired thiazoloquino-
line, thiazolopyridine, and thiazolonaphthyridine derivatives
were formed.
domino reaction between α-enolicdithioesters, cysteam-
ine, arylglyoxal monohydrate and cyclic 1,3-diketones
(dimedone, 4-hydroxycoumarin, and 4-hydroxy-1-me-
thyl-2(1H)-quinolone) under solvent-free conditions at
90 °C. This approach integrated the advantages such as
broad functional scope, cost-effectiveness, short reaction
times, easy work-up and purification, and high yields.
This straightforward approach provided diversified novel
thiazoloquinoline, thiazolopyridine, and thiazolonaphthy-
ridine scaffolds, which can be applied as precursors of
medicinal compounds. In our opinion, this is an impor-
tant protocol based on economical and environmental
points of view, which complete avoiding catalysts and
solvents during reactions. We also avoided column purifi-
cations and products were purified by crystallizations with
H2O–EtOH. That is another great advantage of applying
this protocol.
Conclusions
In summary, we represented a facile approach for syn-
thesis of novel thiazoloquinolines, thiazolopyridines, and
thiazolonaphthyridines via one-pot, four-component, and
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Journal of the Iranian Chemical Society
Table 2 Substrate scope for the
synthesis of thiazoloquinoline
derivatives (5)
Entry
1
Product
Time (min)
60
Yield a (%)
75
5{1,1}
2
50
78
5{1,2}
3
4
60
30
77
84
5{5,1}
5{5,2}
5
6
55
50
83
92
5{6,1}
5{6,2}
7
8
9
35
40
35
85
82
92
5{2,1}
5{3,1)
5{4,1}
aIsolated yield after purification using crystallization, and drying
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Journal of the Iranian Chemical Society
Table 3 Substrate scope for the
synthesis of thiazolopyridine
derivatives (7)
Entry
1
Product
Time (min)
Yield a (%)
25
89
7{1,3}
2
40
83
7{5,1}
3
4
30
70
86
78
7{5,2}
7{6,1}
5
60
85
7{6,2}
7{2,1}
7{3,1}
6
7
20
30
95
92
aIsolated yield after purification using crystallization, and drying
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Journal of the Iranian Chemical Society
Table 4 Substrate scope
for the synthesis of
thiazolonaphthyridine
derivatives (9)
Entry
1
Product
Time (min)
30
Yield a (%)
85
9{5,1}
2
20
89
9{5,3}
25
85
3
4
9{5,2}
60
89
9{6,1}
5
6
50
25
92
90
9{6,2}
9{2,1}
9{3,1)
9{4,1}
7
8
35
30
89
92
aIsolated yield after purification using crystallization, and drying
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Journal of the Iranian Chemical Society
Scheme 2 Proposed mechanism
for thiazoloquinolines, thiazo-
lopyridines, and thiazolonaph-
thyridines generation
4‑Benzoyl‑5‑(hydroxyl(phenyl)methylene)‑8,8‑dime‑
thyl‑1,2,5,7,8,9‑hexahydro‑6H‑thiazolo[3,2‑a]quino‑
lin‑6‑one (5{1, 1})
Experimental
General methods and materials
1
Yellow solid; m.p. 200–202 °C (yield = 75%). H NMR
The commercially available reagents were purchased from
Merck and Sigma-Aldrich companies without further puri-
fication. The α-enolicdithioesters were prepared by the
reported method [23, 24]. The NMR spectra were recorded
on a Bruker Avance 300 MHz instrument in CDCl3. Infrared
(IR) spectra were provided with a JASCO FT-IR460 Plus
spectrophotometer. Mass spectra were recorded applying
an Agilent technologies 5973 network mass selective detec-
tor (MSD) operating at an ionization potential of 70 eV.
Melting points were determined in open capillaries using a
BUCHI510 melting point apparatus. Thin layer chromatog-
raphy (TLC) was performed on silica-gel Poly Gram SIL G/
UV 254 plates.
(300 MHz, CDCl3): δ 7.36(d, 2H, J=7.5 Hz), 7.24–7.05(m,
9H), 3.97(t, 2H, J = 14.7 Hz), 3.40 (t, 2H, J = 14.4 Hz),
1.95–1.64 (m, 4H), 0.72 (S, 3H), 0.59 (S, 3H) ppm; 13C
NMR (75 MHz, CDCl3): δ 197.17, 191.48, 171.23, 141.98,
139.53, 132.65, 131.13, 130.80, 128.73, 128.55, 128.36,
128.06, 116.96, 113.78, 111.01, 50.60, 48.23, 41.85,
34.82, 31.21, 30.07, 29.70, 26.69 ppm; MS (EI, 70 eV) m/z
(%) = 443 (M+, 67), 384 (17), 338 (53), 105 (100); FT-IR
(KBr, cm−1): 3433, 2924, 1598, 1480, 1366, 1155, 700.
4‑Benzoyl‑5‑(hydroxyl(4‑methoxyphenyl)
methylene)‑8,8‑dimethyl‑1,2,5,7,8,9‑hexahy‑
dro‑6H‑thiazolo[3,2‑a]quinolin‑6‑one (5{1, 2})
General procedure for the synthesis of thiazoloquinolines
analogues (5)
1
Yellow solid; m.p. 188–190 °C (yield = 73%). H NMR
(300 MHz, CDCl3): δ 7.36 (d, 2H, J = 7.2 Hz), 7.26–7.12
(m, 3H), 6.97 (d, 2H, J=8.4 Hz), 6.63 (d, 2H, J=8.7 Hz),
6.59(br, 1H), 3.94 (t, 2H, J=14.7 Hz), 3.56 (s, 3H), 3.39 (t,
2H, J=14.7 Hz), 1.90–1.70 (m, 4H), 0.731 (s, 3H), 0.607(s,
3H) ppm; 13C NMR (75 MHz, CDCl3): δ 197.22, 191.42,
171.09, 159.54, 141.56, 139.59, 131.09, 130.07, 128.36,
128.05, 123.15, 116.85, 114.00, 113.23, 111.10, 55.28,
50.64, 48.10, 41.82, 34.80, 31.23, 30.03, 29.70, 26.79 ppm;
MS (EI, 70 eV) m/z (%)=473 (M+, 84), 368 (46), 105 (100),
77 (50); FT-IR (KBr, cm−1): 3435, 2957, 1605, 1466, 1367,
1248, 1031, 840, 743.
A round-bottom flask was charged with the appropri-
ate α-enolicdithioesters (1 mmol), cysteamine (1 mmol)
and they were stirred at 90 °C over a pre-heated oil bath
under solvent-free conditions. When conjugated thiazole
was formed (monitored by TLC), arylglyoxal monohydrate
(1 mmol) and dimedone (1 mmol) were added to reaction
mixture and stirring continued for an appropriate period of
time. The completion of reaction was monitored by TLC.
Then, the yellow solid product was solved in ethanol and
quenched with distilled water. The obtained crude was
dried and crystallized with H2O–EtOH to produce the pure
product.
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4‑(Furan‑2‑carbonyl)‑5‑(hydroxyl(phenyl)
methylene)‑8,8‑dimethyl‑1,2,5,7,8,9‑hexahy‑
dro‑6H‑thiazolo[3,2‑a]quinolin‑6‑one (5{5, 1})
5‑(Hydroxyl(4‑methoxyphenyl)methylene)‑8,8‑dime‑
thyl‑4‑(thiophene‑2‑carbonyl)‑1,2,5,7,8,9‑hexahy‑
dro‑6H‑thiazolo[3,2‑a]quinolin‑6‑one (5{6, 2})
1
1
Yellow solid; m.p. 184–186 °C (yield = 86%). H NMR
(300 MHz, CDCl3): δ 7.53 (s, 1H), 7.44–7.19 (m, 7H),
6.46 (d, 1H, J = 1.8 Hz), 4.32–4.04 (m, 2H), 3.57(t, 2H,
J=14.1 Hz), 2.46–2.01 (m, 4H), 0.98 (s, 3H), 0.80(s, 3H)
ppm; 13C NMR (75 MHz, CDCl3): δ 197.22, 177.37, 172.04,
152.15, 146.04, 139.26, 133.14, 130.97, 128.87, 128.51,
128.23, 118.57, 114.27, 112.19, 111.29, 50.82, 48.22, 42.42,
35.02, 31.28, 29.81, 29.70, 27.07 ppm; MS (EI, 70 eV) m/z
(%)=433 (M+, 100), 374 (42), 338 (50), 95 (100), 55 (12);
FT-IR (KBr, cm−1): 3197, 2926, 1735, 1600, 1368, 1011,
866, 767, 752, 701.
Yellow solid; m.p. 142–144 °C (yield = 95%). H NMR
(300 MHz, DMSO): δ 7.27–7.18 (m, 2H), 6.91–6.86 (m,
1H), 6.71–6.66 (m, 2H), 3.82 (q, 2H, J = 13.2 Hz), 3.428
(s, 3H), 3.31–3.25 (m, 2H), 2.03–1.79 (m, 4H), 0.64 (s,
3H), 0.53 (S, 3H) ppm; 13C NMR (75 MHz, DMSO): δ
206.87, 197.50, 182.56, 171.86, 159.12, 143.99, 139.06,
132.25, 131.74, 130.02, 127.03, 123.73, 117.13, 113.69,
110.65, 55.16, 50.73, 48.03, 42.70, 34.75, 31.29, 30.86,
29.61, 27.12 ppm; MS (EI, 70 eV) m/z (%)=479 (M+, 94),
420 (20), 368 (64), 111 (100); FT-IR (KBr, cm−1): 3438,
2927, 1612, 1466, 1248, 1029, 837.
4‑(Furan‑2‑carbonyl)‑5‑(hydroxyl(4‑methoxyphenyl)
methylene)‑8,8‑dimethyl‑1,2,5,7,8,9‑hexahy‑
dro‑6H‑thiazolo[3,2‑a]quinolin‑6‑one (5{5, 2})
4‑(4‑Bromobenzoyl)‑5‑(hydroxyl(phenyl)methylene)‑8,8‑di‑
methyl‑1,2,5,7,8,9‑hexahydro‑6H‑thiazolo[3,2‑a]quino‑
lin‑6‑one (5{2, 1})
1
1
Yellow solid; m.p. 202–204 °C (yield = 84%). H NMR
Yellow solid; m.p. 182–184 °C (yield = 85%). H NMR
(300 MHz, CDCl3): δ 7.62 (br, 1H), 7.29–7.23(m, 4H), 6.88
(dd, 2H, J = 6 Hz), 6.55 (m, 1H), 4.21(q, 2H, J= 15 Hz),
3.83 (s, 3H), 3.66 (t, 2H, J = 12 Hz), 2.50–2.07 (m, 4H),
1.08 (s, 3H), 0.92 (S,3H) ppm; 13C NMR (75 MHz, CDCl3):
δ 197.36, 177.33, 159.49, 152.15, 145.99, 138.89, 132.93,
130.18, 123.33, 118.48, 113.95, 113.74, 112.16, 111.35,
55.29, 50.83, 48.09, 42.40, 35.00, 31.31, 29.77, 27.17 ppm;
MS (EI, 70 eV) m/z (%)=463 (M+, 100), 404 (31), 368 (40),
135 (25), 95 (56); FT-IR (KBr, cm−1): 3436, 2923, 1613,
1409, 1367, 1249, 1084, 469.
(300 MHz, CDCl3): δ 7.55 (d, 2H, J = 8.1 Hz), 7.48 (d,
2H, J = 9 Hz), 7.37–7.29 (m, 6H), 4.23 (t, 2H, J = 7.5 Hz),
3.69 (t, 2H, J = 7.2 Hz), 2.15–1.95 (m, 4H), 1.0 (s, 3H),
0.86 (S, 3H) ppm; 13C NMR (75 MHz, CDCl3): δ 197.21,
190.17, 171.20, 142.17, 138.34, 132.71, 131.25, 130.59,
129.91, 128.69,128.61, 128.38, 116.65, 113.72, 110.84,
50.59, 48.25, 41.78, 34.84, 31.20, 30.01, 29.70 ppm; MS
(EI, 70 eV) m/z (%) = 523 (M+, 48), 338 (72), 183 (90),
105 (59), 43 (100); FT-IR (KBr, cm−1): 3435, 2925, 1689,
1066.
5‑(Hydroxyl(phenyl)methylene)‑8,8‑dime‑
thyl‑4‑(thiophene‑2‑carbonyl)‑1,2,5,7,8,9‑hexahy‑
dro‑6H‑thiazolo[3,2‑a]quinolin‑6‑one (5{6, 1})
4‑(4‑Chlorobenzoyl)‑5‑(hydroxyl(phenyl)methylene)‑8,8‑di‑
methyl‑1,2,5,7,8,9‑hexahydro‑6H‑thiazolo[3,2‑a]quino‑
lin‑6‑one (5{3, 1})
1
1
Yellow solid; m.p. 174–176 °C (yield = 83%). H NMR
Yellow solid; m.p. 166–168 °C (yield = 82%). H NMR
(300 MHz, CDCl3): δ 7.53 (d, 2H, J = 13.2 Hz), 7.39 (d,
1H, J=4.8 Hz), 7.06-7.00 (m, 5H), 6.88 (s, 1H), 4.05–3.89
(m, 2H), 3.39 (t, 2H, J = 14.4 Hz), 2.23–1.93 (m, 4H),
0.77 (s, 3H), 0.62 (s,3H) ppm; 13C NMR (75 MHz,
CDCl3): δ 204.65, 197.04, 183.27, 172.71, 143.46, 139.17,
133.64, 133.24, 131.08, 128.86, 128.51, 127.51, 117.73,
114.17, 111.26, 50.77, 48.28, 42.62, 35.10, 31.16, 29.86,
29.70, 26.98 ppm; MS (EI, 70 eV) m/z (%) = 449 (M+,
90), 390 (33), 338 (77), 111 (100); FT-IR (KBr, cm−1):
3420,2958,2923,2619, 1736, 1592, 1475, 1369, 845, 707.
(300 MHz, CDCl3): δ 7.55 (d, 2H, J = 8.1 Hz), 7.55 (d,
2H, J = 8.1 Hz), 7.38–7.27 (m, 8H), 4.22 (t, 2H, J = 9 Hz),
3.67 (t, 2H, J = 9 Hz), 2.08–1.06 (m, 4H), 0.99 (s, 3H),
0.85 (S, 3H) ppm; 13C NMR (75 MHz, CDCl3): δ 197.15,
190.11, 171.12, 142.09, 137.89, 137.31, 132.66, 130.65,
129.81, 128.69,128.59, 128.27, 116.67, 113.86, 110.83,
50.58, 48.25, 41.78, 34.85, 31.22, 29.99, 29.68 ppm; MS
(EI, 70 eV) m/z (%) = 477 (M+, 0.3), 139 (8), 43 (100);
FT-IR (KBr, cm−1): 3435, 2925, 1723, 1625,1097.
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5‑(Hydroxyl(phenyl)methylene)‑4‑(4‑methoxybenzoyl)
‑8,8‑dimethyl‑1,2,5,7,8,9‑hexahydro‑6H‑thiazolo[3,2‑a]
quinolin‑6‑one (5{4, 1)
4‑(Furan‑2‑carbonyl)‑5‑(hydroxy(phenyl)methylene)‑1,2‑di‑
hydro‑5H,6H‑chromeno[3,4‑e]thiazolo[3,2‑a]pyridin‑6‑one
(7{5, 1})
1
1
Yellow solid; m.p. 166–168 °C (yield = 92%). H NMR
Yellow solid; m.p. 134–136 °C (yield = 83%). H NMR
(300 MHz, CDCl3): δ 7.65 (d, 2H, J = 9 Hz), 7.29–7.19
(m, 6H), 6.83 (d, 2H, J = 8.7 Hz), 4.17–4.06 (m, 2H),3.79
(s, 3H), 3.55 (t, 2H, J = 9 Hz), 2.30–1.98 (m, 4H), 1.01
(s, 3H), 0.78 (S, 3H) ppm; 13C NMR (75 MHz, CDCl3):
δ 196.99, 189.96, 170.92, 140.23, 138.23, 133.0, 132.92,
131.42, 131.21, 128.84,128.51, 128.14, 117.54, 113.45,
111.44, 55.45, 50.75, 48.24, 42.50, 34.99, 31.10, 30.0,
29.70 ppm; MS (EI, 70 eV) m/z (%) = 473 (M+, 25), 135
(72), 71 (44), 43 (100); FT-IR (KBr, cm−1): 3430, 2926,
1744, 1601, 1170.
(300 MHz, CDCl3): δ 10.10 (br, 1H), 7.57 (d, 1H,
J = 0.6 Hz), 7.44–7.39 (m, 2H), 7.33 (d, 2H, J= 3.3 Hz),
7.22 (br, 3H), 7.19 (br, 3H), 4.37–4.28 (m, 1H), 4.13–4.03
(m, 1H), 3.68–3.54 (m, 2H) ppm; 13C NMR (75 MHz,
CDCl3): δ 178.56, 164.09, 162.24, 153.02, 151.53, 147.23,
139.60, 134.27, 131.90, 130.86, 128.76, 128.46, 124.30,
123.65, 120.65, 116.85, 116.19, 113.72, 112.64, 102.62,
48.41, 35.29, 29.70 ppm; MS (EI, 70 eV) m/z (%)=455 (M+,
24),121 (82), 95 (100), 77 (64); FT-IR (KBr, cm−1): 3413,
2926, 1687, 1620, 1465, 760.
4‑(Furan‑2‑carbonyl)‑5‑(hydroxy(4‑methoxyphenyl)
methylene)‑1,2‑dihydro‑5H,6H‑chromeno[3,4‑e]
thiazolo[3,2‑a]pyridin‑6‑one (7{5, 2})
General procedure for the synthesis of thiazolopyridines
analogues (7)
1
A round-bottom flask was charged with the appropriate
α-enolicdithioesters (1 mmol), cysteamine (1 mmol) and
they were stirred at 90 °C over a pre-heated oil bath under
solvent-free conditions. When conjugated thiazole was
formed (monitored by TLC), arylglyoxal monohydrate
(1 mmol) and 4-hydroxycoumarin (1 mmol) were added to
reaction mixture and stirring continued for an appropriate
period of time. The completion of reaction was monitored
by TLC. Then, the yellow to orange solid product was
solved in ethanol and quenched with distilled water. The
obtained crude was dried and crystallized with H2O–EtOH
to produce the pure product.
Yellow solid; m.p. 148–150 °C (yield = 77%). H NMR
(300 MHz, CDCl3): δ 7.91 (d, 1H, J=9 Hz), 7.53 (s, 1H),
7.44–7.39 (m, 1H), 7.29 (d, 1H, J = 3 Hz), 7.21–7.12 (m,
4H), 6.75 (d, 2H, J = 6 Hz), 6.47 (br, 1H), 4.34–4.21 (m,
1H), 4.08–4.01 (m, 1H), 3.68 (s, 3H), 3.61–3.50 (m, 2H)
ppm; 13C NMR (75 MHz, CDCl3): δ 178.39, 164.07,
162.72, 159.58, 152.94, 151.54, 147.10, 139.62, 134.14,
131.91, 129.84, 124.27, 123.73, 123.10, 120.47, 116.79,
116.20, 114.33, 114.25, 112.62, 102.52, 55.21, 48.27, 35.22,
29.71 ppm; MS (EI, 70 eV) m/z (%)=485 (M+, 100), 135
(28), 121 (38), 95 (48), 43 (39); FT-IR (KBr, cm−1): 3430,
2921, 1698, 1610, 1466, 1249, 1176, 1028, 761.
4‑Benzoyl‑5‑(hydroxy(4‑nitrophenyl)methylene)‑1,2‑dihy‑
dro‑5H,6H‑chromeno[3,4‑e]thiazolo[3,2‑a]pyridin‑6‑one
(7{1, 3})
5‑(Hydroxy(phenyl)methylene)‑4‑(thiophene‑2‑carbon
yl)‑1,2‑dihydro‑5H,6H‑chromeno[3,4‑e]thiazolo[3,2‑a]
pyridin‑6‑one (7{6, 1})
1
Orange solid; m.p. 118–120 °C (yield = 89%). 1H
NMR (300 MHz, CDCl3): δ 10.70 (br, 1H), 8.18 (d,
2H, J = 8.4 Hz), 8.03 (d, 2H, J = 8.4 Hz), 7.83 (d, 2H,
J=8.4 Hz), 7.67–7.41 (m, 3H), 7.33–7.20 (m, 4H), 4.50 (q,
1H, J=18.6 Hz), 4.20–4.06 (m, 1H), 3.66 (t, 2H, J=15 Hz)
ppm; 13C NMR (75 MHz, CDCl3): δ 193.55, 165.07, 162.39,
152.97, 147.19, 143.36, 137.52, 137.37, 133.12, 132.50,
131.98, 129.63, 128.88, 128.60, 124.37, 124.18, 124.03,
118.34, 116.63, 116.33, 101.70, 48.77, 35.30, 29,70 ppm;
MS (EI, 70 eV) m/z (%) = 510 (M+, 0.04), 327 (17), 267
(62), 134 (69), 98 (100), 57 (81); FT-IR (KBr, cm−1): 3430,
2923, 2862, 1676, 1609, 1516, 1342, 1104, 757.
Yellow solid; m.p. 154–156 °C (yield = 85%). H NMR
(300 MHz, CDCl3): δ 10.42 (br, 1 H), 7.80 (d, 1H,
J=8.1 Hz), 7.68 (s, 1H), 7.5 (d, 2H, J=3 Hz), 7.26–7.22
(m, 2H), 7.05 (br, 4H), 6.04 (d, 2H, J=9.6 Hz), 4.23–4.17
(m, 1H), 3.89–3.83 (m, 1H), 345–3.39 (m, 2H) ppm; 13C
NMR (75 MHz, CDCl3): δ 184.75, 164.66, 162.21, 153.02,
142.56, 139.29, 135.51, 135.05, 134.52, 131.91, 130.95,
128.76, 128.41, 128.08, 124.40, 123.65, 118.11, 117.07,
116.16, 113.90, 102.59, 48.50, 35.39, 29.71 ppm; MS (EI,
70 eV) m/z (%)=471 (M+, 16), 111 (77), 43 (100); FT-IR
(KBr, cm−1): 3430, 2932, 1702, 1609, 1495, 1415, 1248,
764.
1 3

Journal of the Iranian Chemical Society
5‑(Hydroxy(4‑methoxyphenyl)methylene)‑4‑(thioph
ene‑2‑carbonyl)‑1,2‑dihydro‑5H,6H‑chromeno[3,4‑e]
thiazolo[3,2‑a]pyridin‑6‑one (7{6, 2})
General procedure for the synthesis of thiazolonaphthyri‑
dines analogues (9)
A round-bottom flask was charged with the appropri-
ate α-enolicdithioesters (1 mmol), cysteamine (1 mmol)
and they were stirred at 90 °C over a pre-heated oil bath
under solvent-free conditions. When conjugated thiazole
was formed (monitored by TLC), arylglyoxal monohy-
drate (1 mmol) and 4-hydroxy-1-methyl-2(1H)-quinolone
(1 mmol) were added to reaction mixture and stirring con-
tinued for an appropriate period of time. The completion
of reaction was monitored by TLC. Then, the yellow solid
product was solved in ethanol and quenched with distilled
water. The obtained crude was dried and crystallized with
H2O–EtOH to produce the pure product.
1
Yellow solid; m.p. 142–144 °C (yield = 78%). H NMR
(300 MHz, CDCl3): δ 10.51 (br, 1H), 7.80 (d, 1H,
J=7.8 Hz), 7.67 (d, 1H, J=3.6 Hz), 7.48 (d, 1H, J=4.8 Hz),
7.25 (t, 1H, J=15.9 Hz), 7.06–6.90 (m, 5H), 6.59 (d, 2H,
J=8.4 Hz), 4.22–4.13 (m, 1H), 3.89–3.81 (m, 1H), 3.53 (s,
3H), 3.46–3.35 (m,2H) ppm; 13C NMR (75 MHz, CDCl3):
δ 184.73, 164.62, 162.24, 159.59, 153.01, 142.60, 138.93,
135.44, 134.95, 134.43, 131.85, 129.76, 128.05, 124.39,
123.62, 123.29, 118.02, 117.12, 116.15, 114.26, 102.71,
55.21, 48.35, 35.36, 29.70 ppm; MS (EI, 70 eV) m/z
(%) = 501 (M+, 19), 121 (77), 111 (100), 65 (22); FT-IR
(KBr, cm−1): 3430, 3075, 2920, 1694, 1608, 1483, 1416,
758.
4‑(Furan‑2‑carbonyl)‑5‑(hydroxyl(phenyl)methylene)‑7‑me‑
thyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]thiazolo[3,2‑a] [1,6]
naphthyridin‑6‑one (9{5, 1})
4‑(4‑Bromobenzoyl)‑5‑(hydroxy(phenyl)methylene)‑1,2‑di‑
hydro‑5H,6H‑chromeno[3,4‑e]thiazolo[3,2‑a]pyridin‑6‑one
(7{2, 1})
1
Yellow solid; m.p. 180–182 °C (yield = 83%). H NMR
1
(300 MHz, CDCl3): δ 8.57 (br, 1H), 8.14 (d, 1H, J=7.5 Hz),
7.58–7.50 (m, 3H), 7.34–7.21 (m, 7H), 6.49–6.48 (m, 1H),
4.47–4.38 (m, 1H), 4.25–4.16 (m, 1H), 3.71–3.66 (m, 2H),
3.54 (s, 3H) ppm; 13C NMR (75 MHz, CDCl3): δ 178.02,
162.82, 159.49, 151.98, 146.34, 139.48, 133.50, 131.17,
130.83, 128.56, 128.39, 127.90, 124.59, 124.03, 121.43,
119.42, 117.26, 116.77, 113.62, 112.26, 108.08, 48.43,
35.17, 29.69, 29.37 ppm; MS (EI, 70 eV) m/z (%) = 468
(M+, 33), 95 (100), 77 (33); FT-IR (KBr, cm−1): 3410, 2924,
1735, 1627, 1467, 755.
Yellow solid; m.p. 188–190 °C (yield = 95%). H NMR
(300 MHz, CDCl3): δ 7.97 (d, 1H, J = 7.8 Hz), 7.68–7.65
(m, 2H), 7.55–7.52 (m, 3H), 7.38–7.22 (m, 8H), 4.44–4.38
(m, 1H), 4.20–4.12 (m, 1H), 3.70–3.60 (m, 2H) ppm; 13
C
NMR (75 MHz, CDCl3): δ 191.69, 163.68, 162.47, 152.96,
142.03, 136.80, 134.37, 132.10, 131.88, 131.68, 130.75,
130.56, 128.88, 128.62, 128.41, 127.53, 124.07, 123.82,
117.40, 116.31,113.37, 102.06, 48.51, 35.24, 29,71 ppm;
MS (EI, 70 eV) m/z (%)=545 (M+, 9), 185 (51), 105 (46),
43 (100); FT-IR (KBr, cm−1): 3434, 2925, 1721, 1099.
4‑(4‑Chlorobenzoyl)‑5‑(hydroxy(phenyl)methylene)‑1,2‑di‑
hydro‑5H,6H‑chromeno[3,4‑e]thiazolo[3,2‑a]pyridin‑6‑one
(7{3, 1})
4‑(Furan‑2‑carbonyl)‑5‑(hydroxyl(4‑nitrophenyl)
methylene)‑7‑methyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]
thiazolo[3,2‑a][1,6]naphthyridin‑6‑one (9{5, 3})
1
Yellow solid; m.p. 158–160 °C (yield = 92%). H NMR
1
Orange solid; m.p. 200–202 °C (yield = 95%). H NMR
(300 MHz, CDCl3): δ 9.57 (br, 1H), 7.97 (d, 1H, J=9 Hz),
7.76 (d, 2H, J = 9 Hz), 7.54–7.49 (m, 2H), 7.40–7.21 (m,
9H), 4.46–4.37 (m, 1H), 4.22–4.11 (m, 1H), 3.65 (t, 2H,
J=14.4 Hz) ppm; 13C NMR (75 MHz, CDCl3): δ 191.52,
163.53, 162.17, 152.99, 141.79, 138.92, 136.38, 134.34,
132.29, 132.09, 130.69, 130.60, 128.85, 128.70, 128.58,
128.42, 124.06, 123.73, 117.48, 116.26,113.46, 102.14,
48.50, 35.24, 29,70 ppm; MS (EI, 70 eV) m/z (%)=499 (M+,
11), 139 (94), 43 (100); FT-IR (KBr, cm−1): 3434, 2923,
2925, 1621, 1100.
(300 MHz, DMSO): δ 8.16 (d, 1H, J = 9 Hz), 7.90 (d,
1H, J = 6 Hz), 7.64–7.58 (m, 4 H), 7.50–7.43 (m, 2H),
7.28–7.17 (m, 2H), 7.01 (d, 1H, J = 3 Hz), 6.48–6.49 (m,
1H), 4.42–4.33 (m, 2H), 3.87–3.78 (m, 2H) ppm; 13C NMR
(75 MHz, DMSO): δ 176.29, 162.96, 161.48, 152.28,
146.48, 146.42, 141.99, 140.43, 139.52, 138.54, 131.79,
129.92, 129.29, 124.07, 123.55, 121.66, 118.94, 117.14,
114.99, 112.19, 98.38, 48.99, 35.05, 29.50, 28.91 ppm; MS
(EI, 70 eV) m/z (%)=513 (M+, 0.01), 316 (13), 175 (100),
146 (40), 132 (48), 77 (19); FT-IR (KBr, cm−1): 3430, 2921,
1596, 1564, 1338, 1240, 1113, 753.
1 3

Journal of the Iranian Chemical Society
4‑(Furan‑2‑carbonyl)‑5‑(hydroxyl(4‑methoxyphenyl)
methylene)‑7‑methyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]
thiazolo[3,2‑a][1,6]naphthyridin‑6‑one (9{5, 2})
4‑(4‑Bromobenzoyl)‑5‑(hydroxyl(phenyl)methylene)‑7‑me‑
thyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]thiazolo[3,2‑a][1,6]
naphthyridin‑6‑one (9{2, 1})
1
1
Yellow solid; m.p. 178–180 °C (yield = 83%). H NMR
Yellow solid; m.p. 220–222 °C (yield = 90%). H NMR
(300 MHz, CDCl3): δ 8.067 (br, 1H), 7.86 (d, 1H,
J = 7.8 Hz), 7.31–7.26 (m, 2H), 7.06–6.97 (m, 5H),
6.55 (d, 2H, J = 8.4 Hz), 6.25–6.24 (m, 1H), 4.15–4.06
(m,1H), 3.99–3.87 (m, 1H), 3.51 (s, 3H), 3.48–3.39 (m,
2H), 3.29 (s 3H) ppm; 13C NMR (75 MHz, CDCl3): δ
177.90, 162.66, 159.24, 159.02, 152.08, 146.18, 139.52,
133.26, 130.72, 129.72, 124.53, 123.60, 121.28, 119.14,
117.11, 116.66, 114.70, 114.05, 113.54, 112.23, 108.20,
55.19, 48.28, 35.15, 29.72, 29.66 ppm; MS (EI, 70 eV) m/z
(%)=498 (M+, 21), 95 (100), 77 (20); FT-IR (KBr, cm−1):
3430, 2924, 1745, 1610, 1464, 1249, 1173, 1028, 757.
(300 MHz, CDCl3): δ 7.95 (d, 1H, J=9 Hz), 7.58–7.53 (m,
2H), 7.45 (d, 2H, J = 9 Hz), 7.32–7.19 (m, 9H), 4.33–4.28
(m, 2H), 3.74–3.66 (m, 2H), 3.50 (s, 3H) ppm; 13C NMR
(75 MHz, CDCl3): δ 190.72, 162.40, 157.93, 142.57,
139.40, 137.94, 132.93, 131.11, 130.67, 129.80, 128.73,
128.34, 128.15, 125.62, 124.05, 121.46, 116.86, 115.57,
114.70, 113.73, 106.87, 48.44, 34.94, 29.72, 29.54 ppm;
MS (EI, 70 eV) m/z (%) = 558 (M+, 15), 293 (20), 184
(45), 105 (100), 43 (89); FT-IR (KBr, cm−1): 3443, 2925,
1627, 1076.
4‑(4‑Chlorobenzoyl)‑5‑(hydroxyl(phenyl)methylene)‑7‑me‑
thyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]thiazolo[3,2‑a][1,6]
naphthyridin‑6‑one (9{3, 1})
5‑(Hydroxyl(phenyl)methylene)‑7‑methyl‑4‑(thiophene‑2
‑carbonyl)‑1,2,5,7‑tetrahydro‑6H‑benzo[h]thiazolo[3,2‑a]
[1,6]naphthyridin‑6‑one (9{6, 1})
1
Yellow solid; m.p. 176–178 °C (yield = 89%). H NMR
1
(300 MHz, CDCl3): δ 7.96 (d, 1H, J = 9 Hz), 7.55 (d, 4H,
J = 9 Hz), 7.32–7.19 (m, 7H), 7.12 (d, 2H, J = 8.1 Hz),
4.31–4.29 (m, 2H), 3.72 (t, 2H, J = 7.2 Hz), 3.50 (s, 3H)
ppm; 13C NMR (75 MHz, CDCl3): δ 190.68, 162.43,
158.08, 142.39, 139.40, 137.41, 133.01, 131.07, 130.74,
129.79,129.34, 128.71, 128.35, 127.77, 124.10, 121.46,
116.98, 115.67, 114.76, 113.67, 106.96, 48.46, 34.97,
29.71, 29.55 ppm; MS (EI, 70 eV) m/z (%) = 512 (M+,
25), 238 (30), 139 (100), 77 (47); FT-IR (KBr, cm−1):
3432, 2925, 1629, 1466, 1091.
Yellow solid; m.p. 190–192 °C (yield = 92%). H NMR
(300 MHz, DMSO): δ 8.75–8.73 (m, 1H), 7.79–7.72 (m,
1H), 7.54–7.49 (m, 1H), 7.33–7.32 (m, 2H), 7.19–6.95
(m, 7H), 6.76–6.69 (m, 1H), 4.13–4.04 (m, 2H), 3.54–3.44
(m, 2H), 3.35 (s, 3H) ppm; 13C NMR (75 MHz, DMSO):
δ 211.55, 187.14, 167.82, 163.04, 148.61, 144.08, 137.09,
136.73, 136.07, 135.39, 133.29, 133.14, 132.43, 131.70,
128.81, 125.87, 122.18, 121.00, 120.58, 118.39, 111.34,
53.21,, 39.73, 35.70, 34.25 ppm; MS (EI, 70 eV) m/z
(%) = 484 (M+, 13), 111 (100), 77 (33); FT-IR (KBr,
cm−1): 3430, 3077, 2924, 1607, 1579, 1415, 1238, 756.
5‑(Hydroxyl(phenyl)methylene)‑4‑(4‑methoxybenzoyl)‑
7‑methyl‑1,2,5,7‑tetrahydro‑6H‑benzo[h]thiazolo[3,2‑a]
[1,6]naphthyridin‑6‑one (9{4, 1})
5‑(Hydroxyl(4‑methoxyphenyl)methylene)‑7‑methyl‑4‑
(thiophene‑2‑carbonyl)‑1,2,5,7‑tetrahydro‑6H‑benzo[h]
thiazolo[3,2‑a][1,6]naphthyridin‑6‑one (9{6, 2})
1
Yellow solid; m.p. 180–182 °C (yield = 92%). H NMR
(300 MHz, CDCl3): δ 8.13 (d, 1H, J = 7.8 Hz), 7.81 (d,
2H, J = 8.7 Hz), 7.63–7.52 (m, 2H), 7.31–7.23 (m, 7H),
6.83 (d, 2H, J = 9 Hz), 4.44–4.38 (m, 1H), 4.25–4.11 (m,
1H), 3.82 (s, 3H), 3.79–3.63 (m, 2H), 3.48 (s, 3H) ppm;
13C NMR (75 MHz, CDCl3): δ 190.34, 162.97, 159.36,
142.14, 139.49, 137.34, 133.26, 131.72, 130.94, 130.71,
128.55, 128.30, 127.79, 126.28, 124.54, 121.25, 116.80,
115.52, 114.66, 113.25, 106.39,55.32, 48.47, 35.21, 29.71,
29.61 ppm; MS (EI, 70 eV) m/z (%) = 508 (M+, 0.1), 149
(13), 83 (20), 57 (51), 43 (100); FT-IR (KBr, cm−1): 3430,
2925, 1629, 1107.
1
Yellow solid; m.p. 206–208 °C (yield = 89%). H NMR
(300 MHz, CDCl3): δ 7.90 (d, 1H, J = 9 Hz), 7.57 (d, 1H,
J = 3 Hz), 7.37 (d, 1H,J = 3 Hz), 7.29 (t, 1H, J = 15 Hz),
7.01–6.96 (m, 4H), 6.79 (t, 1H, J = 4 Hz), 6.56 (d, 2H,
J = 9 Hz), 4.20–4.11 (m, 1H), 3.95–3.87 (m, 1H), 3.51
(s, 3H), 3.45–3.38 (m, 2H), 3.26 (s, 3H) ppm; 13C NMR
(75 MHz, CDCl3): δ 207.04, 183.95, 162.63, 159.75,
159.18, 143.28, 139.47, 138.67, 134.41, 133.81, 130.78,
129.65, 127.55, 124.62, 123.68, 121.35, 116.91, 114.80,
114.02, 113.58, 108.17, 55.18, 48.36, 35.27, 30.96,
29.77 ppm; MS (EI, 70 eV) m/z (%) = 514 (M+, 2), 135
(100), 111 (73), 77 (29); FT-IR (KBr, cm−1): 3435, 2927,
1632, 1511, 1414, 1249, 1174, 1107, 755.
1 3

Journal of the Iranian Chemical Society
14. A.A. Altaf, A. Shahzad, Z. Gul, N. Rasool, A. Badshah, B. Lal,
E. Khan, JDDMC 1, 1 (2015)
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1 3