Organic reactions in water: A distinct approach for the synthesis of quinoline derivatives starting directly from nitroarenes

Article abstract of DOI:10.1055/s-0030-1260191

Three-component reactions of nitroarenes, aldehydes, and phenylacetylene in the presence of indium in dilute hydrochloric acid produce the corresponding quinoline derivatives under reflux. The conversion in this one-pot synthesis involves the following steps: (i) reduction of the nitroarenes to anilines, (ii) coupling of the anilines, aldehydes, and phenylacetylene, (iii) cyclization of the resulting species, and (iv) dehydrogenation of the cyclic intermediates. Several new quinolines have been prepared. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0030-1260191

PAPER
3267
Organic Reactions in Water: A Distinct Approach for the Synthesis of Quino-
line Derivatives Starting Directly from Nitroarenes1
Quinoline
D
eriva
i
tive
s
fr
s
om
N
itroa
w
renesinWater anath Das,* Paramesh Jangili, Jajula Kashanna, Rathod Aravind Kumar
Organic Chemistry Division-1, Indian Institute of Chemical Technology, Hyderabad 500 007, India
Fax +91(40)27193198; E-mail: biswanathdas@yahoo.com
Received 11 June 2011; revised 15 July 2011
Ph
N
Abstract: Three-component reactions of nitroarenes, aldehydes,
and phenylacetylene in the presence of indium in dilute hydrochlo-
In, HCl
H2O
R2CHO
+
Ph
+
ric acid produce the corresponding quinoline derivatives under re-
flux. The conversion in this one-pot synthesis involves the
following steps: (i) reduction of the nitroarenes to anilines, (ii) cou-
pling of the anilines, aldehydes, and phenylacetylene, (iii) cycliza-
tion of the resulting species, and (iv) dehydrogenation of the cyclic
intermediates. Several new quinolines have been prepared.
reflux
18–22 h
R2
R1
R1
NO2
1
2
3
4
59–91%
Scheme 1 Synthesis of quinoline derivatives
Key words: quinolines, multicomponent reactions, one-pot synthe-
sis, nitroarenes, indium, hydrochloric acid
A series of quinolines were prepared from various alde-
hydes and nitroarenes following the above method
(Table 1). Both aromatic and aliphatic aldehydes were
used to produce the quinoline derivatives. The aromatic
aldehydes contained electron-donating as well as elec-
tron-withdrawing groups. A sterically hindered aldehyde,
such as 1-naphthaldehyde (Table 1, entry 7) and an acid
sensitive aldehyde, such as furfuraldehyde (entry 8) un-
derwent the conversion smoothly. The reactions with ali-
phatic aldehydes took somewhat longer than those with
aromatic aldehydes. The reaction was complete within
18–22 hours and the products were formed in good to high
yields (59–91%). Halogen substituents were unaffected
by the reaction. Other substituents such as alkoxy, nitro,
and hydroxy also remained unchanged. The correspond-
ing alcohols, as reduction products of the aldehydes, were
not obtained. Water has recently been used as a reaction
medium in various organic syntheses.16 It has been uti-
lized successfully here for the synthesis of quinoline de-
rivatives, and thus the present conversion is endowed with
eco-economic benefits. The structures of the products
were established from their spectral (IR, 1H and 13C NMR,
and MS) and analytical data.
The quinoline moiety is present in many bioactive natural
products, in particular, alkaloids.2 Some of these com-
pounds play an important role as antimalarial drugs.3 Var-
ious quinoline derivatives exhibit a broad range of
pharmacological properties such as anticancer,4 anti-
HIV,5 antihypertensive,6 antituberculosis,7 and anti-
Alzheimer activities.8 Substituted quinolines function as
antagonists for 5HT3, NK-3, endothelin, and leukotriene
receptors.9 They are also utilized as intermediates for the
design of biopotent molecules.10 Moreover, they have
been applied as agrochemicals, dyestuffs, and corrosion
inhibitors.11 In addition, they are well-known ligands in
the preparation of different useful complexes.12 Quino-
lines are also valuable synthons for the production of
nano- and mesostructures with enhanced electronic and
photonic properties.13 Due to such a wide range of appli-
cations of the quinoline derivatives in medicines, agricul-
ture, and industry, several methods have been developed
for the preparation of these compounds.14 However, harsh
reaction conditions, unsatisfactory yields, unavailability
of the starting materials, and utilization of costly reagents
and catalysts are the disadvantages in many of these meth-
ods. Here, we report a distinct approach for the synthesis
of quinolines in water.
A plausible mechanism of the conversion is shown in
Scheme 2. Initially, the nitroarenes 1 are reduced to
anilines by indium/hydrochloric acid17 and these anilines
react immediately with aldehydes 2, producing the corre-
sponding imines. The imines then react with phenylacety-
lene (3) to form the dihydroquinoline derivative C via the
intermediate propargyl amine A according to path A,18 or
via the vinylic cation intermediate B according to path
B.18a,19 Paths A and B could also operate simultaneously.
Finally, the oxidation of C with air produces the quinoline
derivative 4. The conversion takes place spontaneously
and no intermediate could be isolated.
In connection with our work15 on the development of use-
ful synthetic methodologies, we have observed that the
quinoline derivatives can be synthesized efficiently via
three-component reactions of nitroarenes, aldehydes, and
phenylacetylene when using indium in dilute hydrochlo-
ric acid under reflux (Scheme 1).
SYNTHESIS 2011, No. 20, pp 3267–3270
x
x.
x
x
.
2
0
1
1
Advanced online publication: 24.08.2011
DOI: 10.1055/s-0030-1260191; Art ID: Z60811SS
© Georg Thieme Verlag Stuttgart · New York

3268
B. Das et al.
PAPER
Table 1 Synthesis of Quinoline Derivativesa
Entry
1
R1
R2
Productb
4a
Time (h)
18
Yieldc (%)
72
H
Ph
2
H
2-Naph
Ph
4b
4c
20
85
3
2-OH
2-OH
2-OH
2-OH
2-OH
2-OH
2-OH
2-OMe
3-Me
3-Me
4-Cl
20
89
4
3-HOC6H4
4-HOC6H4
4-BrC6H4
1-Naph
2-furyl
Et
4d
4e
19
91
5
20
85
6
4f
20
71
7
4g
18
87
8
4h
4i
19
73
9
22
83
10
11
12
13
14
15
16
17
Ph
4j
20
75
Ph
4k
4l
19
71
3-HOC6H4
Ph
18
79
4m
4n
4o
19
73
2-Cl
Ph
20
59
4-Br
4-NO2
4-Br
Ph
21
71
Ph
4p
4q
18
77
4-BrC6H4
20
76
a Reagents and conditions: nitroarene 1 (1.0 mmol), aldehyde 2 (1.0 mmol), phenylacetylene (3; 1.5 mmol), In (2.0 mmol), 1 M aq HCl (1 mL),
reflux.
b All the products were fully characterized by the usual spectroscopic techniques.
c Yields of pure isolated products after column chromatography.
R2CHO
2
In conclusion, we have developed an efficient one-pot
synthesis of quinoline derivatives by three-component re-
actions of nitroarenes, aldehydes, and phenylacetylene by
using indium in dilute hydrochloric acid. The direct appli-
cation of nitroarenes and the conversion in water are the
notable features of the present novel method.
In, HCl
InCl3
InCl3
N
NH2
NO2
R2
H+
1
H
Ph
3
Path B
Ph
3
InCl3
Path A
IR spectra were recorded on a Perkin-Elmer RX1 FT-IR spectrom-
eter of samples prepared as KBr pellets. NMR spectra were record-
ed of samples in CDCl3 on a Varian Gemini spectrometer operating
at 200 MHz (1H NMR) and 50 MHz (13C NMR). MS determinations
were carried out by the ESI method on a VG-Autospec micromass
instrument. Elemental analyses were carried out on an Elementar
Vario Micro Cube instrument. Column chromatography was per-
formed on silica gel (200–300 mesh).
InCl3
Ph
HN
R2
HN
R2
+
HN
Ph
Ph
R2
C
B
InCl3
A
O
Ph
N
Quinolines 4; General Procedure
The appropriate aldehyde 2 (1 mmol) and phenylacetylene (3; 1.5
mmol) were added to a mixture of the appropriate nitroarene 1 (1
mmol), 1 M aq HCl (1 mL), and indium (325 mesh; 0.228 g, 2
mmol) in H2O (5 mL). The resulting mixture was stirred under re-
flux, and the reaction was monitored by TLC. After completion of
the reaction, the mixture was washed with sat. aq NaHCO3 (3 × 5
mL) and subsequently extracted with EtOAc (3 × 5 mL). The ex-
tract was concentrated under reduced pressure, and the residue was
R2
4
Scheme 2 Mechanism of the synthesis of quinoline derivatives
Synthesis 2011, No. 20, 3267–3270 © Thieme Stuttgart · New York

PAPER
Quinoline Derivatives from Nitroarenes in Water
3269
subjected to column chromatography (silica gel, hexane–EtOAc);
ESI-MS: m/z (%) = 348 [M + H]+.
this gave the corresponding pure quinoline 4.
The spectral (IR, 1H and 13C NMR, and MS) and analytical data of
the unknown compounds are given below.
Anal. Calcd for C25H17NO: C, 86.46; H, 4.90; N, 4.04. Found: C,
86.57; H, 4.83; N, 4.12.
2-(2-Furyl)-4-phenylquinolin-8-ol (4h)
2,4-Diphenylquinolin-8-ol (4c)
IR (KBr): 3302, 1600, 1553, 1457, 1216 cm–1.
IR (KBr): 3388, 1593, 1551, 1489, 1252 cm–1.
1H NMR (200 MHz, CDCl3): d = 8.30 (br s, 1 H), 7.83 (s, 1 H),
7.62–7.43 (m, 6 H), 7.38–7.27 (m, 2 H), 7.26 (m, 1 H), 7.11 (m, 1
H), 6.55 (m, 1 H).
13C NMR (50 MHz, CDCl3): d = 154.0, 152.9, 149.6, 146.2, 143.9,
138.5, 138.2, 129.9, 129.1, 129.0, 127.1, 126.0, 118.2, 116.0, 112.3,
110.2, 110.0.
1H NMR (200 MHz, CDCl3): d = 8.46 (br s, 1 H), 8.17 (d, J = 8.0
Hz, 2 H), 7.84–7.68 (m, 2 H), 7.59–7.40 (m, 7 H), 7.38–7.20 (m, 2
H), 7.12 (m, 1 H).
13C NMR (50 MHz, CDCl3): d = 154.8, 152.5, 149.6, 138.8, 138.7,
138.1, 129.9, 129.8, 129.0, 128.4, 127.2, 125.9, 120.1, 116.0, 109.9.
ESI-MS: m/z (%) = 298 [M + H]+.
ESI-MS: m/z (%) = 288 [M + H]+.
Anal. Calcd for C21H15NO: C, 84.85; H, 5.05; N, 4.71. Found: C,
84.93; H, 5.11; N, 4.67.
Anal. Calcd for C19H13NO2: C, 79.44; H, 4.53; N, 4.88. Found: C,
79.52; H, 4.48; N, 4.83.
2-(3-Hydroxyphenyl)-4-phenylquinolin-8-ol (4d)
2-Ethyl-4-phenylquinolin-8-ol (4i)
IR (KBr): 3432, 3331, 1599, 1457, 1252 cm–1.
IR (KBr): 3390, 1603, 1496, 1460, 1239 cm–1.
1H NMR (200 MHz, CDCl3): d = 7.81 (s, 1 H), 7.65–7.61 (m, 2 H)
7.59–7.41 (m, 6 H), 7.40–7.28 (m, 4 H), 7.17 (m, 1 H), 6.89 (d,
J = 8.0 Hz, 1 H).
1H NMR (200 MHz, CDCl3): d = 7.78 (s, 1 H), 7.45 (m, 1 H), 7.34–
7.20 (m, 6 H), 7.11 (d, J = 8.0 Hz, 1 H), 7.01 (d, J = 8.0 Hz, 1 H),
2.92 (q, J = 7.0 Hz, 2 H), 1.40 (t, J = 7.0 Hz, 3 H).
13C NMR (50 MHz, CDCl3): d = 158.0, 153.7, 152.4, 149.1, 139.1,
138.2, 137.9, 129.8, 129.2, 128.1, 126.4, 125.2, 119.5, 118.0, 116.8,
115.2, 114.0, 109.6.
13C NMR (50 MHz, CDCl3): d = 160.3, 151.9, 137.0, 130.2, 129.9,
129.4, 129.1, 128.2, 127.3, 126.2, 122.0, 115.8, 110.0, 28.8, 12.0.
ESI-MS: m/z (%) = 250 [M + H]+.
ESI-MS: m/z (%) = 314 [M + H]+.
Anal. Calcd for C17H15NO: C, 81.93; H, 6.02; N, 5.62. Found: C,
81.82; H, 6.09; N, 5.54.
Anal. Calcd for C21H15NO2: C, 80.51; H, 4.79; N, 4.47. Found: C,
80.43; H, 4.72; N, 4.54.
3-(7-Methyl-4-phenyl-2-quinolyl)phenol (4l)
2-(4-Hydroxyphenyl)-4-phenylquinolin-8-ol (4e)
IR (KBr): 3410, 1591, 1455, 1277 cm–1.
IR (KBr): 3371, 3334, 1600, 1550, 1480, 1363, 1244 cm–1.
1H NMR (200 MHz, CDCl3): d = 10.01 (br s, 1 H), 8.18 (d, J = 8.0
Hz, 1 H), 7.64–7.48 (m, 2 H), 7.43–7.18 (m, 10 H), 1.99 (s, 3 H).
13C NMR (50 MHz, CDCl3): d = 157.0, 156.1, 150.8, 149.4, 140.1,
137.9, 135.9, 130.0, 129.9, 129.1, 128.2, 128.0, 122.5, 119.8, 117.2,
115.2, 110.3, 24.0.
1H NMR (200 MHz, CDCl3): d = 8.11 (d, J = 8.0 Hz, 2 H), 7.79 (s,
1 H), 7.60–7.42 (m, 5 H), 7.35–7.30 (m, 2 H), 7.12 (m, 1 H), 6.92
(d, J = 8.0 Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 157.0, 154.2, 152.3, 149.5, 139.3,
139.2, 132.1, 131.8, 129.1, 128.2, 127.6, 126.5, 125.2, 119.2, 115.2,
115.0, 109.8.
ESI-MS: m/z (%) = 312 [M + H]+.
Anal. Calcd for C22H17NO: C, 84.89; H, 5.47; N, 4.50. Found: C,
84.97; H, 5.43; N, 4.58.
ESI-MS: m/z (%) = 314 [M + H]+.
Anal. Calcd for C21H15NO2: C, 80.51; H, 4.79; N, 4.47. Found: C,
80.63; H, 4.85; N, 4.38.
Acknowledgment
2-(4-Bromophenyl)-4-phenylquinolin-8-ol (4f)
The authors thank the UGC and CSIR, New Delhi, for financial as-
sistance.
IR (KBr): 3352, 1547, 1485, 1345, 1218 cm–1.
1H NMR (200 MHz, CDCl3): d = 8.37 (br s, 1 H), 8.09 (d, J = 8.0
Hz, 2 H), 7.80 (s, 1 H), 7.66 (d, J = 8.0 Hz, 1 H), 7.60–7.48 (m, 5
H), 7.40–7.31 (m, 3 H), 7.16 (dd, J = 8.0, 2.0 Hz, 1 H).
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13C NMR (50 MHz, CDCl3): d = 153.2, 152.8, 149.4, 138.2, 137.9,
137.1, 132.2, 132.1, 129.2, 128.5, 128.4, 127.4, 119.4, 115.9, 110.0.
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ESI-MS: m/z (%) = 376, 378 [M + H]+.
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Synthesis 2011, No. 20, 3267–3270 © Thieme Stuttgart · New York