1-butyl-3-methylimidazolium hydrogen sulfate ([bmim]-HSO 4)-mediated synthesis of polysubstituted quinolines

Article abstract of DOI:10.1080/00397911.2010.497596

In this research, polysubstituted quinolines are prepared from the reaction of 2-aminobenzophenones and ethylacetoacetate or ketones in the presence of 1-butyl-3-methylimidazolium hydrogen sulfate [bmim]HSO₄ as an acidic ionic liquid in good to

Full text of DOI:10.1080/00397911.2010.497596

This article was downloaded by: [Umeå University Library]
On: 07 October 2013, At: 09:09
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered
office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and
subscription information:
http://www.tandfonline.com/loi/lsyc20
1-Butyl-3-methylimidazolium Hydrogen
Sulfate ([bmim]-HSO )–Mediated
4
Synthesis of Polysubstituted Quinolines
a b
a
a
Hassan Tajik
, Khodabakhsh Niknam & Marjan Sarrafan
a
Department of Chemistry, Persian Gulf University, Boushehr, Iran
Department of Chemistry, University of Guilan, Rasht, Iran
b
Published online: 20 May 2011.
To cite this article: Hassan Tajik , Khodabakhsh Niknam & Marjan Sarrafan (2011) 1-Butyl-3-
methylimidazolium Hydrogen Sulfate ([bmim]-HSO )–Mediated Synthesis of Polysubstituted Quinolines,
4
Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic
Chemistry, 41:14, 2103-2114, DOI: 10.1080/00397911.2010.497596
To link to this article: http://dx.doi.org/10.1080/00397911.2010.497596
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the
“
Content”) contained in the publications on our platform. However, Taylor & Francis,
our agents, and our licensors make no representations or warranties whatsoever as to
the accuracy, completeness, or suitability for any purpose of the Content. Any opinions
and views expressed in this publication are the opinions and views of the authors,
and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content
should not be relied upon and should be independently verified with primary sources
of information. Taylor and Francis shall not be liable for any losses, actions, claims,
proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or
howsoever caused arising directly or indirectly in connection with, in relation to or arising
out of the use of the Content.
This article may be used for research, teaching, and private study purposes. Any
substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,
systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Conditions of access and use can be found at http://www.tandfonline.com/page/terms-
and-conditions

1
Synthetic Communications , 41: 2103–2114, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.497596
1-BUTYL-3-METHYLIMIDAZOLIUM HYDROGEN
SULFATE ([bmim]-HSO )–MEDIATED SYNTHESIS OF
4
POLYSUBSTITUTED QUINOLINES
1,2
1
Hassan Tajik, Khodabakhsh Niknam, and
1
Marjan Sarrafan
1
Department of Chemistry, Persian Gulf University, Boushehr, Iran
2
Department of Chemistry, University of Guilan, Rasht, Iran
GRAPHICAL ABSTRACT
Abstract In this research, polysubstituted quinolines are prepared from the reaction of
2
methylimidazolium hydrogen sulfate [bmim]HSO
-aminobenzophenones and ethylacetoacetate or ketones in the presence of 1-butyl-3-
as an acidic ionic liquid in good to high
4
ꢀ
yields at 70 C under solvent-free conditions.
4
Keywords 2-Aminobenzophenones; [bmim]HSO ; 1-butyl-3-methylimidazolium hydro-
gen sulfate; ketones; polysubstituted quinolines
INTRODUCTION
ꢀ
Ionic liquids are well known as salts with melting points below 100 C, and they
typically have broad liquid ranges, low vapor pressures, and may be both noncoordi-
nating and highly polar. They are receiving considerable global attention because they
offer a unique environment for chemistry, biocatalysis, separation science, materials
[1]
synthesis, and electrochemistry. Ionic liquids also have several interesting properties
such as excellent chemical and thermal stability, good solvating capability, wide
liquid range, and ease of recycling. Furthermore, their hydrophobicities=hydrophili-
[
1,2]
cities can be tuned by appropriate modification of the cation or anion.
room-temperature ionic liquids have found widespread use in catalytic and noncata-
Therefore,
[2]
lytic reactions. In addition, the synthesis of task-specific ionic liquids, which have a
functional group in their framework, may expand the application of ionic liquids in
[3–5]
organic chemistry.
many organic reactions.
Recently, acidic ionic liquids have been successfully used in
[4–9]
Received February 27, 2010.
Address correspondence to Hassan Tajik, Department of Chemistry, Guilan University, Rasht
1335-1914, Iran. E-mail: tajik@guilan.ac.ir; hasan_tajik@yajoo.com
4
2
103

2104
H. TAJIK, K. NIKNAM, AND M. SARRAFAN
Quinolines and their derivatives are very important biological compounds that
occur widely in natural products. Some members of this family have displayed
interesting physiological activities and found attractive applications in medicinal
[10]
chemistry, being used as antimalarial,
[11]
[12]
antihypertensive,
antibacterial, antiplatelet, and tyrosine kinase–inhibiting agents.
anti-inflammatory,
[12–16]
[13]
In addition,
quinolines are valuable synthons used for the preparation of nanostructures and poly-
mers that combine enhanced electronic, optoelectronic, or nonlinear optical properties
[17]
with excellent mechanical properties. A variety of methods such as Doebner–von
Miller, Skraup, Combes, Friedlander, and Knorr syntheses have been used for prep-
[18]
aration of quinolines and their derivatives. Among various methodologies reported
for the preparation of quinolines, Friedlander annulation is one of the simplest and
most straightforward protocols. This method involves a condensation and cyclization
between a ketone or aldehyde possessing a methylene group and an aromatic
2
base,
-aminoaldehyde or ketone. The Friedlander reaction can occur in the presence of
[24]
[
19]
[20]
[21]
[22]
[23]
Brønsted acid,
Lewis acid,
inorganic salt,
iodine,
solid acid,
phosphotungstic
acid, polyethelene glycol (PEG)–supported sulfonic acid, and dodecylphospho-
[
25]
[26]
[27]
palladium,
metal hydrogen sulfate,
ionic liquid–catalyzed,
[
28]
[29]
[
30]
nic acid
conditions. Generally, better product yields were achieved for the acid-
[19]
catalyzed Friedlander reactions. Most of the reported protocols for the synthesis
of quinolines suffered from the use of harmful organic solvents, high reaction tempera-
tures, prolonged reaction times, poor product yields, and complicated workup proce-
dures. Thus, the development of simple, convenient, and environmentally friendly
approaches for the synthesis of quinolines is still in demand.
In connection with our recent reports on the use of acidic ionic liquids in
[9]
organic synthesis, herein we report the synthesis of quinoline derivatives in the
presence of 1-butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO ] as an
acidic ionic liquid via the Friedlander method (Scheme 1).
4
To study the effect of catalyst loading on the condensation of 2-aminobenzo-
phenones with an enolizable ketone for the synthesis of quinoline derivatives, the
reaction of 2-aminobenzophenone with ethyl acetoacetate was chosen as a model
reaction (Table 1). The results show clearly that [bmim][HSO ] is an effective catalyst
4
for this condensation, and in the absence of [bmim][HSO ] the reaction did not take
4
place, even after 24 h. Although a lower catalyst loading of 0.3 mmol of
[bmim][HSO ] accomplished this condensation, 0.5 mmol of [bmim][HSO ] to proved
4 4
to be optimum in terms of reaction time and isolated yield.
In addition, we investigated the reaction of 2-aminobenzophenone with dime-
done in the presence of different ionic liquids. As shown in Table 2, 1-butyl-3-methy-
limidazolium hydrogen sulfate and pyridinum hydrogen sulfate gave the best results
in reaction time and conversion. These results reveal that the performance of ionic
4
Scheme 1. Synthesis of quinoline derivatives in the presence of [bmim][HSO ].

SYNTHESIS OF POLYSUBSTITUTED QUINOLINES
2105
Table 1. Reaction conditions and yields for the synthesis of quinoline 3a with different amounts of
a
[
4
bmim][HSO ]
Entry
Catalyst
Equivalent
Time (h)
Yield (%)
1
2
3
4
5
6
None
—
0.1
0.3
0.5
0.7
0.9
24
7
Trace
60
85
[bmim]HSO
[bmim]HSO
[bmim]HSO
[bmim]HSO
[bmim]HSO
4
4
4
4
4
4
1
94
95
1
0.92
94
a
Reaction conditions: 2-aminobenzophenone (1.0 mmol), ethyl acetoacetate (1.0 mmol), reaction
ꢀ
temperature 70 C under solvent-free conditions.
liquids is dependent on the character of the side chain of the cation (Brønsted acidic
counterion and the other cations). Therefore, the ionic liquid acts as a Brønsted acid
[
28b]
catalyst as well as a solvent at reaction conditions.
Also, we investigated the reaction of 2-aminobenzophenone with dimedone in
the presence of [bmim][HSO ] in different conditions. As shown in Table 3, with no
4
ꢀ
solvent, 70 C gave the best results in reaction time and conversion. When we used
[bmim][HSO ] as solvent (2 mL), the reaction time is much shorter compared to
4
the other results (Table 3, entry 9).
Table 2. Reaction conditions and yields for the synthesis of quinoline 3c in the presence of different ionic
a
liquids
Entry
1
Acidic ionic liquid
Time (min)
30
Yield (%)
90
2
3
180
85
40
80
4
165
120
75
80
5
a
Reaction conditions: 2-aminobenzophenone (1.0 mmol), dimedone (1.0 mmol), reaction temperature
ꢀ
7
0 C under solvent-free conditions.

2106
H. TAJIK, K. NIKNAM, AND M. SARRAFAN
Table 3. Reaction conditions and yields for the synthesis of quinoline 3c in different conditions catalyzed
a
by [bmim][HSO
4
]
Entry
Solvent
Temperature
Time (min)
Conversion (%)
1
2
3
4
5
6
7
8
9
Solvent-free
Solvent-free
Solvent-free
Solvent-free
Ethanol
rt
50
70
100
70
70
70
70
70
300
300
30
Trace
20
100
100
50
30
300
110
300
100
15
Water
70
45
Acetonitrile
n-Hexane
[bmim][HSO
100
b
4
]
100
a
4
Reaction conditions: 2-aminobenzophenone (1.0 mmol), dimedone (1.0 mmol), [bmim][HSO ]
(0.5 mmol).
b
4
In this case, [bmim][HSO ] was used as solvent (2 mL).
To study the generality of this process, several examples were studied. As seen
from Table 4, 2-aminobenzophenone could be replaced by 2-amino-5-chlorobenzo-
phenone, and a-methylene ketones could be extended from ethyl acetoacetate to
methyl acetoacetate, t-butyl acetoacetate, acyclic 1,3-diketones such as 2,4-
pentadione, cyclic 1,3-diketones such as 1,3-cyclohexane and 5,5-dimethyl-1,3-
cyclohexadione, and simple cyclic ketones such as cyclohexanone derivatives,
cyclopentanone, and cycloheptanone. In the optimized reaction conditions, the-
synthesis of quinoline 3a–s was successfully achieved in very good yields (75–95%)
by the Friedlander condensation between 2-aminobenzophenone with a variety of
carbonyl compounds in the presence of [bmim][HSO4].
After finishing the condensation reaction, the reaction mixture was poured into
an ice-water mixture, and the resultant precipitate was recrystallized from ethanol.
The catalyst (ionic liquid [bmim][HSO ]) was recovered by evaporation of water
4
and the recovered residue with diethyl ether. The recovered catalyst was reused four
times without any loss in activity.
The efficiency of [bmim][HSO ] as a catalyst for the synthesis of 3a as a model
4
compound was compared with other reported ionic liquid catalysts (Table 5). It can
be seen that [bmim][HSO ] is a very efficient catalyst useful in the synthesis of quino-
line derivatives.
4
In conclusion, we have introduced a straightforward, efficient, and
cost-effective synthesis of quinolines by using Friedlander reaction in the presence
of [bmim][HSO ] under solvent-free conditions. The notable advantage of this
4
method are mild reaction conditions and good yields coupled with the safe, non-
volatile, and ecofriendly nature of the [bmim][HSO4] reagent employed.
SELECTED DATA
2,3,4-Triphenylquinoline (3b)
ꢀ
ꢁ1
Mp 201–203 C; IR (KBr) n (cm ) ¼ 3050, 1600, 1540, 1470, 1430, 1335, 1070,
ꢁ
1 1
020, 760, 745, 695 cm ; H NMR (500 MHz, CDCl ): d (ppm) ¼ 6.92–6.94 (m, 2H,
1
3

2
107

2
108

2
109

2
110

SYNTHESIS OF POLYSUBSTITUTED QUINOLINES
2111
Table 5. Comparison results of different catalysts to the [bmim][HSO ] in the synthesis of 3a
4
a
Entry
Catalyst
Time (min)
Yield (%)
Ref.
1
2
3
4
5
6
7
8
9
[bmim][HSO
4
]
60
180
180
90
94
94
92
95
96
89
80
83
85
Present work
[Hbim]BF
bmimCl:ZnCl
CeCl
ꢂ 7H
PEG-SO
NH SO
NaHSO -SiO
Y(OTf)
Dodecylphosphonic acid
4
28b
28c
21d
29
2
3
2
O
3
H
40
90
2
3
H
20
4
2
240
360
140
26b
21b
30
3
Arom), 7.03–7.05 (m, 3H, Arom), 7.18 (dd, J ¼ 7.4 Hz, J ¼ 1.8 Hz, 2H, Arom),
1
2
7
7
.24–7.26 (m, 3H, Arom), 7.29–7.32 (m, 3H, Arom), 7.41–7.43 (m, 2H, Arom),
.49 (m, 1H, Arom), 7.63 (d, J ¼ 8.9, 1H, Arom), 7.75–7.77 (m, 1H, Arom), 8.31
1
3
(
1
1
d, J ¼ 8.4, 1H, Arom); C NMR (125 MHz, CDCl ): d (ppm) ¼ 126.76, 127.02,
3
27.05, 127.1, 127.72, 127.77, 128.05, 128.1, 128.22, 129.82, 130.1, 130.36, 130.73,
31.81, 133.40, 137.38, 138.75, 141.5, 147.69, 159.41. Mass (m=e %): 358 (M þ 1)
þ
þ
(19.4), 357 (M ) (76.4), 356 (base peak), 280 (8.3), 170 (15.3). Calc. for C H N:
C, 90.72; H, 5.36; N, 3.92. Found: C, 90.53; H, 5.30; N, 3.76.
2
7
19
tert-Butyl-2-methyl-4-phenylquinolin-3-carboxylate (3e)
ꢀ
ꢁ1
1 1
Mp 117–120 C; IR (KBr) n (cm ) ¼ 3050, 2980, 1710, 1560, 1480, 1440, 1390,
ꢁ
1
(
365, 1295, 1240, 1080, 760, 700 cm ; H NMR (500 MHz, CDCl ): d (ppm) ¼ 1.27
3 3
3
s, 9H, CH ), 2.83 (s, 3H, CH ), 7.39–7.41 (m, 2H, Arom), 7.42–7.45 (m, 1H, Arom),
.50–7.57 (m, 4H, Arom), 7.71–7.74 (m, 1H, Arom), 8.10 (d, J ¼ 8.42, 1H, Arom);
7
1
3
C NMR (125 MHz, CDCl ) d (ppm) ¼ 24.06, 28.01, 82.78, 125.82, 126.71,
3
1
1
26.84, 128.58, 128.76, 129.01, 129.18, 130.04, 130.41, 136.18, 145.88, 147.85,
54.95, 167.89. Mass (m=e %): 321 (M þ 2) (7.1), 320 (M þ 1) (35.9), 319 (M )
þ
þ
þ
(39.3), 263 (base peak), 246 (26.8), 218 (38.4), 176 (10.7), 57 (21.4). Calc. for
C H NO : C, 78.97; H, 6.62; N, 4.38. Found: C, 78.79; H, 6.57; N, 4.23.
2
1
21
2
2-tert-Butyl-7-chloro-1,2,3,4-tetrahydro-9-phenylacridine (3r)
ꢀ
ꢁ1
Mp 155–154 C; IR (KBr) n (cm ) ¼ 3040, 2980, 2890, 1600, 1560, 1475, 1370,
ꢁ1
1
1
360, 1160, 1070, 950, 825, 760, 700 cm
;
H NMR (500 MHz, CDCl ): d
3
(
1
ppm) ¼ 0.87 (s, 9H, CH ), 1.48–1.60 (m, 2H), 2.14–2.16 (m, 1H), 2.29–2.35 (m,
3
H), 2.67–2.70 (m, 1H), 3.09–3.16 (m, 1H), 3.31–3.34 (m, 1H), 7.22–7.24 (m, 2H,
Arom), 7.31 (s, 1H, Arom), 7.49–7.58 (m, 4H, Arom), 7.97 (d, J ¼ 7.85, 1H, Arom);
1
3
C NMR (125 MHz, CDCl ): d (ppm) ¼ 24.46, 27.54, 29.82, 32.99, 35.24, 45.05,
3
1
1
3
24.98, 127.81, 128.5, 129.27, 129.51, 129.61, 130.20, 130.48, 131.53, 136.71,
45.09, 146.29, 160.13. Mass (m=e %): 352 (M þ 3) (8.5), 351 (M þ 2) (32.8),
þ
þ
þ
þ
50 (M þ 1) (31.4), 349 (M ) (85.7), 293 (48.2), 292 (base peak), 57 (60.0). Calc.
for C H ClN: C, 78.96; H, 6.91; Cl, 10.13; N, 4.00. Found: C, 78.79; H, 6.84;
3
2
24
Cl, 9.93; N, 3.78.

2112
H. TAJIK, K. NIKNAM, AND M. SARRAFAN
EXPERIMENTAL
Chemicals were purchased from the Fluka, Merck, and Aldrich chemical com-
panies. Infrared (IR) spectra were run on a Shimadzu IR-435 instruments. The
1
H NMR spectroscopy was conducted using a Bruker Avance DRX (500 MHz).
With thin-layer chromatography (TLC) using silica-gel SILG=UV 254 plates, the
progress of reaction was followed. All the products are known compounds and were
1
characterized by comparison of their spectral (IR, H NMR), TLC, and physical
data with the data previously reported in the literature. The 1-butyl-3-methylimida-
zolium hydrogen sulfate [bmim][HSO ] and the other ionic liquids were prepared
4
[
5–9]
according to previously reported procedures.
General Procedure
A suspension of 2-aminobenzophenone (1 mmol), a-methylene ketone
1 mmol), and [bmim][HSO ] (0.5 mmol) was heated in an oil bath at 70 C under
ꢀ
(
4
solvent-free conditions for the specified times in Table 4. The progress of the reaction
was monitored by TLC. After completion of the reaction, the mixture was poured
into ice water (20 ml). Then, the precipitates were filtered and recrystallized from
ethanol to give the corresponding quinoline derivatives. The [bmim][HSO ] was
4
recovered by evaporating the water and washing the resultant residue several times
with diethyl ether.
ACKNOWLEDGMENT
We are thankful to the Persian Gulf University Research Council for their
partial support of this work.
REFERENCES
1
2
3
. Welton, T. Room-temperature ionic liquids: Solvents for synthesis and catalysis. Chem.
Rev. 1999, 99, 2071–2084.
. Zhao, G.-Y.; Jiang, T.; Gao, H.-X.; Han, B.-X.; Huang, J.; Sun, D.-H. Mannich reaction
using acidic ionic liquids as catalysts and solvents. Green Chem. 2004, 6, 75–77.
. Ishida, Y.; Sasaki, D.; Miyauchi, M.; Saigo, K. Design and synthesis of novel
imidazolium-based ionic liquids with a pseudo crown-ether moiety: Diastereomeric
interaction of a racemic ionic liquid with enantiopure europium complexes. Tetrahedron
Lett. 2004, 45, 9455–9459.
4
5
6
. Fraga-Dubreuil, J.; Bourahla, K.; Rahmouni, M.; Bazureau, J. P.; Hamelin, J. Catalysed
esterifications in room temperature ionic liquids with acidic counteranion as recyclable
reaction media. Catal. Commun. 2002, 3, 185–190.
. Singh, V.; Kaur, S.; Sapehiyia, V.; Singh, J.; Kad, G. L. Microwave accelerated
preparation of [bmim][HSO4] ionic liquid: An acid catalyst for improved synthesis of
coumarins. Catal. Commun. 2005, 6, 57–60.
. Gupta, N.; Sonu, Kad, G. L.; Singh, J. Acidic ionic liquid [bmim]HSO4: An efficient cata-
lyst for acetalization and thioacetalization of carbonyl compounds and their subsequent
deprotection. Catal. Commun. 2007, 8, 1323–1328.

SYNTHESIS OF POLYSUBSTITUTED QUINOLINES
2113
7
8
9
. Hajipour, A. R.; Khazdooz, L.; Ruoho, A. E. Brønsted acidic ionic liquid as an efficient
catalyst for chemoselective synthesis of 1,1-diacetates under solvent-free conditions. Catal.
Commun. 2008, 9, 89–96.
. Dabiri, M.; Salehi, P.; Baghbanzadeh, M.; Shakouri, M.; Otokesh, S.; Ekrami, T.; Doosti,
R. Efficient and eco-friendly synthesis of dihydropyrimidinones, bis(indolyl)methanes,
and N-alkyl and N-arylimides in ionic liquids. J. Iran. Chem. Soc. 2007, 4, 393–401.
. (a) Tajik, H.; Niknam, K.; Parsa, F. Using acidic ionic liquid 1-butyl-3-methylimidazo-
lium hydrogen sulfate in selective nitration of phenols under mild conditions. J. Iran.
Chem. Soc. 2009, 6, 159–164; (b) Niknam, K.; Zolfigol, M. A.; Saberi, D.; Khonbazi,
M. 1-Butyl-3-methylimidazolium hydrogen sulfate [bmim]HSO
acidic ionic liquid for the formylation of alcohols. Chin. J. Chem. 2009, 27, 1548–1552;
4
c) Niknam, K.; Damya, M. 1-Butyl-3-methylimidazolium hydrogen sulfate [bmim]HSO :
4
: An efficient reusable
(
An efficient reusable acidic ionic liquid for the synthesis of 1,8-dioxo-octahydroxanthenes.
J. Chin. Chem. Soc. 2009, 56, 659–665.
1
1
1
0. Balausubramanian, M.; Keay, J. G. In Comprehensive Heterocyclic Chemistry II; A. R.
Katritzky, C. W. Rees, and E. F. V. Scriven (Eds.); Pergamon: New York, 1996; Vol. 5,
p. 245.
1. Morizawa, Y.; Okazoc, T.; Wang, S. Z.; Sasaki, J.; Ebisu, H.; Nishikawa, M.; Shinyyama,
H. A novel trifluoromethanesulfonamidophenyl-substituted quinoline derivative, GA
0
113: Synthesis and pharmacological profiles. J. Fluorine Chem. 2001, 109, 83.
2. Roma, G.; Braccio, M. D.; Grossi, G.; Mattioli, F.; Ghia, M. 1,8-Naphthyridines IV:
-Substituted N,N-dialkyl-5-(alkylamino or cycloalkylamino) [1,2,4]triazolo[4,3-a]
1,8]naphthyridine-6-carboxamides, new compounds with anti-aggressive and potent
9
[
anti-inflammatory activities. Eur. J. Med. Chem. 2000, 35, 1021–1035.
1
3. Chen, Y. L.; Fang, K. C.; Sheu, J. Y.; Hsu, S. L.; Tzeng, C. C. Synthesis and antibacterial
evaluation of certain quinolone derivatives. J. Med. Chem. 2001, 44, 2374–2376.
4. Larsen, R. D.; Corley, E. G.; King, A. O.; Carrol, J. D.; Davis, P.; Verhoeven, T. R.;
Reider, P. J.; Labelle, M.; Gauthier, J. Y.; Xiang, Y. B.; Zamboni, R. J. Practical route
to a new class of LTD4 receptor antagonists. J. Org. Chem. 1996, 61, 3398.
5. Ferrarini, P. L.; Mori, C.; Badwneh, M.; Manera, C.; Martinelli, A.; Miceli, M.;
Ramagnoli, F.; Saccomanni, G. Unusual nitration of substituted 7-amino-1,8--
naphthyridine in the synthesis of compounds with antiplatelet activity. J. Heterocycl.
Chem. 1997, 34, 1501.
1
1
1
6. Ko, T. C.; Hour, M. J.; Lien, J. C.; Teng, C. M.; Lee, K. H.; Kuo, S. C.; Huang, L. J.
Synthesis of 4-alkoxy-2-phenylquinoline derivatives as potent antiplatelet agents. Bioorg.
Med. Chem. Lett. 2001, 11, 279.
1
7. (a) Agrawal, A. K.; Jenekhe, S. A. Electrochemical properties and electronic structures of
conjugated polyquinolines and polyanthrazolines. Chem. Mater. 1996, 8, 579–589; (b)
Jenekhe, S. A.; Lu, L.; Alam, M. M. M. New conjugated polymers with donor–acceptor
architectures: Synthesis and photophysics of carbazole-quinoline and phenothiazine-
quinoline copolymers and oligomers exhibiting large intramolecular charge transfer.
Macromolecules 2001, 34, 7315–7324; (c) Je
poly(arylene ethynylene)s containing quinoline and 3-alkylthiophene. Macromolecules
001, 34, 7926–7928.
´
gou, G.; Jenekhe, S. A. Highly fluorescent
2
1
8. (a) Abass, M. Fused quinolines: Recent synthetic approaches to azoloquinolines: A review.
Heterocycles 2005, 65, 901–965; (b) Kouznetsov, V. V.; Mendez, L. Y. V.; Gomez, C. M. M.
Recent progress in the synthesis of quinolines. Curr. Org. Chem. 2005, 9, 141–143; (c)
Denmark, S. E.; Venkatraman, S. On the mechanism of the Skraup–Doebner–Von Miller
quinoline synthesis. J. Org. Chem. 2006, 71, 1668–1676.
19. (a) Fehnel, E. A. Friedl a¨ nder syntheses with o-aminoaryl ketones, I: Acid-catalyzed
condensations of o-aminobenzophenone with ketones. J. Org. Chem. 1966, 31, 2899; (b)

2114
H. TAJIK, K. NIKNAM, AND M. SARRAFAN
Dormer, P. G.; Eng, K. K.; Farr, R. N.; Hamphrey, G. R.; McWilliams, J. C.; Reider,
¨
P. J.; Sager, J. W.; Volante, R. P. Highly regioselective Friedlander annulations with
unmodified ketones employing novel amine catalysts: Syntheses of 2-substituted quino-
lines, 1,8-naphthyridines, and related heterocycles. J. Org. Chem. 2003, 68, 467.
0. Yadav, J. S.; Rao, P. P.; Sreenu, D.; Rao, R. S.; Kumar, V. N.; Nagaiah, K.; Prasad, A.
2
2
R. Sulfamic acid: An efficient, cost-effective, and recyclable solid acid catalyst for the
Friedlander quinoline synthesis. Tetrahedron Lett. 2005, 46, 7249–7253.
1. (a) Arcadi, A.; Chiarini, M.; Di Giuseppe, S.; Marinelli, F. A new green approach to the
Friedl a¨ nder synthesis of quinolines. Synlett 2003, 203–206; (b) De, S. K.; Gibbs, R. A. A
mild and efficient one-step synthesis of quinolines. Tetrahedron Lett. 2005, 46, 1647–1649;
(
synthesis catalyzed by FeCl or Mg (ClO . Synlett 2005, 2653–2657; (d) Bose, D. S.;
c) Wu, J.; Zhang, L.; Diao, T.-N. An expeditious approach to quinolines via Friedla
¨
nder
3
4 2
)
Kumar, R. K. An efficient, high-yielding protocol for the synthesis of functionalized
quinolines via the tandem addition=annulation reaction of o-aminoaryl ketone with
a-methylene ketones. Tetrahedron Lett. 2006, 47, 813–816.
2
2. Yadav, J. S.; Reddy, B. V. S.; Premlatha, P.; Rao, R. S.; Nagaiah, K. Silver phosphotung-
state: A novel and recyclable heteropoly acid for Friedl a¨ nder quinoline synthesis.
Synthesis 2004, 2381–2385.
2
3. Zolfigol, M. A.; Salehi, P.; Ghaderia, A.; Shiria, M. Iodine-catalyzed Friedl a¨ nder quino-
line synthesis under solvent-free conditions. J. Chin. Chem. Soc. 2007, 54, 267–271.
4. Das, B.; Damodar, K.; Chowdhury, N.; Kumar, R. A. Application of heterogeneous solid
acid catalysts for Friedl a¨ nder synthesis of quinolines. J. Mol. Catal. A: Chem. 2007, 274,
2
148–152.
25. Cho, C. S.; Ren, W. X. A recyclable palladium-catalyzed modified Friedl a¨ nder quinoline
synthesis. J. Organometal. Chem. 2007, 692, 4182.
26. (a) Niknam, K.; Zolfigol, M. A.; Dehghani, A. Friedlander quinoline synthesis catalyzed
by M(HSO
2513–2521; (b) Desai, U. V.; Mitragotri, S. D.; Thopate, T. S.; Pore, D. M.; Wadgaonkar,
4
)
n
(M¼ Al, Mg, Ca) under solvent-free conditions. Heterocycles 2008, 75,
P. P. A highly efficient synthesis of trisubstituted quinolines using sodium hydrogensulfate
on silica as a reusable catalyst. Arkivoc 2006, 15, 198–204.
2
2
7. Dabiri, M.; Bashiribod, S. Phosphotungstic acid: An efficient, cost-effective, and recycl-
able catalyst for the synthesis of polysubstituted quinolines. Molecules 2009, 14,
1
126–1133.
8. (a) Wang, J.; Fan, X.; Zhang, X.; Han Can, L. Green preparation of quinoline derivatives
through FeCl -6H O-catalyzed Friedl a¨ nder reaction in ionic liquids. Can. J. Chem. 2004,
2, 1192–1196; (b) Palimkar, S. S.; Siddiqui, S. A.; Daniel, T.; Lahoti, R. J.; Srinivasan,
J. V. Ionic liquid–promoted regiospecific Friedlander annulation: Novel synthesis of
3
2
8
¨
quinolines and fused polycyclic quinolines. J. Org. Chem. 2003, 68, 9371–9376; (c)
Karthikeyan, G.; Perumal, P. T. A mild, efficient, and improved protocol for the
Friedlander synthesis of quinolines using Lewis acidic ionic liquid. J. Heterocycl. Chem.
¨
2004, 41, 1039–1042.
2
3
9. Zhang, X. L.; Wang, Q. Y.; Sheng, S. R.; Wang, Q.; Liu, X. L. Efficient Friedlander
synthesis of quinoline derivatives from 2-aminoarylketones and carbonyl compounds
mediated by recyclable PEG-supported sulfonic acid. Synth. Commun. 2009, 39,
3293–3304.
0. Ghassamipour, S.; Sardarian, A. R. Friedlander synthesis of poly-substituted quinolines
in the presence of dodecylphosphonic acid (DPA) as a highly efficient, recyclable, and
novel catalyst in aqueous media and solvent-free conditions. Tetrahedron Lett. 2009, 50,
514–519.