Efficient method for the synthesis of 3-arylbenzoquinoline, pyranoquinoline, and thiopyranoquinoline derivatives using PEG1000-based dicationic acidic ionic liquid as recyclable catalyst via a one-pot multicomponent reaction

Article abstract of DOI:10.1080/00397911.2016.1204460

A series of 3-arylbenzoquinoline, pyranoquinoline, and thiopyranoquinoline derivatives have been synthesized by one-pot, multicomponent reaction of aromatic aldehyde, naphthalen-2-amine, and ketone using polyethylene glycol (PEG₁₀₀₀)–based dica

Full text of DOI:10.1080/00397911.2016.1204460

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
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ISSN: 0039-7911 (Print) 1532-2432 (Online) Journal homepage: http://www.tandfonline.com/loi/lsyc20
Efficient Method for the Synthesis of 3-
arylbenzoquinoline, Pyranoquinoline and
Thiopyranoquinoline Derivatives Using PEG1000-
based Dicationic Acidic Ionic Liquid as Recyclable
Catalyst via a One-Pot Multicomponent Reaction
Yi-Ming Ren & Ren-Chun Yang
To cite this article: Yi-Ming Ren & Ren-Chun Yang (2016): Efficient Method for the Synthesis of
3-arylbenzoquinoline, Pyranoquinoline and Thiopyranoquinoline Derivatives Using PEG1000
based Dicationic Acidic Ionic Liquid as Recyclable Catalyst via a One-Pot Multicomponent
Reaction, Synthetic Communications
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Date: 27 June 2016, At: 07:14

Efficient method for the synthesis of 3-arylbenzoquinoline, pyranoquinoline and
thiopyranoquinoline derivatives using PEG1000-based dicationic acidic ionic liquid as
recyclable catalyst via a one-pot multicomponent reaction
Yi-Ming Ren1, Ren-Chun Yang1
1Department of Biochemical Engineering, Anhui Polytechnic University, Wuhu, Anhui,
China
Corresponding author to Yi-Ming Ren: E-mail: yimingren@ahpu.edu.cn
Abstract
A series of 3-arylbenzoquinoline, pyranoquinoline and thiopyranoquinoline derivatives
have been synthesized by one-pot multicomponent reaction of aromatic aldehyde,
naphthalen-2-amine, and ketone using PEG1000-based dicationic acidic ionic liquid as
recyclable catalyst with high yields. The PEG ionic liquid and toluene have the
advantages of both homogeneous and heterogeneous phases at different temperatures
(biphasic conditions at lower temperatures and monophasic at higher temperatures) with
the ease of product as well as catalyst separation. Recycling studies have shown that the
ionic liquid can be readily recovered and reused several times without significant loss of
activity.
1

NH2
Heat
HO3S
R
N
X
ArCHO
+
Ketone
Ar
N
Ar
Toluene
Cool
PEG1000-DAIL
Homogeneous
Recovered and reused
N
+
-
N
O
2 HSO4
PEG1000-DAILS:
O
N
n
+
N
SO3H
KEYWORDS: Ionic liquids; thermoregulated; 3-arylbenzoquinoline; pyranoquinoline;
thiopyranoquinoline
INTRODUCTION
The length of a synthesis is dependent upon the average molecular complexity produced
per operation, which depends in turn on the number of chemical bonds being created.
Therefore, devising reactions that achieve multi-bond formation in one operation is
becoming one of the major challenges in searching for step-economic syntheses.
Multicomponent reactions (MCRs) processes, in which three or more reactants are
combined in a single chemical step to produce products that incorporate substantial
portions of all the components, naturally comply with many of these stringent
requirements for ideal organic syntheses.[1,2]
2

Quinoline and its derivatives represent an important class of nitrogen-containing
heterocycles as they are widely occurring natural alkaloids known for a wide range of
pharmacological and biological activities, such as antiplasmodial, antimicrobial,
antituberculosis, antibacterial, antiproliferative, antimalarial and anticancer activities.[3-8]
In view of the importance of quinoline and its derivatives, a number of synthetic
strategies have been developed for the preparation of substituted quinolines.[9-13]
However, many of these reported methods suffer from drawbacks such as harsh reaction
conditions, unsatisfactory yields, prolonged reaction time, and cumbersome product
isolation procedure. So, novel strategies for the synthesis of quinolines continued to
receive considerable attention in the field of organic synthetics chemistry.[14-17]
Ionic liquids (ILs), as environmental friendly reaction media or catalysts, have attracted
increasing attention because of their particular properties, for example negligible vapor
pressure, wide liquid range, and high thermal stability, making them a greener alternative
to volatile organic solvents.[18-23] In addition, some ILs have been found to be an efficient
and recyclable catalysts for the MCRs.[24-30] Among the numerous ILs developed,
recyclable ones were figured as the most important research targets. Unfortunately, ILs
showed more or less solubility in commonly used molecular solvents, which caused
inconvenience for product separation and catalyst recovery, especially in homogeneous
catalysis. Recently, poly(ethylene glycol) linked dicationic neutral ionic liquids
(PEG-DILs)[31,32] and poly(ethylene glycol) linked dicationic acidic ionic liquids
(PEG-DAILs) (Scheme 1) have been explored as a powerful catalyst for various organic
3

transformations.[33-44] The PEG-D(A)ILs and toluene have the advantages of both
homogeneous and heterogeneous phases at different temperatures (biphasic conditions at
lower temperatures and monophasic at higher temperatures) with the ease of product as
well as catalyst separation.[31,38]
To the best of our knowledge, there is no report on the application of PEG1000-DAIL as
acid catalysts for the preparation of 3-arylbenzoquinoline, pyranoquinoline and
thiopyranoquinoline derivatives. This paper forms part of our ongoing interest in ILs[31–37]
and MCRs.[1,45–48] We report herein a simple and efficient procedure for the preparation of
3-arylbenzoquinoline, pyranoquinoline and thiopyranoquinoline derivatives using
PEG1000-DAIL as an effective and reusable catalyst.
RESULTS AND DISCUSSION
Model exploratory experiments indicated that PEG1000-DAIL efficiently catalyzed the
reaction of 4-fluorobenzaldehyde, naphthalen-2-amine and acetone to give the
corresponding product 3-(4-fluorophenyl)-1-methylbenzo[f]quinoline 4a. Although the
yield rose with increasing temperatures (Table 1, Entries 1-6), the results showed the
optimal temperature to be 80 °C. The yields did not increase when higher temperature
was employed (Table 1, Entries 7 and 8).
4

The condensation of 4-fluorobenzaldehyde, naphthalen-2-amine and acetone under the
conditions described in Table 1 with PEG1000-DAIL as catalysts was run for seven
consecutive cycles with satisfying results (Table 1, entry 6). The underlayer of
PEG1000-DAIL was reused with removal of water under reduced pressure and the
work-up procedure of recycling is accomplished by simple phase separation only.
In order to evaluate the efficiency of PEG1000-DAIL as a catalyst, a range of aromatic
aldehydes were similarly treated with naphthalen-2-amine and acetone in the presence of
PEG1000-DAIL; the corresponding 3-arylbenzoquinolines (4a-4j) were formed in high
yields (Table 2, Entries 1-10). Similarly, the corresponding products (4k-4r) were
obtained in high yields when acetophenone was employed with longer reaction time
(Table 2, Entries 11-18). The position and/or nature of substituent on the aromatic ring
had a negligible effect on the yields of the final products. However, the reaction failed to
proceed with aliphatic aldehydes under the same reaction conditions. A possible reason is
that the activity of aliphatic aldehydes is less than that of aromatic aldehydes.
This success led us to extend the reaction to the use of aromatic aldehydes with
naphthalen-2-amine, and heterocycloketones (tetrahydropyran-4-one or
tetrahydrothiopyran-4-one) under the same conditions. Table 3 shows that the reactions
proceeded efficiently under similarly conditions to afford the corresponding
pyranoquinoline (6a-6j) (Table 3, Entries 1-10) and thiopyranoquinoline derivatives
5

(6k-6p) (Table 3, Entries 11-16) in good yields. It can be observed that the process
tolerates both electron-donating and electron-withdrawing substituents on the aromatic
aldehydes.
Comparison of PEG1000-DAIL, molecular iodine, hydrochloric acid, [NMP][HSO4],
H3[PW12O40], H4[Si(W3O10)4] showed that the higher activity could be achieved with
PEG1000-DAIL as catalyst for the synthesis of
3-(4-fluorophenyl)-1-methylbenzo[f]quinoline. The results are represented in Table 4.
In conclusion, we have developed a simple, novel and effective method for the
preparation of 3-arylbenzoquinoline, pyranoquinoline and thiopyranoquinoline
derivatives catalyzed by PEG1000-DAIL. The advantages of our protocol include good
yields, easy isolation of the compounds, the elimination of the metals, and good
thermoregulated biphasic behavior of PEG1000-DAIL. Moreover, the PEG1000-DAIL could
be readily recovered and reused for several consecutive cycles, thus making this
methodology environmentally more acceptable.
EXPERIMENTAL
IR spectra were recorded on a Bomem MB154S infrared analyzer. 1H NMR were
recorded with Bruker Advance RX400. ESI-MS were recorded on a Themo Finningan
Trace TSQ. The PEG1000-DAIL was prepared by the procedure given in the literature.[38]
6

All the other chemicals and reagents are obtained from commercial resource.
Commercially available reagents were used without further purification. Products are all
known compounds and were identified by comparing of their physical and spectra data
with those reported in the literature.
Typical Procedure For The Syntheses Of 3-Arylbenzoquinoline, Pyranoquinoline And
Thiopyranoquinoline Derivatives Catalyzed By PEG1000-DAIL
To a solution of arylaldehyde (2 mmol), naphthalen-2-amine (2 mmol) and ketone
(acetone, acetophenone, tetrahydropyran-4-one or tetrahydrothiopyran-4-one) (2 mmol)
in toluene (1 mL) was added PEG1000-DAIL (1 mL) at room temperature. Then the
mixture was stirred at 80 °C for the specified time and monitored by TLC. After the
reaction, the mixture was cooled to room temperature, the upper toluene contained the
expected product was separated by decantation. The toluene was evaporated to give
corresponding products purified by recrystallization from DMF. The bottom phase was
the PEG1000-DAIL that contained the produced water. The PEG1000-DAIL was reused
after the removal of water under reduced pressure.
Funding
The project sponsored by the Natural Science Foundation of the Anhui Higher Education
Institutions of China (No. KJ2015A033).
7

SUPPLEMENTARY DATA
Full experimental detail, Mp and NMR spectra. This material can be found via the
“Supplementary Content” section of this article’s webpage.
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15

Table 1. Studies on the reaction temperature of 4-fluorobenzaldehyde,
naphthalen-2-amine and acetone in PEG1000-DAIL
CH3
N
CHO
PEG1000-DAIL
toluene
NH2
O
+
+
CH3
CH3
F
F
Yield (%)a
Entry
T (°C)
r.t.
Time (h)
1
2
3
4
5
6b
7
8
12
12
10
9
tarce
25
40
50
47
60
63
70
7
81
80
5
95, 95, 95, 93, 92, 91, 90
90
5
95
95
100
5
aIsolated yields.
bThe PEG1000-DAIL was run for seven consecutive cycles.
16

Table 2. PEG1000-DAIL catalyzed the synthesis of 3-arylbenzoquinoline derivatives
R
PEG1000-DAIL
NH2
O
+
ArCHO +
toluene
80 C
CH3
R
N
Ar
1
2
3
4
Entry Ar
R
Products
t (h)
Yield
(%)a
95
92
90
89
90
91
88
86
87
85
82
84
86
85
4-FC6H4
4-ClC6H4
1
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
5
4a
4b
4c
4d
4e
4f
2
5
3-ClC6H4
3
7
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
4-BrC6H4
4
5
5
6
6
5
7
5
4g
4h
4i
3-BrC6H4
8
6
4-CH3OC6H4
3,4-(CH3)2C6H3
9
7
10
11
12
13
14
7
4j
4-FC6H4
3-BrC6H4
3-BrC6H4
4-ClC6H4
4-BrC6H4
C6H5
12
12
13
13
4k
4l
4-FC6H4
4m
4n
4-CH3C6H4
17

15
16
17
18
4-ClC6H4
4-NO2C6H4
4-NO2C6H4
4-BrC6H4
10
10
12
14
90
91
82
84
4o
4p
4q
4r
3-NO2C6H4
3-NO2C6H4
3-ClC6H4
4-BrC6H4
a Isolated yields
18

Table 3. PEG1000-DAIL catalyzed the synthesis of pyranoquinoline and
thiopyranoquinoline derivatives
X
O
PEG1000-DAIL
NH2
+
ArCHO +
toluene
80 C
N
Ar
X
1
2
5
6
Entry Ar
X
Products
t (h)
Yield
(%)a
85
4-FC6H4
2-FC6H4
1
O
O
O
O
O
O
O
O
O
O
S
11
8
6a
6b
6c
6d
6e
6f
2
87
4-ClC6H4
3
13
8
90
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
4-BrC6H4
2-CH3OC6H4
4-CH3C6H4
C6H5
4
91
5
8
90
6
8
85
7
12
14
14
13
13
10
88
6g
6h
6i
8
82
9
78
10
11
12
79
6j
C6H5
84
6k
6l
4-FC6H4
S
86
19

2-FC6H4
13
14
15
16
S
S
S
S
8
87
91
89
91
6m
6n
6o
4-ClC6H4
13
13
8
4-BrC6H4
3-NO2C6H4
6p
a Isolated yields.
20

Table 4. Different catalytic systems for the condensation of 4-fluorobenzaldehyde,
naphthalen-2-amine and acetone
CH3
CHO
NH2
O
Catalyst
+
+
CH3
CH3
N
F
F
Yield (%)a
95
Entry
Catalysts
PEG1000-DAIL
I2
solvents
toluene
THF
T (°C)
Time (h)
1
2
3
4
5
6
80
5
6
6
5
5
5
Reflux
Reflux
80
96[12]
68[49]
81
Hydrochloric acid
[NMP][HSO4]
H3[PW12O40]
EtOH
toluene
EtOH
Reflux
Reflux
85
H4[Si(W3O10)4]
EtOH
83
aIsolated yields.
21

Scheme 1. Poly(ethylene glycol) linked dicationic acidic ionic liquids.
Products
Reactants
Toluene
Cool
Heat
PEG-DAIL
Homogeneous
Recovered and reused
N
PEG-DAILS: HO S
+
3
-
N
O
2 HSO4
O
N
n
+
N
SO3H
22