Novel SO3H-functionalized ionic liquids - Catalyzed facile and efficient synthesis of polyhydroquinoline derivatives via Hantzsch condensation under ultrasound irradiation

Article abstract of DOI:10.1002/jhet.2070

A facile and efficient synthesis of polyhydroquinolines has been developed via four-component condensation reactions of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in the presence of Novel SO₃H-functionalized ionic liquid catalysts through Hantzsch reaction under ultrasound irradiation without solvent. Simple work-up procedure, environmentally friendly, inexpensive, and non-toxic catalyst, shorter reaction times along with excellent product yields are the significant features of this practical method.

Full text of DOI:10.1002/jhet.2070

Month 2014 Novel SO3H-Functionalized Ionic Liquids – Catalyzed Facile and Efficient
Synthesis of Polyhydroquinoline Derivatives via Hantzsch Condensation
under Ultrasound Irradiation
*
Bai Lin Li, Ai Guo Zhong, and An Guo Ying
Department of Pharmaceutical and Chemical Engineering, Taizhou College, Linhai, Zhejiang 317000,
People's Republic of China
*
E-mail:lbliso@sina.com
Received March 23, 2012
DOI 10.1002/jhet.2070
Published online 00 Month 2014 in Wiley Online Library (wileyonlinelibrary.com).
O
O
O
Ph
O
O
ILs, RT
NH OAc
+
OC2H5
CH3
4
+
PhCHO
+
O
Ultrasound
O
N
H
A facile and efficient synthesis of polyhydroquinolines has been developed via four-component condensation
reactions of aldehydes, dimedone, ethyl acetoacetate, and ammonium acetate in the presence of Novel
SO3H-functionalized ionic liquid catalysts through Hantzsch reaction under ultrasound irradiation without solvent.
Simple work-up procedure, environmentally friendly, inexpensive, and non-toxic catalyst, shorter reaction times
along with excellent product yields are the significant features of this practical method.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
SO3H-functionalized ILs that have two alkyl sulfonic acid
groups in imidazolium cations were designed and applied
for xanthenedione derivatives synthesis in water under
ultrasound irradiation (Fig. 1) [29]. However, there is no
report on the use of SO3H-functionalized ionic liquids
(ILs) as a catalyst in the Hantzsch condensation, we wish
to demonstrate the catalytic activity of these ILs in the
synthesis of polyhydroquinolines under ultrasound irradia-
tion without solvent.
Compounds containing the 4-substituted 1,4-dihydropyridine
(DHP) nucleus comprise a large family of medicinally important
compounds. They can cure the disordered heart ratio as a chain-
cutting agent of factor IV channel, possess the calcium channel
agonist–antagonist modulation activities [1–3], and also behave
as neuroprotectants, cerebral antiischaemic agents, and
chemosensitizers [4,5]. A recent computational analysis of the
comprehensive medicinal chemistry database found the DHP
framework to be among the most prolific chemotypes found.
Thus, the synthesis of 4-substituted 1,4-dihydro-pyridines
(1,4-DHPs) is of continuing interest. Recently, several
methods have been reported comprising the use of conditions
such as conventional heating [6], solar thermal energy [7],
ionic liquid [8], TMSCl-NaI [9], metal triflates [10], grinding
[11], Hy-Zeolite [12], montmorillonite K-10 [13], cerium(IV)
ammonium nitrate [14], iron(III) trifluoroacetate [15], HClO4-
SiO2 [16], heteropoly acid [17], molecular iodine [18], p-TSA
[19], L-proline and derivatives [20], nickel [21], polymers
[22], Baker's yeast [23], Glycine [24], L-proline [25],
guanidine hydrochloride [26], ZnO-nanoparticle [27]. Most
of these processes, however, suffer from one or other
drawbacks such as longer reaction time, lower product yield,
harsh conditions, high costs, difficult to reuse, usually
required in large amounts, and use of hazardous
catalysts. As a result, an eco-safe and efficient alternative
method for the preparation of polyhydroquinoline is
highly desirable.
RESULTS AND DISCUSSION
We report herein a benign, rapid, and efficient four-com-
ponent, one-pot synthesis of polyhydroquinolines in excel-
lent yields by using aromatic aldehydes, dimedone, ethyl
acetoacetate, and ammonium acetate in the presence of
catalytic amount of ILs (1 mol %) under ultrasound
irradiation without solvent. Initially, the model reaction was
carried out under ultrasound irradiation (Scheme 1). The
results of ILs catalyzed condensation reactions are shown
in Table 1. First, 97.0% yields obtained when the reaction
was catalyzed by 1.0 % fresh ILs (Table 1, entry 1). Because
the products are insoluble in water, the reaction mixture was
washed with cold water to remove the ILs after the reaction
completed, the remaining ILs could be reused for the subse-
quent catalytic cycle of the reaction directly after removal of
water under vacuum, without an obvious decrease in the
reaction performance after 10 recycles in terms of the rate
and the yield. We also carried out the model reaction without
any catalyst, but the product was isolated in poor yield after
40min (entry 11).
Ultrasonic chemistry has received an increasing attention
in recent years [28]. A large number of organic reactions
can be carried out in higher yields, shorter reaction time
and milder conditions under ultrasound irradiation than that
of conventional methods. In our previous work, the novel
As ILs have a similar structure and property with P-TSA
[19], its mechanism as a catalyst for the Hantzsch reaction
under solvent-free conditions is proposed (Scheme 2). It
© 2014 HeteroCorporation

B. L. Li, A. G. Zhong, and A. G. Ying
Vol 000
CF3SO3
N SO3H
and efficient method for the synthesis of polyhy-
droquinoline derivatives. The present method has many
obvious advantages compared with those reported in the
previous literatures, including the avoidance of discharging
harmful organic solvents, the high yields, the short reaction
times, the generality, and the simplicity of the methodol-
ogy and recycling of the catalyst.
HO3S
N
Figure 1. Novel Brønsted acidic ionic liquids (ILs) bearing two alkyl
sulfonic acid groups.
Scheme 1
O
EXPERIMENTAL
O
O
NH OAc
+
4
+
PhCHO
+
OC2H5
O
General melting points were determined on a Kofler hot-stage
apparatus and were uncorrected. IR spectra were recorded on a
NicoletFT/IR-5700 spectrophotometer.1H-NMR spectra were
recorded on a BRUKER AVANCE DPX spectrometer at
200 MHz. NMR spectra were obtained on solutions in CDCl3
by using TMS as an internal standard. Ultrasound reaction was
conducted by using XO-SM100 ultrasound synthesis system
(NAN JING SINO INSTRUMENTS MANUFACTURE Co.,
LTD) (Sinopharm Chemical Reagent Co., Ltd, ShangHai, China).
TLC was carried out on GF254 silica gel plates. Commercially
available chemicals were used without further purification.
General experimental procedure. A mixture of aldehyde
(10 mmol), dimedone (10 mmol), ethyl acetoacetate (10 mmol),
ammonium acetate (11 mmol), and ILs (0.1 mmol) was
irradiated at 35 kHz for 0.5–3 mins, after the reaction was
complete, the reaction mixture was cooled to room temperature,
poured into crushed ice, and stirred for several minutes. The
resulting solid was filtered under suction and recrystallized from
hot ethanol to afford the pure products. Finally, the remaining
[(HSO3-p)2im][CF3SO3] was reused after removal of water
under vacuum. The spectral and analytical data for the
compounds are presented in the later text (5a–5u).
O
O
Ph
ILs, RT
OC2H5
CH3
Ultrasound
N
H
might catalyze the Knoevenagel-type coupling of
aldehydes with active methylene compounds and then the
Michael-type addition of intermediates through either path
A or path B to give the 1,4-DHPs.
Encouraged by the previous results, we have treated a va-
riety of substituted aldehydes, dimedone, ethyl acetoacetate,
and ammonium acetate in the presence of ILs catalyst to form
the corresponding polyhydroquinolines. Excellent yields of
polyhydroquinolines were obtained by carrying out the reac-
tion under ultrasound irradiation at room temperature for 0.
5–3 min (Table 2). This method has the ability to tolerate a
variety of functional groups such as hydroxyl, methoxy,
methyl, nitro, and halides under the reaction conditions. Both
the electron-rich and electron-deficient aldehydes as well as
heterocyclic aldehydes (entries 16, 17) worked well, leading
to high yields of product. However, aliphatic aldehydes
afforded relevant lower yields (entry 21). (Scheme 3)
5a IR (KBr): 3287, 3077, 2964, 1696, 1610 cmÀ1 1H-NMR
;
(200 MHz, CDCl3): δ = 0.92 (s, 3H), 1.07 (s, 3H), 1.18 (t,
J= 7.3 Hz, 3H), 2.13–2.25 (m, 4H), 2.38 (s, 3H), 4.05 (q,
J= 7.33 Hz, 2H), 5.02 (s, 1H), 5.8 (s, 1H, NH), 6.85–6.89 (m, 2H),
7.23–7.27 (m, 2H); 13C-NMR (62.5 MHz, CDCl3): δ = 195.70,
167.47, 148.72, 147.05, 143.67, 127.96, 127.83, 125.98, 111.92,
105.93, 59.78, 50.72, 40.85, 36.55, 32.64, 29.41, 27.08, 19.24, 14.17.
5b IR (KBr): 3275, 3080, 2960, 1700, 1650 cmÀ1 1H-NMR
;
(200MHz, CDCl3): 0.95 (s, 3H), 1.07 (s, 3H), 1.21 (t, J = 6.4Hz,
3H), 2.17–2.25 (m, 4H), 2.23 (s, 3H), 2.35 (s, 3H), 4.04 (q,
J = 7.0 Hz, 2H), 5.00 (s, 1H), 6.09(s, 1H), 7.01 (d, J = 7.6 Hz, 2H),
7.18 (d, J = 8.0 Hz, 2H); 13C-NMR (62.5 MHz, CDCl3):
δ = 195.68, 167.39, 148.74, 146.95, 143.71, 127.97, 127.83,
126.07, 112.01, 105.98, 59.83, 50.77, 40.92, 36.59, 32.73, 29.45,
27.06, 19.81, 19.23, 14.16.
CONCLUSIONS
In conclusion, we have demonstrated that the four-
component ultrasound-asisted Hantzsch reaction can
effectively be performed with the promotion of novel
SO3H-functionalized ionic liquids, which provide a simple
Table 1
Recycling of the catalyst in the condensation reaction.
Entry
1
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11b
Time (min)
Yield (%)c
5
97
5
97
5
96
5
95
5
96
5
95
5
95
5
95
5
95
5
94
5
94
40
85
aReaction conditions: benzaldehyde (10 mmol), dimedone(10 mmol), ethyl acetoacetate (10 mmol), ammonium acetate (11 mmol), and ILs (0.1 mmol);
ultrasound irradiation for 5 min, [(HSO3-p)2im][ CF3SO3] was reused.
bThe reaction was carried out without any catalyst for 40 min.
cIsolated yield.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Novel SO3H-Functionalized Ionic Liquids – Catalyzed Facile and Efficient Synthesis of
Polyhydroquinoline Derivatives via Hantzsch Condensation under Ultrasound Irradiation
Scheme 2
4.05 (q, J = 7.2Hz, 2H), 5.02(s, 1H), 6.10 (s, 1H), 7.14–7.27 (m,
4H); 13C-NMR (62.5MHz, CDCl3): δ = 195.64, 167.31, 149.20,
144.53, 133.55, 129.11, 128.08, 126.23, 111.14, 105.12, 59.79,
50.67, 40.64, 36.58, 32.59, 29.34, 27.01, 19.06, 14.13.
O
O
OC2H5
Ph
+
5e IR (KBr): 3291, 2961, 1695, 1610, 1490, 1380, 1221, 1025,
H2O + AcOH
H2N
CH3
O
764 cmÀ1 1H-NMR (200 MHz, CDCl3): 0.93 (s, 3H), 1.07 (s,
;
H2O
ILs
Path A3
3H), 1.19 (t, J = 7.0 Hz, 3H), 2.15–2.30 (m, 4H), 2.37 (s, 3H),
4.05 (q, J = 7.0 Hz, 2H), 5.03 (s, 1H), 6.14 (s, 1H), 6.83–6.92
(m, 2H), 7.23–7.29 (m, 2H); 13C-NMR (62.5 MHz, CDCl3):
δ = 195.65, 167.55, 153.72, 149.27, 144.60, 138.63, 129.51,
112.17, 106.25, 59.84, 50.78, 40.97, 36.12, 32.71, 29.42, 27.15,
19.31, 14.22.
PhCHO
NH4OAc
Path A2
Path A1
ILs
O
O
Ph
O
O
OC2H5
CH3
OC2H5
N
H
O
O
CH3
5f IR (KBr): 3391, 2956, 1702, 1645, 1590, 1480, 1385, 1220,
ILs
Path B1
782 cmÀ1 1H-NMR (200 MHz, CDCl3): 0.85 (s, 3H), 1.00 (s,
;
NH4OAc
Path B3
ILs
Ph
PhCHO
Path B2
3H), 1.13 (t, J = 7.0 Hz, 3H), 1.97–2.48 (m, 4H), 2.50 (s, 3H),
3.97 (q, J = 6.8 Hz, 2H), 4.73(s, 1H), 6.54 (d, J = 8.6 Hz, 2H),
6.92 (d, J = 8.4 Hz, 2H), 8.98 (s, 1H), 9.05 (s, 1H); 13C-NMR
(62.5 MHz, CDCl3): δ = 195.69, 167.47, 148.70, 147.02, 143.57,
127.86, 127.82, 125.96, 111.90, 105.91, 59.76, 50.71, 40.83,
36.52, 32.61, 29.40, 27.05, 19.22, 14.16.
O
O
H2O
H2O + AcOH
OC2H5
CH3
+
NH2
O
5g IR (KBr): 3283, 3078, 2930, 2885, 2841, 1688, 1650, 1610,
1574, 1558, 1487, 1443 cmÀ1; 1H-NMR (200 MHz, CDCl3): 0.91
(s, 3H), 1.04 (s, 3H), 1.17 (t, J = 7.0 Hz, 3H), 2.11–2.28 (m, 4H),
2.26 (s, 3H), 3.78 (s, 3H), 3.99 (q, J = 1.2 Hz, 2H), 5.23(s, 1H),
5.98 (s, 1H), 6.75–6.83 (m, 2H), 6.91–7.21 (m, 1H), 7.25–7.29
(m, 1H); 13C-NMR (62.5 MHz, CDCl3): δ = 195.67, 167.51,
157.72, 148.18, 143.21, 139.60, 128.91, 126.81, 114.31,
113.20, 112.21, 106.24, 59.75, 55.08, 50.73, 40.95, 35.67,
32.64, 29.41, 27.13, 19.31, 14.21.
5c IR (KBr): 3276, 2957, 1705, 1647, 1605, 1497, 1382, 1217,
1030, 767 cmÀ1; 1H-NMR (200 MHz, CDCl3): 0.94 (s, 3H), 1.06
(s, 3H), 1.21 (t, J = 7.0 Hz, 3H), 2.17-2.27 (m, 4H), 2.23 (s, 3H),
2.36 (s, 3H), 3.73 (s, 3H), 4.06 (q, J = 7.0 Hz, 2H), 5.99 (s, 1H),
6.19(s, 1H), 6.73 (d, J = 6.6 Hz, 2H), 7.21 (d, J = 8.6 Hz, 2H);
13C-NMR (62.5 MHz, CDCl3): δ = 195.65, 167.51, 157.72,
148.18, 143.21, 139.60, 128.91, 113.20, 112.21, 106.24, 59.75,
55.08, 50.73, 40.95, 35.67, 32.64, 29.41, 27.13, 19.31, 14.21.
5h IR (KBr): 3296, 3093, 2969, 2940, 1699, 1612, 1525 cmÀ1
;
1
5d IR (KBr): 3274, 3206, 3085, 2938, 1705, 1606 cm-1;
1H-NMR (200 MHz, CDCl3): 0.88 (s, 3H), 1.05 (s, 3H), 1.09 (t,
1H-NMR (200 MHz, CDCl3) : 0.92 (s, 3H), 1.07 (s, 3H),
J = 7.0 Hz, 3H), 2.12–2.28 (m, 4H), 2.35 (s, 3H), 4.02 (q,
1.19 (t, J = 7.2 Hz, 3H), 2.09–2.29 (m, 4H), 2.37 (s, 3H),
Table 2
Synthesis of polyhydroquinolines catalyzed by ionic liquids (ILs) under ultrasound irradiation.a
mp (°C)
Time
(min)
Yield b
(%)
Product
R1
R2
R3
Products
Obs
Lit
1
2
3
4
5
6
7
8
C6H5
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
H
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OEt
OMe
Me
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
5s
1
1
1
1
1
1.5
1
3
2
3
0.5
1
0.5
1
1
1
0.5
1
0.5
1
97
95
93
94
92
94
93
91
93
92
98
98
98
90
91
98
97
91
96
93
88
202–203
258–260
255–257
245–248
184–187
230–234
250–253
201–203
208–211
205–207
201–203
192–194
234–235
234–236
197–199
245–247
240–243
240–242
263–274
199–201
157–158
203–205[24]
259–260[24]
256–257[24]
246–248[24]
184–185[24]
232–234[19]
251–254[19]
203–206[19]
207–210[19]
206–208[19]
202–204[15]
192–193[19]
235–237[19]
234–235[19]
198–200[15]
247–248[19]
241–242[19]
240–241[15]
—
4-CH3C6H4
4-CH3OC6H4
4-ClC6H4
4-FC6H4
4-HOC6H4
2-CH3OC6H4
2-NO2C6H4
2-HOC6H4
2-ClC6H4
3-CH3OC6H4
3-ClC6H4
3-BrC6H4
2-Cl-5-NO2C6H3
2-Naphthal
2-Furyl
2-Thioanyl
C6H5
C6H5
C6H5
(CH3)2CH
9
10
11
12
13
14
15
16
17
18
19
20
21
CH3
CH3
CH3
5t
5u
—
—
OEt
3
aReaction conditions: aldehyde 1 (10 mmol), dimedone 2 (10 mmol), 3 (10 mmol), ammonium acetate 4 (11 mmol), and ILs (0.1 mmol).
bIsolated yield.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

B. L. Li, A. G. Zhong, and A. G. Ying
Vol 000
Scheme 3
O
O
R1
O
O
R3
CH3
O
ILs, RT
R2
R2
NH OAc
+
R
R2
R CHO
4
+
2
+
1
R3
N
H
5
Ultrasound
O
3
1
2
4
J = 7.0 Hz, 2H), 5.87 (s, 1H), 6.23 (s, 1H), 7.22–7.27(m, 1H),
7.44–7.49 (m, 2H), 7.71–7.75 (m, 1H); 13C-NMR (62.5 MHz,
CDCl3): δ = 195.79, 167.51, 141.02, 132.33, 131.12, 128.74,
127.15, 125.96, 114.25, 109.24, 101.34, 55.13, 52.94, 50.52,
48.91, 46.85, 42.47, 32.37, 31.26, 29.16, 26.55.
5o IR (KBr): 3199, 3058, 2958, 2922, 1676, 1635, 1602,
1448 cmÀ1 1H-NMR (200 MHz, CDCl3): 0.89 (s,3H), 1.04 (s,
;
3H), 1.19 (t, J = 7.0 Hz, 3H), 2.14–2.26 (m, 4H), 2.42 (s, 3H),
4.04 (q, J = 7.0 Hz, 2H), 5.23 (s, 1H), 6.16 (s, 1H), 7.35–7.53
(m, 3H), 7.67–7.76 (m, 4H); 13C-NMR (62.5 MHz, CDCl3):
δ = 195.71, 167.46, 148.71, 147.05, 143.67, 127.96, 127.83,
127.58, 126.31, 126.01, 125.98, 125.52, 111.92, 105.93, 59.78,
50.72, 40.85, 36.55, 32.64, 29.41, 27.08, 19.24, 14.17.
5p IR (KBr): 3288, 3078, 2969, 1687, 1602, 1493, 1034, 941, 877,
826 cmÀ1; 1H-NMR (200 MHz, CDCl3): 1.03 (3H, s), 1.12 (3H, s),
1.26 (3H, t, J= 6.9 Hz), 2.21–2.27 (3H, m), 2.35–2.38 (4H, m),
4.10–4.18 (2H, m), 5.25 (1H, s), 5.80 (1H, s), 6.02 (1H, s), 6.20
(1H, s), 7.17 (1H, s); 13C-NMR (62.5 MHz, CDCl3): δ = 195.57,
167.34, 157.94, 150.61, 144.26, 140.85, 111.13, 105.03, 103.07,
59.83, 50.63, 36.88, 32.48, 29.71, 27.03, 19.08, 14.17.
5i IR (KBr): 3284, 3080, 2936, 2880, 1730, 1652, 1575,
1558, 1515, 1457 cmÀ1 1H-NMR (200 MHz, CDCl3): 0.88
;
(s,3H), 1.01 (s, 3H), 1.23 (t, J = 7.4 Hz, 3H), 1.89 (s, 3H),
2.15 (s, 4H), 4.10 (m, 2H), 4.67 (d, J = 2.8 Hz, 1H), 5.30
(s, 1H), 6.76-6.85 (m, 2H), 6.76–6.85 (m, 2H), 7.00–7.05
(m, 1H),7.33–7.37 (m, 1H); 13C-NMR (62.5 MHz, CDCl3):
δ = 195.69, 167.47, 148.70, 147.02, 143.57, 127.86, 127.82,
125.96, 121.30, 114.12, 111.90, 105.91, 59.76, 50.71, 40.83,
36.52, 32.61, 29.40, 27.05, 19.22, 14.16.
5j IR (KBr): 3292, 3072, 2956, 2930, 1698, 1637, 1607, 1423,
1379, 1279, 1072 cmÀ1; 1H-NMR (200 MHz, CDCl3): 0.94 (s,3H),
1.06 (s, 3H), 1.27 (t, J= 7.4 Hz, 3H), 2.14–2.22 (m, 4H), 2.26 (s,
3H), 4.04 (q, J=2.2Hz, 2H), 5.38 (s, 1H), 6.37 (s, 1H), 7.02–7.13
(m, 2H), 7.21–7.27 (m, 1H), 7.37–7.42 (m, 1H); 13C-NMR
(62.5 MHz, CDCl3): δ = 195.41, 167.23, 149.38, 142.42, 133.67,
132.78, 132.04, 129.13, 126.86, 111.13, 104.59, 60.11, 50.58,
41.07, 32.73, 29.12, 27.37, 19.11, 14.17.
5q IR (KBr): 3218, 3079, 2963, 2934, 1695, 1652, 1611, 1457,
1
1447, 1383, 1398, 1282 cmÀ1; H-NMR (200 MHz, CDCl3): 0.93
(s, 3H), 1.02 (s, 3H), 1.18 (t, J=7.0Hz, 3H), 2.08–2.51 (m, 4H),
2.33 (s, 3H), 4.05 (q, J= 7.2 Hz, 2H), 5.16(s, 1H), 6.64–6.66 (m,
1H), 6.79–6.83 (m, 1H),7.15–7.18 (s, 1H), 9.25 (s, 1H); 13C-NMR
(62.5 MHz, CDCl3): δ = 195.56, 167.33, 157.92, 150.61, 144.23,
140.85, 115.15, 108.03, 103.06, 59.83, 50.65, 36.85, 32.47, 29.71,
27.03, 19.08, 14.17.
5k IR (KBr): 3283, 3078, 2930, 2885, 2841, 1688, 1650, 1610,
1574, 1558, 1487 cmÀ1
;
1H-NMR (200 MHz, CDCl3): 0.95
5r IR (KBr): 3283, 3077, 2962, 2879, 1690, 1645, 1607 cmÀ1
;
(s,3H), 1.07 (s, 3H), 1.21 (t, J = 7.0Hz, 3H), 2.15–2.29 (m, 4H),
2.36 (s, 3H), 3.75 (s, 3H), 4.08 (q, J = 7.0Hz, 2H), 5.04 (s, 1H),
6.00 (s, 1H), 6.62–6.68 (m, 1H), 6.86–6.92 (m, 2H), 7.08–7.15
(m, 1H); 13C-NMR (62.5 MHz, CDCl3): δ = 195.66, 167.50,
157.71, 148.17, 143.20, 139.61, 128.90, 126.80, 114.30, 113.19,
112.21, 106.23, 59.74, 55.07, 50.72, 40.95, 35.66, 32.63, 29.41,
27.12, 19.30, 14.21.
1H-NMR (200 MHz, CDCl3): 1.18 (t, J = 7.4 Hz, 3H), 1.62 (s,
2H), 1.94–1.99 (m, 2H), 2.29–2.44 (m, 7H), 4.04 (q, J = 7.0 Hz,
2H), 5.08 (s, 1H), 5.98 (s, 1H), 7.09–7.32 (m, 5H); 13C-NMR
(62.5 MHz, CDCl3): δ = 195.69, 167.47, 148.71, 147.04, 143.65,
127.95, 127.82, 125.96, 111.91, 105.93, 59.77, 40.85, 36.54,
32.65, 29.41, 19.24, 14.17.
5s IR (KBr): 3277, 3078, 2937, 2873, 1683, 1648, 1606 cmÀ1
;
5lIR (KBr): 3274, 3202, 3074, 2934, 1704, 1605 cmÀ1; 1H-NMR
(200 MHz,CDCl3):0.95(s,3H),1.07(s,3H),1.21(t,J = 7.2Hz,3H),
2.18–2.29(m, 4H), 2.36(s,3H), 4.02–4.13(m, 2H), 5.03(s, 1H),6.42
(s, 1H), 7.08–7.17 (m, 2H), 7.21–7.27 (m, 2H); 13C-NMR
(62.5 MHz, CDCl3): δ = 195.40, 167.22, 149.37, 142.41, 133.66,
132.76, 132.02, 129.12, 126.85, 111.12, 104.58, 60.11, 50.58,
41.06, 32.72, 29.12, 27.36, 19.11, 14.15.
1H-NMR (200 MHz, CDCl3): 0.93 (s, 3H), 1.07 (s, 3H), 2.16–
2.29 (m, 4H), 2.38 (s, 3H),3.60 (s, 3H), 5.07 (s, 1H), 6.05 (s,
1H), 7.09–7.32 (m, 5H); 13C-NMR (62.5 MHz, CDCl3):
δ = 195.70, 167.47, 148.72, 147.05, 143.67, 127.96, 127.83,
125.98, 111.92, 105.93, 59.78, 50.72, 40.85, 36.55, 32.64,
29.41, 27.08, 19.24, 14.17. Anal. Calcd. for C20H23NO3: C,
73.82; H, 7.12; N, 4.31. Found: C, 73.73; H, 4.38; N, 4.29.
5t IR (KBr): 3271, 3072, 2961, 2871, 1647, 1595,1506 cmÀ1; 1H-
NMR (200 MHz, CDCl3): 1.10 (s, 6H), 1.24 (s, 3H), 2.37 (s, 3H),
2.35–2.43 (m, 4H), 5.54(s, 1H), 7.07–7.12 (m, 2H), 7.07–7.12 (m,
2H), 11.87 (s, 1H); 13C-NMR (62.5 MHz, CDCl3): δ = 195.70,
167.47, 148.72, 147.05, 143.67, 127.96, 127.83, 125.98, 111.92,
105.93, 50.72, 40.85, 36.55, 32.64, 29.41, 27.08, 22.21, 19.24. Anal.
Calcd. for C20H23NO2: C, 77.64; H, 7.49; N, 4.53. Found: C, 77.70;
H, 4.50; N, 4.51.
5m IR (KBr): 3275, 3204, 3074, 2957, 1703, 1605 cmÀ1;1H-NMR
(200 MHz, CDCl3) : 0.96 (s, 3H), 1.08 (s, 3H), 1.21 (t, J= 7.4Hz, 3H),
2.19–2.29 (m, 4H), 2.37 (s, 3H), 4.06 (q, J= 5.8 Hz, 2H), 5.02 (s, 1H),
7.00–7.10(m, 1H), 7.21–7.27 (m, 2H), 7.39–7.40 (m, 2H); 13C-NMR
(62.5 MHz, CDCl3): δ = 196.40, 168.25, 149.37, 144.42, 133.64,
132.73, 132.02, 129.10, 126.84, 111.13, 104.55, 60.12, 50.59,
41.08, 32.74, 29.15, 27.40, 19.13, 14.17.
5n IR (KBr): 3294, 3093, 2969, 2940, 1699, 1612, 1525, 1379,
1279, 1072 cmÀ1
;
1H-NMR (200 MHz, CDCl3) : 0.96 (s, 3H),
5u IR (KBr): 3271, 3072, 2964, 2870, 1717, 1652, 1583, 1418,
1.08 (s, 3H), 1.21 (t, J = 7.4 Hz, 3H), 2.19À2.29 (m, 4H), 2.37
(s, 3H), 4.06 (q, J = 5.8 Hz, 2H), 5.02 (s, 1H), 7.38–7.40 (m,
1H), 7.88–7.90 (m, 1H), 8.02–8.12 (m, 1H); 13C-NMR
(62.5 MHz, CDCl3): δ = 196.41, 168.28, 150.12, 145.42, 134.61,
133.70, 133.02, 129.20, 127.34, 112.13, 105.55, 60.22, 50.64,
41.38, 32.75, 29.16, 27.41, 19.15, 14.19.
1363, 1339 cmÀ1 1H-NMR (200 MHz, CDCl3, δppm): 0.84(d,
;
J = 6.4 Hz, 6H), 1.07(s, 6H), 1.18 (t, J = 7.0 Hz, 3H), 2.29 (s,
3H), 2.25–2.31 (m, 4H), 2.43–2.51 (m, 1H), 2.87–3.01(s, 1H),
4.06 (q, J = 5.8 Hz, 2H), 12.45 (s, 1H); 13C-NMR (62.5 MHz,
CDCl3): δ = 195.70, 167.47, 148.72, 147.05, 111.92, 105.93,
59.78, 50.72, 36.55, 32.64, 30.18, 29.41, 27.08, 21.21, 19.23,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
Novel SO3H-Functionalized Ionic Liquids – Catalyzed Facile and Efficient Synthesis of
Polyhydroquinoline Derivatives via Hantzsch Condensation under Ultrasound Irradiation
[12] Das, B.; Ravikanth, B.; Ramu, R.; Rao, V. B. Chem Pharm
Bull 2006, 54, 1044.
[13] Song, G.; Wang, B.; Wu, X.; Kang, Y.; Yang, L. Synth
Commun 2005, 35, 2875.
14.15. Anal. Calcd. for C18H27NO3: C, 70.79; H, 8.91; N, 4.59.
Found: C, 70.80; H, 8.93; N, 4.58.
[14] Reddy, C. S.; Raghu, M. Chin Chem Lett 2008, 19, 775.
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Acknowledgment. We are pleased to acknowledge the financial
support from Tai zhou University.
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet