The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst for diketene-based, four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions

Article abstract of DOI:10.1016/j.cclet.2013.03.020

An efficient diketene ring-opening synthesis of polyhydroquinoline derivatives using SBA-15 sulfonic acid modified mesoporous substrates a green and reusable catalyst in a single-pot four-component coupling reaction of diketene, alcohol, enamine, and alde

Full text of DOI:10.1016/j.cclet.2013.03.020

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CCLET-2505; No. of Pages 3
Chinese Chemical Letters xxx (2013) xxx–xxx
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Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Original article
The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst for
diketene-based, four-component synthesis of polyhydroquinolines and
dihydropyridines under neat conditions
*
Sadegh Rostamnia , Fatemeh Pourhassan
Organic and Nano Group (ONG), Department of Chemistry, Faculty of Science, University of Maragheh, P.O. Box 55181-83111, Maragheh, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
An efficient diketene ring-opening synthesis of polyhydroquinoline derivatives using SBA-15 sulfonic
acid modified mesoporous substrates a green and reusable catalyst in a single-pot four-component
coupling reaction of diketene, alcohol, enamine, and aldehydes is reported. Dihydropyridine derivatives
based on neat adduct of diketene, alcohols and aldehydes using SBA-15/SO3H nanoreactor as catalyst via
a four-component reactions are also synthesized. The advantages of the present method include the use
of a small amount catalyst, simple procedure with an easy filterable work-up, waste-free, green and
direct synthetic method with an excellent yield of products with efficient use of catalyst and a short
reaction time.
Received 4 January 2013
Received in revised form 2 February 2013
Accepted 28 February 2013
Available online xxx
Keywords:
SBA-15/SO3H
Nanoreactor
Diketene
ß 2013 Sadegh Rostamnia. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights
reserved.
Polyhydroquinoline
1. Introduction
however, there exist significant drawbacks, such as high tempera-
ture, long reaction time, low product yields and requirements for
The functionalized SBA-15 silica family of mesoporous materi-
als with nano-channels have shown excellent catalytic perfor-
mance because of their high surface area, high thermal and
mechanical stability as a result of small nanoparticle pore sizes [1].
Hydrothermally stable, the sulfonic acid modified SBA-15 nanor-
eactor (SBA-15/PrSO3H or SBA-15/SO3H) with organic–inorganic
mesochannels as catalyst provides a synergistic means to acidic
sites, and suitable mesochannels to drive out the products for
further recycles [1]. Additionally, based on green chemistry
desires, the development of new strategies for recycling of the
catalyst, which minimizes the consumption of auxiliary sub-
stances, energy and time required in achieving separations, can
result in significant economic and environmental benefits [1].
Polyhydroquinolines, as interesting and versatile N-hetero-
cycles, have attracted much attention due to their pharmacological
properties, such as antitumor, bronchodilator, antidiabetic, anti-
inflammatory, antibacterial, and antimalarial agents [2]. Conse-
quently, many different synthetic methods for producing poly-
hydroquinolines derivatives have been reported using ionic
liquids, molecular iodine, HClO4–SiO2, HY-zeolites, CAN, hetero-
polyacid, and polymers [3]. With regard to most of these methods,
high amounts of organic solvents and catalysts. In addition, the use
of soluble metal catalysts in organic reactions requires several
catalyst separation steps. As a result, the challenge in this field
becomes that of developing waste-free and effective green
approaches with high yields.
Veryrecently,wediscoveredanewmulti-componentmethod[4]
for the ring-opening of diketenes to achieve some interesting
heterocycles based on Biginelli condensation [5]. In this work, our
aim has been to investigate fabrication of the mesoporous sulfonic
acid catalyst to accomplish the desired polyhydroquinolines with a
minimum of by-products, based on ring-opening of the diketene
under clean, neat conditions.
2. Experimental
In this work SBA-15 nanoreactor was synthesized by the
procedure reported by Zhao et al. [6a] and then modified with
mercaptopropyltrimethoxysilane (MPTMS) and oxidized to the
sulfonic acid [6b] nanoparticle using hydrogen peroxide (Fig. 1).
A mixture of diketene (3 mmol), aldehyde (1 mmol), enamine
(1 mmol) and alcohol (4 mL) and SBA-15/SO3H (0.07 g,
ꢀ4 mol%) was reacted under neat conditions for appropriate
time (TLC). After that, 20 mL hot EtOH was added to the reaction
vessel and, with simple centrifuging, the catalyst was removed
as filtrate, washed and then the product recrystallized from hot
ethanol. All of the products are synthesized by four-component
* Corresponding author.
E-mail addresses: rostamnia@maragheh.ac.ir, srostamnia@gmail.com
(S. Rostamnia).
1001-8417/$ – see front matter ß 2013 Sadegh Rostamnia. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
http://dx.doi.org/10.1016/j.cclet.2013.03.020
Please cite this article in press as: S. Rostamnia, F. Pourhassan, The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst
for diketene-based, four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions, Chin. Chem. Lett.
(2013), http://dx.doi.org/10.1016/j.cclet.2013.03.020

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CCLET-2505; No. of Pages 3
2
S. Rostamnia, F. Pourhassan / Chinese Chemical Letters xxx (2013) xxx–xxx
Fig. 1. SEM and TEM images of SBA-15/SO3H nanoreactor.
method and were identified by their physical and spectral data
(mp, IR, 1H NMR and 13C NMR). Methyl 4-(2-chlorophenyl)-
2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydro-3-quinolinecar-
boxylate (3d, Table 1). IR (KBr, cmÀ1): vmax 3289, 2951, 1707,
1654, 1608, 1490, 1222, 1080, 1034, 827, 773, 540. 1H NMR
40.96, 50.62, 50.83, 105.17, 111.37, 126.42, 127.26, 129.61,
131.64, 131.64, 133.10, 143.87, 144.33, 148.92, 167.91, 195.51.
Diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-dicar-
boxylate (Table 2, entry 4). IR (KBr, cmÀ1): vmax 3346, 1703,
1657, 1473, 1198. 1H NMR (300 MHz, CDCl3):
d 1.20 (t, 6 H,
(300 MHz, CDCl3):
H), 3.57 (s, 3 H), 5.38 (s, 1 H), 6.81 (s, 1 H), 7.00–7.34 (m, 4 H).
13C NMR (75 MHz, CDCl3):
d
0.91 (s, 3H), 1.07 (s, 3 H), 2.04–2.36 (m, 7
J = 7.0 Hz, 2Â OCH2CH3), 2.31 (s, 6H, 2Â CH3), 4.09 (q, 4 H,
J = 7.0 Hz, 2Â OCH2CH3), 5.01 (s, 1 H, CH), 6.20 (s, 1 H, NH), 7.10–
7.39 (m, 5H, C6H5).
d 19.19, 27.15, 29.37, 32.54, 35.61,
Table 1
SBA-15/SO3H catalyzed the neat four-component synthesis of polyhydroquinolines derivatives of 3.
O
O
Ar
O
O
+
SBA-15/SO3H
4 mol%
O
R
R
OH
+
+
Ar
O
60 oC
O
NH2
(excess)
N
H
2
3
1
.
Entry
Ar
R
Time (min)
mp (8C)
Yield (%)
Found
Reported [3]
3a
3b
3c
3d
3e
3f
C6H5
H
25
25
25
25
30
30
25
20
25
35
257–259
220–222
260–264
235–238
247–250
217–223
244–246
234–243
238–240
201–205
258–260
221–222
–
90
90
85
85
90
85
95
90
90
85
4-Cl-C6H4
H
2-Me-C6H4
2-Cl-C6H4
H
H
–
4-OMe-C6H4
2-Cl-C6H4
H
–
Me
Me
Me
Me
Me
208–210
242–244
257–259
245–246
–
3g
3h
3i
4-NO2-C6H4
4-OMe-C6H4
4-Cl-C6H4
3j
2-Me-C6H4
Table 2
The neat four-component synthesis of dihydropyridines derivatives of 4.
O
Ar
O
O
+
SBA-15/SO3H
4 mol%
O
R
O
O
R
R
OH +
+
Ar
2
O
60 o
C
O
OH.NH3
(excess)
N
H
1
2
4
.
Entry
Ar
R
mp (8C)
Yield (%)
Found [4b]
Reported
1
2
3
4
5
6
7
8
C6H5
Me
H
150–153
168–169
163–165
160–162
122–126
123–124
146–149
125–129
152–153
171–172
161–165
164–166
123–126
120–125
144–147
124–126
90
84
80
84
80
91
91
93
3-OMe-C6H4
4-NO2-C6H4
2-OMe-C6H4
2-Cl-C6H4
H
H
Me
Me
Me
Me
3-Cl-C6H4
4-Cl-C6H4
4-NO2-C6H4
Please cite this article in press as: S. Rostamnia, F. Pourhassan, The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst
for diketene-based, four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions, Chin. Chem. Lett.
(2013), http://dx.doi.org/10.1016/j.cclet.2013.03.020

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S. Rostamnia, F. Pourhassan / Chinese Chemical Letters xxx (2013) xxx–xxx
3
of polyhydroquinoline and dihydropyridine derivatives based on
the diketene ring-opening reaction under neat conditions and
short reaction times. Simple separation, easy recovery and
reusability of the catalyst make it a highly efficient and
convenient catalyst.
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Fig. 2. Recycle of the SBA-15/SO3H catalyst.
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SBA-15/SO3H as an efficient and convenient catalyst in synthesis of
polyhydroquinolines by a one-pot, four-component reaction of
diketene, alcohols, enamine, and aldehydes under neat conditions.
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4. Conclusion
In conclusion, we demonstrated that covalently bonded
sulfonic acid SBA-15 is an efficient solid catalyst for the synthesis
Please cite this article in press as: S. Rostamnia, F. Pourhassan, The SBA-15/SO3H nanoreactor as a highly efficient and reusable catalyst
for diketene-based, four-component synthesis of polyhydroquinolines and dihydropyridines under neat conditions, Chin. Chem. Lett.
(2013), http://dx.doi.org/10.1016/j.cclet.2013.03.020