ClO4 ?/Zr-MCM-41 nanoparticles prepared at mild conditions: a novel solid acid catalyst for the synthesis of polyhydroquinolines

Article abstract of DOI:10.1007/s13738-016-0848-4

One-pot four-component reaction of aldehydes, dimedone, ethyl cyanoacetate or ethyl acetoacetate and ammonium acetate was studied in the presence of perchlorated Zr-MCM-41 (ClO₄ ^?/Zr-MCM-41) nanoparticles for the synthesis of dihydropyridines. Zr-MCM-41 nanoparticles with various molar ratios of Si/Zr were synthesized by sol–gel method under mild conditions, and then ClO₄ ^?/Zr-MCM-41 samples with different calcination temperatures were prepared and characterized by XRD, FT-IR and SEM techniques. The characterization results show the presence of perchlorate in the mesostructure of Zr-MCM-41 and the catalytic performance experiments show that ClO₄ ^?/Zr-MCM-41 with Si/Zr molar ratio of 25 and calcinations temperature of 300?°C has the best catalytic activity. The catalyst can be recovered easily and reused many times with moderate decrease in activity.

Full text of DOI:10.1007/s13738-016-0848-4

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J IRAN CHEM SOC
DOI 10.1007/s13738-016-0848-4
ORIGINAL PAPER
−
ClO4 /Zr-MCM-41 nanoparticles prepared at mild conditions:
a novel solid acid catalyst for the synthesis of polyhydroquinolines
Mohammad Abdollahi-Alibeik1 · Sahar Saadat Hoseinikhah1
Received: 22 August 2015 / Accepted: 21 March 2016
© Iranian Chemical Society 2016
Abstract One-pot four-component reaction of aldehydes,
dimedone, ethyl cyanoacetate or ethyl acetoacetate and
ammonium acetate was studied in the presence of perchlo-
rated Zr-MCM-41 (ClO4−/Zr-MCM-41) nanoparticles for
the synthesis of dihydropyridines. Zr-MCM-41 nanoparti-
cles with various molar ratios of Si/Zr were synthesized by
sol–gel method under mild conditions, and then ClO4−/Zr-
MCM-41 samples with different calcination temperatures
were prepared and characterized by XRD, FT-IR and SEM
techniques. The characterization results show the presence
of perchlorate in the mesostructure of Zr-MCM-41 and the
catalytic performance experiments show that ClO4−/Zr-
MCM-41 with Si/Zr molar ratio of 25 and calcinations tem-
perature of 300 °C has the best catalytic activity. The cata-
lyst can be recovered easily and reused many times with
moderate decrease in activity.
associated to their use, avoiding the complicated purifica-
tion operations and allowing savings of both solvents and
reagents. Recently, MCRs have been used as the best way
for the synthesis of heterocycles, which are of considerable
importance in the design and discovery of new biologically
active molecules [1]. Among them, polyhydroquinolines
as an important group of nitrogen containing heterocycles
have attracted much attention because of their diverse ther-
apeutic and pharmacological properties, such as calcium
channel blockers, vasodilator, hepatoprotective, antiath-
erosclerotic, bronchodilator, antitumor, geroprotective and
antidiabetic activity [2–4].
The general method for the synthesis of polyhydroqui-
nolines involves the four-component reaction of aldehydes,
ethyl cyanoacetate or ethyl acetoacetate, ammonium acetate
and cyclic 1,3-dicarbonyl compounds such as dimedone,
in the presence of acid or base catalysts. Many catalysts
have been used for this transformation such as molecu-
lar iodine [5], ceric ammonium nitrate [6], Hafnium(IV)
bis(perfluorooctanesulfonyl)imide [7], Yb(OTf)3 [8],
Cu(OTf)2 [9], guanidine hydrochloride [10], trifluoroetha-
nol [11], Pd-nanoparticles [12], Montmorillonite supported
Ni0-nanoparticles [13], cerium(IV) ammonium nitrate [14],
scandium triflate [15] and MCM-41 [16].
Keywords Nanoparticle · Zr-MCM-41 · Perchlorated ·
Polyhydroquinoline · Multi-component reaction · Solid
acid catalyst · Reusability
Introduction
Multi-component reactions (MCRs) have been attracted
considerable attention as a powerful synthetic tool for the
creation of several bonds in a single operation. They have
also many remarkable advantages such as user and envi-
ronmental friendliness, step reduction, atom economy
However, many of these methodologies suffer from one
or more disadvantages such as the use of expensive cata-
lyst, the use of large amount of catalyst, long reaction times
and non-reusability of the catalyst. Therefore, there is a
need to develop new methodologies using reusable cata-
lytic systems for this type of reaction.
Recently, the application of mesoporous material as
catalyst support has received more attention due to their
remarkable advantages such as high surface area and the
role of mesopores as nanoreactors [17]. MCM-41 with
highly ordered mesostructure [18] has been used as catalyst
* Mohammad Abdollahi-Alibeik
abdollahi@yazd.ac.ir; moabdollahi@gmail.com
1
Department of Chemistry, Yazd University,
Yazd 89158-13149, Iran
1 3

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Scheme 1 Synthesis of polyhydroquinolines by reaction of aryl aldehydes, dimedone, ethyl cyanoacetate or ethyl acetoacetate and ammonium
acetate in the presence of perchlorated Zr-MCM-41
and catalyst support in many organic reactions [19–22].
Although, MCM-41 has very high surface area, this com-
pound lacks the Brønsted acid sites and usually exhibits only
mild Lewis acidity [23]. Surface acidity enhancement of
MCM-41 can be achieved by incorporation of foreign ions
like Ti4+, Al3+, Zr4+, and Cu2+ into the Si framework [24] or
surface modification by inorganic or organic materials [25].
In this paper, we aim to report preparation, characteriza-
tion and catalytic application of perchlorated Zr-MCM-41
(ClO4−/Zr-MCM-41) nanoparticles as a novel solid acid
catalyst for the synthesis of polyhydroquinolines by one-
pot, four-component reaction of aryl aldehydes, dimedone,
ethyl cyanoacetate or ethyl acetoacetate and ammonium
acetate (Scheme 1).
bromide (CTAB) as the template and ammonia as the pH
control agent with the gel composition of Si:Zr:CTAB:NH4
OH:H2O = 1:0.04:0.123:0.267:530 by modification of our
previous method [27].
In a typical procedure, to a solution of CTAB (1.29 g,
3.54 mmol) in deionized water (270 mL), TEOS (6.4 mL)
was added dropwise at 70 °C for about 1 h and then a solu-
tion of ZrCl4 (0.27 g, 1.15 mmol) in water (3 mL) was
added dropwise. The mixture was allowed to cool to room
temperature and then aqueous ammonia (10 wt %) was
added until the pH of the solution was adjusted to 10.5.
The gel was stirred for 12 h and then separated by centri-
fuge and washed with distilled water (20 mL) and EtOH
(2 × 10 mL), respectively. The solid was dried in an oven
at 120 °C for 4 h and then calcined at 550 °C for 4 h.
−
The ClO4 /Zr-MCM-41 was prepared by impregnation of
Experimental
Zr-MCM-41 using HClO4 and the calcinations of obtained
solid at various temperatures. In a typical experiment, Zr-
MCM-41 (1 g) was added to a solution of 0.1 M HClO4
(15 mL) and allowed to stirred at ambient temperature for
4 h. The mixture was separated by centrifuge and washed
with deionized water (2 × 3 mL). The obtained solid was
dried in an oven at 120 °C for 4 h and then calcined at 250,
300, and 350 °C for 4 h. The obtained samples were denoted
as PZM-120, PZM-250, PZM-300, PZM-350, respectively.
Materials and methods
All chemicals were commercial products. MCM-41 was
prepared by our previously reported method [26]. All reac-
tions were monitored by TLC and all yields refer to iso-
lated products. Melting points were obtained by Buchi
B-540 apparatus and are uncorrected. H and 13C NMR
1
spectra were recorded in CDCl3 on a Bruker AVANCE
1
III (400 MHz for H and 100 MHz for 13C) spectrometer.
General procedure for the synthesis
of polyhydroquinoline derivatives in the presence
of ClO4−/Zr-MCM-41
Infrared spectra of the catalysts and reaction products were
recorded on a Bruker FT-IR Equinax-55 spectrophotometer
in KBr pellets. XRD patterns were recorded on a Bruker D8
ADVANCE X-ray diffractometer using nickel filtered Cu
Kα radiation (λ = 1.5406 Å). The morphology was studied
using a KYKY-EM3200 scanning electron microscopy.
A mixture of dimedone (1 mmol), aldehyde (1 mmol),
ethyl cyanoacetate or ethyl acetoacetate (1 mmol), ammo-
nium acetate (1.3 mmol) and catalytic amount of ClO4
−
/
Zr-MCM-41 (10 mg) was stirred in ethanol (1 mL) at reflux
condition. After completion of the reaction (monitored by
TLC, eluent; n-hexane:EtOAc, 8:2), the catalyst was sepa-
rated by centrifuge and washed with EtOH (2 × 3 mL).
After evaporation of the solvent, the crude products were
recrystallized from EtOH to give pure polyhydroquinolines.
Preparation of ClO4−/Zr-MCM-41 nanoparticles
The synthesis of nanosized Zr-MCM-41 was carried out
using tetraethyl orthosilicate (TEOS) as the Si source, zirco-
nium tetrachloride as Zr source, cetyltrimethylammonium
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Fig. 1 SEM images of a ZM-550 and b PZM-300
Physical and spectroscopic data for new compounds
5i: MP: 136–137 °C, FT-IR (KBr) υmax: 3435, 3305,
1
2951, 1695, 1521, 1350, 1202, 1196, 1038, 690 cm−1. H
5f: MP: 182–183 °C, FT-IR (KBr) υmax: 3420, 3307, 3217,
NMR (400 MHz, CDCl3): δ (ppm) = 1.02 (s, 3H), 1.13
(s, 3H), 1.2 (t, 3H, J = 7.0 Hz), 2.18 (d, 1H, J = 12.7 Hz),
2.27 (d, 1H, J = 12.7 Hz), 2.46 (s, 2H), 4.08 (m, 2H), 4.7
(s, 1H), 6.28 (s, 2H, NH2), 7.1 (t, 1H, J = 7.6 Hz), 7.23 (d,
1H, J = 7.7 Hz), 7.26 (d, 1H, J = 7.8 Hz), 7.42 (s, 1H),.
13C NMR (100 MHz, CDCl3): δ (ppm) = 14.2, 27.1, 29.0,
32.1, 34.2, 41.1, 50.9, 60.1, 80.2, 116.0, 122.1., 127.2,
129.0, 130.1, 131.1., 147.9, 149.2, 157.9, 162.0, 169.1,
197.1. Anal. Calcd for C20H23BrN2O3: C, 57.29; H, 5.52;
N, 6.68. Found: C, 57.11; H, 5.40; N, 6.54.
1
1692, 1652, 1613, 1530, 1395, 1285, 1038, 757 cm−1. H
NMR (400 MHz, DMSO-d6): δ (ppm) = 0.93 (s, 3H), 1.02
(t, 3H, J = 7.2 Hz), 1.03 (s, 3H), 2.02 (d, 1H, J = 16.1 Hz),
2.25 (d, 1H, J = 16.1 Hz), 2.51 (m, 2H), 3.91 (q, 2H,
J = 7.0 Hz), 4.83 (s, 1H), 7.23 (m, 4H), 7.65 (s, 2H, NH2).
13C NMR (100 MHz, DMSO-d6): δ (ppm) = 14.1, 26.4,
28.6, 31.7, 32.2, 49.9, 55.67, 76.32, 113.9, 126.3, 127.3,
129.2, 131.8, 132.6, 142.7, 159.2, 162.2, 168.1, 195.6.
Anal. Calcd for C20H23ClN2O3: C, 64.08; H, 6.18; N, 7.47.
Found: C, 63.96; H, 5.98; N, 7.53.
5 g: MP: 155–158 °C, FT-IR (KBr) υmax: 3400, 3287,
2950, 1693, 1649, 1595, 1538, 1490, 1367, 1252, 1202,
Results and discussions
1034, 865, 694 cm−1 1H NMR (400 MHz, CDCl3): δ
.
(ppm) = 1.02 (s, 3H), 1.21 (s, 3H), 1.21 (t, 3H, J = 7.1 Hz),
2.21 (d, 1H, J = 12.8 Hz), 2.28 (d, 1H, J = 12.8 Hz), 2.45
(s, 2H), 3.8 (s, 3H, OMe), 4.1 (m, 2H), 4.73 (s, 1H), 6.23
(s, 2H, NH2), 6.68 (d.d, 2H, J = 7.7 Hz), 6.87 (s, 1H) 6.9
(d, 1H, J = 7.5 Hz) 7.15 (t, 1H, J = 7.7 Hz). 13C NMR
(100 MHz, CDCl3): δ (ppm) = 14.2, 28.2, 28.9, 32.1, 34.3,
41.1, 51.1, 55.2, 60.1, 81.1, 110.9, 114.2, 116.9, 121.1,
129.1, 147.0, 159.1, 160.2, 162.1, 169.1, 196.0. Anal.
Calcd for C21H26N2O4: C, 68.09; H, 7.07; N, 7.56. Found:
C, 68.37; H, 6.99; N, 7.64.
5 h: MP: 179–180 °C, FT-IR (KBr) υmax: 3335,
3200, 2958, 1690, 1663, 1543, 1369, 1279, 1200, 1040,
707 cm−1. 1H NMR (400 MHz, CDCl3): δ (ppm) = 0.99 (s,
3H), 1.12 (s, 3H), 1.16 (t, 3H, J = 7.0 Hz), 2.17 (d, 1H,
J = 16.2 Hz), 2.25 (d, 1H, J = 16.2 Hz), 2.46 (s, 2H), 4.04
(m, 2H), 4.71 (s, 1H), 6.29 (s, 2H, NH2), 7.15 (m, 1H), 7.61
(m, 1H), 8.37 (m, 1H), 8.53 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ (ppm) = 14.2, 27.5, 29.0, 39.9, 40.6, 50.6, 59.8,
79.7, 115.8, 122.8, 135.8, 141.3, 147.4, 150.0, 158.4,
161.7, 168.7, 196.2. Anal. Calcd for C19H23N3O3: C, 66.84;
H, 6.79; N, 12.31. Found: C, 66.73; H, 6.61; N, 12.37.
The catalyst characterization
The Zr-MCM-41 and PZM samples were characterized by
FT-IR, SEM and XRD techniques. The SEM images of Zr-
MCM-41 and PZM-300 show spherical nanoparticles with
the size of less than 100 nm (Fig. 1).
The FT-IR spectra of PZM-300, PZM-120, HClO4,
Zr-MCM-41, MCM-41, and ZrO2 are shown in Fig. 2.
MCM-41 shows characteristic peaks at 410, 810, 960,
and 1083 cm−1 (Fig. 2a). The spectrum of ZrO2 shows
corresponding peaks at 498, 584, 754, 1060, 1127, 1200,
1350, and 1450 cm−1. The Zr-MCM-41 calcined at 550 °C
(ZM-550) sample exhibits characteristic peaks of MCM-
41 at 455 and 804 cm−1 and also the peak at 1010 and
1350 cm−1 corresponded to ZrO2. In the spectrum of PZM-
120 (Fig. 2e), weak peak at 630 cm−1 corresponded to
HClO4. The main peak of HClO4 overlaps with the main
peak of Zr-MCM-41 in the region of 1100 cm−1
.
Perchlorate peaks in the range of 1089 and 1145 cm−1
overlap with the strong peak of MCM-41 around 960
and 1083 cm−1 resulting in increase of the intensity and
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(a)
(b)
(c)
(d)
(e)
(f)
(a)
(b)
(c)
2
4
6
8
10
2θ(°)
Fig. 3 Low angle XRD patterns of a MCM-41 b ZM-550 and
c PZM-300
2000
1600
1200
800
400
2θ(°)
500
400
Fig. 2 FT-IR spectra of a MCM-41 b ZrO2 c ZM-550 d HClO4
e PZM-120 and f PZM-300
'PZM-250'
'PZM-300'
'PZM-350'
broadening of this peak. In the spectrum of PZM-300
(Fig. 2f), the characteristic peaks of perchlorate clearly
cannot be observed. This may be due to changes in sym-
metry groups because of the formation of covalent bonds
with silica during calcination. This may be also due to the
removal of nonbonded perchlorate ions on the surface of
Zr-MCM-41 during the calcination process.
The low angle XRD patterns of MCM-41, ZM-550 and
PZM-300 are shown in Fig. 3. The characteristic peaks of
MCM-41 (Fig. 3a) have appeared at 2θ = 2.42 °, 4.14 °,
4.74 °, and 6.18 °. As shown in Fig. 3b after surface modi-
fication with Zr, the intensity of the main pak of MCM-41
was decreased and its width was increased. These changes
are due to decrease in long-range order of hexagonal meso-
structure of MCM-41 by incorporation of foreign ion.
The catalytic acidity of MCM-41 and PZM-300 were
compared by potentiometric titration using 0.02 N solution
of n-butylamine in acetonitrile. According to this method,
300
'MCM-41'
200
100
0
0.0
0.4
0.8
1.2
1.6
2.0
meq/g
Fig. 4 Potentiometric titration curve of MCM-41, PZM-250, PZM-
300 and PZM-350
1 3