Nanorod vanadatesulfuric acid as a novel, recyclable and heterogeneous catalyst for the one-pot synthesis of tetrahydrobenzopyrans

Article abstract of DOI:10.1166/jnn.2013.7592

Vanadatesulfuric acid (VSA), as a novel and heterogeneous nanorod catalyst, was used for an efficient synthesis of tetrahydrobenzo[b]pyrans using an aldehydes, 1,3-cyclohexanediones or β-ketoester and malononitrile in C ₂H₅OH/H₂

Full text of DOI:10.1166/jnn.2013.7592

Copyright © 2013 American Scientific Publishers
All rights reserved
Printed in the United States of America
Journal of
Nanoscience and Nanotechnology
Vol. 13, 5004–5011, 2013
Nanorod Vanadatesulfuric Acid as a Novel,
Recyclable and Heterogeneous Catalyst for the
One-Pot Synthesis of Tetrahydrobenzopyrans
Masoud Nasr-Esfahani∗ and Tooba Abdizadeh
Department of Chemistry, Yasouj University, Yasouj 75918-74831, Iran
Vanadatesulfuric acid (VSA), as a novel and heterogeneous nanorod catalyst, was used for
an efficient synthesis of tetrahydrobenzo[b]pyrans using an aldehydes, 1,3-cyclohexanediones or
ꢀ-ketoester and malononitrile in C2H5OH/H2O mixture under reflux conditions. VSA is prepared
via the reaction of sodium metavanadate and chlorosulfonic acid in high purity. The catalyst was
characterized by FT-IR, XRD, TEM and EDAX analysis. Compared to the conventional method,
this method consistently has the advantage of high yields, simple workup, short reaction times and
reusability of the catalyst.
Keywords: Vanadatesulfuric Acid, Tetrahydrobenzopyrans, Reusable Catalyst, Solvent-Free,
Heterogeneous Catalyst, Nanorod Particle.
Delivered by Publishing Technology to: Adelaide Theological Library
1. INTRODUCTION
organic solvents or water.8–12 Each of the above methods
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
has its own merits, while some are plagued by limitations
Copyright: American Scientific Publishers
The compounds containing benzopyran rings which have
received considerable attention in recent years due to
their wide range of biological properties,1 such as
spasmolytic, diuretic, anti-coagulant, anti-cancer, anti-
ancaphylactia activity.2 In addition, they can be used in var-
ious applications as cognitive enhancers, for the treatment
of neurodegenerative disease, including Alzheimer’s dis-
ease, amyotrophic lateral sclerosis, Huntington’s diseases,
Parkinson’s disease, AIDS associated dementia and Down’s
syndrome as well as for the treatment of schizophrenia and
myoclonus.3 4H-Pyrans also constitute the structural unit
of a series of natural products.4 A number of 2-amino-
4H-pyrans can be employed as photoactive materials,5
pigments6 potential biodegradable agrochemicals.7
The condensation of aromatic aldehydes with dime-
done and malononitrile under reflux in acetic acid is
a conventional method for synthesis of tetrahydro-4H-
benzopyrans.8 The wide biological and pharmaceutical
activities of 4H-pyrans has led many researchers to syn-
thesize them using various catalysts like tetramethylguani-
dinium trifluoroacetate as an ionic liquid,9 diammonium
hydrogen phosphate,10 iodine,11 N-methylimidazole,12
sodium selenate,13 and hexadecyldimethylbenzyl ammo-
nium bromide.14 Electrochemical reactions have also been
used15 as well as microwave heating in the solid state16 and
of poor yields, long reaction times, difficult workup pro-
cedures, effluent pollution, and the use of expensive cata-
lysts that are harmful to the environment. Therefore, there
is scope to develop alternative methods for the synthesis
of tetrahydrobenzo[b]pyran derivatives under environmen-
tally benign conditions.
In recent years, application of nanoparticles as catalyst
have attracted worldwide attention due to high catalytic
activity and improved selectivity.17 In the context of green
chemistry, the multicomponent reactions (MCRs) are very
powerful and efficient bond forming tools in organic, com-
binatorial and medicinal chemistry.18 The MCRs are very
flexible, atom economic in nature, and proceed through a
sequence of reaction equilibria, yielding the target product.
Along with other reaction parameters, the nature of the
catalyst plays a significant role in determining yield, selec-
tivity, and general applicability. Thus, development of an
inexpensive, mild, reusable, and general catalyst for MCRs
remains an issue of interest.
From an environment protection laws point of view,
there has been an increased emphasis on the design and
use of environmentally benign solid acid or base hetero-
geneous catalysts to reduce the amount of toxic waste and
byproducts from chemical processes.19 The main advan-
tage of a heterogeneous catalyst is that, being a solid
material, it is easy to separate from the gas or liquid phase
reactants and products after the catalytic reaction.
∗Author to whom correspondence should be addressed.
5004
J. Nanosci. Nanotechnol. 2013, Vol. 13, No. 7
1533-4880/2013/13/5004/008
doi:10.1166/jnn.2013.7592

Nasr-Esfahani and Abdizadeh
Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
O
O
O
+
ClSO3H
+
NaCl
V ONa
V OSO3H
O
Scheme 1. Synthesis of nanorod vanadatesulfuric acid.
Solid acids have emerged as potential alternate cata-
lysts to the common liquid acids due to their safe nature,
enhanced selectivity, requirements in catalytic amounts
and easier work up.20 The ease of separation without
resulting into problem of waste disposal and option of
reuse of the solid acid catalysts render the processes
employing solid acid catalysts as green processes.
In continuation of the above and of our studies on
the application of solid acids,21 we found that anhydrous
sodium metavanadate reacts with chlorosulfonic acid (1:1
mole ratio) in dry CHCl3 to give nanorod vanadatesulfuric
acid (VSA) particles. The reaction is performed easy, clean
and the product, VSA, was isolated by simple filtration
(Scheme 1).
Fig. 1. Powder X-ray diffraction pattern of the VSA particles.
2. RESULTS AND DISCUSSION
In connection with our recent interest in the application
of solid acids,21 herein we wish to report a simple and
efficient method for synthesis of tetrahydrobenzo[b]pyran
derivatives using the nanorod particles of vanadatesulfuric
acid (VSA) as a new, green, recyclable and heterogeneous
Delivered by Publishing Technology to: Adelaide Theological Library
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
catalyst (Scheme 2).
Copyright: American Scientific Publishers
2.1. Characterization of Vanadatesulfuric Acid
In the IR spectrum of NaVO3, several absorptions appear
which are apparently the result of V O stretching modes
for each of several, different oxygen atoms according to
the particular location or arrangement within the lattice.22
For vanadatesulfuric acid, the infrared vibration bands
Fig. 2. The TEM image showing needle-like VSA particles of
15–20 nm in size.
O
O
O
R1
O
R2 R2
3 (a:R2 = H, b:R2 = CH3)
CN
R2
VSA NRs
NH2
R2
H2O/EtOH, Reflux
5
R1CHO
1
NC
+
CN
O
O
O
R1
O
2
OEt
H3C
C N
E tO
Me
4
VSA NRs
H2O/EtOH, Reflux
NH2
6
Scheme 2. Nanorod VSA-catalyzed tetrahydrobenzo[b]pyrans formation reaction.
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013
5005

Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
Nasr-Esfahani and Abdizadeh
Table II. Solvent effect on the reaction of benzaldehyde, malononitrile
and dimedone catalyzed by VSA NRs.
Entry
Solvent (reflux)
Time (h)
Yielda (%)
1
2
3
4
5
6
CH3CH2OH
CH3OH
CH3CN
H2O
CH3CH2OH/H2O
Solvent-freeb
2ꢀ5
5
6
3ꢀ5
0ꢀ33
10
68
30
35
42
92
15
Notes: aIsolated yields; bAt 80 ꢀC.
The morphology and size of the VSA were investi-
gated by transmission electron microscopy (TEM) (Fig. 2).
They had needle-like morphology with a narrow size dis-
tribution from 15 to 20 nm and a mean size of 17 nm,
confirming the results calculated from Scherrer’s equation.
The presence of some larger particles should be attributed
to aggregating or overlapping of smaller particles.
Energy-dispersive X-ray spectroscopy (EDAX) results
confirm the presence of V, O, and S in nanorod particles of
vanadatesulfuric acid (Fig. 3). The elemental distribution
mapping of the catalyst by EDAX shows a constant vana-
dium: oxygen: sulfur signal ratio of 50.62:40.94:8.44 wt%
over different areas.
Elt. Line Intensity Atomic Conc Units
(c/s)
7.06
%
67.06
6.90
O
S
Ka
Ka
Ka
40.94 wt.%
8.44 wt.%
50.62 wt.%
19.07
72.97
V
26.05
100.00 100.00 wt.% Total
Fig. 3. Energy dispersive spectroscopy (EDS) pattern of nanorod
particles.
are consigned as follows: The bands found at 3450 and
1640 cm−1 are attributed to the stretching and bending
vibration of –OH group, respectively. The bands at 1050,
2.2. Effect of Solvent and Catalyst Concentration on
Delivered by Publishing Technology to: Adelaide Theological Library
and 1180 cm−1 are assigned for the sulfonic acid bonds,
the Synthesis of Tetrahydrobenzopyrans
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
S
OH, S O stretching, and S O asymmetric stretch-
Copyright: American Scientific Publishers
Initially, in order to evaluate the catalytic activity of
VSA NRs, the three-component reaction of benzalde-
hyde, 5,5-dimethyl-1,3-cyclohexanedione (dimedone, 3b)
and malononitrile (2) under reflux condition as a model
reaction was investigated. The corresponding product was
obtained in 92% yield during 20 min. This compound and
some tetrahydrobenzopyran derivatives have been synthe-
sized under various conditions by other researchers that
some of them is presented in Table I that have compa-
rable or higher yield/time ratios in compared to current
conditions.
ing, respectively. The bands appearance in 960, 840 and
603 cm−1 related to V O and V O stretching.
Figure 1 shows the XRD patterns of vanadatesulfu-
ric acid. A number of prominent Bragg reflections reveal
that the resultant particles of vanadatesulfuric acid have a
monoclinic structure (Space group: P2/m; a = 12ꢀ170 Å,
b = 3ꢀ602 Å, c = 7ꢀ780 Å, JCPDS card no. 16-0601). The
size of the VSA particles was also determined from X-ray
line broadening using the Debye-Scherrer formula (D =
kꢁ/ꢂcosꢃ, where D is the average crystalline size, k is
Sherrer constant, ꢁ is the X-ray wavelength used, ꢂ is the
angular line width at half maximum intensity, and ꢃ is the
Bragg’s angle). For the (001) reflection the average size of
the VSA particles was estimated to be around 16 nm.
Then, the solvent effect in the condensation of ben-
zaldehyde (1 mmol), malononitrile (2, 1 mmol) and dime-
done (3b, 1 mmol) in the presence of vanadatesulfuric acid
Table I. Comparison of efficiency of various catalysts in synthesis of tetrahydrobenzo[b]pyrans.
Entry
Catalyst
Amount of catalystb
Conditions
Yield/Timea
Reference
1
2
3
4
5
6
7
8
9
Na2SeO4
TMAH
Electrolysis (10 mA)
Molecular idoine
HDHBAB
Mg/La mixed oxide
TBAF
10
10
−
10
12
5
25
−
5
C2H5OH/H2O (reflux)
H2O (r.t)
Electrode platinum
DMSO (reflux)
H2O (reflux)
CH3OH (reflux)
H2O (reflux)
DMAc (r.t)
80–98/1–3
79–92/0.5–2
89–96/4–5
85–92/3–4
84–95/5.5–8
52–92/1–3
73–98/0.5–5
48–83/30
76–95/0.08–0.8
[23]
[24]
[25]
[26]
[14]
[27]
[28]
[29]
–
Baker’s yeast
VSA
C2H5OH/H2O (reflux)
Notes: aValues refer to yield (%)/time (h); bAmount of catalysts are in mol%.
5006
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013

Nasr-Esfahani and Abdizadeh
Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
NRs (0.05 mmol) as a model has been studied. As
shown in Table II, among the tested solvents, such as
ethanol, methanol, acetonitrile, water, chloroform and a
solvent-free system, the best result was obtained after
20 min under refluxing C2H5OH/H2O mixture conditions
in excellent yield (92%).
The reaction conditions were then optimized by con-
ducting the reaction in different catalyst loading. The best
result was obtained by carrying out the reaction with
5 mol% of catalyst under reflux condition (Fig. 4).
In the absence of VSA, the model reaction gives,
according to TLC monitoring, only trace of the product
after 12 h under reflux condition. The conversion and yield
of the corresponding tetrahydrobenzopyran increased with
Fig. 4. Graph of isolated yield of 2-amino-4-phenyl-3-cyno-5-oxo-4H-
5,6,7,8-tetrahydrobenzo[b]pyran versus mol% of the catalyst (reaction
conditions: benzaldehyde (1 mmol), malononitrile (2, 1 mmol) and dime-
done (3b, 1 mmol), and time 20 min under refluxing EtOH/H2O mixture).
incremental increasing catalyst concentration from 1 to
5 mol%. Further addition of catalyst had no noticeable
effect on the yield. This was because beyond a certain
Table III. Preparation of substituted tetrahydrobenzopyrans catalyzed by VSA.
Mp (ꢀC)
Compounds
R1
R2
Time (min)
Yieldb (%)
Founda
Reported
5a
5b
5c
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
C6H5
H
H
H
H
25
15
40
30
20
30
30
15
25
20
5
10
20
10
15
35
30
30
35
25
50
45
40
10
20
35
40
35
40
20
10
35
30
12
13
45
35
25
90
91
85
82
93
220–200
224–226
230–232
235–236
224–226
186–188
224–226
208–210
197–199
226–28
220–22231
225–22732
232–23332
234–23633
225–22732
186–18931
−
4-O2NC6H4
4-CH3C6H4
4-OHC6H4
4-ClC6H4
Delivered by PublishiHHng Technology to: Adelaide Theological Library
4-CH3OC6H
2,4-Cl2C6H3
3-O2NC6H4
2-O2NC6H4
C6H5
80
87
4 IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
H
H
H
91
90
92
92
90
90
92
90
88
83
85
85
92
78
80
85
91
90
82
87
85
87
90
95
83
84
92
91
76
89
88
210–21130
196–19833
228–23024
176–17830
211–21424
224–22623
207–20924
228–23030
150–15223
197–19930
204–20530
210–21324
180–18224
292–29330
228–23331
220–22232
212–21430
208–21030
−
Copyright: American Scientific Publishers
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
Me
−
4-O2NC6H4
3-NO2C6H4
2-O2NC6H4
4-BrC6H4
3-Br-C6H4
2-BrC6H4
177–179
210–212
222–224
205–207
227–229
151–153
198-200
206–208
212–214
181–183
192–194
229–231
221–223
210–211
210–212
202–203
232–234
249–250
206–207
194–195
171–173
176–178
143–145
181–183
180–182
184–186
210–212
191–193
4-OCH3C6H4
4-OHC6H4
4-CH3C6H4
2,4-ClC6H3
CH3CH2CH2CHO
2-Furyl
5s
5t
5u
5v
5w
5x
5y
5z
5aꢁ
5bꢁ
5cꢁ
6a
6b
6c
6d
6e
6f
2-thiophene
4-ClC6H4
2-ClC6H4
2-CH3OC6H4
2-OH-3-CH3OC6H3
2,6-Cl2C6H3
2-Cl-6-FC6H3
C6H5
−
−
−
195–19634
172–17434
177–17934
142–14430
180–18334
182–18334
185–18627
−
4-ClC6H4
−
4-CH3C6H4
4-CH3OC6H4
4-O2NC6H4
3-O2NC6H4
CH3CH2CHO
2-Cl-6-FC6H3
2-BrC6H4
−
−
−
−
6g
6h
6i
−
−
−
−
Notes: aAll products were characterized by 1H NMR and IR spectroscopy and comparison with these reported in the literature; bIsolated yields.
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013
5007

Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
Nasr-Esfahani and Abdizadeh
concentration, there exist an excess of catalyst sites over
what is actually required by the reactant molecules, and
hence, the additional catalyst does not increase the rate
of the reaction. Therefore, in all further reactions 5 mol%
of the catalyst were used because of satisfactory yield of
the product (92%) in reasonably short time. In other to
improve the yields, the reaction is performed using differ-
ent quantities of reagents. The best results were obtained
with a 1:1:1 ratio of benzaldehyde, malononitrile and
dimedone, respectively.
To generalize this procedure, a series of tetrahydroben-
zopyrans were synthesized with benzaldehyde derivatives
and the results are shown in Table III. The reaction worked
well with electron withdrawing (NO2, Br, Cl) as well
as electron donating (Me, OMe, OH) substituents giv-
ing various tetrahydrobenzopyrans in yield 80–95% yields.
Moreover, acid sensitive aldehydes such as furyl (5v) and
Fig. 5. XRD patterns of the catalyst (a) fresh catalyst (b) recovered
thienyl carbaldehyde (5w) furnished products in yield of
80% and 85%, respectively. In addition, the aliphatic alde-
hydes such as butanal afforded a 78% yield in 50 min.
A standard leaching experiment was conducted to prove
that the reaction is heterogeneous. The reaction was pre-
ceded for 10 min in the presence of catalyst and then cat-
alyst was removed by filtration. The reaction was allowed
to proceed without catalyst. There was no change in yield
even after 10 h under reflux, indicating that no homoge-
neous catalyst was involved. The activity of the recycled
catalyst after fourth use.
Delivered by Publishing Technology to: Adelaide Theological Library
VSA was also examined according to the typical exper-
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
iment condition. It is noteworthy that the catalyst was
Copyright: American Scientific Publishers
recovered simply by filtration without any acidic or basic
workup even after its fourth use. Two types of experiments
were performed. After completion of the reaction of ben-
zaldehyde, malononitrile and dimedone, the catalyst was
recovered from the reaction mixture and recovered cata-
ꢀ
Fig. 6. FT-IR spectra of vanadatesulfuric acid: (a) before use and
(b) after reuse four times.
lyst was dried in oven at 120 C for 2 h prior to use. The
recovered catalyst was then added to fresh substrates under
the same experimental conditions for four runs without a
noticeable decrease in the product yield and its catalytic
activity (Table IV).
It well-known that vanadium based catalyst systems,
including Vanadium phosphorous oxides catalysts such as
(VO)2P2O7 are prone to structural changes when used in
liquid-phase oxidations.35 The XRD diffraction patterns of
fresh and used VSA catalyst in the synthesis of tetrahy-
drobenzopyrans are presented in Figure 5. Both the fresh
catalyst and that recovered after fourth use exhibited sim-
ilar XRD patterns, indicating that the structural properties
of the catalysts were not affected by the reaction medium.
Infrared spectra of fresh and used VSA catalyst also
confirmed the fact that the structure and morphology of
the catalyst remained the same after recycling (Fig. 6).
Table IV. Reusability of vanadatesulfuric acid in the synthesis of
tetrahydrobenzopyran of benzaldehyde, malononitrile and dimedone.
Isolated yielda (%)
Cycles
Type 1b
Type 2c
3. CONCLUSION
Fresh
92
91
92
92
90
92
90
89
87
85
We have found a rapid and very efficient, nanorod
vanadatesulfuric acid (VSA NRs) catalyzed one-pot
three-component reaction of ꢂ-dicarbonyl compounds,
benzaldehyde derivatives and an active methylene com-
pound for the synthesis of tetrahydrobenzo[b]pyran deriva-
tives in aqueous ethanol media. This novel catalytic system
demonstrates the advantages of environmentally benign
1
2
3
4
Notes: aCatalyst could be recycled by washing with ethanol and dried at 120 ꢀC
for 2 h; bWith makeup, loss of catalyst (<4%) was made up by fresh catalyst;
cWithout makeup.
5008
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013

Nasr-Esfahani and Abdizadeh
Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
character, mild reaction conditions, short reaction times,
high yields, easy handling as well as good reusability.
Moreover, non-hygroscopic and inexpensive for this trans-
formation are other advantages of this procedure.
(400 MHz, DMSO-d6ꢄ ꢅ (ppm): 1.87–1.99 (m, 2 H), 2.17–
2.33 (m, 2 H), 2.57–2.66 (m, 2 H), 4.68 (s, 1 H), 7.07 (s,
2 H), 7.21 (dꢆ J = 8ꢀ4 Hz, 1 H), 7.34 (ddꢆ J = 6ꢀ4 Hz,
J = 2ꢀ0 Hz, 1 H), 7.51 (dꢆ J = 1ꢀ6 Hz, 1 H).; 13C NMR
(125 MHz, DMSO-d6ꢄ ꢅ (ppm): 19.73, 26.42, 32.35,
36.20, 56.28, 112.38, 119.13, 127.69, 128.56, 131.22,
131.68, 132.95, 140.88, 158.50, 165.34, 195.90; Anal.
Calcd. for C16H12Cl2N2O2: C, 57.33; H, 3.61; Cl, 21.15;
N, 8.36; O, 9.55; found: C 57.40, H 3.70, N 8.30.
4. EXPERIMENTAL
Chemicals were purchased from Merck, Fluka and Aldrich
chemical companies. Transmission electron microscopy
was studied using a Philips, CM-10 TEM instrument oper-
ated at 100 kV. The compositional analysis is carried
out using energy dispersive X-ray spectroscopy (EDAX).
Melting points were determined using a Barnstead Elec-
trothermal (BI 9300) apparatus and are uncorrected.
IR spectra were obtained using a FT-IR JASCO-680 spec-
trometer instrument. NMR spectra were taken with a
Bruker 400 MHz Ultrashield spectrometer at 400 MHz
(1H) and 125 MHz (13C) using DMSO-d6 as the solvent
with TMS as the internal standard.
2-amino-4-(2-methoxyphenyl)-3-cyano-7,7-dimethyl-5-oxo
-4H-5,6,7,8-tetrahydrobenzo[b]pyran (Table III, 5z): Mp:
ꢀ
202–203 C; Rf = 0ꢀ56 (n-hexane:ethyl acetate = 4:1);
IR (KBr): 3396, 3329, 3011, 2965, 2188, 1686, 1654,
1
1605, 1493, 1371, 1212, 1037, 858, 755 cm−1; H NMR
(400 MHz, DMSO-d6ꢄ ꢅ (ppm): 0.97 (s, 3 H), 1.05 (s,
3 H), 2.07 (dꢆ J = 16ꢀ0 Hz, 1 H), 2.26 (dꢆ J = 16ꢀ0 Hz,
1 H), 2.46 (dꢆ J = 17ꢀ2 Hz, 1 H), 2.56 (dꢆ J = 17ꢀ2 Hz,
1 H), 3.75 (s, 3 H), 4.49 (s, 1 H), 6.84 (m, 1 H), 6.86 (s,
2 H), 6.96 (dꢆ J = 8ꢀ4 Hz, 1 H), 7.00 (dꢆ J = 6ꢀ8 Hz, 1
H), 7.14–7.18 (m, 1 H).; 13C NMR (125 MHz, DMSO-
d6ꢄ ꢅ (ppm): 25.67, 26.50, 28.59, 30.29, 31.74, 50.00,
55.56, 57.29, 111.42, 111.84, 119.83, 120.29, 127.77,
128.52, 132.11, 156.78, 158.96, 163.07, 195.56.; Anal.
Calcd. for C19H20N2O3: C, 70.35; H, 6.21; N, 8.64; O,
14.80; found: C 70.43, H 6.30, N 8.56.
4.1. Preparation of Vanadatesulfuric Acid
Anhydrous sodium metavanadate was prepared by dry-
ing of sodium metavanadate monohydrate (NaVO3 · H2O,
ꢀ
MW = 139ꢀ94) in the oven at 200 C for 4 h. To mixture
of chlorosulfonic acid (0.1 mol, 11.6 g, 7.7 mL) and dry
2-amino-4-(2-hydroxy-3-methoxyphenyl)-3-cyano-7,7-di-
Delivered by Publishing Technology to: Adelaide Theological Library
CHCl3 in 250 mL round bottom flask in an ice-bath, anhy-
drous sodium metavanadate (0.1 mol, 12.2 g) was added
gradually with vigorous stirring. After the completion of
addition of anhydrous sodium metavanadate, the reaction
mixture was filtered and a dark red solid of vanadatesul-
ꢁ
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
methyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (Table III, 5a ):
Copyright: American Scientific Publishers
ꢀ
Mp: 232–234 C; Rf = 0ꢀ46 (n-hexane:ethyl acetate =
4:1); IR (KBr): 3577, 3329, 3180, 3198, 3076, 2961,
2210, 1692, 1644, 1605, 1491, 1383, 1235, 1088, 845,
ꢀ
1
748 cm−1; H NMR (400 MHz, DMSO-d6ꢄ ꢅ (ppm): 0.95
furic acid, 16.3 g (91%), Mp 256 C (dec.) was obtained.
Characteristic IR bands (KBr, cm−1ꢄ: 3540–3300 (OH, bs),
1640 (OH, m), 1250–1140 (S O, bs), 1050 (S-O, m), 960
(V O, m), 840 (V O, m), 630 (V O, m).
(s, 3 H), 1.09 (s, 3 H), 2.07 (dꢆ J = 16ꢀ0 Hz, 1 H), 2.26
(dꢆ J = 16ꢀ0 Hz, 1 H), 2.46 (dꢆ J = 17ꢀ2 Hz, 1 H), 2.56
(dꢆ J = 17ꢀ2 Hz, 1 H), 3.93 (s, 3 H), 4.65 (s, 1 H), 7.32
(s, 2 H), 7.35 (dꢆ J = 8ꢀ0 Hz, 1 H), 7.40 (t, J = 7ꢀ0 Hz,
1 H), 7.50 (d, J = 8ꢀ0 Hz, 1 H), 10.95 (s, 1 H); 13C
NMR (125 MHz, DMSO-d6ꢄꢅ (ppm): 26.04, 26.30, 28.95,
31.74, 32.07, 45.24, 49.65, 56.02, 116.84, 117.53, 120.89,
124.64, 125.06, 125.36, 143.85, 155.17, 164.66, 167.00,
196.30; Anal. Calcd. for C19H20N2O4: C, 67.05; H, 5.92;
N, 8.23; O, 18.80; found: C 67.12, H 5.85, N 8.30.
4.2. General Procedure for Preparation of
Tetrahydrobenzo[b]pyrans
A mixture of aldehyde (1 mmol), ꢂ-dicarbonyl (1 mmol)
and malononitrile (1 mmol) and VSA (0.05 mmol) in
EtOH/H2O (10 mL) was heated under reflux condition
with stirring for an appropriate time. The progress of
the reaction was monitored by TLC using ethyl acetate:
n-hexane (1:4) as eluent. After completion of the reaction,
the catalyst was separated by filtration and the filtrate was
cooled and the solid was collected and washed with water
and recrystallized from ethanol to give pure product in
75–95% yields (Table III). The physical and spectroscopic
data of new compounds is given below:
2-amino-4-(2,6-dichlorophenyl)-3-cyano-7,7-dimethyl-
5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (Table III,
5bꢁ): Mp: 249–251 ꢀC; Rf = 0ꢀ53 (n-hexane: ethyl
acetate = 4:1); IR (KBr): 3417, 3330, 3035, 2960, 2190,
1685, 1655, 1603, 1455, 1419, 1362, 1218, 1032, 884,
1
783 cm−1; H NMR (400 MHz, DMSO-d6ꢄ ꢅ (ppm): 0.99
(s, 3 H), 1.04 (s, 3 H), 2.06 (dꢆ J = 16ꢀ0 Hz, 1 H), 2.26
(dꢆ J = 16ꢀ0 Hz, 1 H), 2.37 (dꢆ J = 17ꢀ2 Hz, 1 H), 2.53
(dꢆ J = 17ꢀ2 Hz, 1 H), 5.21 (s, 1 H), 7.12 (s, 2 H), 7.24
(tꢆ J = 8ꢀ0 Hz, 1 H), 7.35 (ddꢆ J = 7ꢀ2 Hz, J = 0ꢀ8 Hz,
1 H), 7.46 (ddꢆ J = 6ꢀ8 Hz, J = 1ꢀ2 Hz, 1 H).; 13C
NMR (125 MHz, DMSO-d6ꢄꢅ (ppm):26.84, 28.44, 31.51,
2-amino-4-(2,4-dichlorophenyl)-3-cyano–5-oxo-4H-5,6,
7,8-tetrahydrobenzo[b]pyran (Table III, 5 g): Mp: 224–
226 ꢀC; Rf = 0ꢀ51 (n-hexane:ethyl acetate
1469, 1420, 1368, 1213, 1049, 861, 765 cm−1; H NMR
=
4:1);
IR (KBr): 3314, 3158, 2962, 2189, 1682, 1649, 1608,
1
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013
5009

Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
Nasr-Esfahani and Abdizadeh
32.22, 49.89, 53.47, 55.99, 109.93, 118.96, 128.45, 128.95,
130.17, 134.11, 135.79, 136.30, 159.40, 163.73, 195.66.;
Anal. Calcd. for C18H16Cl2N2O2: C, 59.52; H, 4.44; Cl,
19.52; N, 7.71; O, 8.81; found: C 59.60, H 4.52, N 7.65.
2-amino-4-(2-chloro-6-fluorophenyl)-3-cyano-7,7-
Abstr. 96, 135383e (1982); (c) L. Bonsignore, G. Loy, D. Secci, and
A. Calignano, Eur. J. Med. Chem. 28, 517 (1983); (d) E. C. Witte,
P. Neubert, and A. Roesch, Chem. Abstr. 104, 224915f (1986).
3. (a) C. S. Konkoy, D. B. Fick, S. X. Cai, N. C. Lan, and
J. F. W. Keana, PCT Int. Appl. WO 00 75, 123 (2000);
(b) C. S. Konkoy, D. B. Fick, S. X. Cai, N.C. Lan, and
J. F. W. Keana, Chem. Abstr. 134, 29313a (2000).
4. (a) S. Hatakeyama, N. Ochi, H. Numata, and S. Takano, J. Chem.
Soc. Chem. Commun. 1202 (1988); (b) R. Gonzalez, N. Martin,
C. Seoane, and J. Soto, J. Chem. Soc. Perkin Trans. 1, 1202 (1985).
5. D. Arnesto, W. M. Horspool, N. Martin, A. Ramos, and C. Seaone,
J. Org. Chem. 54, 3069 (1989).
dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran
(Table III, 5cꢁ): Mp: 206–207 ꢀC; Rf = 0ꢀ55 (n-
hexane:ethyl acetate = 4:1); IR (KBr): 3415, 3330, 3070,
2964, 2197, 1683, 1654, 1600, 1453, 1417, 1369, 1214,
1
1037, 898, 781 cm−1; H NMR (400 MHz, DMSO-d6ꢄ ꢅ
(ppm): 0.95 (s, 3 H), 1.05 (s, 3 H), 2.07 (dꢆ J = 16ꢀ0 Hz,
1 H), 2.28 (dꢆ J = 16ꢀ4 Hz, 1 H), 2.37 (dꢆ J = 17ꢀ2 Hz,
1 H), 2.53 (dꢆ J = 17ꢀ2 Hz, 1 H), 4.89 (s, 1 H), 7.13
(s, 2 H), 7.15–7.18 (m, 1 H), 7.26–7.29 (m, 2 H); 13C
NMR (125 MHz, DMSO−d6ꢄ ꢅ (ppm): 26.25, 28.59,
29.49, 31.66, 49.83, 51.87, 56.00, 112.11, 114.04, 119.21,
123.69, 129.06, 129.16, 132.76, 133.59, 159.29, 163.54,
195.66.; Anal. Calcd. for C18H16ClFN2O2: C, 62.34; H,
4.65; Cl, 10.22; F, 5.48; N, 8.08; O, 9.23; found: C 62.44,
H 4.73, N 8.17.
6. G. P. Ellis, The Chemistry of Heterocyclic Compounds Chromenes,
Chromanones and Chromones, Weissberger A, Taylor E C, Wiley,
New York (1977), Vol. 31.
7. E. A. A. Hafez, M. H. Elnagdi, A. G. A. Elagamey, and
F. M. A. A. Eltaweel, Heterocycle 26, 903 (1987).
8. K. Singh, J. Singh, and H. Singh, Tetrahedron 52, 14273 (1996).
9. A. Shaabani, S. Samadi, Z. Baderi, and A. Rahmati, Catal. Lett.
104, 39 (2005).
10. S. Abdolmohammadi and S. Balalaie, Tetrahedron Lett. 48, 3299
(2007).
11. R. S. Bhosale, C. V. Magar, K. S. Solanke, S. B. Mane,
S. S. Choudhary, and R. P. Pawar, Synth. Commun. 37, 4353
(2007).
12. X. Z. Lian, Y. Huang, Y. Q. Li, and W. J. Zheng, Monatsh. Chem.
139, 129 (2008).
13. V. Hekmatshoar, S. Majedi, and K. Bakhtiari, Catal. Commun. 9, 307
(2008).
14. T. S. Jin, A. Q. Wang, F. Shi, L. S. Han, L. B. Liu, and T. S. Li,
Arkivoc 14, 78 (2006).
15. L. Fotouhi, M. M. Heravi, A. Fatehi, and K. Bakhtiari, Tetrahedron
5-Ethoxycarbonyl-2-amino-4-(2-chloro-6-fluorophenyl)-
3-cyano-6-methyl-4H-pyran (Table III, 6h): Mp: 210–
ꢀ
212 C; Rf = 0ꢀ53 (n-hexane:ethyl acetate = 4:1); IR
(KBr): 3474, 3324, 3065, 2961, 2186, 1683, 1658, 1593,
1
1466, 1367, 1216, 1083, 890, 780, 544 cm−1; H NMR
(400 MHz, DMSO-d6ꢄꢅ (ppm): 1.01 (tꢆ J = 7ꢀ2 Hz,
3 H), 2.29 (s, 3 H), 3.95 ꢇqꢆ J = 6ꢀ4 Hz, 2 H), 5.03
Delivered by Publishing Technology to: Adelaide Theological Library
Lett. 48, 5379 (2007).
(s, 1 H), 7.03 (s, 2 H), 7.17 (tꢆ J = 2ꢀ8 Hz, 1 H), 7.31
IP: 83.128.41.246 On: Thu,106.4IF. Deebvi2, B0.1S6. D1.8K:u4m8a:r1, a9nd P. J. Bhuyan, Tetrahedron Lett. 44, 8307
13
Copyright: American Scientific Publishers
(dꢆ J = 2ꢀ4 Hz, 2 H); C NMR (125 MHz, DMSO-d6ꢄꢅ
(ppm): 13.53, 18.15, 31.65, 53.10, 60.11, 103.48, 115.14,
119.18, 125.84, 128.53, 129.33, 133.61, 158.56, 159.10,
160.33, 165.10.; Anal. Calcd. for C16H14ClFN2O3: C,
57.07; H, 4.19; Cl, 10.53; F, 5.64; N, 8.32; O, 14.25;
found: C 57.15, H 4.27, N 8.24.
(2003).
17. S. Wang, Z. Wang, and Z. Zha, Dalton Trans. 9363 (2009).
18. (a) P. Lu and Y. G. Wang, Synlett 165 (2010); (b) B. Ganem, Acc.
Chem. Res. 42, 463 (2009); (c) A. Dömling, Chem. Rev. 106, 17
(2006); (d) D. J. Ramo’ n and M. Yus, Angew. Chem. Int. Ed.
44, 1602 (2005); (e) R. V. A.Orru, M. de Greef, Synthesis 1471
(2003).
5-Ethoxycarbonyl-2-amino-4-(2-bromophenyl)-3-cyano-
6-methyl-4H-pyran (Table III, 6i): Mp: 191–193 ꢀC;
Rf = 0ꢀ58 (n-hexane:ethyl acetate = 4:1); IR (KBr):
3433, 3333, 3066, 2977, 2190, 1686, 1641, 1602, 1466,
19. F. Igueras, Top Catal. 29, 189 (2004).
20. J. H. Clark, Acc. Chem. Res. 35, 791 (2002).
21. (a) M. Nasr-Esfahani, M. Montazerozohori, M. Moghadam,
I. Mohammadpoor-Baltork, and S. Moradi, Phosphorus Sulfur Sili-
con. 185, 261 (2010); (b) M. Nasr-Esfahani, M. Montazerozohori,
and T. Gholampour, Bul. Korean Chem. Soc. 31, 3653 (2010);
(c) M. Nasr-Esfahani, M. Montazerozohori, and S. Mehrizi, J. Het-
erocycl. Chem. 48, 249 (2011); (d) M. Nasr-Esfahani, S. J. Hoseini,
and F. Mohammadi, Chin. J. Catal. 32, 1484 (2011).
22. L. D. Frederickson and D. M. Hausen, Anal. Chem. 35, 818
(1963).
23. R. Hekmatshoar, S. Majedi, and K. Bakhtiari, Catal. Commun.
9, 307 (2008).
24. S. Balalaie, M. Sheikh-Ahmadi, and M. Bararjanian, Catal. Com-
mun. 8, 1724 (2007).
25. L. Fotouhi, M. M. Heravi, A. Fatehi, and K. Bakhtiari, Tetrahedron
Lett. 48, 5379 (2007).
1
1379, 1213, 1061, 827, 743 cm−1; H NMR (400 MHz,
DMSO-d6ꢄ ꢅ (ppm): 0.97 (tꢆ J = 7ꢀ2 Hz, 3 H), 2.34
(s, 3 H), 3.92 (qꢆ J = 4ꢀ0 Hz, 2H), 4.88 (s, 1 H), 6.95
(s, 2 H), 7.13–7.20 (m, 2 H), 7.33–7.37 (m, 1 H), 7.56
(ddꢆ J = 6ꢀ8 Hz, J = 1ꢀ2 Hz, 1 H).; 13C NMR (125 MHz,
DMSO-d6ꢄ ꢅ (ppm): 13.62, 18.07, 37.51, 56.14, 60.06,
106.19, 119.05, 122.61, 128.36, 128.4, 132.46, 143.84,
157.73, 158.35, 165.12; Anal. Calcd. for C16H15BrN2O3:
C, 52.91; H, 4.16; Br, 22.00; N, 7.71; O, 13.22; found: C
53.00, H 4.23, N 7.64.
26. E. S. Bhosale, C. V. Magar, K. S. Solanke, S. B. Mane,
S. S. Choudhary, and R. P. Pawar, Synth. Commun. 37, 4353 (2007).
27. N. S. Babu, N. Pasha, K. T. V. Rao, P. S. S. Prasad, and N. Lingaiah,
Tetrahedron Lett. 29, 2730 (2008).
28. S. Gao, C. H. Tsai, C. Tseng, and C. F. Yao, Tetrahedron 64, 9143
(2008).
References and Notes
1. G. R. Green, J. M. Evans, and A. K. Vong, Comprehensive Hete-
rocyclic Chemistry II, edited by A. R. Katritzky, C. W. Rees, and
E. F. V. Scriven, Pergamon Press, Oxford (1995), vol. 5, p. 469.
2. (a) L. L. Andreani and E. Lapi, Bull. Chim. Fr. 99, 583 (1960); (b) Y.
L. Zhang, B. Z. Chen, K. Q. Zheng, M. L. Xu, and X. H. Lei, Chem.
29. U. R. Pratap, D. V. Jawale, P. D. Netankar, and R. A. Mane, Tetra-
hedron Lett. 52, 5817 (2011).
5010
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013

Nasr-Esfahani and Abdizadeh
Nanorod Vanadatesulfuric Acid as a Novel, Recyclable and Heterogeneous Catalyst
30. S. Banerjee, A. Horn, H. Khatri, and G. Sereda, Tetrahedron Lett.
52, 1878 (2011).
34. D. Kumar, V. B. Reddy, S. Sharad, U. Dube, and S. Kapur, Europ.
J. Med. Chem. 44, 3805 (2009).
31. J. Zheng and Y. Li, Mendeleev Commun. 21, 280 (2011).
32. A. Hasaninejad, M. Shekouhy, N. Golzar, A. Zare, and
M. M. Doroodmand, Appl. Catal. A: Gen. 402, 11 (2011).
33. J. C. Xu, W. M. Li, H. Zheng, Y. F. Lai, and P. F. Zhang, Tetrahedron
61, 1539 (2011).
35. (a) P. R. Makgwane, E. E. Ferg, and B. Zeelie, App. Catal. A:
Gen. 373, 132 (2010); (b) I. Sádaba, S. Lima, A. A. Valente,
and M. L. Granados, Carbohyd. Res. 346, 2785 (2011);
(c) P. R. Makgwane, E. E. Ferg, and B. Zeelie, ChemCatChem
3, 180 (2011).
Received: 29 October 2012. Accepted: 31 January 2013.
Delivered by Publishing Technology to: Adelaide Theological Library
IP: 83.128.41.246 On: Thu, 04 Feb 2016 18:48:19
Copyright: American Scientific Publishers
J. Nanosci. Nanotechnol. 13, 5004–5011, 2013
5011