Poly(4-vinylpyridine): As a green, efficient and commercial available basic catalyst for the synthesis of chromene derivatives

Article abstract of DOI:10.1016/j.cclet.2013.01.020

Poly(4-vinylpyridine) is reported as a green, commercial available and efficient basic recyclable catalyst for the synthesis of chromene derivatives. This catalyst can be easily recovered by simple filtration and recycled up to 5 consecutive runs without

Full text of DOI:10.1016/j.cclet.2013.01.020

Chinese Chemical Letters 24 (2013) 208–210
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Chinese Chemical Letters
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Original article
Poly(4-vinylpyridine): As a green, efficient and commercial available basic
catalyst for the synthesis of chromene derivatives
b
b
Jalal Albadi a, , Azam Mansournezhad , Mohammad Darvishi-Paduk
*
a College of Science, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran
b Department of Chemistry, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
Poly(4-vinylpyridine) is reported as a green, commercial available and efficient basic recyclable catalyst
for the synthesis of chromene derivatives. This catalyst can be easily recovered by simple filtration and
recycled up to 5 consecutive runs without any loss of its efficiency.
Received 17 August 2012
Received in revised form 25 December 2012
Accepted 31 December 2012
Available online 7 March 2013
ß 2013 Jalal Albadi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
Keywords:
Poly(4-vinylpyridine)
Chromene
Basic catalyst
b
-Naphthol
Malononitrile
1. Introduction
pyridine is a highly flammable and highly toxic compound and can
be absorbed through the skin mucous membranes. Therefore
Numerous reactions such as isomerizations, alkylations, con-
densations, additions, and cyclizations were carried out industrially
by using liquid bases catalysts [1]. The replacement of liquid bases
by cleaner catalytic alternatives is quite necessary in the view of
being environmentally benign. Solid base catalysts have many
advantages over liquid bases. They are noncorrosive, environmen-
tally benign and present fewer disposal problems while allowing
easier separation and recovery of the products, catalysts and the
solvent. Thus, solid base catalysis is one of the economically and
ecologically important field. Catalysis and the replacement of liquid
bases with heterogeneous catalysts are becoming more and more
important in the chemical industry. Many solid basic catalysts have
been studied, including ion-exchange resins [2], modified silicas
such as xonotlite [3], hydrotalcite [4], sepioloites [5], and supports
with surface oxynitrides [6]. Pyridine was used as a polar, basic, low-
reactive solvent for example in Knoevenagel condensations. It is
especially suitable for dehalogenation, where it acts as the base for
the elimination reaction and bonds the resulting hydrogen halide to
form a pyridinium salt. In esterifications and acylations, pyridine
activatesthecarboxylicacidhalidesoranhydrides.Pyridinewasalso
used as a liquid base in condensation reaction [7]. Nevertheless,
replacement of the pyridine with the corresponding cleaner solid
alternatives, possessing desirable characteristics such as being
nonstoichiometric, non-corrosive and reusable, is necessary in view
of being environmentally benign. Poly(4-vinylpyridine) (PVPy) has
been used as the support for the numerous reagents and catalysts in
many organic reaction transformations. Cross-linked poly(4-vinyl-
pyridine) as an insoluble polymer has remarkable properties and
attracted much attention. It undergoes facile functionalization
and has a large proportion of functional groups which showed good
accessibility. Moreover, it is non-hygroscopic, prepared readily and
is available commercially. Also it is easy to filter and swells in many
organic solvents. The cross-linked PVPy by divinylbenzene (DVB)
was used most often because of its commercial availability, its
stability, reasonably high loading capacity, good swelling char-
acteristics and good physicochemical structure [8]. However, to the
best of the our knowledge, there is no report which utilizes poly(4-
vinylpyridine) as a solid basic catalyst in the organic synthesis.
Chromene derivatives are an important class of compounds that
received significant attention from many pharmaceutical and
organic chemists because of the broad spectrum of their biological
and pharmaceutical properties such as antisterility and anticancer
agents [9]. Moreover, these compounds can also be employed as
cosmetics and pigments [10]. Therefore, various synthetic proce-
dures have been developed for the preparation of chromene
derivatives [11–25]. Herein we wish to report the applicability of
* Corresponding author.
E-mail address: jalal.albadi@gmail.com (J. Albadi).
1001-8417/$ – see front matter ß 2013 Jalal Albadi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
http://dx.doi.org/10.1016/j.cclet.2013.01.020

J. Albadi et al. / Chinese Chemical Letters 24 (2013) 208–210
209
Table 1
CN
Synthesis of chromene derivatives catalyzed by PVPy.
Ar
NH
2
OH
+
PVPy
Solvent-free, 80 oC
+ NC CN
Yield (%)a
Mp (8C)b
ArCHO
O
Entry
Aldehyde
Time (min)
1
2
C6H5CHO
10
8
93
89
93
93
90
93
89
87
89
89
88
88
86
89
92
274–276
233–235
186–187
258–260
205–206
214–216
242–244
217–218
210–211
258–259
233–234
270–272
246–248
253–255c
201–202c
3-O2NC6H4CHO
4-O2NC6H4CHO
2-ClC6H4CHO
Scheme 1. Synthesis of chromene derivatives catalyzed by PVPy.
3
5
4
12
10
8
5
4-ClC6H4CHO
6
2,4-ClC6H3CHO
4-BrC6H4CHO
poly(4-vinylpyridine) as a green, commercial available and efficient
basic recyclable catalyst for the synthesis of chromene derivatives
via the one-pot three-component condensation of b-naphthol with
7
15
30
40
12
15
20
45
20
10
8
4-MeOC6H4CHO
3,4-MeOC6H3CHO
4-CNC6H4CHO
4-FC6H4CHO
9
10
11
12
13
14
15
aromatic aldehydes and malononitrile (Scheme 1).
4-MeC6H4CHO
4-HOC6H4CHO
4-MeCONHC6H4CHO
4-Cl-3-O2NC6H3CHO
2. Experimental
General: All products were characterized by comparison of their
spectroscopic data (1H NMR, IR) and physical properties with those
reported in the literature. Chemicals were purchased from Fluka,
Merck, and Aldrich Chemical. Yields refer to isolated pure products.
General procedure for the synthesis of chromene derivatives: A
a
Isolated yield.
b
Products were characterized by comparison of their spectroscopic data (NMR
and IR) and melting points with those reported in the literature [13,15,19].
c
New compounds.
mixture of
b-naphthol (1 mmol), malononitrile (1 mmol), alde-
hyde (1 mmol) and PVPy (0.1 g) was heated in an oil bath (80 8C)
for the appropriate times as shown on Table 1. After completion of
the reaction (monitored by TLC), the resulting mixture was cooled,
ethylacetate (10 mL) was added and the catalyst was recovered by
filtration to be reused subsequently. Evaporation of the solvent
from the filtrate and recrystallization of the solid residue from hot
ethanol affords the pure products in high yields.
37.8, 57.4, 115.5, 117.3, 120.2, 120.6, 124.0, 125.5, 127.7, 129.0,
129.7, 130.2, 130.5, 131.3, 132.1, 145.6, 147.3, 160.2.
Table 1, entry 9: IR (KBr, cmÀ1): nmax 3450, 3300, 2200, 1640,
1400, 1300, 1000. 1H NMR (400 MHz, DMSO-d6):
d 3.72 (s, 3H,
OCH3), 3.77 (s, 3H, OCH3), 5.58 (s, 1H, CH), 7.20 (s, 2H, NH2), 7.37 (d,
1H, J = 9.2 Hz, Ar), 7.43–7.51 (m, 3H), 7.68 (d, 1H, J = 8 Hz, Ar), 7.85
(d, 1H, J = 8.0 Hz, Ar), 7.94–8.00 (m, 3H, Ar). 13C NMR (100 MHz,
The spectral and analytical data for the known compounds are
as follows:
DMSO-d6): d 37.35, 56.45, 56.92, 57.90, 114.49, 117.39, 120.51,
123.72, 123.80, 124.21, 125.64, 127.95, 129.10, 130.30, 130.60,
131.30, 132.65, 132.86, 147.12, 147.37, 148.00, 160.41.
Table 1, entry 1: IR (KBr, cmÀ1): nmax 3420, 3340, 3150, 2190,
1640, 1580, 1000–1300, 690, 710. 1H NMR (400 MHz, DMSO-d6):
d
Table 1, entry 10: IR (KBr, cmÀ1): nmax 3462, 3356, 2200, 2190,
5.32 (s, 1H), 7.04 (s, 2H, NH2), 7.13–7.28 (m, 5H), 7.35–7.46 (m, 3H),
7.84–7.95 (m, 3H). 13C NMR (100 MHz, DMSO-d6):
38.51, 58.38,
1654, 1589. 1H NMR (400 MHz, DMSO-d6):
d 5.43 (s, 1H, CH), 7.16
d
(s, 2H, 9.5. 7.24–7.41 (m, 3H, Ar), 7.58–7.86 (m, 2H, Ar), 7.88 (d, 1H,
116.16, 117.27, 121.04, 124.10, 125.40, 127.08, 127.48, 127.55,
128.94, 129.19, 129.97, 130.65, 131.30, 146.21, 147.32, 160.20.
Table 1, entry 2: IR (KBr, cmÀ1): nmax 3400, 3300, 3200, 2900,
2200, 1645, 1550, 1350, 1400, 1300–1000. 1H NMR (400 MHz,
J = 9.2 Hz, Ar), 7.42 (d, 2H, J = 8.0 Hz Ar), 8.12 (d, 2H, J = 8.0 Hz, Ar).
13C NMR (100 MHz, DMSO-d6):
d 38.50, 60.22, 113.74, 116.40,
117.40, 121.10, 124.20, 125.45, 127.44, 127.57, 129.02, 129.79,
129.95, 130.72, 131.39, 136.20, 143.35, 147.30, 160.30
Table 1, entry 12: IR (KBr, cmÀ1): nmax 3310, 3410, 3050, 2190,
1640, 1580, 1400, 1000–1300, 810. 1H NMR (400 MHz, DMSO-d6):
DMSO-d6):
d
5.62(s, 1H, CH), 7.15 (s, 2H, NH2), 7.37 (d, 1H, J = 8.9Hz,
Ar), 7.41–7.47 (m, 2H, Ar), 7.56 (t, 1H, J = 7.8 Hz, Ar), 7.68 (d, 1H,
J = 7.7 Hz, Ar), 7.85 (d, 1H, J = 8.2 Hz, Ar), 7.94 (d, 1H, J = 7.6 Hz, Ar),
7.97 (d, 1H, J = 8.9 Hz, Ar), 8.02 (d, 1H, J = 8.07 Hz, Ar), 8.09 (s,1H,
d
2.19 (s, 3H, CH3), 5.26 (s, 1H, CH), 6.99 (s, 2H, NH2), 7.04–7.10 (m,
4H), 7.33 (d, 1H J = 8 Hz, Ar), 7.39–7.46 (m, 2H), 7.83 (d, 1H,
J = 8.0 Hz) 7.90–7.94 (t, 2H). 13C NMR (100 MHz, DMSO-d6):
Ar). 13C NMR (100 MHz, DMSO-d6):
d
57.81, 115.46, 117.75, 121.05,
d
122.17, 122.73, 124.35, 126.02, 128.29, 129.47, 130.77, 130.94,
131.34, 131.74, 134.58, 147.83, 148.756, 148.85, 160.83.
21.02, 38.22, 58.51, 116.27, 117.26, 121.06, 124.14, 125.35, 127.38,
127.50, 128.92, 129.72, 129.88, 130.66, 131.29, 136.16, 143.30,
147.24, 160.09.
Table 1, entry 3: IR (KBr, cmÀ1): nmax 3430, 3325, 2190, 1650,
1610, 1582, 1540, 1502, 1340, 1244, 1200, 1070, 810. 1H NMR
The spectral and analytical data for the new compounds are as
follows:
(400 MHz, DMSO-d6):
7.52 (m, 3H, Ar), 7.69–8.03 (m, 2H, Ar), 7.98 (d, 1H, J = 9.2 Hz, Ar),
7.44 (d, 2H, Ar), 8.15(d, 2H, Ar). 13C NMR (100 MHz, DMSO-d6):
d 5.45 (s, 1H, CH), 7.20 (s, 2H, NH2). 7.36–
Table 1, entry 14: White solid, mp: 253–255 8C; IR (KBr, cmÀ1):
d
n
max 3400, 3300, 2200, 1650, 1600–1400, 1320, 1100, 810. 1H NMR
38.53, 60.27, 116.45, 117.47, 121.17, 124.24, 125.49, 127.48,
127.62, 129.05, 129.82, 129.99, 130.74, 131.42, 136.23, 143.37,
147.33, 160.38.
(400 MHz, DMSO-d6): d 1.99 (s, 3H, Me), 5.24 (s, 1H, CH), 6.98 (s,
2H, NH2), 7.11 (d, 2H, J = 8.4 Hz, Ar), 7.34 (d, 1H, J = 8.8 Hz, Ar),
7.40–7.45 (m, 4H, Ar), 7.83 (d, 1H, J = 8.0 Hz, Ar), 7.90–7.95 (m, 2H,
Ar), 9.89 (s, 1H, NH). 13C NMR (100 MHz, DMSO-d6):
d 24.34(Me),
Table 1, entry 5: IR (KBr, cmÀ1): nmax 3450, 3300, 2200, 1640,
1400, 1300–1000. 1H NMR (400 MHz, DMSO-d6):
d
5.37 (s, 1H, CH),
38.05, 58.36, 116.15, 117.29, 119.83, 121.04, 124.15, 125.38,
127.51, 127.76, 128.93, 129.90, 130.65, 131.28, 138.24, 140.86,
147.18, 160.01, 168.60. Elem. Anal. Found: C, 74.41; H, 4.79 N,
11.88 (calculated for C22H17O2 N3: C, 74.35; H, 4.82; N, 11.82).
Table 1, entry 15: Yellow solid, mp: 201–202 8C; IR (KBr, cmÀ1):
7.09 (s, 2H, NH2), 7.21 (d, 2H, J = 8.4 Hz, Ar), 7.31–7.37 (m, 3H, Ar),
7.40–7.47 (m, 2H, Ar), 7.81 (d, 1H, J = 8.0 Hz, Ar), 7.90–7.96 (m, 2H,
Ar). 13C NMR (100 MHz, DMSO-d6):
d 37.85 (CH), 57.90 (CN),
115.63, 117.29, 120.87, 124.02, 125.47, 127.65, 128.99, 129.18,
129.33, 130.17, 130.53, 131.31, 131.67, 132.60, 145.16, 147.29,
160.21.
Table 1, entry 7: IR (KBr, cmÀ1): nmax 3416, 3323, 3194, 3051,
2193, 1641, 1591, 1485, 1410, 1234, 1080, 1012, 819, 736. 1H NMR
n
max 3400, 3300, 2200, 1640, 1550, 1350, 1300– 1000, 800– 740. 1H
NMR (400 MHz, DMSO-d6): 5.58(s, 1H, CH), 7.20 (s, 2H, NH2), 7.37
d
(d, 1H, J = 9.2 Hz, Ar), 7.43–7.51 (m, 3H), 7.68 (d, 1H, J = 8 Hz, Ar),
7.85 (d, 1H, J = 8.0 Hz, Ar), 7.94–8.00 (m, 3H, Ar). 13C NMR
(400 MHz, CDCl3):
J = 8.4 Hz), 7.27 (d, 2H, J = 6.3 Hz), 7.45–7.40 (m, 3H), 7.63 (d, 1H,
J = 6.4 Hz), 7.84(d, 2H, J = 8.5 Hz). 13C NMR (100 MHz, CDCl3):
d
5.23(s, 1H, CH), 4.64 (s, 2H, NH2), 7.07 (d, 2H,
(100 MHz, DMSO-d6): d 37.37, 56.95, 114.52, 11.41, 120.54, 123.74,
123.84, 124.24, 125.66, 127.97, 129.13, 130.34, 130.65, 131.34,
132.69, 132.91, 147.17, 147.42, 148.03, 160.44. Elem. Anal. Found:
d

210
J. Albadi et al. / Chinese Chemical Letters 24 (2013) 208–210
Table 2
Acknowledgment
Recyclability study of PVPy.
Run
1
10
93
2
10
93
3
15
91
4
20
91
5
30
90
6
45
90
We are thankful to the Behbahan Khatam Alanbia University of
Technology, for the partial support of this work.
Time(min)
Yield (%)a
a
Isolated yield.
References
C, 63.65; H, 3.24 N, 11.14 (calculated for C20H12O3N3Cl:C, 63.58; H,
3.20; N, 11.12).
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At first, for the optimization of the reaction conditions, the
reaction of benzaldehyde,
b-naphthol and malononitrile was
investigated as a model and its behavior was studied under various
conditions. The best results were achieved by carrying out the
reaction of benzaldehyde, b-naphthol and malononitrile (with 1:
1:1 mol ratio) in the presence of 0.1 g of PVPy at 80 8C for 10 min
under solvent-free conditions (Table 1, entry 1). Using these
optimized conditions, the reaction of various aromatic aldehydes,
containing electron-donating and electron-withdrawing groups,
was explored. All the products were cleanly isolated with simple
filtration and evaporation of the solvent. The solid products were
easily recrystallized from hot ethanol and were obtained in good to
high yields during the short reaction times. All the known products
were identified by comparison of the melting points and the
analytical data (IR, NMR) of those reported for authentic samples. A
distinct characterization of the present method, illustrated in this
work, is the formation of corresponding products without by-
product.
It is also noteworthy that PVPy does not suffer from extensive
mechanical degradation after running. When using a heteroge-
neous catalyst, the key point is the recyclability of the catalyst. In
order to exhibit the recyclability of the PVPy, the reaction of
benzaldehyde, b-naphthol and malononitrile was selected again as
a model. After reaction completion, the PVPy was washed with
ethylacetate, dried and stored for another consecutive reaction
run. This process was repeated for five runs and no appreciable
yield decrease was observed. Almost consistent activity was
observed over five runs and desired products were obtained in high
yields after 1–5 runs, respectively (Table 2). Finally, in order to
evaluate the efficiency and superiority of our method, we began to
run the reaction between benzaldehyde,
b-naphthol and mal-
ononitrile in the presence of pyridine at the same conditions. The
obtained results showed that solid base catalyst (PVPy) has an
advantage over pyridine in term of high reactivity and easily
recyclable. PVPy is very cheap, easy to handle and can be recovered
simply by filtration. It can be reused in the next runs without
significant yield decrease of the products. Further, PVPy makes the
chromenes synthesis eco-friendly, with the possibility of scale-up
to an environmentally benign and clean technology.
4. Conclusion
In conclusion, we have developed a mild, simple and green
procedure for the one-pot synthesis of chromene derivatives using
recyclable PVPy under solvent-free conditions. PVPy as
a
commercial available basic catalyst can promote the yields over
5 runs. Moreover, high yields of the products, short reaction times,
recyclability of the reagent, solvent-free nature of the reaction,
ease of work-up and clean procedure, will make the present
method an efficient and important addition to the present
methodologies for the synthesis of chromene derivatives.
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