A recyclable and highly effective ZnO-beta zeolite as a catalyst for one-pot three-component synthesis of tetrahydrobenzo[b]pyrans

Article abstract of DOI:10.1002/cjoc.201190052

4H-Benzo[b]pyrans was synthesized under reflux condition in ethanol via condensation of benzaldehyde, malononitrile and dimedone with ZnO-beta zeolite as an inexpensive and effective catalyst. The key features of the reported protocols are good to excelle

Full text of DOI:10.1002/cjoc.201190052

NOTE
A Recyclable and Highly Effective ZnO-beta Zeolite as a
Catalyst for One-pot Three-Component Synthesis of
Tetrahydrobenzo[b]pyrans
Katkar, Santosh Shriram
Lande, Machhindra Karbhari*
Gaikwad, Suresh Tukaram
Arbad, Balasaheb Ramrao
Department of Chemistry, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad-431004,
Maharashtra, India
4
H-Benzo[b]pyrans was synthesized under reflux condition in ethanol via condensation of benzaldehyde,
malononitrile and dimedone with ZnO-beta zeolite as an inexpensive and effective catalyst. The key features of the
reported protocols are good to excellent yields, short reaction time and recovery and reusability of catalytic mate-
rial.
Keywords heterogeneous, 4H-benzo[b]pyrans, ZnO-beta zeolite, multicomponent, cyclocondensation
Introduction
backs including long reaction times, unsatisfactory
yields, higher temperatures and use of expensive non
reusable catalyst.
Multi-component reactions (MCRs) are important
for the achievement of high levels of shortness and di-
versity. They allow more than two simple and flexible
building blocks to be combined in practical, time-saving
one-pot operations, giving rise to complex structures by
simultaneous formation of two or more bonds, accord-
To avoid these limitations, the discovery of a mild
and efficient catalyst with high catalytic activity, short
reaction time, simple work-up procedure and recyclabil-
ity of catalyst is still being actively pursued for the syn-
thesis of 4H-benzo[b]pyrans. In order to overcome these
problems, zeolite seems to be an excellent candidate to
take over the catalytic job, since the use of a zeolite as
the catalyst will be very promising not only from an
economical point of view but also from an ecological
viewpoint because of their suitable acidity, thermal sta-
bility, easy work-up, recyclability and environment-
friendly nature. Zeolites have been used as catalyst in
1
ing to the domino principle. MCRs contribute to the
requirements of an environmentally friendly process by
reducing the number of synthetic steps, energy con-
sumption and waste production. Researchers have
transformed this powerful technology into one of the
most efficient and economic tools for combinatorial and
2
parallel synthesis. 4H-Benzo[b]pyrans represent a
medicinally and pharmaceutically important class of
compounds, because of their diverse range of biological
activities, such as anticoagulant, spasmolytic, diuretic,
17,18
the petroleum refining and chemical industries.
Their properties and thus their performance as catalyst
can be adjusted by modification by ion exchange with
3
anticancer and antianaphylactin activities. Some
metal ions, acid treatment and hydrothermal treat-
2
-amino-4H-pyrans can be employed as photoactive
19,20
ment.
There have been extensive efforts to utilize the
4
materials. In addition, polysubstituted 4H-benzopyrans
zinc loaded zeolites in organic transformations such as
also constitute a structural unit of a series of natural
21
22
Heck reaction, propane aromatization, dehydrogena-
5
products.
23
tion of small paraffins, aromatization of in situ gener-
4
H-Benzo[b]pyrans are useful in organic synthesis
24
25,26
ated ethylene and the hydration of acetylene.
To
because of their biological importance. Therefore, vari-
ous synthetic methods are reported, using microwave,
the best of our knowledge the use of ZnO-beta zeolite as
a catalyst in the synthesis of 4H-benzo[b]pyrans has not
been reported yet. In view of the importance of hetero-
geneous solid acids as reusable catalyst in organic syn-
thesis and in continuation of our ongoing work using
zeolite as a solid acid catalyst for developing new syn-
6
7
ultrasonic irradiation, organic solvents, such as acetic
8
9,10
acid or DMF and in aqueous media, also reported by
1
1
12
tetrabutylammonium bromide, (S)-proline, rare earth
1
3
perfluorooctanoates,
hexadecyltrimethylammonium
1
4
15
bromide, diammonium hydrogen phosphate and io-
27
thetic methodologies, we would like to report herein
1
6
dine. However, most of the methods to prepare
H-benzo[b]pyran derivatives suffer from certain draw-
an efficient synthesis of 4H-benzo[b]pyrans using ZnO-
beta zeolite as catalyst.
4
*
E-mail: mkl_chem@yahoo.com; Tel.: ＋91240-2403311; Fax: ＋91240-2403335
Received April 9, 2010; revised June 17, 2010; accepted September 19, 2010.
Chin. J. Chem. 2011, 29, 199— 202
© 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
199

Katkar et al.
NOTE
We have previously reported synthesis, characteriza-
thyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (4d)
1
tion and catalytic applications of ZnO-beta zeolite in the
synthesis of benzothiazoles, quinoxalines and polyhy-
H NMR δ: 0.94 (s, 3H), 1.03 (s, 3H), 2.10 (d, J＝8 Hz,
1H), 2.23 (d, J＝8 Hz, 1H), 2.48 (s, 2H), 4.04 (s, 1H),
2
8,29
droquinolines.
Since the ZnO-beta zeolite has been
6.63 (s, 1H), 6.89—6.92 (m, 4H), 9.25 (s, 1H); IR (KBr)
－
1
exploited in the organic synthesis, as a nontoxic, inex-
pensive, eco-friendly, easy handling and mild catalyst,
we investigated ZnO-beta zeolite as a catalyst for the
synthesis of 4H-benzo[b]pyrans by cyclocondensation
of aldehyde, malononitrile and 5,5-dimethyl-
ν: 3350, 2957, 2176, 1658, 1399, 1218 cm ; EI-MS
(m/z): 310 (M ).
＋
2-Amino-3-cyano-4-(3-nitrophenyl)-7,7-dimethyl-5-
1
oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (4e)
H
NMR δ: 0.96 (s, 3H), 1.05 (s, 3H), 2.11 (d, J＝8 Hz,
1H), 2.27 (d, J＝8 Hz, 1H), 2.55 (s, 2H), 4.42 (s, 1H),
7.17 (s, 2H), 7.59—8.09 (m, 4H); IR (KBr) ν: 3426,
1
,3-cyclohexanedione (dimedone) at reflux condition in
ethanol (Scheme 1).
－
1
2
955, 2185, 1676, 1530, 1210 cm ; EI-MS (m/z): 339
＋
Scheme 1
(
M ).
2
-Amino-3-cyano-4-(3-hydroxyphenyl)-7,7-dime-
thyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (4f)
1
H NMR δ: 0.97 (s, 3H), 1.04 (s, 3H), 2.10 (d, J＝8 Hz,
1
6
H), 2.26 (d, J＝8 Hz, 1H), 2.57 (s, 2H), 4.06 (s, 1H),
.54 (s, 2H), 6.97—7.08 (m, 4H), 9.31 (s, 1H); IR (KBr)
－
1
ν: 3310, 2964, 2191, 1652, 1359, 1211 cm ; EI-MS
(
＋
m/z): 310 (M ).
2
-Amino-3-cyano-4-(4-methoxyphenyl)-7,7-dime-
thyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b]pyran (4i)
1
H NMR δ: 0.95 (s, 3H), 1.03 (s, 3H), 2.08 (d, J＝8 Hz,
1
3
4
H), 2.22 (d, J＝8 Hz, 1H), 2.25 (s, 3H), 2.49 (s, 2H),
.34 (s, 3H), 4.11 (s, 1H), 6.85 (s, 2H), 6.82—7.06 (m,
H); IR (KBr) ν: 3356, 2969, 2157, 1658, 1382, 1217
－
1
＋
cm ; EI-MS (m/z): 324 (M ).
Experimental
All chemicals are purchased from Aldrich and
Rankem chemical suppliers and used as received. The
uncorrected melting points of compounds were taken in
an open capillary in a paraffin bath. H NMR spectra
were recorded on an 400 MHz FT-NMR spectrometer in
Results and discussion
To optimize the reaction conditions, benzaldehyde,
malononitrile and dimedone were employed as a model
reaction to examine the effect of various solvent, such as
acetone, toluene, chloroform, acetonitrile, methanol and
ethanol and varying amounts of ZnO-beta zeolite (0.01,
0.05, 0.1 and 0.2 g). The use of acetone, toluene and
chloroform gave the product 4a in low yield (Table 1,
Entries 2—4). Acetonitrile and methanol gave moderate
yields (Table 1, Entries 5 and 6) in 60 min and 90 min.
respectively. Finally, the reaction in ethanol with 0.1 g
of catalyst afforded 4a in 95% yield (Table 1, Entry 7)
1
CDCl
3
as a solvent and chemical shifts (δ) values are
Si) as an in-
recorded relative to tetramethylsilane (Me
4
ternal standard. The X-ray powder diffraction patterns
were recorded by using Bruker 8D X-ray diffractometer
using Cu Kα radiation of wavelength 1.54056 Å. FT-IR
spectra were recorded on JASCO FT-IR-4100, Japan.
Scanning electron microscope image with energy dis-
persive X-ray spectroscopy (SEM-EDS) was obtained
on JEOL, JSM-6330 LA operated at 20.0 kV 1.0000 nA.
The surface area of catalyst was determined by the ni-
trogen adsorption on Quantachrome Autosorb Instru-
ment.
Table 1 Optimization of various solvents and amount of cata-
lyst for the reaction of benzaldehyde, malononitrile and dimedone
a
b
Entry
Solvent
Ethanol
Catalyst/g
—
Time
3 h
Yield /%
General procedure for the synthesis of tetrahydro-
benzo[b]pyran
1
2
3
4
5
6
7
8
9
—
35
52
41
85
79
95
87
95
Acetone
Toluene
0.1
2 h
A mixture of aldehyde (10 mmol), malononitrile (10
mmol), dimedone (10 mmol) and ZnO-beta zeolite (0.1
g) in ethanol (10 mL) was refluxed until the reaction
completed (monitored by TLC). After completion of
reaction, catalyst was separated by simple filtration,
crude product was obtained and resulting solid was pu-
rified by recrystallization from hot methanol to afford
the pure products 4a—4l.
0.1
2.5 h
3 h
Chloroform
Acetonitrile
Methanol
Ethanol
0.1
0.1
1 h
0.1
1.5 h
35 min
45 min
35 min
0.1
Ethanol
0.05
0.2
Ethanol
a
All reactions were carried out using ZnO-beta zeolite at reflux
Spectroscopic data of typical compounds
b
condition. Isolated yields.
2
-Amino-3-cyano-4-(4-hydroxyphenyl)-7,7-dime-
2
00
www.cjc.wiley-vch.de
© 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2011, 29, 199— 202

ZnO-beta Zeolite as a Catalyst for Synthesis of Tetrahydrobenzo[b]pyrans
within 35 min. Therefore, we selected ethanol as a sol-
vent and 0.1 g of catalyst for this reaction. As shown in
Table 1, no desirable product could be detected in the
absence of catalyst for 180 min (Table 1, Entry 1),
which indicated that the catalyst should be absolutely
necessary for this reaction.
Based on the above result, this process was then ex-
tended to variety of aldehydes containing electron-
donating and electron-withdrawing groups to prepare
corresponding 4H-benzo[b]pyrans. No significant sub-
stituent effect was observed on the yields of the products
portant benefits and makes them useful for commercial
applications, thus the recovery and reusability of
ZnO-beta zeolite was investigated. The separated cata-
lyst can be reused after washing with n-hexane and dry-
ing at 120 ℃ for 1 h. The reusability of the catalyst
was checked by the reaction of benzaldehyde,
malononitrile and dimedone under optimized reaction
condition (Table 3). The results clearly indicate that the
catalyst can be reused four times without loss of its ac-
tivity.
(
Table 2, Entries 1—12). Further that 4H-benzo[b]pyran
Conclusion
bearing nitro functionality on the aryl ring was obtained
in good yields (Table 2, Entries 3 and 5). Encouraged by
these results, we have also carried out the cycloconden-
sation of heterocyclic aldehyde, that is, furfuraldehyde
with malononitrile and dimedone to obtain the respec-
tive tetrahydrobenzo[b]pyran (Table 2, Entry 12) in a
better yield. A plausible mechanism for the synthesis of
tetrahydrobenzo[b]pyran is shown in Scheme 2.
In summary, we have demonstrated a new and im-
portant catalytic activity of ZnO-beta zeolite as an inex-
pensive, effective, reusable and non-corrosive catalyst
for the synthesis of tetrahydrobenzo[b]pyrans in high to
excellent yields. Compared to the existing method, it has
the several advantages, such as simple experimental
procedure combined with the easy work-up, high to ex-
cellent yields of products and reusability of catalyst.
The reusability of the catalyst is one of the most im-
a
Table 2 Synthesis of tetrahydrobenzo[b]pyran derivatives catalyzed by ZnO-beta zeolite
m.p./℃
b
Entry
Ar
Product
Time/min
Yield /%
Found
Reported
1
3
3
4
4
5
5
5
2
4
4
3
b
1
2
3
4
5
6
7
8
9
C
6
H
5
4a
4b
4c
4d
4e
4f
35
40
50
40
48
40
42
35
45
40
40
52
95
93
87
89
86
88
91
95
91
95
89
91
227—228
215—216
177—178
213—214
213—214
234—235
207—208
209—210
200—201
217—218
115—116
219—220
226—228
214—216
178—179
214—215
213—217
230—235
207—209
209—211
199—201
217—218
115—117
218—220
1
1
1
1
1
1
1
1
1
1
8
3 6 4
4-CH C H
4-NO C H
2
6
4
4-OHC
6
H
4
3-NO C H
2
6
4
3-OHC H
6
4
4-BrC
6
H
4
4g
4h
4i
4-ClC H
6
4
4-OMeC H
6
4
10
11
12
2-ClC
6
H
4
4j
2,4-Cl C H
4k
4l
2
6
3
Furyl
a
b
All reactions were carried out at reflux condition using aldehyde (10 mmol), malononitrile (10 mmol) and dimedone (10 mmol). Yield
refer to isolated products, which were characterized by comparing IR, H NMR, mass spectral data and melting points with those reported
1
in literature.
Scheme 2 Plausible mechanism for the synthesis of tetrahydrobenzo[b]pyran catalyzed by ZnO-beta zeolite
Chin. J. Chem. 2011, 29, 199— 202
© 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
201

Katkar et al.
NOTE
Table 3 Reusability of catalyst for the reaction of benzaldehyde,
malononitrile and dimedone (Table 2, Entry 1)
Synlett 2006, 263.
13 Wang, L. M.; Shao, J. H.; Tian, H.; Wang, Y. H.; Liu, B. J.
Fluorine Chem. 2006, 127, 97.
a
Entry
Cycle
1
2
3
4
14
15
16
Jin, T. S.; Wang, A. Q.; Wang, X.; Zhang, J. S.; Li, T. S.
Synlett 2004, 871.
Balalaie, S.; Bararjanian, M.; Sheikh-Ahmadi, M.; Hekmat,
S.; Salehi, P. Synth. Commun. 2007, 37, 1097.
Bhosale, R. P.; Magar, C. V.; Solanke, K. S.; Mane, S. B.;
Choudhary, S. S.; Pawar, R. P. Synth. Commun. 2007, 37,
Fresh
95
First
95
Second
Third
93
b
Yield /%
94
a
b
Reaction were carried out at reflux condition. Isolated yields.
Acknowledgement
4
353.
We are grateful to the Head, Department of Chemis-
try, Dr. Babasaheb Ambedkar Marathwada University,
Aurangabad-431004 (MS), India for providing the
laboratory facility.
1
7
8
Parveen, A.; Ahmed, M. R. S.; Shaikh, K. A.; Deshmukh, S.
P.; Pawar, R. P. ARKIVOC 2007, 16, 12.
(a) Breck, D. W. Zeolite Molecular Sieves, Wiley, New
York, 1974.
1
(
b) Dyer, A. An Introduction to Zeolite Molecular Sieves,
References
Wiley, Chichester, 1988.
1
2
2
2
9
0
1
2
Dorado, F.; Romero, R.; Canizares, P. Appl. Catal. A 2002,
1
2
3
Zhu, J.; Bienayme, H. Multicomponent Reactions,
Wiley-VCH, Weinheim, Germany, 2005.
Beck, B.; Hess, S.; Domling, A. Bioorg. Med. Chem. Lett.
2
36, 235.
Wang, L.; Yu, B.; Li, Y. H. Acta Petrol. Sin. 2001, 17, 27
in Chinese).
Djakovitch, L.; Koehler, K. J. Am. Chem. Soc. 2000, 132,
990.
Biscardi, J. A.; Meitzner, G. D.; Iglesia, E. J. Catal. 1998,
79, 192.
(
2
000, 10, 1701.
(a) Andreani, L. L.; Lapi, E. Boll. Chim. Farm. 1960, 99,
83.
b) Bonsignore, L.; Loy, G.; Secci, D.; Calignano, A. Eur. J.
5
5
(
1
Med. Chem. 1993, 28, 517.
Armetso, D.; Horspool, W. M.; Martin, N.; Ramos, A. J.
Org. Chem. 1989, 54, 3069.
Hatakeyama, S.; Ochi, N.; Numata, H.; Takano, S. J. Chem.
Soc., Chem. Commun. 1988, 1202.
Zhou, J. F.; Tu, S. J.; Gao, Y.; Ji, M. Chin. J. Org. Chem.
2
2
3
4
Ono, Y. Catal. Rev. Sci. Eng. 1992, 34, 179.
4
5
6
7
Hagen, A.; Roessner, F.; Krager, H. G.; Weitkamp, J. In
Studies in Surface Science and Catalysis, Vol. 98, Elsevier,
Amsterdam, The Netherlands, 1999, p. 189.
Onyestak, G. Y.; Kallo, D.; Delmon, B.; Froment, G. F. In
Studies in Surface Science and Catalysis, Vol. 34, Elsevier,
Amsterdam, The Netherlands, 1987, p. 605.
25
26
27
2
001, 21, 742 (in Chinese).
Tu, S. J.; Jiang, H.; Zhuang, Q. Y.; Miao, C. B.; Shi, D. Q.;
Wang, X. S.; Gao, Y. Chin. J. Org. Chem. 2003, 23, 488 (in
Chinese).
Onyestak, G. Y.; Papp, J.; Kallo, D.; Karge, H. G.; Weit-
kamp, J. In Studies in Surface Science and Catalysis, Vol.
46, Elsevier, Amsterdam, The Netherlands, 1989, p. 241.
8
(a) Singh, K.; Singh, J.; Singh, H. Tetrahedron 1996, 52,
(a) Shinde, S. V.; Jadhav, W. N.; Lande, M. K.; Gadekar, L.
S.; Arbad, B. R.; Kondre, J. M.; Karade, N. N. Catal. Lett.
4
273.
(b) Wang, X. S.; Shi, D. Q.; Tu, S. J.; Yao, C. S. Synth.
2
(
008, 125, 57.
b) Gadekar, L. S.; Mane, S. R.; Katkar, S. S.; Arbad, B. R.;
Lande, M. K. Cent. Eur. J. Chem. 2009, 7, 550.
c) Gadekar, L. S.; Katkar, S. S.; Mane, S. R.; Arbad, B. R.;
Commun. 2003, 33, 119.
9
0
1
2
Shi, D. Q.; Zhang, S.; Zhuang, Q. Y.; Tu, S. J.; Hu, H. W.
Chin. J. Org. Chem. 2003, 23, 877 (in Chinese).
Shi, D. Q.; Mou, J.; Zhuang, Q. Y.; Wang, X. S. J. Chem.
Res., Synop. 2004, 821.
Jin, T. S.; Xiao, J. C.; Wang, S. J.; Li, T. S.; Song, X. R.
Synlett 2003, 2001.
(
1
1
1
Lande, M. K. Bull. Korean Chem. Soc. 2009, 30, 2534.
Katkar, S. S.; Mohite, P. H.; Gadekar, L. S.; Vidhate, K. N.;
Lande, M. K. Chin. Chem. Lett. 2010, 21, 421.
2
8
9
2
Katkar, S. S.; Mohite, P. H.; Gadekar, L. S.; Arbad, B. R.;
Lande, M. K. Cent. Eur. J. Chem. 2010, 8, 320.
Balalaie, S.; Bararjanian, M.; Amani, A. M.; Movassagh, B.
(E1004096 Cheng, B.; Zheng, G.)
2
02
www.cjc.wiley-vch.de
© 2011 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2011, 29, 199— 202