G Model
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J. Albadi et al. / C. R. Chimie xxx (2013) xxx–xxx
Table 2
2. Experimental
Recyclability of P4VPy-CuI.
Chemicals were purchased from Fluka, Merck and
Aldrich Chemical companies. Products were characterized
by comparison of their spectroscopic data (NMR, IR) and
physical properties with those reported in the literature.
All yields refer to isolated products. P4VPy-CuI was
prepared according to our previous articles [37,38].
Run
1
2
3
4
5
6
7
8
Time (min)
Yield (%)a
15
92
15
92
15
89
17
89
20
88
20
88
20
85
25
82
a
Isolated yields.
2.1. General procedure
event after prolonged heating (Table 1, entry 16). The
experimental procedure with this catalyst is very simple
and the catalyst can be recovered easily by filtration. Very
low amount of the catalyst (0.1 gr) and ethyl acetoacetate
or methyl acetoacetate (1 mmol) is needed. This catalyst is
cheap, easy to handle and its preparation is simple and
straightforward. Moreover, our procedure is environmen-
tally friendly as it does not use any toxic auxiliary or
solvent. The activity of the recovered catalyst was also
examined under the optimized conditions and the desired
product was obtained in high yields after one to eight runs
(Table 2). To investigate these properties for our intro-
duced catalyst, the reaction of 3-methoxy phenol and ethyl
acetoacetate was selected as the model (Table 2). After
reaction completion, P4VPy-CuI was washed with ethyla-
cetate, dried and stored for another consecutive reaction
run. This process was repeated for eight runs and no
appreciable yield decrease was observed. Next we checked
the leaching of CuI into the reaction mixture from the
poly(4-vinylpyridine) support using ICP-AES. The differ-
ence between the copper content of the fresh and reused
catalyst (8th run) is only 3% which indicates the low
leaching amount of copper iodide catalyst into the reaction
mixture.
A mixture of the phenol (1 mmol), ethyl acetoacetate or
methyl acetoacetate (1 mmol) and poly(4-vinylpyridine)-
CuI (0.1 g) was heated in an oil bath (80 8C) for the
appropriate times according to Table 1. The progress of the
reaction was monitored by TLC. After completion, the
mixture reaction was allowed to cool, ethyl acetate (5 mL)
was added and the catalyst was recovered to use
subsequently by filtration. Evaporation of the solvent
from the filtrate and recrystallization of the solid residue
from hot ethanol (0.83–0.91 mmol) afforded the pure
products in high yields.
3. Results and discussion
The copper(I) iodide immobilized on poly(4-vinylpyr-
idine) was readily prepared in a one-step procedure.
Poly(4-vinylpyridine) was refluxed with a solution of CuI
under N2 atmosphere in EtOH for the synthesis of polymer-
supported CuI particles. This method was developed for
the effective synthesis of copper particles incorporated
heterogeneously as catalyst in some organic reactions [39].
At first, for the optimization of the reaction conditions, a
mixture of 3-methoxy phenol and ethyl acetoacetate was
investigated as a model and its behavior was studied under
a variety of conditions. The best result was achieved by
caring out the reaction of 3-methoxy phenol and ethyl
acetoacetate (with 1: 1 mol ratio) in the presence of 0.1 g of
P4VPy-CuI at 80 8C under solvent-free conditions (Table 1,
entry 1). Using these optimized conditions, the reaction of
4. Conclusion
In conclusion, we have developed a green and efficient
procedure for the synthesis of coumarin derivatives by the
Pechmann reaction catalyzed by P4VPy-CuI under solvent-
free conditions. This catalytic system is stable and can
promote the yields and reaction times over eight runs
without any loss of activity. Moreover, heterogeneous
reaction conditions, high yields of products, short reaction
times, ease of work-up and clean procedure will make this
procedure a useful addition to the available methods. We
are exploring further applications of P4VPy-CuI for the
other types of organic reactions in our laboratory.
other phenolic substrates with
explored (Scheme 1).
b-ketonic esters was
As shown in Table 1, all substrates were efficiently
converted to their corresponding coumarins in good to
high yields during short reaction times. All the products
were cleanly isolated with simple filtration and evapora-
tion of solvent. The solid products were easily recrystal-
lized in hot ethanol. Among the various phenols studied,
compounds containing electron donating were found to be
most reactive and converted to their corresponding
coumarins under the same reaction conditions. When
the reaction was performed on phenols with electron-
withdrawing groups, starting materials remain intact
Acknowledgement
We are thankful to the Behbahan Khatam Al-Anbia
University of Technology, for the partial support of this
work.
Appendix A. Supplementary data
O
O
P4VPy-CuI
+
OH
OR2
R2= Me, Et
°
Solvent-free, 80 C
R1
O
O
R1
Supplementary data associated with this article can be
Scheme 1. Synthesis of coumarin derivatives catalyzed by P4VPy-CuI.
Please cite this article in press as: Albadi J, et al. A green, efficient and recyclable poly(4-vinylpyridine)-supported
copper iodide catalyst for the synthesis of coumarin derivatives under solvent-free conditions. C. R. Chimie (2013),
Albadi, Jalal
