Polyvinylpolypyrrolidone-bound boron trifluoride (PVPP-BF3); A mild and efficient catalyst for synthesis of 4-metyl coumarins via the Pechmann reaction

Article abstract of DOI:10.1016/j.crci.2012.03.004

Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for synthesis of 4-methyl coumarin by the Pechmann reaction. The reaction proceeded smoothly with hydroxyl phenols and ethyl acetoacetate in good yields in ethanol at reflux conditions. The polyvinylpolypyrrolidone-boron trifluoride complex is a non-corrosive and stable solid catalyst elevated Lewis acid property.

Full text of DOI:10.1016/j.crci.2012.03.004

C. R. Chimie 15 (2012) 530–532
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Polyvinylpolypyrrolidone-bound boron trifluoride (PVPP-BF3); a mild
and efficient catalyst for synthesis of 4-metyl coumarins via the
Pechmann reaction
b
Masoud Mokhtary a, , Faranak Najafizadeh
*
a Department of Chemistry, Rasht Branch, Islamic Azad University, Rasht, Iran
b Department of Chemistry, Amol Branch, Islamic Azad University, Amol, Iran
A R T I C L E I N F O
A B S T R A C T
Article history:
Polyvinylpolypyrrolidone-supported boron trifluoride has been studied for synthesis of 4-
methyl coumarin by the Pechmann reaction. The reaction proceeded smoothly with
hydroxyl phenols and ethyl acetoacetate in good yields in ethanol at reflux conditions. The
polyvinylpolypyrrolidone-boron trifluoride complex is a non-corrosive and stable solid
catalyst elevated Lewis acid property.
Received 9 November 2011
Accepted after revision 12 March 2012
Available online 23 April 2012
Keywords:
ß 2012 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Polyvinylpolypyrrolidone
Boron trifluoride
Ethyl acetoacetate
4-Methyl coumarin
Pechmann reaction
1. Introduction
acids at the three positions [17,18]. Later, researchers
condensed etylcyanoacetate and various o-hydroxyaceto-
Coumarins are used in the fields of biology, medicine,
and polymer science. They are also present or used in
perfumes and cosmetics [1–3], alcoholic beverages [4], and
laser dyes [5–9]. In addition to these uses, coumarins are
well documented as therapeutic agents and have been
used as medicines in ancient Egypt and in aboriginal
cultures [10,11]. One example, warfarin, is the most
prescribed anti-coagulant on the market [12,13]. Recently,
coumarin derivatives were utilized to synthesize of
photoreversible polymer systems [14–16].
Coumarin derivatives were first synthesized via the
Perkin reaction in 1868, and many simple coumarins are
still derived from this method. In the early 1900s, the
Knoevenagel reaction emerged as an important synthetic
method to synthesize coumarin derivates with carboxylic
phenones to synthesize 4-methylcoumarine derivatives
[19,20]. In the conventional production of coumarins by
the Pechmann reaction, concentrated sulfuric acid is used
as the catalyst [21]. However, as an alternative to sulfuric
acid, other acid catalysts such as Montmorillonite clay [22],
[bmim]Cl.2AlCl3 [23], InCl3 [24], P2O5/molecular sieve 3A8
[25], sulfamic acid [26], BiCl3 [27], VCl3 [28], zeolite [29],
ZrOCl2.8H2O [30], HClO4.SiO2 [31], sulfated zirconia [32],
Keggin heteropoly acids [33], SnCl2.2H2O [34] and sulfonic
acid nanoreactors [35] are employed to improve the
Pechmann reaction.
However, some of these methods suffer from at least one
of the following disadvantages: moisture sensitivity of the
majority of Lewis acids to the water produced in the
Pechmann condensation renders them unsuitable for use in
large scale application, strongly acidic wastes, high cost and
toxicity of the reagent, tedious work-up procedures,
unsatisfactory yields, and nonrecyclable reagents. There-
fore, it seems that the major task of current research is to
replace both homogeneous and less efficient and traditional
* Corresponding author.
E-mail addresses: mmokhtary@iaurasht.ac.ir,
masoud.mokhtary@gmail.com (M. Mokhtary).
1631-0748/$ – see front matter ß 2012 Acade´mie des sciences. Published by Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.crci.2012.03.004

M. Mokhtary, F. Najafizadeh / C. R. Chimie 15 (2012) 530–532
531
heterogeneous acid catalysis procedures by more accept-
able methods based on improved stable and recoverable
catalysts. Substantial investigations have been made to
introduce novel supported catalysts and chemical reagents.
These include dispersing catalysts on inorganic supports
such as metal oxide, alumina, silica, and zeolite. There are a
numberofadvantagesinusing polymer-supportedcatalysts
over the conventional catalysis. The reactions can be
performed under mild condition and purification of the
product is simplified because of the use of an insoluble solid
support. Polymer-supported catalysts can also be recycled
after use [36]. Poly (vinyl pyrrolidone) displays a strong
binding affinity toward small molecules. Furthermore, its
iodine complex, povidon-iodine, is widely used as an anti-
infective agent in clinical treatments[37]. Recoveryof boron
triflouride from the reaction, however, results in the
formation of large amounts of waste, which on an industrial
Fig. 1. The FT-IR spectrum of polyvinylpolypyrrolidone (PVPP) and
scale is environmentally unacceptable. The use of
a
(PVPP-BF3) complex.
heterogeneous BF3 system would offer ease of catalyst
recovery and minimize the production of waste currently
formed during BF3 recovery. However, a suitable replace-
ment supported system must also exhibit activities and
selectivities comparable to the existing homogenous route.
In spite of boron trifluoride etharate, polyvinylpolypyrro-
lidone-boron trifluoride (PVPP-BF3) is non-corrosive and
stable solid catalyst elevated Lewis acid property. Following
our interest in the use of PVPP-BF3 for amidation of
benzhydrol with nitriles via Ritter reaction [38], herein,
we found that PVPP-BF3 could be used for the preparation of
4-methyl coumarins by the Pechmann reaction in good to
excellent yields.
P-UV-Com instrument. Products were separated by simple
filtration, and identified by comparison IR, and 1H NMR
spectra, with those reported for authentic samples.
2.1. Catalyst preparation
In this method, boron trifluoride etherate was immo-
bilized on PVPP to give a stable polymeric Lewis acid
reagent according to our previous article [38]. To a
suspension of 3 g PVPP in 25 ml CH2Cl2, a solution of
5 ml BF3.Et2O in 15 ml CH2Cl2 was added dropwise and the
mixture stirred for 1 h at room temperature. The resulting
resin was filtered and washed with 2 Â 10 ml CH2Cl2 and
dried in a vacuum desiccator to give a stable and non-
hygroscopic powder.
2. Experimental
Polyvinylpolypyrrolidone (PVPP) was purchased from
Fluka chemical company. Other chemicals were purchased
from Merck chemical company. Melting points were
recorded on an electro thermal melting point apparatus.
The NMR spectra were recorded in CDCl3 with TMS as an
internal standard on a Bruker Avance DRX 400 MHz
spectrometer. IR spectra were determined on a SP-1100,
2.2. Synthesis of 4-meyl coumarins: general procedure
A solution of 3 mmol phenol and 3.1 mmol ethyl
acetoacetate in 5 ml ethanol was prepared. 1 mmol
(0.1 g) PVPP-BF3 was added to the solution and the
Table 1
Synthesis of coumarins via Pechmann condensations of phenols with ethyl acetoacetate by PVPP-BF3.a
O
O
OH
O
O
PVPP-BF3
R
R
+
reflux
EtOH
/
OEt
Entry
R
Time (h)
Yield (%)b
1
2
3-OH
2
91
89
96
95
90
88
85
78
82
76
4-OH
2
3
3,5-(OH)2
3-Me-5-OH
2-Me-3-OH
2,3-(OH)2
3,5-(Me)2
3-MeO
2
4
2
5
2
6
2.5
2.5
3
7
8
9
2-COOH-4-OH
1-naphtol
2
10
3
a
All entries were carried on phenols (3 mmol), ethyl acetoacetate (3.1 mmol) and PVPP-BF3 (1 mmol) in ethanol (5 ml) under reflux conditions.
All yields refer to isolated products.
b

532
M. Mokhtary, F. Najafizadeh / C. R. Chimie 15 (2012) 530–532
References
reaction mixture was stirred for 2–3 h under reflux
conditions until TLC analysis showed that no phenol
remained. The reaction mixture was filtered, and the
solvent was evaporated on a rotatory evaporator under
diminished pressure. The solid residue was recrystalized
from water/ethanol to afford pure crystals of the proper
coumarins in 72–96% yields. The products were charac-
terized by FT-IR, 1HNMR and physical constants.
[1] J.J. Yourick, R.L. Bronaugh, J. Appl. Toxicol. 17 (1997) 153.
[2] G.J. Keating, R. Okennedy, R.D. Thornes (Eds.), Coumarins: biology,
applications and mod of action, John Wiley & Sons, New York, 1997.
[3] H. Yamazaki, M. Tanaka, T. Shimada, J. Chromatogr. B 721 (1999) 13.
[4] M.E.F. Izquierdo, J.Q. Granados, V.M. Mir, M.C.L. Martinez, Food. Chem.
70 (2000) 251.
[5] R.F. Zhang, H.P. Zhang, J.C. Shen, Synth. Metal. 106 (1999) 157.
[6] J.C. de Melo, P.F. Fernandes, J. Mol. Struct. 565 (2001) 69.
[7] B. Cohen, D. Huppert, J. Phys. Chem. A 105 (2001) 7157.
[8] T. Eckardt, V. Hagen, B. Schada, R. Schmidt, C. Schweitzer, J. Bending, J.
Org. Chem. 67 (2002) 703.
3. Results and discussion
[9] R. Jakubiak, T.J. Bunning, R.A. Vaia, L.V. Natarajan, V.P. Tondiglia, Adv.
Mater. 15 (2003) 241.
[10] A.J. Killard, R. Okennedy, D.P. Bogan, J. Pharm. Biomed. Anal. 14 (1996)
1585.
[11] S.J. Semple, S.F. Nobbs, S.M. Pyke, G.D. Reynolds, R.L.P. Flower, J.
Ethnopharmacol. 68 (1999) 283.
[12] G. Hirsh, V. Fuster, J. Ansell, J.L. Halperin, J. Am. Coll. Cardiol. 41 (2003)
1633.
[13] M. Pisklak, D. Maciejewska, F. Herold, I. Wawer, J. Mol. Struct. 649
(2003) 169–176.
[14] S.R. Trenor, A.R. Shultz, B.J. Love, T.E. Long, Chem. Rev. 104 (2004) 3059.
[15] C.M. Liu, J.J. Qiu, R. Bao, C. Zhao, X.J. Cheng, Y. Xnu, Y. Zhou, React. Func.
Polym. 66 (2006) 455.
Characterizing of the Lewis acid sites presented on the
polymer was performed by recording the FT-IR spectrum
of PVPP-BF3, which shows a strong broad absorption at
1000–1060 cmÀ1 for the B-F bonds and a moderate
absorption at 1646 cmÀ1 corresponds to the imine group
on the backbone (Fig. 1). Loading capacity of the reagent
was determined by titration and found to be 10 mmol/g,
whereas its silica-supported analogue has
capacity of less than 4 mmol/g [39,40].
a loading
[16] C.J. Tsai, Y. Chen, React. Func. Polym. 66 (2006) 1327.
[17] E. Knoevenagel, Ber. Dtsch. Chem. Ges. Berlin 37 (1904) 4461.
[18] A.M. Song, X.B. Wang, K.S. Lam, Tetrahedron Lett. 44 (2003) 1755.
[19] C.H. Schroeder, K.P. Link, J. Am. Chem. Soc. 75 (1953) 1886.
[20] C. Wiener, C.H. Schroeder, K.P. Link, J. Am. Chem. Soc. 79 (1957) 5301.
[21] E.C. Horning, Org. Synth. 3 (1955) 281.
[22] S. Frere, V. Thiery, T. Besson, Tetrahedron Lett. 42 (2001) 2791.
[23] K.M. Potdar, S.S. Mohile, M.M. Salunkhe, Tetrahedron Lett. 42 (2001)
9285.
[24] D.S. Bose, A.P. Rudradas, M.H. Babu, Tetrahedron Lett. 43 (2002) 9195.
[25] A. Shockravi, H. Valizadeh, M.M. Heravi, Phosphorus Sulfur Silicon 177
(2002) 2835.
[26] P.R. Singh, D.U. Singh, S.D. Samant, Synlett. (2004) 1909.
[27] S.K. De, R.A. Gibbs, Synthesis (2005) 1231.
[28] B.S. Kumar, P.S. Kumar, N. Srinivasulu, B. Rajitha, Y.T. Reddy, P.N. Reddy,
R.H. Udupi, Chem. Heterocycl. Comp. 42 (2006) 172.
[29] A. Hegedus, Z. Hell, Catal. Lett. 112 (2006) 105.
[30] J.C. Rodrı´guez-Domı´nguez, G. Kirsch, Synthesis (2006) 1895.
[31] M. Maheswara, V. Siddaiah, G.L.V. Damu, Y.K. Rao, C.V. Rao, J. Mol. Catal.
A Chem. 255 (2006) 49.
[32] J.C. Rodrı´guez-Domı´nguez, G. Kirsch, Tetrahedron Lett. 47 (2006) 3279.
[33] R. Torviso, D. Mansilla, A. Belizan, E. Alesso, G. Moltrasio, P. Vazquez, L.
Pizzio, M. Blanco, C. Caceres, Appl. Catal. A Gen. 339 (2008) 53.
[34] K.K. Upadhyay, R.K. Mishra, A. Kumar, Catal. Lett. 121 (2008) 118.
[35] B. Karimi, D. Zareyee, Org. Lett. 10 (2008) 3989.
[36] S.V. Ley, I.R. Baxendale, R.N. Bream, P.S. Jackson, A.G. Leach, D.A.
Longbottom, M. Nesi, J.S. Scott, R.I. Storer, S.J. Taylor, J. Chem. Soc.
Perkin Trans. 1 (2000) 3815.
A variety of coumarins was prepared from phenols and
ethyl acetoacetate in the presence of PVPP-BF3 in good to
excellent yields (Table 1, entries 1–10). It is worth
mentioning that the corresponding coumarin was isolated
by simple filtration of the catalyst followed by crystalliza-
tion from the crude filtrate. In some cases, the products
were further purified by column chromatography. Inter-
estingly, this reagent gives not only good yields of the
products but also regenerates easily. Furthermore, the
PVPP-BF3 can be reused and retained its activity after
several months of storage.
4. Conclusion
We have developed a simple and efficient method for
the Pechmann reaction using PVPP-BF3 complex as a high
loading of Lewis acid, which is stable, easy to prepare and
handle, and represents effective activity for the Pechmann
reaction. This method provides an easy access to a variety
of 4-methyl coumarins.
[37] C. Liu, S. Cui, Z. Wang, X. Zhang, J. Phys. Chem. B 109 (2005) 14807.
[38] M.M. Lakouraj, M. Mokhtary, Monatsh. Chemie 140 (2009) 53.
[39] K. Wilson, J.H. Clark, Chem. Commun. (1998) 2135.
[40] K. Wilson, D.J. Adams, G. Rothenberg, J.H. Clark, J. Mol. Catal. A Chem.
156 (2000) 309.
Acknowledgements
We are grateful to Islamic Azad University of Rasht
Branch for financial assistance in this work.