Short communication
Efficient Synthesis of Benzopyrans and Dihydropyranochromenes Catalyzed by Poly(4-vinylpyridine) as a Green and Commercially
Available Basic Catalyst
Jalal Albadi,1'* Azam Mansournezhad2 and Fatemeh Akbari Balout-Bangan3
1 College of Science, Behbahan Khatam Alanbia University of Technologhy, Behbahan, Iran
2 Department of Chemistry, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran
3 Department of Chemistry, Qom Branch, Islamic Azad University, Qom, Iran
* Corresponding author: E-mail: Jalal.albadi@gmail.com; Chemalbadi@gmail.com
Tel/Fax: +986712229969
Received: 15-05-2013
Abstract
Poly(4-vinylpyridine) is used as a green, commercially available and recyclable basic catalyst for the multicompo-nent synthesis of benzopyrans and dihydropyranochromenes by one-pot condensation of aromatic aldehydes, 3-methyl-1-phenyl-2-pyrazolin-5-one, and malononitrile or 4-hydroxycoumarin in ethanol at reflux temperature. This procedure provides several advantages such as mild reaction conditions, short reaction times, simple work-up and high yields.
Keywords: Poly(4-vinylpyridine), benzopyran, dihydropyranochromene, malononitrile, aldehyde, 3-methyl-1-phenyl-2-pyrazolin-5-one, 4-hydroxycoumarin.
1. Introduction
Benzopyrans and dihydropyranochromenes are considered as interesting heterocyclic compounds that have already received significant attentions because of their biological and pharmaceutical properties such as antisteri-lity and anticancer activity.1-2 The pyran pharmacophore is an important core structure of many natural products showing antibacterial, antitumor, antiallergic, antibiotic, hypolipidemic and immunomodulating activities.3 Due to the great importance of dihydropyranochromenes and benzopyrans in recent years, various synthetic procedures have been developed for the preparation of these com-pounds.4-27 However, some of these procedures suffer from one or more of the following disadvantages such as use of toxic solvents, tedious work-up procedure, long reaction times, low yields, use of corrosive reagents, effluent pollution, and non-recyclable catalysts. Therefore, there is a need to develop an alternative method for the
synthesis of these compounds. In the condensation reaction, pyridine was used as a basic catalyst. It was especially suitable for the dehalogenation, where it acted as the base for the and bonds the resulting hydrogen halide to form a pyridinium salt. Nevertheless, pyridine is a highly flammable and toxic compound, and can be absorbed through the skin mucous membranes. Recenty, poly(4-vinylpyridine) (PVPy) has been used as a support for the numerous reagents and catalysts in many organic reaction transformations. It has been reported that PVPy as a basic catalyst can catalyze the synthesis of chromene derivati-ves.28 Also, in the previous research, the application of PVPy for the protection of different types of functional groups has been reported.29As part of our research program to develop efficient and green methods, and catalysts in organic synthesis,30-32 we wish to report the applicability of (PVPy) as a green, commercially available and recyclable basic catalyst for the synthesis of benzop-yrans and dihydropyranochromenes in ethanol at reflux temeprature (Scheme 1).
Scheme 1. Synthesis of benzopyrans and dihydropyranochromenes catalyzed by PVPy.
2. Results and Discussion
PVPy is cheap and commercially available reagent, and its structure convinced us that this reagent could be used as an efficient, green and basic catalyst in the synthesis of dihydropyranochromenes and benzop-yrans. At first the catalytic role of PVPy in the reaction of dihydropyranochromenes via three-component condensation of aldehydes, malononitrile and 4-hydroxy-coumarin was examined. The best result was achieved by running the reaction of benzaldehyde, malononitrile and 4-hydroxycoumarin (with 1: 1: 1 mol ratio) in the presence of 0.1 g of PVPy in ethanol at reflux temperature (Table 1, entry 1).
Using the optimized conditions, the reaction of various aromatic aldehydes was explored without additional purification (Table 1). Similarly, benzopyrans were obtained by the condensation of aromatic aldehydes, malono-nitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one in ethanol at reflux temperature (Table 2). According to the results of Table 1 and 2, different aromatic aldehydes with either electron-donating or electron-withdrawing groups,
efficiently reacted to afford the desired products in good to high yields. It was also observed that aliphatic aldehydes remain intact under the same reaction conditions. All products were isolated with simple filtration and evaporation of the solvent. Solid products were easily recrystalli-zed from hot ethanol in good to high yields during the short reaction times. All products have been identified by comparison of their melting points and analytical data (IR, NMR) with those reported for authentic samples. A distinct advantage of this method is the formation of corresponding products without by-products. The experimental procedure using PVPy as a catalyst is very simple and the catalyst can be recovered easily by filtration. Moreover, the applied procedure is environmentally friendly as it did not use any toxic auxiliary or solvent.
In order to exhibit the recyclability of the PVPy in the synthesis of dihydropyranochromenes, the reaction of benzaldehyde, 4-hydroxycoumarin and malononitrile was selected as a model. After completion of the reaction, the PVPy was washed with ethylacetate, dried and stored for another consecutive reaction run. This process was repeated for five runs and no significant decreasing in yield was
Table 1. Synthesis of dihydropyranochromene derivatives catalyzed by PVPy.
Entry	Substrate	Time (min)	Yield (%)a	Mp (°C) Found Reported	
1	c6h5cho	20	90	260-262	263-2657
2	2-ClC6H4CHO	18	90	242-244	2407
3	4-ClC6H4CHO	15	89	259-261	252-2558
4	2,4-Cl2C6H3CHO	12	90	257-259	250-2547
5	3-NO2C6H4CHO	12	90	251-252	248-2505
6	4-NO2C6H4CHO	10	92	257-259	250-2528
7	4-MeC6H4CHO	20	89	255-257	259-2608
8	4-MeOC6H4CHO	32	87	228-229	226-2308
9	3,4,5-(MeO)3C6H2CHO	60	86	274-276	276-2787
10	4-HOC6H4CHO	60	85	265-267	260-2638
11	4-BrC6H4CHO	20	89	250-252	244-2467
12	4-FC6H4CHO	20	90	262-263	258-2618
a Yields of pure isolated products.
Table 2. Synthesis of benzopyrans catalyzed by PVPy.
Entry	Substrate	Time (min)	Yield (%)a	Mp (°C) Found Reported	
1	CóH5CHO	9	9ó	16S-17G	169-17123
2	4-O2NCóH4CHO	?	92	193-195	196-19S23
3	3-O2NCóH4CHO	1G	94	19G-192	19G-19123
4	2,4-Cl2CóH4CHO	1G	93	1S3-1S5	1S5-1S723
5	4-ClCóH4CHO	1G	93	1?ó-1?S	175-17723
ó	2-ClCóóH44CHO	15	92	145-14?	144-14623
?	3-ClCóóH44CHO	12	92	157-159	15S-15923
S	4-MeOCóH4CHO	35	S?	172-174	174-17623
9	4-MeCóH4CHO	2G	93	177-179	176-17S24
1G	4-FCóH4CHO	1S	92	16S-169	167-16S24
11	4-HOCóH4CHO	25	S9	2GS-21G	211-21224
12	4-CNCóóH44CHO	S	Só	217-219	21ó-21S1S
a Yields of pure isolated products.
Table 3. The recyclability of PVPy in the synthesis of dihydropyra-nochromenes.a
Run	1	2	3	4	5
Time (min)	2G	2G	25	25	3G
Yield (%)b	9G	9G	9G	S9	S9
a Reaction conditions: benzaldehyde (1 mmol), 4-hydroxycoumarin (1 mmol), malononitrile (1 mmol), and catalyst (0.1 g) in ethanol at reflux temperature. b Yields of pure isolated products.
Table 4. The recyclability of PVPy in the synthesis of benzop-yrans.a
Run	1	2	3	4	5	6
Tim (min)	9	9	1G	12	12	15
Yield (%)b	9ó	95	95	92	92	9G
a Reaction conditions: benzaldehyde (1 mmol), 3-methyl-1-phenyl-2-pyrazolin-5-one (1 mmol), malononitrile (1 mmol), and catalyst (0.1 g) in ethanol at reflux temperature. b Yields of pure isolated products.
Table 5. Comparison of the efficiency of various catalysts in the synthesis of dihydropyranochromenes from benzaldehyde.
Entry	Catalyst	Conditions	Time (min)	Yield (%)a	Reference
1	Nano ZnO	H2O/7G °C	1SG	S7	4
2	Trisodium citrate	H2O-2EtOH/reflux	4G	ó5	5
3	Morpholine	2 H2O/reflux	1SG	9G	S
4	magnetic nano-organocatalyst	H22O/reflux	1G	7S	9
5	PVPy	EtOH/reflux	2G	9G	This work
a Yields of pure isolated products.
observed. Almost consistent activity was observed over five runs and the desired products were obtained in high yields (Table 3).
The activity of the recovered catalyst was also examined in the synthesis of benzopyrans using benzaldehyde, 3-methyl-1-phenyl-2-pyrazolin-5-one and malononitrile under the optimized conditions. As shown in the Table 4, PVPy can be recycled up to 6 consecutive runs without any lost of its efficiency and the desired product was obtained in high yields.
In order to show the efficiency of method, Table 5 compares the results of the synthesis of dihydropyranoc-hromenes with various catalysts. In comparison with previously reported methods, low amounts of PVPy effi-
ciently promoted the reaction and gave the desired product in very short times and high yields. Moreover, the PVPy is cheap, easy to handle and commercially available. It can be simply recovered by filtration and reused in the next runs without significant decrease of catalytic activity. Finally, our method does not use any toxic auxiliary or solvent.
3. Experimental
All products were characterized by comparison of their spectroscopic data (NMR, IR) and physical properties with those reported in the literature. Chemicals were
purchased from Fluka and Merck chemical companies and used as received. IR spectra were recorded on a Per-kin Elmer 781 spectrophotometer. All NMR spectra were recorded on a Bruker Avance 500 MHz spectrometer using tetramethylsilane (TMS) as an internal standard. Melting points were recorded on Bransted Electrothermal 9100BZ melting point apparatus.
3. 1. General Procedure for Synthesis of Dihydropyranochromenes and Benzopyrans
A mixture of aldehyde (1 mmol), malononitrile (1 mmol), 4-hydroxycoumarin or 3-methyl-1-phenyl-2-pyra-zolin-5-one (1 mmol), and PVPy (0.1 g) in ethanol (10 mL) was stirred at reflux temperature. After completion of the reaction (moitored by TLC; n-hexane/ethyl acetate, 3:1), the catalyst was recovered by filtration to be reused subsequently, and the reaction mixture allowed to cool at room temperature. Evaporation of the solvent from the filtrate and recrystallization of the solid residue from hot et-hanol afforded pure products in high yields. The structure of the products was identified by meltig points, IR, 1H and 13C NMR spectroscopy (see Supplementary Material), and compared with authentic samples prepared by reported methods.
The analytical and spectroscopic data for the known compounds are as follows:
Table 1, entry 1: IR (KBr): v 3395, 3320, 3190, 2930, 2200, 1650, 1405, 1305, 1100 cm-1. 1H NMR (500 MHz, DMSO-d6): 84.46 (s, 1H), 7.23-7.28 (m, 3H), 7.33 (t, 2H, J = 7.6 Hz), 7.41 (s, 2H), 7.45-7.52 (m, 2H), 7.72 (t, 1H, J = 7.6 Hz), 7.90 (d, 1H, J = 8 Hz) ppm. 13C NMR (125 MHz, DMSO-d6,): 837.5, 58.5, 104.5, 113.5, 117.1, 119.7, 123.0, 125.1, 127.6, 128.1, 129.0, 133.4, 143.8, 152.6, 153.9, 158.5, 160.0 ppm.
Table 1, entry 2: IR (KBr): v 3415, 3300, 3195, 2910, 2205, 1655, 1405, 1315, 1105 cm-1. 1H NMR (500 MHz, DMSO-d6): 84.74 (s, 1H, CH), 7.48 (t, 1H, J = 8.4 Hz), 7.52 (d, 1H, J = 7.6 Hz), 7.56 (s, 2H), 764 (t, 1H, J = 8 Hz), 7.72-7.76 (m, 1H), 7.81 (d, 1H, J = 7.6 Hz), 8.12 (s, 1H), 8.14 (s, 1H) ppm. 13C NMR (125 MHz, DMSO-d6): 837.1, 57.4, 103.4, 113.4, 117.1, 119.4, 122.8, 122.9, 123.1, 125.2, 130.6, 133.6, 135.3, 146.0, 148.3, 152.8, 154.4, 158.6, 160.1 ppm.
Table 1, entry 3: IR (KBr): v 3420, 3320, 3195, 2920, 2110, 1675, 1470, 1345, 1150 cm-1. 1H NMR (500 MHz, DMSO-d6) 84.49 (s, 1H,), 7.31 (d, 2H, J = 8.4 Hz), 7.36 (d, 2H, J = 8.4 Hz), 7.44-7.50 (m, 4H), 7.70 (t, 1H, J = 7.6 Hz), 7.89 (d, 1H, J = 7.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): 8 36.9, 58.0, 104.0, 113.4, 117.0,
119.6,	123.0, 125.1, 128.9, 130.1, 132.2, 133.5, 142.8,
152.7,	154.0, 158.5, 160.0 ppm.
Table 1, entry 4: IR (KBr): v 3320, 3315, 3190, 2930, 2100, 1680, 1465, 1345, 1150 cm-1. 1H NMR (500 MHz, DMSO-d6): 8 4.99 (s, 1H), 7.35-7.41 (m, 2H),
7.48-7.54 (m, 4H), 7.59 (m, 1H), 7.72-7.76 (m, 1H), 7.90 (m, 2H, J = 8 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): 8 34.4, 56.5, 103.0, 113.3, 117.2, 119.2, 123.0, 125.2, 128.4, 129.3, 132.6, 132.9, 133.6, 133.8, 139.9, 152.7,
154.6,	158.6, 159.9 ppm.
Table 1, entry 5: IR (KBr): v 3315, 3310, 3195, 2920, 2200, 1655, 1475, 1325, 1100 cm-1. 1H NMR (500 MHz, DMSO-d6): 8 4.98 (s, 1H), 7.25-7.29 (m, 2H), 7.31-7.34 (m, 1H), 7.41-7.52 (m, 5H), 7.70-7.74 (m, 1H), 7.91-7.93 (m, 1H) ppm. 13C NMR (125 MHz, DM-SO-d6): 8 34.8, 57.0, 103.4, 113.3, 117.1, 119.3, 123.0, 125.2, 128.2, 129.3, 130.1, 131.1, 132.9, 133.5, 140.7,
152.7,	154.5, 158.6, 159.9 ppm.
Table 1, entry 6: IR (KBr): v 3410, 3310, 3195, 2930, 2210, 1655, 1475, 1335, 1050 cm-1. 1H NMR (500 MHz, DMSO-d6): 8 4.69 (s, 1H), 7.47-7.62 (m, 6H), 7.74 (t, 1H, J = 8 Hz), 7.92 (d, 1H, J = 8 Hz), 8.18 (d, 2H, J = 8.8 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): 8
37.3,	57.3, 103.3, 113.4, 117.1, 119.4, 123.1, 124.2,
125.2,	129.7, 133.7, 147.1, 151.2, 152.8, 154.4, 158.5, 160.1 ppm.
Table 1, entry 7: IR (KBr): v 3415, 3315, 3205, 2910, 2215, 1650, 1405, 1305, 1015 cm-1.1H NMR (500 MHz, DMSO-d6): 81.33 (3H), 4.50 (s, 1H), 7.16 (d, 2H, J = 8.4 Hz), 7.38 (d, 2H, J = 8.8 Hz), 7.43 (s, 2H), 7.46-7.52 (m, 2H), 7.68-7.74 (m, 1H), 7.92 (d, 1H, 2H, J = 7.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): 8 32.1, 35.6, 58.6, 103.7, 110.2, 112.3, 115.1, 117.7, 120.8,
124.0,	126.1, 131.3, 133.7, 150.4, 150.5, 155.3, 155.7, 160.1 ppm.
Table 1, entry 8: IR (KBr): v 3415, 3310, 3200, 2920, 2210, 1650, 1405, 1305, 1010 cm-1.1H NMR (500 MHz, DMSO-d6): 8 3.73 (s, 3H), 4.73 (s, 1H), 6.87 (d, 2H, J = 7.8 Hz), 7.18 (d, 2H, J = 7.8 Hz), 7.37 (s, 2H), 7.48 (m 2H), 7.71 (m, 1H), 7.91 (m, 1H) ppm. 13C NMR (125 MHz, DMSO-d6): 8 36.7, 55.5, 58.7, 104.8, 113.5,
114.3,	117.0, 119.8, 122.9, 125.1, 129.2, 133.3, 135.9, 152.6, 153.6, 158.4, 158.8, 160.0 ppm.
Table 1, entry 9: IR (KBr): v 3410, 3320, 3205, 2980, 1996, 1670, 1415, 1305, 1010 cm-1. 1H NMR (500 MHz, DMSO-d6): 8 3.64 (s, 3H, OCH3), 3.73 (s, 6H), 4.45 (s, 1H), 6.564 (s, 2H), 7.38 (s, 2H), 747-7.52 (m, 2H), 7.70-7.74 (m, 1H), 7.90 (d, 1H, J = 7.2 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): 8 37.7, 56.4,
58.4,	60.4, 104.2, 105.5, 113.6, 117.1, 119.7, 123.0,
125.1,	133.4, 137.1, 139.5, 152.7, 153.3, 154.0, 158.5, 160.1 ppm.
Table 1, entry 10: IR (KBr): v 3410, 3320, 3205, 2980, 1996, 1670, 1415, 1305, 1010 cm-1.1H NMR (500 MHz, DMSO-d6): 8 4.34 (s, 1H), 6.69 (d, 2H, J = 8.4 Hz), 7.04 (d, 2H, J = 8.4 Hz), 7.34 (s, 2H), 744-7.50 (m, 2H), 7.70 (t, 1H, J = 7.6 Hz), 7.88 (d, 1H, J = 7.6 Hz), 9.36 (s, 1H) ppm. 13C NMR (125 MHz, DMSO-d6): 8 36.6, 58.9, 105.0, 113.5, 115.7, 117.0, 119.9, 122.9, 125.1, 129.2, 133.3, 134.2, 152.5, 153.5, 157.0, 158.4, 160.0 ppm.
Table 1, entry 11: IR (KBr): v 3410, 3320, 3210, 2920, 2210, 1655, 1405, 1305, 1000 cm-1. 1H NMR (500 MHz, DMSO-d6): ¿4.48 (s, 1H), 7.26 (d, 2H, J = 7.8 Hz), 7.49 (m, 6H), 7.71 (m, 1H), 7.90 (d, 1H, J = 7.8 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 37.0, 57.9, 103.9,
113.4,	117.1, 119.6, 120.7, 123.0, 125.2, 130.5, 131.8,
133.5,	143.0, 152.7, 154.0, 158.4, 160.0 ppm.
Table 1, entry 12: IR (KBr): v 3335, 3310, 3190, 2920, 2115, 1675, 1475, 1345, 1150 cm-1. 1H NMR (500 MHz, DMSO-d6): S4.48 (s, 1H), 7.35 (d, 2H, J = 8.4 Hz), 7.39 (d, 2H, J =8.4 Hz), 7.45-7.51 (m, 4H), 7.70 (t, 1H, J = 7.6 Hz), 7.88 (d, 1H, J = 7.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 36.9, 59.1, 103.8, 113.4, 116.8, 119.4, 122.8, 125.2, 128.9, 130.2, 132.3, 132.9, 142.7,
152.6,	154.1, 158.4, 160.1 ppm.
Table 2, entry 1: IR (KBr): v 3390, 3305, 3200, 29005, 2190, 1655, 1405, 1300, 1010 cm-1. 1H NMR (400 MHz, CDCl3): S 1.79 (s, 3H), 4.78 (s, 2H), 5.29 (s, 1H), 7.22-7.27 (m, 3H), 7.30 (t, 2H, J = 7.8 Hz), 7.32 (s, 2H), 7.35 (m, 1H), 7.46 (m, 2H), 7.75 (d, 2H, J = 7.8 Hz) ppm. 13C NMR (100 MHz, CDCl3): S 12.8, 32.4, 60.8, 96.7,
117.4,	120.3, 125.9, 127.1, 128.4, 129.3, 130.4, 132.8, 136.3, 136.8, 142.9, 145.3, 158.7 ppm.
Table 2, entry 2: IR (KBr): v 3320, 3080, 2200, 1675, 1590, 1455, 1335, 1255, 1125, 1070, 1020 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.75 (s, 3H), 4.72 (s, 1H), 7.45-7.56 (m, 3H), 7.61-7.70 (m, 4H), 7.82 (d, 2H, J = 8.6 Hz), 7.88 (d, 2H, J = 8.0 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.5, 37.5, 58.1, 98.5, 110.8, 119.6,
120.0,	120.9, 126.9, 129.8, 130.1, 133.8, 138.6, 145.0, 145.9, 150.1, 160.5 ppm.
Table 2, entry 3: IR (KBr): v 3325, 3085, 2200, 1675, 1590, 1475, 1335, 1250, 1120, 1100, 1020 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.79 (s, 3H), 4.80 (s, 1H), 7.30-7.55 (m, 5H), 7.40-7.8 (m, 5H), 7.92 (m, 1H, Ar), 7.98 ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.5, 57.9, 99.5, 111.2, 119.6, 121.6, 121.9, 127.2,
129.5,	130.2, 132.9, 137.8, 144.5, 146.9, 150.2, 160.4 ppm.
Table 2, entry 4: IR (KBr): v 3400, 3300, 3200, 2900, 2200, 1645, 1400, 1300, 1000 cm-1. 1H NMR (400 MHz, CDCl3): S 1.90 (s, 3H), 4.80 (s, 2H), 5.30 (s, 1H), 7.17 (d, 1H, J = 8.4 Hz), 7.26 (s, 1H), 7.35 (t, 1H, J = 7.2 Hz), 7.46-7.51 (m, 3H), 7.66 (d, 2H, J = 8 Hz) ppm. 13C NMR (100 MHz, CDCl3): S 12.8, 33.5, 61.9, 97.6, 118.6, 121.3, 127.0, 128.0, 129.4, 129.7, 131.5, 133.9, 137.4, 137.9, 144.0, 146.1, 158.9 ppm.
Table 2, entry 5: IR (KBr): v 3289, 3082, 2200, 1675, 1585, 1510, 1390, 1230, 1120, 1070, 1030 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.75 (s, 3H), 4.82 (s, 1H), 7.25-7.30 (m, 3H), 7.45-76.51 (m, 4H), 7.75 (d, 2H, J = 8.6 Hz), 7.80 (d, 2H, J = 8.4 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.5, 57.9, 97.9, 110.8, 118.9,
120.6,	120.9, 127.1, 129.8, 130.1, 133.5, 138.0, 144.9,
146.1,	150.1, 160.3 ppm.
Table 2, entry 6: IR (KBr): v 3305, 3300, 3200,
2900, 2200, 1645, 1400, 1300, 1000 cm-1. 1H NMR (400 MHz, CDCl3): S 1.89 (s, 3H), 4.82 (s, 2H), 5.32 (s, 1H), 7.17-7.39 (m, 5H), 7.42-7.45 (m, 2H), 7.56 (m, 1H) ppm. 13C NMR (100 MHz, CDCl3): S 12.8, 32.8, 61.0, 97.5, 117.2, 120.3, 125.7, 126.9, 128.4, 128.9, 130.5, 132.8, 136.4, 136.4, 141.9, 145.6, 158.6 ppm.
Table 2, entry 7: IR (KBr): v 3250, 3100, 2205, 1680, 1570, 1220, 1120, 1100, 1020 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.78 (s, 3H), 4.82 (s, 1H), 7.15-7.21 (m, 5H), 7.30-77.38 (m, 3H), 7.42 (s, 2H), 7.78 (m, 1H) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.5, 57.9, 99.5, 111.2, 119.6, 121.6, 121.9, 127.2, 129.5, 130.2, 132.9, 137.8, 144.5, 146.9, 150.2, 160.4 ppm.
Table 2, entry 8: IR (KBr): v 3410, 3310, 3205, 2910, 2215, 1675, 1405, 1315, 1015 cm-1.1H NMR (500 MHz, DMSO-d6): S 1.79 (s, 3H), 3.75 (3H), 4.50 (s, 1H), 7.20 (s, 2H), 7.31 (t, 1H, J = 7.4 Hz), 7.30 (d, 2H, J = 8 Hz), 7.42 (d, 2H, J = 8 Hz), 7.46 (t, 2H, J = 7.6 Hz), 7.70 (d, 2H, J = 7.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 31.8, 37.5, 57.9, 98.5, 110.8, 119.0, 120.6, 120.9,
127.1,	129.8, 131.1, 134.2, 138.3, 145.3, 145.9, 150.2, 160.2 ppm.
Table 2, entry 9: IR (KBr): v 3380, 3312, 3200, 2910, 2215, 1670, 1415, 1315, 1010 cm-1.1H NMR (500 MHz, DMSO-d6): S 1.78 (s, 3H), 1.85 (3H), 4.55 (s, 1H), 7.12 (s, 2H), 7.68 (t, 1H, J = 7.4 Hz), 7.21 (d, 2H, J = 8 Hz), 7.28 (d, 2H, J = 8 Hz), 7.36 (t, 2H, J = 7.6 Hz), 7.60 (d, 2H, J = 7.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 36.7, 37.5, 56.9, 97.4, 110.1, 116.8, 119.5, 1204
125.2,	128.7, 130.1, 133.1, 137.3, 144.3, 145.6, 150.2, 160.2 ppm.
Table 2, entry 10: IR (KBr): v 3315, 3010, 2210, 1670, 1580, 1510, 1235, 1120, 1075, 1030 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.74 (s, 3H), 4.82 (s, 1H), 7.32-7.40 (m, 3H), 7.48-7.55 (m, 4H), 7.87 (d, 2H, J = 8.6 Hz), 7.92 (d, 2H, J = 8.6 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.6, 57.9, 97.9, 110.8, 118.9,
120.7,	121.0, 128.1, 129.8, 130.1, 133.5, 138.6, 145.7,
146.2,	151.2, 160.4 ppm.
Table 2, entry 11: IR (KBr): v 3400, 3300, 3100, 2200, 1645, 1400, 1300, 1000 cm-1.1H NMR (500 MHz, DMSO-d6): S 1.79 (s, 3H), 4.55 (s, 1H), 6.71 (d, 2H, J = 7.8 Hz), 7.03 (d, 2H, J = 7.81 Hz), 7.2 (s, 2H), 7.31 (t, 1H, J = 7.03 Hz), 7.48 (t, 2H, J = 7.31 Hz), 7.77 (d, 2H, J = 7.74 Hz), 9.32 (s, 1H) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.5, 57.9, 98.5, 110.8, 119.6, 120.6, 120.9, 127.1, 129.8, 130.1, 133.5, 138.3, 144.9, 145.9, 150.0, 160.0 ppm.
Table 2, entry 12: IR (KBr): v 3089, 3082, 2200, 2215, 1673, 1590, 1515, 1390, 1250, 1120, 1070, 1030 cm-1. 1H NMR (500 MHz, DMSO-d6): S 1.77 (s, 3H), 4.83 (s, 1H), 7.30-7.33 (m, 3H), 7.47-7.50 (m, 4H), 7.78 (d, 2H, J = 8.5 Hz), 7.82 (d, 2H, J = 8.0 Hz) ppm. 13C NMR (125 MHz, DMSO-d6): S 13.4, 37.5, 57.9, 98.5,
110.8,	119.6, 120.7, 120.9, 127.1, 129.8, 130.1, 133.6,
138.3,	144.9, 145.9, 150.1, 160.5 ppm.
4. Conclusions
We have developed a mild, simple and green procedure for the one-pot synthesis of benzopyrans and dihydropyranochromenes in the presence of PVPy as a commercially available and recyclable basic catalyst at reflux temperature. Moreover, short reaction times, ease of work-up, high yields and clean procedure are the most important advantages of this method, making the procedure a useful addition to the available methods.
5. Acknowledgement
We are thankful to research council of Behbahan Khatam Alanbia University of Technology, for the support of this work.
6. References
1.	L. Bonsignore, G. Loy, D. Secci, A. Calignano, Eur. J. Med. Chem. 1993, 28, 517-520.
2.	M. Kidwai, S. Saxena, M. K. R. Khan, S. S. Thukral, Bioorg. Med. Chem. Lett. 2005, 15, 4295-4298.
3.	M. Rueping, E. Sugiono, E. Merino, Chem. Eur. J. 2008, 14, 6329-6332.
4.	S. Paul, P. Bhattacharyya, A. R. Das, Tetrahedron Lett. 2011, 52, 4636-4641.
5.	J. Zheng, Y. Q. Li, Arch. Appli. Sci. Res. 2011, 3, 381-388.
6.	R. Ghorbani-Vaghe, Z. Toghraei-Semiromi, R. Karimi-Na-mi, J. Braz. Chem. Soc. 2011, 22, 905-909.
7.	J. M Khurana, B. Nand, P. Saluja, Tetrahedron Lett. 2010, 66, 5637-5641.
8.	M. M. Heravi, M. Zakeri, N. Mohammadi, Chin. J. Chem.
2011,	29, 1163-1166.
9.	M. Khoobi, L. Mamani, F. Rezazadeh, Z. Zareie, A. Forou-madi, A. Ramazani, A. Shafiee, J. Mol. Catal. A: Chem.
2012,	359, 74-80.
10.	M. M. Heravi, S. Sadjadi, N. Mokhtari Haj, H. A. Oskooie, F. F. Bamoharram, Catal. Commun. 2009, 10, 1643-1646.
11.	M. M. Heravi, B. A. Jani, F. Derikvand, F. F. Bamoharram, H. A. Oskooie, Catal. Commun. 2008, 10, 272-275.
12.	J. M. Khurana, S. Kumar, Tetrahedron Lett. 2009, 50, 4125-4127.
13.	M. M. Heravi, B. Baghernezhad, H. A. Oskooie, J. Chin. Chem. Soc. 2008, 55, 659-662.
14.	H. Mehrabi, M. Kazemi-Mireki, Chin. Chem. Lett. 2011, 22, 1419-1422.
15.	V. K. Ahluwalia, R. Kumar, A. Khurana, R. A. Bhatla, Tetrahedron. 1990, 46, 3953-3962.
16.	P. Srivastava, A. S. Saxena, V. J. Ram, Synthesis. 2000, 541-544.
17.	Z. Ye, R. Xu, X. Shao, X. Xu, Z. Li, Tetrahedron Lett. 2010, 51, 4991-4994.
18.	A. Hasaninejad, M. Shekouhy, N. Golzar, A. Zare, M. M. Doroodmand, Appl. Catal. A: Gen. 2011, 402, 11-22.
19.	S. Banerjee, A. Horn, H. Khatri, G. Sereda, Tetrahedron Lett.
2011,	52, 1878-1881.
20.	U. R. Pratap, D. V. Jawale, P. D. Netankar, R. A. Mane, Tetrahedron Lett. 2011, 52, 5817-5819.
21.	P. P. Salvi, A. M. Mandhare, A. S. Sartape, D. K. Pawar, S. H. Han, S. S. Koleka, Compt. Rend. Chim. 2011, 14, 878882.
22.	L. Fotouhi, M. M. Heravi, A. Fatehi, K, Bakhtiari, Tetrahedron Lett. 2007, 48, 5379-5381.
23.	T. S. Jin, A. Q. Wang, Z. L. Cheng, J. S. Zhang, T. S. Li, Synth. Commun. 2005, 35, 137-143.
24.	D. Shi, J. Mou, Q. Zhuang, L. Niu, N. Wu, X. Wang, Synth. Commun. 2004, 34, 4557-4563.
25.	J. Albadi, A. Mansournezhad, M. Darvishi-Paduk, Chin. Chem. Lett. 2013, 24, 208-210.
26.	R. J. Kalbasi, N. Mosadegh, Catal. Commun. 2011, 12, 1231-1237.
27.	K. Hemalatha, G. Madhumitha, A. Kajbafvala, N. Anupama, R. Sompalle, S. M. Roopan, J. Nanomat. 2013 (Review).
28.	F. Shirini, N. Gaffari-Khaligh, J. Iran. Chem. Soc. 2012, 9, 495-502.
29.	J. Albadi, M. Keshavarz, M. Abedini, M. Vafaie-nezhad. Chin. Chem. Lett. 2012, 23, 797-800.
30.	J. Albadi, N. Iravani, M. Khoshakhlagh, Iran. J. Catal. 2012, 2, 85-89.
31.	J. Albadi, M. Keshavarz, F. Shirini, M. Vafaie-Nezhad. Catal. Commun. 2012, 27, 17-20.
32.	J. Albadi, N. Iravani, F. Shirini, F. Dehghan, J. Chem. Res.
2012,	610-611.
Povzetek
V prispevku je opisana uporaba poli(4-vinilpiridina) kot zelenega, komercialno dosegljivega in obnovljivega bazičnega katalizatorja za multikomponentno sintezo benzopiranov in dihidropiranokromenov z enostopenjsko kondenzacijo aro-matskih aldehidov, 3-metil-1-fenil-2-pirazolin-5-ona in malononitrila, oziroma 4-hidroksikumarina, v etanolu pri temperaturi refluksa. Prednosti tega postopka so mili reakcijski pogoji, kratki reakcijski časi, enostavna izolacija produktov in visoki izkoristki.
Supporting Materials
Efficient Synthesis of Benzopyrans and Dihydropyranochromenes Catalyzed by Poly(4-vinylpyridine) as a Green and Commercially
Available Basic Catalyst
Jalal Albadi,1'* Azam Mansournezhad2 and Fatemeh Akbari Balout-Bangan3
1 College of Science, Behbahan Khatam Alanbia University of Technologhy, Behbahan, Iran
2 Department of Chemistry, Gachsaran Branch, Islamic Azad University, Gachsaran, Iran
3 Department of Chemistry, Qom Branch, Islamic Azad University, Qom, Iran
* Corresponding author: E-mail: Jalal.albadi@gmail.com:Chemalbadi@gmail.com:
Tel/Fax: +986712229969
Received: 15-05-2013