Zr(HSO4)4 as an efficient catalyst for the preparation of 10-aryl-6,8-dimethyl-6,10dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones under solvent-free conditions

ARTICLE

Zr(HSO₄)₄ as an efficient catalyst for the preparation of 10-aryl-6,8-dimethyl-6,10dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones under solvent-free conditions

Jiangli Zhang^I; Wei Lin Li^II; Li Qiang Wu^II,*

^IThe Department Psychology of the Second Affiliated, Xinxiang Medical University, 453000 Xinxiang, Henan, P. R. China

^IISchool of Pharmacy, Xinxiang Medical University, 453000 Xinxiang, Henan, P. R. China

ABSTRACT

A one-pot three-component condensation of 3,4-methylenedioxyphenol, aromatic aldehydes, and 1,3-dimethylbarbituric acid, efficiently promoted in the presence of Zr(HSO₄)₄ under solvent-free conditions, produced 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3] dioxole-7,9-diones. The method offers several advantages including simple, easy and clean work-up procedure, relatively short reaction times and good to high yields of the products.

Keywords: benzo[1,3]dioxoles, 3,4-methylenedioxyphenol, Zr(HSO₄)_4, solvent-free

RESUMO

A condensação de três componentes "one pot" de 3,4-metilenodioxifenol, aldeídos aromáticos, e ácido 1,3-dimetilbarbitúrico, eficientemente promovida na presença de Zr(HSO₄)₄, livre de solvente, produziu 10-aril-6,8-dimetil-6,10-diidro-5-oxa-6,8-diazaantra[2,3-d][1,3]dioxol-7,9-dionas. O método oferece diversas vantagens incluindo a simplicidade, facilidade e limpeza do procedimento extrativo, tempos de reação relativamente curtos e bons a altos rendimentos dos produtos.

Introduction

Benzo[1,3]dioxoles constitute a major class of naturally occurring compounds,¹ and interest in their chemistry continues unabated because of their wide range of biological and therapeutic properties such as spasm,² synergistic,³ antitumour,⁴ antimicrobial,⁴ anti-proliferative,⁵ antioxidant,^1,6 anti-inflammatory,⁶ anti-HIV,⁷ antineoplastic and antiviral activities.⁸ Considering the above reports, the development of new and simple synthetic methods for the efficient preparation of new benzo[1,3]dioxoles is therefore an interesting challenge.

Pyrano[2,3-d]pyrimidines and chromeno[2,3-d] pyrimidines are two 'privileged medicinal scaffolds'which are used for the development of pharmaceutical agents of various applications. Compounds with these motifs show a wide range of pharmacological activities such as antiviral,⁹ antimicrobial,¹⁰ antifungal,¹¹ anticonvulsant and analgesic activities.¹² Moreover, they are also useful reagents in organic synthesis, for example, 5-deaza-10-oxaflavin has the ability to oxidize alcohols to the corresponding carbonyl compounds.¹³

In recent years, metal hydrogen sulfates have been used as efficient reagents in organic chemistry.¹⁴ A broad range of reactions including deprotection, oxidation, C-C, C-N and C-O bond formation and cleavage took place in the presence of these reagents under mild and heterogeneous conditions. In addition, stability, cheapness, ability to produce highly efficient products in a short time and in many cases reusability are among other important advantages of these reagents.

We herein report that Zr(HSO₄)₄ efficiently catalyzes the one-pot syntheses of 10-aryl-6,8-dimethyl-6,10-dihydro5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones by condensation of 3,4-methylenedioxyphenol, aromatic aldehydes, and 1,3-dimethylbarbituric acid under solvent-free conditions (Scheme 1).

Results and Discussion

Initially, we conducted the reaction of 3,4-methylenedioxyphenol, benzaldehyde, and 1,3-dimethylbarbituric acid in the presence of various metal hydrogen sulfates such as NaHSO₄, Mg(HSO₄)₂, Fe(HSO₄)₃, Zr(HSO₄)₄,Al(HSO₄)₃ separately at 100 ºC under solvent-free conditions. The corresponding 10-phenyl-6,8-dimethyl-6,10-dihydro-5oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione was formed in 49, 65, 58, 89 and 79% yield (Table 1). Zr(HSO₄)₄ was thus selected as the most effective catalyst to carry out this reaction.

Next, to optimize the amount of catalyst and the reaction temperature, the reaction of 3,4-methylenedioxyphenol, benzaldehyde and 1,3-dimethylbarbituric acid was studied under solvent-free conditions in the presence of Zr(HSO₄)₄ at different temperatures. The results are summarized in Table 2, and showed that the reaction using 10 mol% Zr(HSO₄)₄ at 100 ºC proceeded in highest yield.

With this optimized procedure in hand, the scope of application of this three-component reaction was examined using different aldehydes as staring materials. As seen from Table 3, aromatic aldehydes having electron-donating as well as electron-withdrawing groups were uniformly transformed into the corresponding 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra [2,3-d][1,3]dioxole-7,9-diones in high to excellent yields within 60 min. Substituents on the aromatic ring had no obvious effect on yield or reaction time under the above optimal conditions (Table 3). All of the products 4a-4i exhibited a singlet in their ¹H spectra at d 4.98-5.58 ppm for H-10, two doublets at d 5.90-5.98 ppm for -OCH₂O- and two singlets at d 6.44-6.71 ppm for H-4 and H-11.A distinguishing peak at d 38.2-39.2 ppm for C-10 in their ¹³C nuclear magnetic resonance (NMR) spectra, and two distinguishing peak at d 97.9-98.4 ppm for C-4, 11.

The plausible mechanism of the reaction is shown in Scheme 2. It is conceivable that Zr(HSO₄)₄ catalyzes the formation of a carbocation in a reversible reaction with the aromatic aldehyde. The higher reactivity of the carbocation compared with the carbonyl species is utilized to facilitate Knoevenagel condensation between arylaldehyde 2 and 1,3-dimethylbarbituric acid 3 via intermediate 5, and after dehydration olefin 6 is produced. Subsequent Michael-type addition of 1 to the olefin followed by cyclization and dehydration affords the corresponding products 4a-4i.

Conclusions

In conclusion, we have developed a highly efficient methodology for the three-component reaction of 3,4-methylenedioxyphenol, aromatic aldehydes, and 1,3-dimethylbarbituric acid catalyzed by safe Zr(HSO₄)₄, furnishing a class of 10-aryl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-diones in high yield. This method is advantageous in terms of simplicity and mildness, and could find wide application in synthesis of complex benzo[1,3]dioxole-containing compounds.

Experimental

IR spectra were determined on a FTS-40 infrared spectrometer; NMR spectra were determined on a Bruker AV-400 instrument at room temperature using TMS as internal standard; coupling constants (J) were measured in Hz. Elemental analysis were performed by a Vario-III elemental analyzer; mass spectra were taken on a Macro mass spectrometer (Waters) by electro-spray method (ES); melting points were determined on a XT-4 binocular microscope and were uncorrected; commercially available reagents were used without further purification.

General procedure for the preparation of 4

A mixture of 3,4-methylenedioxyphenol (1 mmol), aldehyde (1 mmol), 1,3-dimethylbarbituric acid (1 mmol) and Zr(HSO₄)₄ (0.1 mmol) was heated at 100 ºC for an appropriate time (TLC). After completion, the reaction mixture was washed with water (15 mL) and the residue was recrystallized to afford the pure product 4.

10-Phenyl-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4a )

White powder, mp 245-246ºC; IR (KBr) ν_max/cm^-1: 3076, 2972, 2899, 1703, 1667, 1659, 1482, 1432, 1211, 1139, 1031, 929, 878, 826, 745, 702, 572, 517, 421; ¹H NMR (CDCl₃, 400 MHz) δ 7.26-7.16 (m, 5H, ArH), 6.68 (s, 1H,ArH), 6.52 (s, 1H, ArH), 5.95 (d, 1H, J 0.8 Hz, OCH₂O), 5.91 (d, 1H, J 0.8 Hz, OCH₂O), 5.03 (s, 1H, CH), 3.55 (s, 3H, CH₃), 3.28 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.9, 152.6, 150.7, 147.2, 145.6, 145.1, 143.1, 128.6, 127.8, 127.7, 126.9, 116.8, 108.2, 101.8, 98.0, 90.0, 39.2, 29.0, 28.1; MS (ESI): m/z 365[M+H]⁺;Anal.calc.forC₂₀:C65.93, ^H16^N2º5H 4.43, N 7.69; found: C 65.90, H 4.48, N 7.74.

10-(4-Chlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4b )

White powder, mp 254-255 ºC; IR (KBr) ν_max/cm^-1: 3089, 2958, 2872, 1701, 1667, 1660, 1478, 1434, 1214, 1142, 1088, 1036, 1015, 975, 934, 854, 772, 751, 571, 521, 421; ¹H NMR (CDCl₃, 400 MHz) δ 7.22 (d, 2H, J 6.4 Hz, ArH), 7.18 (d, 2H, J 6.8 Hz, ArH), 6.67 (s, 1H, ArH), 6.47 (s, 1H, ArH), 5.97 (d, 1H, J 0.8 Hz, OCH₂O), 5.92 (d, 1H, J 0.8 Hz, OCH₂O), 5.00 (s, 1H, CH), 3.54 (s, 3H, CH₃), 3.28 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.8, 152.6, 150.6, 147.4, 145.7, 143.6, 143.0, 132.7, 129.3, 128.8, 128.7, 116.1, 108.0, 101.9, 98.1, 89.6, 38.6, 29.0, 28.1; MS (ESI): m/z 399 [M+H]⁺; Anal. calc. for C₂₀H₁₅ClN₂O₅: C 60.23, H 3.79, N 8.89; found: C 60.19, H 3.85, N 8.95.

10-(4-Fluorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione (4c )

White powder, mp 253-254 ºC; IR (KBr) ν_max/cm^-1: 3079, 2962, 2859, 1707, 1667, 1648, 1522, 1436, 1353, 1212, 1142, 1031, 977, 930, 864, 817, 751, 703, 570, 516, 422; ¹H NMR (CDCl₃, 400 MHz) δ 7.22-7.19 (m, 2H, ArH), 6.95-6.91 (m, 2H, ArH), 6.67 (s, 1H, ArH), 6.48 (s, 1H, ArH), 5.96 (d, 1H, J 1.2 Hz, OCH₂O), 5.92 (d, 1H, J 1.2 Hz, OCH₂O), 5.01 (s, 1H, CH), 3.54 (s, 3H, CH₃), 3.28 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.9, 152.5, 150.6, 147.3, 145.6, 143.0, 140.9, 129.4, 116.5, 115.4, 115.2, 108.1, 101.9, 98.0, 89.8, 38.4, 29.0, 28.1; MS (ESI): m/z 383 [M+H]⁺; Anal. calc. for C₂₀H₁₅FN₂O₅: C 62.83, H 3.95, N 7.33; found: C 62.90, H 3.89, N 7.40.

10-(4-Methylphenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4d )

White powder, mp 248-249 ºC; IR (KBr) ν_max/cm^-1: 3078, 2956, 2870, 1708, 1671, 1644, 1478, 1434, 1211, 1140, 1032, 930, 930, 790, 572, 519, 421; ¹H NMR (CDCl₃, 400 MHz) δ 7.14 (d, 2H, J 8.0 Hz, ArH), 7.07 (d, 2H, J 8.0 Hz, ArH), 6.67 (s, 1H, ArH), 6.52 (s, 1H, ArH), 5.95 (d, 1H, J 0.8 Hz, OCH₂O), 5.90 (d, 1H, J 0.8 Hz, OCH₂O), 4.99 (s, 1H, CH), 3.54 (s, 3H, CH₃), 3.28 (s, 3H, CH₃), 2.27 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.9, 152.5, 150.7, 147.1, 145.5, 143.0, 142.3, 136.5, 129.3, 129.2, 127.7, 127.6, 117.0, 108.2, 101.8, 98.0, 90.1, 38.8, 29.0, 28.1, 21.0; MS (ESI): m/z 379 [M+H]⁺; Anal. calc. for C₂₁H₁₈N₂O₅: C 66.66, H 4.79, N 7.40; found: C 66.70, H 4.69, N 7.49.

10-(4-Nitrophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4e )

White powder, mp 259-260 ºC; IR (KBr) ν_max/cm^-1: 3089, 2991, 2881, 1706, 1668, 1650, 1522, 1437, 1395, 1352, 1213, 1143, 1032, 978, 929, 863, 816, 752, 570, 517, 423; ¹H NMR (CDCl₃, 400 MHz) δ 8.12 (d, 2H, J 8.8 Hz, ArH), 7.43 (d, 2H, J 8.4 Hz, ArH), 6.71 (s, 1H, ArH), 6.44 (s, 1H, ArH), 5.98 (d, 1H, J 0.8 Hz, OCH₂O), 5.95 (d, 1H, J 0.8 Hz, OCH₂O), 5.15 (s, 1H, CH), 3.56 (s, 3H, CH₃), 3.27 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.8, 152.8, 152.1, 150.5, 147.8, 146.8, 145.9, 143.1, 128.9, 123.9, 114.9, 107.9, 102.1, 98.3, 88.8, 39.1, 29.1, 28.1; MS (ESI): m/z 410 [M+H]⁺; Anal. calc. for C₂₀H₁₅N₃O₇: C 58.68, H 3.69, N 10.27; found: C 58.60, H 3.72, N 10.20.

10-(3-Nitrophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4f )

White powder, mp 262-263 ºC; IR (KBr) ν_max/cm^-1: 3052, 2944, 2852, 1701, 1666, 1659, 1529, 1504, 1486, 1436, 1351, 1224, 1171, 1038, 934, 871, 737, 717; ¹H NMR (CDCl₃, 400 MHz) δ 8.05-8.03 (m, 1H, ArH), 8.00-7.98 (m, 1H, ArH), 7.72 (d, 1H, J 7.6 Hz, ArH), 7.46 (t, 1H, J 7.6 Hz, ArH), 6.71 (s, 1H, ArH), 6.44 (s, 1H, ArH), 5.98 (d, 1H, J 0.8 Hz, OCH₂O), 5.94 (d, 1H, J 0.8 Hz, OCH₂O), 5.15 (s, 1H, CH), 3.57 (s, 3H, CH₃), 3.27 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.8, 152.8, 150.5, 148.5, 147.8, 147.1, 145.9, 143.0, 134.5, 129.3, 122.9, 115.0, 107.9, 102.1, 98.4, 88.8, 39.1, 29.1, 28.1; MS (ESI): m/z 410 [M+H]⁺; Anal. calc. for C₂₀H₁₅N₃O₇: C 58.68, H 3.69, N 10.27; found: C 58.72, H 3.75, N 10.22.

10-(3,4-Dichlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4g )

White powder, mp 247-248 ºC; IR (KBr) ν_max/cm^-1: 3092, 2972, 2861, 1682, 1588, 1561, 1426, 1383, 1318, 1250, 1112, 1036, 934, 868, 762, 562; ¹H NMR (CDCl₃, 400 MHz) δ 7.33 (d, 1H, J 8.0 Hz, ArH), 7.26-7.25 (m, 1H, ArH), 7.15 (dd, 1H, J 2.0, 8.0 Hz, ArH), 6.68 (s, 1H, ArH), 6.45 (s, 1H, ArH), 5.98 (d, 1H, J 0.8 Hz, OCH₂O), 5.94 (d, 1H, J 0.8 Hz, OCH₂O), 4.98 (s, 1H, CH), 3.55 (s, 3H, CH₃), 3.28 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.8, 152.7, 150.6, 147.6, 145.8, 145.3, 143.0, 132.6, 131.0, 130.4, 129.8, 127.5, 115.4, 107.9, 102.0, 98.2, 89.0, 38.5, 29.1, 28.1; MS (ESI): m/z 433 [M+H]⁺;Anal. calc. for C₂₀H₁₄Cl₂N₃O₂: C 55.45, H 3.26, N 6.47; found: C 55.50, H 3.20, N 6.50.

10-(2,4-Dichlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa6,8-diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4h )

White powder, mp 277-278 ºC; IR (KBr) ν_max/cm^-1: 3082, 2979, 2870, 1700, 1667, 1641, 1480, 1433, 1395, 1219, 1148, 1037, 934, 878, 794, 755, 594; ¹H NMR (CDCl₃, 400 MHz) δ 7.36 (d, 1H, J 2.0 Hz, ArH), 7.14-7.12 (m, 2H, ArH), 6.63 (s, 1H, ArH), 6.55 (s, 1H, ArH), 5.96 (d, 1H, J 1.6 Hz, OCH₂O), 5.92 (d, 1H, J 1.6 Hz, OCH₂O), 5.52 (s, 1H, CH), 3.57 (s, 3H, CH₃), 3.27 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ 161.7, 153.1, 150.7, 147.4, 145.6, 142.7, 141.0, 133.5, 133.2, 131.2, 129.7, 127.6, 115.1, 107.5, 101.9, 98.0, 88.2, 38.6, 29.1, 28.1; MS (ESI): m/z 433 [M+H]⁺; Anal. calc. for C₂₀H₁₄Cl₂N₃O₇: C 55.45, H 3.26, N 6.47; found: C 55.38, H 3.24, N 6.52.

10-(2-Chlorophenyl)-6,8-dimethyl-6,10-dihydro-5-oxa-6,8diazaanthra[2,3-d][1,3]dioxole-7,9-dione ( 4i )

White powder, mp 233-234 ºC; IR (KBr) ν_max/cm^-1: 3082, 2965, 2858, 1701, 1663, 1520, 1435, 1361, 1281, 1118, 1036, 936, 736, 427; ¹H NMR (CDCl₃, 400 MHz) δ 7.34 (d, 1H, J 7.6 Hz, ArH), 7.17-7.12 (m, 3H, ArH), 6.63 (s, 1H, ArH), 6.61 (s, 1H, ArH), 5.95 (d, 1H, J 0.8 Hz, OCH₂O), 5.90 (d, 1H, J 0.8 Hz, OCH₂O), 5.58 (s, 1H, CH), 3.57 (s, 3H, CH₃), 3.27 (s, 3H, CH₃); ¹³C NMR (CDCl₃, 100 MHz) δ161.7, 153.1, 150.8, 147.3, 145.5, 142.7, 142.3, 132.8, 130.3, 130.0, 128.1, 127.2, 115.7, 107.7, 101.8, 97.9, 88.7, 38.2, 29.1, 28.1; MS (ESI): m/z 399 [M+H]⁺; Anal. calc. for C₂₀H₁₅ClN₂O₅:C 60.23, H 3.79, N 8.89; found: C 60.22, H 3.80, N 8.92.

Supplementary Information

The spectroscopic ¹H NMR, ¹³C NMR, and IR data of 4a-4i are provided as supplementary information and available free of charge at http://jbcs.sbq.org.br as PDF file.

Acknowledgments

We are pleased to acknowledge the financial support from Xinxiang Medical University.

References

1. Rao, K. V.; Rao, N. S.; J. Nat. Prod. 1990,53,212; Kuo, Y.-H.; Chem, C.-H.; Lin, Y.-L.; Chem. Pharm. Bull. 2002,50,978; Hartwell, J. L.; Johnson, J. M.; Fitzgerald, D. B.; Belkin, M.; J. Am. Chem. Soc. 1953,75,235; de Diaz, A. M. P.; Phytochemistry 1997,44,345; McCredie, R. S.; Ritchie, E.; Taylor, W. C.; Aust. J. Chem. 1969,22,1011; Kim, E. S.; Hyun, J. W.; Shin, J. C.; Chung, H. S.; Bull. Korean Chem. Soc. 2009,30,739; Cheng, M.-J.; Wang, B.-C.; Wang, W.-Y.; Lai, J.-T.; Yuan, G.-F.; J. Chil. Chem. Soc. 2007,52,1338.

2. Dallacker, F.; Reichrath, G.; Schnackers, G.; Z. Naturforsch. C 1980,35,49.

3. Walia, S.; Saxena, V. S.; Mukerjee, S. K.; J. Agric. Food Chem. 1985,33,308.

4. Leite, A. C. L.; Silva, K. P.; Souza, I. A.; Araujo, J. M.; Brondani, D. J.; Eur. J. Med. Chem. 2004,39,1059; Micale, N.; Zappala, M.; Grasso, S.; Farmaco 2002,57,853.

5. Zhang, W.-G.; Zhao, R.; Ren, J.; Ren, L.-X.; Lin, J.-G.; Liu, D.-L.; Wu,Y.-L.;Yao, X.-S.; Arch. Pharm. Chem. Life Sci. 2007,340,244.

6. Burguete, A.; Pontiki, E.; Hadjipavlou-Litina, D.; Villar, R.; E. Vicente, E.; Solano, B.; Ancizu, S.; Perez-Silanes, S.; Aldana, I.; Monge, A.; Bioorg. Med. Chem. 2007,17,6439.

7. Chen, D. F.; Zhang, S. X.; Chen, K.; Zhou, B. N.; Wang, P.; Cosentino, L. M.; Lee, K. H.; J. Nat. Prod. 1996,59,1066.

8. Liu, Y.-Q.; Yang, L.; Tian, X.; Curr. Bioact. Compd. 2007,3,37.

9. Shamroukh, A. H.; Zaki, M. E. A.; Morsy, E. M. H.; Abdel-Motti, F. M.; Abdel-Megeid, F. M. E.; Arch. Pharm. 2007,340,236.

10. Mostafa, M. S.; J. Environ. Sci. 2008,36,255; Eid, F. A.; Abd El-Wahab, A. H. F.; El-Hag Ali, G. A. M.; Khafagy, M. M.; Acta Pharm. 2004,54,13; Bedair, A. H.; Emam, H. A.; El-Hady, N. A.; Ahmed, K. A. R.; El-Agrody, A. M.; Farmaco 2001,56,965; Ahluwalia, V. K.; Chopra, M.; Chandra, R.; J. Chem. Res. (S) 2000,162.

11. Akluwalia, V. K.; Bala, M.; Indian J. Chem., Sect. B 1996,35B,742.

12. Joshi, K. C.; Jain, R.; Sharma, K.; Bhattacharya, S. K.; Goel, R. K.; J. Indian Chem. Soc. 1988,65,202.

13. Yoneda, F.; Hirayama, R.; Yamashita, M.; Chem. Lett. 1980,1157; Chen, X.; Tanaka, K.; Yoneda, F.; Chem. Pharm. Bull. 1990,38,307.

14. Das, B.; Venkataiah, B.; Synthesis 2000,1671; Ramesh, C.; Ravindranath, N.; Das, B.; J. Org. Chem. 2003,68,7101; Shirini, F.; Zolfigol, M. A.; Safari, A.; Indian J. Chem., Sect. B 2005,44B,201; Khodaei, M. M.; Salehi, P.; Zolfigol, M. A.; Sirouszadeh, S.; Polish J. Chem. 2004,78,38; Shirini, F.; Zolfigol, M. A.; Mallakpour, B.; Russ. J. Org. Chem. 2005,41,625; Shaabani, A.; Bazgir, A.; Soleimani, K,; Salehi, P.; Synth. Commun. 2003,33,2935; Mirjalili, B. F.; Zolfigol, M. A.; Bamoniri, A.; Karimi-Zarchi, M. A.; Zaghaghi, Z.; Parvaideh, M.; J. Iran. Chem. Soc. 2007,4,340; Shaabani, A.; Zolfigol, M. A.; Abedini, M.; Bull. Chem. Soc. Jpn. 2005,78,1982.

Submitted: October 25, 2010

Published online: February 24, 2011

Supplementary Information

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Publication Dates

• Publication in this collection
  22 July 2011
• Date of issue
  July 2011

History

• Accepted
  24 Feb 2011
• Received
  25 Oct 2010