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South African Journal of Chemistry

On-line version ISSN 1996-840X
Print version ISSN 0379-4350

S.Afr.j.chem. (Online) vol.67  Durban Jan. 2014

 

RESEARH ARTICLE

 

An Efficient and Rapid Access to the Synthesis of Tetrahydrochromeno[4,3-b]chromene-6,8-dione Derivatives by Magnesium Perchlorate

 

 

Hamideh Emtiazi; Mohammad Ali Amrollahi*

Department of Chemistry, Yazd University, P.O.Box 89195-741, Yazd. Iran

 

 


ABSTRACT

A rapid and green procedure has been introduced for the preparation of tetrahydrochromeno[4,3-b]chromene-6,8-dione derivatives in the presence of magnesium perchlorate. This solvent-free procedure offers some advantages such as short reaction times, high yields, an easy-to-handle catalyst, and avoidance of organic solvents. In this work four new compounds are reported.

Keywords: Tetrahydrochromeno[4,3-b]chromene-6,8-dione, solvent-free, magnesium perchlorate, three-component reactions.


 

 

1. Introduction

Multi-component reactions (MCRs), involving three or more reactants in one pot, have been used to synthesize structurally diverse bioactive heterocyclic compounds.1 A number of tetra-hydrochromeno[4,3-fc]chromene-6,8-dione derivatives have been synthesized utilizing one-pot three-component reactions.2-6 There are a few reports on coupling of 4-hydroxy-coumarin, aldehydes, and cyclic 1,3-diketone compounds.7-10 However, these methods for preparing tetrahydrochromeno [4,3-b]chromene-6,8-dione derivatives have not been entirely satisfactory and involve some disadvantages such as long reaction times and use of organic solvents. Magnesium perchlorate [Mg(ClO4)2] is a non-toxic, cheap, commercially available, moisture stable white crystal. In continuation of our research on the applications of solid acids in organic synthesis,11 it was found interesting to develop a green and more general protocol for the efficient one-pot three-component synthesis of tetrahydrochro-meno[4,3-fc]chromene-6,8-dione derivatives in the presence of Mg(ClO4)2.

 

2. Results and Discussion

The 10,10-dimethyl-7-phenyl-10,11-dihydrochromeno[4,3-b] chromene-6,8(7H,9H)-dione was synthesized by the condensation of 4-hydroxycoumarin, 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and benzaldehyde in the presence of Mg(ClO4)2 as a catalyst. Initially, we explored the catalytic efficiency of Mg(ClO4)2 and the other Lewis acids such as MgSO4, MgBr2 MgCl2 and LiClO4. However, MgSO4, MgBr2 and LiClO4 did not exhibit any significant catalytic activity, and only a 70% yield was obtained in the presence of MgCl2. This establishes the fact that amongst the various salts used, Mg(ClO4)2 was the most effective catalyst for the synthesis of 10,10-dimethyl-7-phenyl-10,11-dihydrochromeno[4,3-fc]chromene-6,8(7H,9H)-dione. To optimize the reaction conditions, dimedone 1 (1 mmol), 4-hydroxycoumarin 2 (1 mmol) and benzaldehyde 3 (1 mmol) were used in the presence of Mg(ClO4)2 under different conditions. We found that using a 0.04 g (0.18 mmol) catalyst at 90 0C in solvent-free conditions gave optimum results (Table 1, Entries 7, 10-14). We also observed that, besides 4a, a trace of 4b was formed in the above optimized conditions. This is due to the high reactivity of the 3-position of 4-hydroxycoumarins. When the reaction was carried out in the presence of a solvent, 4b was obtained in a higher yield in comparison to the amount obtained in solvent-free conditions. To examine the reusability of Mg(ClO4)2 under solvent-free conditions, after each run, the catalyst residue was washed with hot CH2Cl2 and reused. The catalyst was reusable although a gradual decline was observed in its activity (Table 1, Entry 12).

We investigated the generality of this reaction by using, dimedone 1, 4-hydroxycoumarin 2, and various aromatic aldehydes under the optimized conditions (Table 2).

Aromatic aldehydes containing electron-withdrawing groups reacted very well with higher yields in a shorter time than aromatic aldehydes with electron-donating groups (Table 2, Entry 3, 12). Also, α,β -unsaturated aldehydes such as cinnam-aldehyde were easily converted to the desired product under the same experimental conditions, but in lower yields (Table 2, Entry 14). Entries 4,10,12 and 14 in Table 2 are new compounds.

Finally, in order to assess the efficiency and generality of this methodology, we compared this method with some reported results in the literature. From comparison with the results depicted in Table 3, it was found that Mg(ClO4)2 is the most efficient catalyst with respect to reaction time, temperature and yield of the product (Table 3).

It is clear from the results that our method compare better than the best methods currently available in literature. Although the mechanism of the reaction has not yet been established experimentally, the formation of the product can be rationalized as outlined in Scheme 1.

In summary, this paper reports a quick and efficient procedure for the synthesis of tetrahydrochromeno[4,3-fc]chromene-6,8-dione derivatives via a one-pot three-component reaction. The short reaction time, high yield, and availability of Mg(ClO4)2 as a catalyst are the prominent features of this transformation. Moreover, the experimental procedure for this reaction is remarkably simple and without the use of hazardous or expensive organic solvents.

 

3. Experimental

3.1. Materials and Instruments

The products were characterized by IR, 1H-, and 13C-NMR and by comparison of their physical properties with those reported in the literature. IR spectra were recorded on a Bruker, Eqinox 55 spectrometer. 1H- and 13C-NMR spectra were obtained using a Bruker Avance 400- and 500-MHz spectrometer (DRX). The melting points were determined with a Buchi melting point B-540 B.V.CHI apparatus.

3.2. General Procedure for the Synthesis of 10,11-Dihydro-chromeno[4,3-fr]chromene-6,8(7fm,9fl)-dione Derivatives

A mixture of dimedone (1 mmol, 0.14 g), 4-hydroxycoumarin (1 mmol, 0.16 g), aldehyde (1 mmol) and Mg(ClO4)2 (0.18 mmol, 0.04 g) was heated under solvent-free conditions at 90 0C for an appropriate time. After completion of the reaction, for isolation of catalyst the mixture was dissolved in hot CH2Cl2 and filtered. The solvent of resulted filtrate was evaporated and the pure product was obtained by recrystalization from ethanol. In Table 2, entries 4, 10, 12 and 14 are new tetrahydrochromeno[4,3-fr] chromene-6,8-dione derivatives. The IR and NMR spectra of the new compounds are provided as supplementary material.

3.3. Spectroscopic Data

10/10-Dimethyl-7-phenyl-10/11-dihydrochromeno[4/3-b ]chro-mene-6/8(7H/9H)-dione (Table 2, Entry 1): M.p. 220-222 0C [7], IR: 2960,1711,1664,1604,1490,1452,1364,1324,1288,1182,1164, 1051,1031,892,764. Ή-NMR (500 MHz, CDC3): 1.09 (s, 3 H); 1.11 (s, 3 H); 2.22 (d, J = 16.4 Hz, 2 H); 2.64 (d, J = 16.4 Hz, 2 H); 4.96 (s, 1 H); 7.17 (t, J = 7.4 Hz, 1 H); 7.25 (t, J = 7.4 Hz, 2 H); 7.29 (d, J = 7.6 Hz, 2 H); 7.37-7.44 (m, 2 H); 7.62 (t, J = 8.0 Hz, 1 H); 7.85 (dd, J = 8.0 Hz, J = 1.8 Hz, 1H). 13C-NMR (125 MHz, CDC3): 27.2,28.9, 32.0, 33.2 40.3, 50.9, 105.0, 114.2, 115.3, 115.9, 120.1, 123.2, 125.3, 127.6, 128.5, 131.2, 140.3, 153.3, 153.7, 161.9, 196.2.

10/10-Dimethyl-7-(3-nitrophenyl)-10/11-dihydrochromeno[4/3-b] chromene-6/8(7H/9H)-dione (Table 2, Entry 2): M.p. 230-232 0C [9], IR: 2973,1719,1657,1609,1526,1351,1181,1142,1093,1034,1031, 818, 764.1H-NMR (500 MHz, CDC3): 1.10 (s, 3 H); 1.13 (s, 3 H); 2.24 (d, J = 16.0 Hz, 2 H); 2.41 (d, J = 16.4 Hz, 2 H); 4.99 (s, 1 H); 7.22 (t, J = 7.5 Hz, 1H); 7.29 (d, J = 7.5 Hz, 1H); 7.40 (d, J = 7.6 Hz, 2 H); 7.61-7.68 (m, 2 H); 7.88 (t, J = 7.8 Hz, 1H); 8.05 (d, J = 7.8 Hz, 1 H). 13C-NMR (125 MHz, CDC3): 28.3,29.2, 30.5, 34.8, 39.4, 51.2 107.0, 113.4, 114.0, 115.6, 122.6, 124.0, 127.0, 128.2, 128.9, 130.9, 132.8, 136.4, 138.4, 149.5, 155.0, 163.2, 196.0.

10/10-Dimethyl-7-(4-nitrophenyl)-10/11-dihydrochromeno[4/3-b] chromene-6/8(7H/9H)-dione (Table 2, Entry 3): M.p. 208-210 0C [9], IR: 2930,1719,1651,1605,1528,1458,1342,1178,1098,1033,863, 760. Ή-NMR (400 MHz, CDCl3): 1.10 (s, 3 H); 1.12 (s, 3 H); 2.18 (d, J = 16.4 Hz, 1 H); 2.26 (d, J = 16.4 Hz, 1 H); 2.67 (d, J = 18.1 Hz, 1H); 2.73 (d, J = 18.1 Hz, 1H); 4.95 (s, 1H); 6.90 (d, J = 8.8 Hz, 2 H); 7.04 (d, J = 8.8 Hz, 2 H); 7.34-7.40 (m, 2 H); 7.59 (t, J = 8.2 Hz, 1H); 7.89 (dd, J = 8.2 Hz, J = 1.6 Hz 1 H). 13C-NMR (100 MHz, CDC3): 27.3, 29.3, 31.2, 32.8, 40.8, 50.7, 114.8, 115.0, 115.1, 115.3, 115.5, 117.0, 122.5, 124.4, 129.8, 129.9, 130.2, 130.3, 132.4, 162.0, 162.3, 163.0, 196.5.

10/10-Dimethyl-7-(3-fluorophenyl)-10/11-dihydrochromeno[4/3-b ] chromene-6/8(7H/9H)-dione (Table 2, Entry 4): M.p. 247-249 0C, IR: 2957,1720,1664,1607,1362,1260,1175,1054,1030,889, 766 . Ή-NMR (500 MHz, CDC3): 1.14 (s, 3 H); 1.21 (s, 3 H), 2.32 (d, J = 16.5 Hz, 1 H); 2.37 (d, J = 16.5 Hz, 1 H); 2.70 (d, J = 16.5 Hz, 1 H); 2.77 (d, J = 18.5 Hz, 1 H); 5.01 (s, 1 H); 6.87-6.91 (m, 1 H); 7.08 (d, J = 10.0 Hz, 1 H); 7.24-7.28 (m, 2 H); 7.37 (d, J = 8.5 Hz, 1 H); 7.42 (t, J = 8.0 Hz, 1 H); 7.62 (t, J = 7.5 Hz, 1H); 7.91 (dd, J = 8.0 Hz, J = 1.5 Hz, 2 H). 13C-NMR (100 MHz, CDCL): 27.5, 29.8, 31.8, 32.6, 39.3.50.9.105.3.115.2.115.4.123.3.123.6.123.7128.1.128.2.131.0, 132.0, 143.3, 147.2, 147.9, 159.8, 161.3, 164.0, 196.4. Anal. calc. for C24H19FO4 (390.40): C 73.84, H 4.91; found C 73.5, H 4.8.

10.10-Dimethyl-7-(4-chlorophenyl)-10,11-dihydrochromeno[4,3-b ] chromene-6,8(7H,9H)-dione (Table 2, Entry 6): M.p. 248-250 0C [9], IR: 2983, 1718, 1662, 1607, 1490, 1360, 1189, 1092, 1013, 895, 762. Ή-NMR (500 MHz, CDCL): 1.02 (s, 3 H); 1.10 (s, 3 H); 2.20 (d, J = 16.0 Hz, 1 H); 2.33 (d, J = 15.5 Hz, 1 H); 2.73-2.82 (m, 2 H); 4.66 (s, 1H); 7.01 (d, J = 8.0 Hz, 2 H); 7.12 (d, J = 8.0 Hz, 2 H); 7.46 (m, 2 H); 7.70 (t, J = 7.5 Hz, 1 H); 7.95 (d, J = 7.5 Hz, 1 H). 13C-NMR (125 MHz, CDCl3): 27.5, 28.2, 30.7, 34.7, 39.5, 57.0, 105.9, 113.0, 116.6, 119.0, 122.5, 123.8, 124.7, 133.0, 135.5, 138.8, 148.2, 149.0, 152.2, 153.8 158.0, 162.9, 196.2.

10.10-Dimethyl-7-(4-methylphenyl)-10,11-dihydrochromeno[4,3-b ] chromene-6,8(7H,9H)-dione (Table 2, Entry 7): M.p. 208-210 0C [8], IR: 2957,1714,1666,1605,1562,1453,1353,1307,1265,1192,1034, 952, 762. 1H-NMR (500 MHz, CDCl3): 1.00 (s, 3 H); 1.09 (s, 3 H); 2.27 (d, J = 16.6 Hz, 2 H); 2.46 (d, J = 16.6 Hz, 2 H); 4.74 (s, 1 h); 7.31 (d, J = 8.0 Hz, 2 H); 7.40 (d, J = 8.0 Hz, 2 H); 7.52 (m, 2H); 7.75 (t, J = 8.0 Hz, 1H); 7.91 (dd, J = 8.1 Hz, J = 1.5 Hz, 1 H). 13C-NMR (125 MHz, CDCl3): 28.2, 28.4, 29.7, 33.0, 38.9, 52.2, 105.1, 111.2, 114.9, 116.6, 124.2, 125.8, 126.2, 130.8, 136.9, 137.1, 141.2, 148.5, 152.4, 155.1, 157.3, 161.9, 196.1.

10.10-Dimethyl-7-(3-bromophenyl)-10,11-dihydrochromeno[4,3-b] chromene-6,8(7H,9H)-dione (Table 2, Entry 8): M.p. 258-260 0C [10], IR: 2970,1719,1664,1607,1568,1454,1360,1185,1140,1054, 1050,1034, 755. Ή-NMR (500 MHz, CDCL): 1.30 (s, 3 H), 1.19 (s, 3 H), 2.29 (d, J = 16.8 Hz, 1H); 2.35 (d, J = 16.4 Hz, 1H); 2.67 (d, J = 17.1 Hz, 1 H); 2.76 (d, J = 17.1 Hz, 1 H); 4.94 (s, 1 H); 7.16 (t, J = 8.0 Hz, 1 H); 7.28-7.43 (m, 5 H); 7.61 (t, J = 7.6 Hz, 1 H); 7.90 (dd, J = 8.0 Hz, J=1.2 Hz,1 H). 13C-NMR (125 MHz, CDCL): 27.6,29.1, 32.4, 33.3, 40.8, 50.7, 106.1, 113.7, 114.7, 117.0, 122.4, 128.0, 129.8, 130.3, 131.3, 132.5, 144.7, 150.0, 154.1, 160.6, 162.3, 195.9.

10.10-Dimethyl-7-(4-methoxyphenyl)-10,11-dihydrochromeno[4,3-b] chromene-6,8(7H,9H)-dione (Table 2, Entry 9): M.p. 187-189 0C [7], IR: 2957,1725,1660,1606,1509,1456,1359,1302,1250,1183,1167, 1140,1033,893,764. Ή-NMR (500 MHz, CDCL): 1.14 (s, 3 H); 1.17 (s, 3 H); 2.21 (m, 2 H); 2.39 (m,2H); 4.85 (s, 1 H); 7.24 (d, J = 7.5 Hz,2 H); 7.43 (d, J = 7.5 Hz, 2 H); 7.55 (m, 2 h); 7.79 (t, J = 8.0Hz,1 H); 7.98 (d, J = 8.0 Hz, 1 H). 13C-NMR (125 MHz, CDCL): 27.0, 27.2, 28.4, 30.1, 37.0, 54.5, 106.3, 114.0, 114.1, 115.2, 123.0, 123.8, 128.3, 135.9, 136.2, 138.2, 143.9, 150.8, 153.1, 156.8, 158.1, 161.0, 195.9.

10.10-Dimethyl-7-(3,4-dimethoxyphenyl)-10,11-dihydrochromeno[4, 3-b]chromene-6,8(7H,9H)-dione (Table 2, Entry 10): M.p. 184-185 0C, IR: 2921,1721,1660,1620,1513,1455,1361,1262,1139, 896, 742. Ή-NMR (400 MHz, CDCL): 1.13 (s, 3 H); 1.19 (s, 3 H); 2.30 (d, J = 16.0 Hz, 1 H); 2.35 (d, J = 16.0 Hz, 1 H); 2.68 (d, J = 17.6 Hz, 1 H); 2.74 (d, J = 17.6 Hz, 1 H); 3.81 (s, 3 H); 3.89 (s, 3 H); 4.93 (s, 1H); 6.74 (d, J = 8.1 Hz, 1 H); 6.82 (dd, J = 8.0 Hz, J=1.6 Hz,1 H); 7.05 (s, 1 H); 7.33-7.39 (m, 2 H); 7.58 (t, J = 8.0 Hz, 1 H); 7.88 (d, J = 8.0 Hz, 1 H). 13C-NMR (100 MHz, CDCL): 27.5, 29.3, 32.4, 32.8.40.9.50.7.106.9.110.9.112.7.113.7.115.2.116.9.120.2.122.4, 124.3, 132.2, 135.4, 148.0, 148.6, 152.6, 153.7, 160.7, 161.9, 196.2. Anal. calc. for C26H24O6 (432.47): C 72.21, H 5.59; found C 72.0, H 5.8.

10.10-Dimethyl-7-(3-hydroxyphenyl)-10,11-dihydrochromeno[4,3-b] chromene-6,8(7H,9H)-dione (Table 2, Entry 11): M.p. 267-269 0C [7], IR: 3400, 2983, 1697, 1665, 1607, 1488, 1364, 1175, 1137, 1058, 897,767. Ή-NMR (500 MHz, DMSO-d6): 1.00 (s, 3 H); 1.10 (s, 3 H); 2.75 (sbr, 2 H); 2.37 (d, J = 16.5 Hz, 1 H); 4.62 (s, 1H); 6.55 (dd, J = 7.5 H , J = 2.1 Hz, 1 H); 6.66 (d, J = 7.0 Hz, 1 h); 6.71 (s, 1 H); 7.03 (t, J = 8.0 Hz, 1 H); 7.44 (d, J = 8.5 Hz, 1 H); 7.46 (t, J = 7.0 Hz, 1H); 7.69 (t, J = 7.5 Hz, 1H); 7.93 (dd, J = 7.5 Hz, J = 1.5 Hz, 1H); 9.29 (s, 1H). 13C-NMR (125 MHz, DMSO-d6): 27.6, 29.4, 32.9, 33.6, 50.9, 106.8, 114.0, 114.7, 114.8, 116.4, 117.4, 119.7, 123.4, 125.6, 129.9, 133.7, 145.0, 152.8, 154.5, 158.0, 163.4, 196.7.

10.10-Dimethyl-7-(4-hydroxyphenyl)-10,11-dihydrochromeno[4,3-b] chromene-6,8(7H,9H)-dione (Table 2, Entry 12): M.p. 267-268 0C, IR: 3431, 1697, 1665, 1607, 1585, 1488, 1364, 1176, 897, 767. Ή-NMR (400 MHz, DMSO-d6): 1.03 (s, 3 H); 1.09 (s, 3 H); 2.18 (d, J = 16.6 Hz, 2H); 2.33 (d, J = 16.6 Hz, 2 H); 4.60 (s, 1H); 6.62 (d, J = 8.6 Hz, 2 H); 7.05 (d, J = 8.6 Hz, 2 H); 7.46 (m, 2 H); 7.70 (t, J = 7.6 Hz, 1 h); 7.94 (t, J = 7.6 Hz, 1 H); 9.29 (s, 1 H). 13C-NMR (100 MHz, DMSO-d6): 26.7,28.5,31.9,32.0,39.5,50.0,106.2,113.2,114.1, 114.8, 116.5, 122.5, 124.7, 129.3, 132.7, 133.3, 151.9, 153.3, 156.1,159.9,162.3,195.9. Anal. calc. for C24H20O5 (388.41): C 74.21, H 5.19; found C 73.9, H 5.0.

10.10-Dimethyl-7-(4-hydroxy-3-methoxyphenyl)-10,11-dihydrochro meno[4,3-b]chromene-6,8(7H,9H)-dione (Table 2, Entry 13): M.p. 271-273 0C [7], IR: 3434, 2993, 1713, 1662, 1608, 1514, 1361, 1272, 1181,1033,863, 779. Ή-NMR (400 MHz, DMSO-d6): 1.02 (s, 3 H); 1.10 (s, 3 H); 2.20 (d, J = 16.0 Hz, 1 H); 2.34 (d, J = 16.0 Hz, 1 h); 2.76 (s, 2H), 3.70 (s, 3H); 4.61 (s, 1H); 6.61 (d, J = 8.0 Hz, 1 H); 6.64 (d, J = 8.0 Hz, 1H); 6.81 (d, J = 1.6 Hz, 1H); 7.43-7.48 (m, 2 H); 7.69 (t, J = 7.8 Hz, 1 h); 7.92 (d, J = 8.0 Hz, 1 h); 8.88 (s, 1 H). 13C-NMR (100 MHz, DMSO-d6): 26.5,28.6, 31.9, 32.2, 39.6, 50.0,55.6,106.1, 112.8, 113.2, 114.0, 115.1, 116.5, 120.5, 122.5, 124.7, 132.6, 133.8, 145.5, 147.0, 151.8, 153.3, 160.0, 162.4, 196.0.

10.10-Dimethyl-7-styryl-10,11-dihydrochromeno[4,3-b]chromene-6, 8(7H,9H)-dione (Table 2, Entry 14): M.p. 132-134 0C, IR: 2956, 1713,1661,1609,1453,1361,1239, 1173, 1138,1032, 970, 762, 696. Ή-NMR (400 MHz, CDCl3):1.10 (s, 3 H); 1.12 (s, 3 H); 2.36 (s, 2 H); 2.53 (d, J = 16.8 Hz, 1 H); 2.62 (d, J = 16.8 Hz, 1 H); 4.56 (br s, 1 h); 6.22 (dd, J = 16.0 Hz, J = 6.4,1 H); 6.32 (d, J = 16.0 Hz, 1 H); 7.09 (t, J =7.2 Hz, 1 H); 7.14-7.23 (m, 4 H); 7.26-7.31 (m, 2 H); 7.51 (t, J = 8.0 Hz, 1 H); 7.76 (d, J = 7.2 Hz, 1 H). 13C-NMR (100 MHz, CDCL): 27.6, 29.0, 32.2, 33.5, 40.9, 50.8, 107.1, 116.9, 122.4, 124.3, 126.4, 126.5, 127.5, 128.3, 128.4, 129.5, 131.8, 132.3, 147.6, 162.1, 165.0, 166.9, 196.6. Anal. calc. for C32H26O4 (474.55): C 80.99, H 5.52; found C 81.3, H 5.8.

10.10-Dimethyl-7(2,4-dichlorophenyl)-10,11-dihydrochromeno[4,3-b ]chromene-6,8(7H,9H)-dione (Table 2, Entry 15): M.p. 250-252 0C [7], IR: 2956, 1716, 1664, 1611, 1583, 1470, 1360, 1265, 1173, 1061, 1052, 832, 753. Ή-NMR (400 MHz, CDCL): 1.08 (s, 3 H), 1.12 (s, 3 H); 2.22 (d, J = 16.0 Hz, 1 H); 2.28 (d, J = 16.0 Hz, 1 H); 2.69 (s, 2H); 4.92 (s, 1 H); 7.01 (d, J = 8.0 Hz, 1 H); 7.13 (d, J = 8.0 Hz, 1 H); 7.30 (s, 1 H); 7.39-7.49 (m, 2H); 7.69 (t, J = 7.6 Hz, 1 H); 7.98 (d, J = 7.8 Hz, 1 H). 13C-NMR (100 MHz, CDCL): 28.0, 28.9, 31.9, 33.1, 40.9,52.3,107.2,112.2,114.8,115.1,116.0,118.2,123.9,124.1,124.3, 135.4, 137.9, 144.2, 150.0, 151.0, 156.9, 158.3, 160.9, 195.0.

 

Acknowledgements

The authors thank the Research Council of Yazd University for the financial support.

Supplementary Material

The IR and NMR spectra of the four new compounds reported herein are provided as supplementary material.

 

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Received 29 December 2013
Revised 27 September 2014
Accepted 29 September 2014.

 

 

* To whom correspondence should be addressed. E-mail:mamrollahi@yazd.ac.ir

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