research article a fast, highly efficient, and green protocol for … · 2020-01-17 · cient...

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 179013 5 pageshttpdxdoiorg1011552013179013

Research ArticleA Fast Highly Efficient and Green Protocol for Synthesis ofBiscoumarins Catalyzed by Silica Sulfuric Acid Nanoparticles asa Reusable Catalyst

Bahareh Sadeghi and Tayebe Ziya

Department of Chemistry Yazd Branch Islamic Azad University PO Box 89195-155 Yazd 8916871967 Iran

Correspondence should be addressed to Bahareh Sadeghi bsadeghiagmailcom

Received 13 May 2013 Accepted 11 July 2013

Academic Editor Christophe Len

Copyright copy 2013 B Sadeghi and T Ziya This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Silica sulfuric acid nanoparticles have been prepared and shown to efficiently catalyse the reaction between an aromatic aldehydeor phenylglyoxal and a 4-hydroxycoumarin at reflux in EtOH to afford the biscoumarin derivatives in high yield

1 Introduction

A variety of biological activities are associated with coum-arins and biscoumarins for example anticoagulants andantianthelmintic and antifungal activities [1ndash3] Further-more these compounds can be complexed with rare earthmetals as anti-HIV agents [4] The synthesis of biscoumarinshas been reported in the presence of piperidine [5]moleculariodine [6] tetrabutylammonium bromide [7] [bmim]BF

4

[8] sodium dodecyl sulfate [9] SO3H-functionalized ionic

liquid [10] and [MIM(CH2)4SO3H][HSO

4] [11]

In this paper we report a simple and efficient method forsynthesis of biscoumarin derivatives using different aromaticaldehydes and phenylglyoxals and 4-hydroxycoumarin in thepresence of silica sulfuric acid nanoparticles under reflux inethanol The catalyst is recyclable with reproducible resultswithout any loss of its activity The morphology of the silicasulfuric acid nanoparticles was observed using a scanningelectron microscope (SEM)

2 Experimental

21 General IR spectra were recorded on a Shimadzu IR-470spectrometer in KBr discs The NMR spectra were obtainedon a Bruker Avance DRX-500 FT spectrometer (1H NMRat 500Hz 13C NMR at 125Hz) using CDCl

3as solvent with

TMS as internal standard Melting points were determined

with an Electrothermal 9100 apparatus Elemental analyseswere performed using a Costech ECS 4010 CHNS-O analyzerat Analytical Laboratory of Science and Researches Unit ofIslamic Azad University The morphology of the catalystwas observed using an SEM model VEGATESCAN withan accelerating voltage of 15 kV The chemicals used in thiswork were purchased from Sigma Aldrich and Fluka (BuchsSwitzerland) and were used without further purification

22 Synthesis of Silica Sulfuric Acid Nanoparticles The rea-gent was prepared by combination of chlorosulfonic acid(233 g) drop by drop over 10min via a syringe to nanosilicagel powder (60 g) in a 100mL flask at 0∘C The reactionmixture was then stirred and then after 30min the whitepowder was separatedThe dimensions of nanoparticles wereobserved with SEM (Figure 1)The size of particles is between28 and 32 nm

23 General Procedure for the Synthesis of Biscoumarin Amixture of 4-hydroxycoumarin (2mmol) aromatic aldehydeor arylglyoxal (1mmol) SiO

2-OSO

3H NPs (0003 g) and

EtOH (5mL) was placed in a round bottom flask Thematerials were mixed and refluxed for 20min The progressof the reaction was followed by TLC (n-hexaneethylacetate)After completion of the reaction the mixture was filtered toremove the catalyst By evaporation of the solvent the crude

2 Journal of Chemistry

Figure 1 The SEM images of SiO2-OSO

3H NPs

product was recrystallized from hot ethanol to obtain thepure compound

24 Selected Spectral Data

331015840-Bis (4-hydroxy coumarin-3yl) (3-nitro-4-chlorophenyl)methane (4m) IR (KBr) ]max 3450 3015 1664 1603 15611348 761 cmminus1 1H NMR (500MHz CDCl

3) 120575 63 (119904 1H

CH) 727 (119889 2H 119869 = 75Hz aromatic) 734 (119889 2H 119869 =82Hz aromatic) 748 (119889 1H 119869 = 82Hz aromatic) 755ndash759 (119898 3H aromatic) 779 (119904 1H aromatic) 788 (119889 2H119869 = 77Hz aromatic) 123 (broad 119904 2H OH) ppm 13CNMR(125MHz CDCl

3) 120575 369 1041 1168 1189 1226 1246 1317

1327 1333 1434 1485 1532 1652 1666 ppm Anal CalcdFor C

25H14ClNO

8 C 6103 H 283 N 283 Found C 6102

H 287 N 285

331015840-Bis (4-hydroxy coumarin-3yl) (24-dichlorophenyl) meth-ane (4n) IR (KBr) ]max 3485 3085 1664 1603 766 cm

minus11H NMR (500MHz CDCl

3) 120575 61 (119904 1H CH) 726 (119905119889 2H

119869 = 85Hz 119869 = 2Hz aromatic) 739 (119905119889 2H 119869 = 61 Hz119869 = 2Hz aromatic) 741 (119889 2H 119869 = 8Hz aromatic) 743(119904 1H aromatic) 766 (119905119889 2H 119869 = 85Hz 119869 = 13Hzaromatic) 805 (119889 2H 119869 = 64Hz aromatic) 1168 (broad119904 2H OH) ppm 13C NMR (125MHz CDCl

3) 120575 319 1021

1142 1191 1214 1237 1303 1329 1333 1358 1435 15211659 1671 ppm Anal Calcd For C

25H14Cl2O6 C 6238 H

293 Found C 6232 H 279

331015840-Bis (4-hydroxy coumarin-3yl) (4-nitrophenyl) ethanon(5a) IR (KBr) ]max 3355 3015 1696 1664 1547 1357754 cmminus1 1H NMR (500MHz CDCl

3) 120575 64 (119904 1H CH)

734 (119905119889 2H 119869 = 74Hz 119869 = 2Hz aromatic) 736 (119898 2Haromatic) 758 (119889119889 2H 119869 = 74Hz 119869 = 2Hz aromatic) 778(119898 2H aromatic) 791 (119889 2H 119869 = 8Hz aromatic) 829 (1198892H 119869 = 8Hz aromatic) 113 (broad 119904 2H OH) ppm 13CNMR (125MHz CDCl

3) 120575 802 1041 1157 1192 1217 1242

1284 1302 1329 1421 1537 1582 1629 1672 1980 ppmAnal Calcd For C

26H15NO9 C 6433 H 311 N 288 Found

C 6421 H 304 N 285

331015840-Bis (4-hydroxy coumarin-3yl) (4-bromophenyl) ethanon(5b) IR (KBr) ]max 3335 3085 1696 1648 759 cm

minus1 1HNMR (500MHz CDCl

3) 120575 631 (119904 1H CH) 724 (119889 2H

119869 = 75Hz aromatic) 727 (119889 2H 119869 = 83Hz aromatic)75 (119905 2H 119869 = 7Hz aromatic) 758 (119889 2H 119869 = 85Hzaromatic) 771 (119889 2H 119869 = 85Hz aromatic) 784 (119889 2H119869 = 75Hz aromatic) 1041 (broad 119904 2HOH) ppm 13CNMR(125MHz CDCl

3) 120575 800 1025 1167 1190 1216 1242 1247

1302 1320 1324 1531 1643 1672 1652 1965 ppm AnalCalcd For C

26H15BrO7 C 6013 H 291 Found C 6008 H

289

331015840-Bis (4-hydroxy coumarin-3yl) (phenyl) ethanon (5c) IR(KBr) ]max 3405 3015 1692 1637 764 cmminus1 1H NMR(500MHz CDCl

3) 120575 635 (119904 1H CH) 729 (119905119889 2H 119869 =

74Hz 119869 = 2Hz aromatic) 735 (119898 3H aromatic) 747 (1198892H 119869 = 78Hz aromatic) 757 (119898 2H aromatic) 771 (1198982H aromatic) 782 (119889 2H 119869 = 8Hz aromatic) 1041 (broad119904 2H OH) ppm 13C NMR (125MHz CDCl

3) 120575 803 1019

1155 1187 1210 1243 1297 1301 1318 1332 1362 15131618 1674 1942 ppm Anal Calcd For C

26H16O7 C 709

H 366 Found C 707 H 359

3 Results and Discussion

In continuation of our investigations of the application ofsolid acids in organic synthesis [12ndash16] we have investigatedthe synthesis of biscoumarin derivatives by condensationof a 4-hydroxycoumarin 1 and an aromatic aldehyde 2 orphenylglyoxals 3 in the presence of 0003 g SiO

2-OSO

3HNPs

catalystThe stable silica gel nanoparticles are easily prepared [17]

and used for preparation of catalyst (SiO2-OSO

3H NPs)

To optimize the reaction conditions the reaction ofbenzaldehyde and 4-hydroxycoumarin was used as a modelreaction Initially the catalytic activity of SiO

2-OSO

3H NPs

has been compared with other catalysts according to theobtained data and this catalyst afforded good yields howeverit has limitations of long reaction time harsh reactionconditions and often expensive catalysts (Table 1 entry 1ndash6)In order to determine the optimum quantity of SiO

2-OSO

3H

NPs model reaction was carried out at reflux in ethanolcondition (Table 1 entry 7ndash9) SiO

2-OSO

3H NPs (0003 g)

gave an excellent yield in 20min (Table 1 entry 8) Theprevious reaction was also examined in various solvents Thebest results were obtainedwhen EtOHwas used as a solvent atreflux (Table 1 entry 8) An interesting feature of this methodis that the reagent can be regenerated at the endof the reactionand can be used several times without losing its activityTo recover the catalyst after completion of the reaction themixture was filtered and catalyst was washed with CHCl

3

and then the solid residue dries This process was repeatedfor two cycles and the yield of product 4a did not changesignificantly (Table 1 entry 12 13)

Journal of Chemistry 3

Table 1 Synthesis of 4a under various conditions

Entry Catalyst (amount) CondSol Time (min) Yielda () Reference1 I2 (10mol) 100∘CH2O 25 97 [6]2 TBABb (4mol) 120∘Cmdash 20 85 [7]3 [bmim]BF4 (4mmol) 60ndash70∘Cmdash 120 84 [8]4 SDSc (02mol 576mg) 60∘CH2O 140 90 [9]5 [PSebim][OTf] (05mol) 70∘Cmdash 120 95 [10]6 [MIM(CH2)4SO3H][HSO4](3mol) 80∘Cmdash 30 92 [11]7 SiO2-OSO3H NPs (0001 g) 80∘CEtOH 20 89 mdash8 SiO2-OSO3H NPs (0003 g) 80∘CEtOH 20 93 mdash9 SiO2-OSO3H NPs (0005 g) 80∘CEtOH 20 93 mdash10 SiO2-OSO3H NPs (0003 g) 100∘CH2O 20 87 mdash11 SiO2-OSO3H NPs (0003 g) 40∘CCH2Cl2 20 82 mdash12 SiO2-OSO3H NPs (0003 g) 2nd run 80∘CEtOH 20 89 mdash13 SiO2-OSO3H NPs (0003 g) 3rd run 80∘CEtOH 20 87 mdashaIsolated yield btetrabutylammonium bromide and csodium dodecyl sulfate

Table 2 SiO2-OSO3H NPs catalyzed the synthesis of biscoumarin derivatives

Entry Ar Product Yielda mp∘CFound Reported [Ref]

1 C6H5 4a 93 228ndash230 229ndash231 [11]2 4-BrC6H4 4b 86 266ndash268 265ndash267 [9]3 4-FC6H4 4c 90 211ndash213 213ndash215 [9]4 4-MeC6H4 4d 96 268ndash270 266ndash269 [11]5 2-OHC6H4 4e 94 253ndash255 254ndash256 [11]6 4-OHC6H4 4f 93 194ndash196 193 [5]7 4-(CH3)2NC6H4 4g 92 221ndash223 222ndash224 [9]8 3-NO2C6H4 4h 95 215ndash217 214-215 [11]9 4-NO2C6H4 4i 96 233ndash235 233ndash235 [11]10 3-ClC6H4 4j 91 222ndash224 221ndash223 [11]11 4-ClC6H4 4k 95 262ndash264 261ndash263 [11]12 3-Pyridyl 4l 88 279ndash281 278 [5]13 3-NO2-4-ClC6H3 4m 92 249ndash252 mdash14 24-ClC6H3 4n 89 198ndash200 mdash15 4-NO2C6H4CO 5a 96 249ndash251 mdash16 4-BrC6H4CO 5b 90 204ndash207 mdash17 C6H5CO 5c 93 209ndash211 mdashaIsolated yield

To study the scope of the reaction a series of aro-matic aldehydes or phenylglyoxals and 4-hydroxycoumarincatalysed by SiO

2-OSO

3H NPs were examined (Scheme 1)

The results are shown in Table 2 In all cases aromaticaldehyde or phenylglyoxals substituted with either electron-donating or electron-withdrawing groups underwent thereaction smoothly and gave products in excellent yields

The compounds 4andashl were characterised by their 1H-NMR and IR spectroscopies and elemental analyses Spectraldata were compared with the literature data [5 9 11]

Compounds 4m n and 5andashc were new and their struc-tures were deduced by elemental and spectral analysis The1H-NMR spectrum of compound 5a exhibited proton ofmethine at 64 ppm and OH proton is observed at 113 ppm

which disappears after addition of some D2O to the CDCl

3

solution of 5a There are observed multiplets between 734and 829 ppm which are related to aromatic protons The13C-NMR spectrum of compound 5a showed 15 signals inagreement with the proposed structure The IR spectrum ofcompound 5a also supported the suggested structure

4 Conclusion

In summary we have reported an easy and efficient protocolfor the synthesis of biscoumarins in the easily accessible SiO

2-

OSO3H nanoparticles The method offers marked improve-

ment with its operational simplicity and short reaction timeand affords excellent yieldThe solid phase acidic catalyst was


H

H+

+

1

1

2

3

SiO2-OSO

3H NPs

SiO2-OSO

3H NPs

Reflux EtOH 20min

Reflux EtOH 20min

Ar

Ar

O

O

OO

O

OH

OH

O

O

O OO

OHOH

O

O OO O

O

Ar

OHOHAr

5andashc

4andashn

Scheme 1 Synthesis of biscoumarins by condensation of 4-hydroxycoumarinwith an aromatic aldehyde or phenylglyoxals using SiO2-OSO

3H

NPs as catalyst

reusable for a number of times without appreciable loss ofactivity The present method does not involve any hazardousorganic solvent Therefore this procedure could be classifiedas green chemistry

Acknowledgment

The authors gratefully acknowledge the financial supportfrom the Research Council of Islamic Azad University ofYazd

References

[1] J H Lee H B Bang S Y Han and J-G Jun ldquoAn efficientsynthesis of (+)-decursinol from umbelliferonerdquo TetrahedronLetters vol 48 no 16 pp 2889ndash2892 2007

[2] R D R S Manian J Jayashankaran and R RaghunathanldquoA rapid access to indolo[21-a]pyrrolo[410158403101584045]pyrano[56-c]coumarin[65-c]chromone derivatives by domino Knoeve-nagal intramolecular heteroDiels-Alder reactionsrdquoTetrahedronLetters vol 48 no 8 pp 1385ndash1389 2007

[3] H Zhao N Neamati H Hong et al ldquoCoumarin-basedinhibitors of HIV integraserdquo Journal of Medicinal Chemistryvol 40 no 2 pp 242ndash249 1997

[4] I Manolov S Raleva P Genova et al ldquoAntihuman immun-odeficiency virus type 1 (HIV-1) activity of rare earth metalcomplexes of 4-hydroxycoumarins in cell culturerdquo BioinorganicChemistry and Applications vol 2006 Article ID 71938 7 pages2006

[5] K M Khan S Iqbal M A Lodhi et al ldquoBiscoumarin newclass of urease inhibitors Economical synthesis and activityrdquoBioorganic and Medicinal Chemistry vol 12 no 8 pp 1963ndash1968 2004

[6] M Kidwai V Bansal P Mothsra et al ldquoMolecular iodine aversatile catalyst for the synthesis of bis(4-hydroxycoumarin)methanes in waterrdquo Journal of Molecular Catalysis A vol 268no 1-2 pp 76ndash81 2007

[7] J M Khurana and S Kumar ldquoTetrabutylammonium bromide(TBAB) a neutral and efficient catalyst for the synthesis of

biscoumarin and 34-dihydropyrano[c]chromene derivatives inwater and solvent-free conditionsrdquo Tetrahedron Letters vol 50no 28 pp 4125ndash4127 2009

[8] J M Khurana and S Kumar ldquoIonic liquid an efficient andrecyclablemedium for the synthesis of octahydroquinazolinoneand biscoumarin derivativesrdquoMonatshefte fur Chemie vol 141no 5 pp 561ndash564 2010

[9] HMehrabi andHAbusaidi ldquoSynthesis of biscoumarin and 34-dihydropyrano[c]chromene derivatives catalysed by sodiumdodecyl sulfate (SDS) in neat waterrdquo Journal of the IranianChemical Society vol 7 no 4 pp 890ndash894 2010

[10] W Li Y Wang Z Wang L Dai and Y Wang ldquoNovelSO3H-functionalized ionic liquids based on benzimidazolium

cation efficient and recyclable catalysts for one-pot synthesis ofbiscoumarin derivativesrdquo Catalysis Letters vol 141 no 11 pp1651ndash1658 2011

[11] N Tavakoli-Hoseini M M Heravi F F Bamoharram ADavoodnia and M Ghassemzadeh ldquoAn unexpected tetracyclicproduct isolated during the synthesis of biscoumarins cat-alyzed by [MIM(CH

2)4SO3H] [HSO

4] characterization and X-

ray crystal structure of 7-(2-hydroxy-4-oxo-4H-chromen-3-yl)-6H7H-chromeno[43-b]chromen-6-onerdquo Journal of MolecularLiquids vol 163 no 3 pp 122ndash127 2011

[12] B Sadeghi A Hassanabadi and S Bidaki ldquoSynthesis ofnanoparticles silica supported sulfuric acid (NPs SiO

2-H2SO4)

a solid phase acidic catalyst for one-pot synthesis of 4H-chromene derivativesrdquo Journal of Chemical Research vol 35 no11 pp 666ndash668 2011

[13] M Khazaei M Anary-Abbasinejad A Hassanabadi and BSadeghi ldquoZnO nanoparticles an efficient reagent simple andone-pot procedure for synthesis of highly functionalized dihy-dropyridine derivativesrdquo E-Journal of Chemistry vol 9 no 2pp 615ndash620 2012

[14] B Sadeghi A Namakkoubi and A Hassanabadi ldquoBF3SiO2

nanoparticles a solid phase acidic catalyst for efficient one-pot Hantzsch synthesis of 14-dihydropyridinesrdquo Journal ofChemical Research vol 37 pp 11ndash13 2013

[15] B Sadeghi S Zavar andAHassanabadi ldquoMonolayer-protectedsilver nanoparticles an efficient and versatile reagent forthe synthesis of 34-dihydropyrimidine-2-(1H)-ones (thiones)rdquoJournal of Chemical Research vol 36 pp 343ndash346 2012


[16] B Sadeghi and M Ghasemi Nejad ldquoSilica sulfuric acid an eco-friendly and reusable catalyst for synthesis of benzimidazolederivativesrdquo Journal of Chemistry vol 2013 Article ID 5814655 pages 2013

[17] K Lee A N Sathyagal and A V McCormick ldquoA closer lookat an aggregation model of the Stober processrdquo Colloids andSurfaces A vol 144 no 1ndash3 pp 115ndash125 1998

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

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Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Figure 1 The SEM images of SiO2-OSO

3H NPs

product was recrystallized from hot ethanol to obtain thepure compound

24 Selected Spectral Data

331015840-Bis (4-hydroxy coumarin-3yl) (3-nitro-4-chlorophenyl)methane (4m) IR (KBr) ]max 3450 3015 1664 1603 15611348 761 cmminus1 1H NMR (500MHz CDCl

3) 120575 63 (119904 1H

CH) 727 (119889 2H 119869 = 75Hz aromatic) 734 (119889 2H 119869 =82Hz aromatic) 748 (119889 1H 119869 = 82Hz aromatic) 755ndash759 (119898 3H aromatic) 779 (119904 1H aromatic) 788 (119889 2H119869 = 77Hz aromatic) 123 (broad 119904 2H OH) ppm 13CNMR(125MHz CDCl

3) 120575 369 1041 1168 1189 1226 1246 1317

1327 1333 1434 1485 1532 1652 1666 ppm Anal CalcdFor C

25H14ClNO

8 C 6103 H 283 N 283 Found C 6102

H 287 N 285

331015840-Bis (4-hydroxy coumarin-3yl) (24-dichlorophenyl) meth-ane (4n) IR (KBr) ]max 3485 3085 1664 1603 766 cm

minus11H NMR (500MHz CDCl

3) 120575 61 (119904 1H CH) 726 (119905119889 2H

119869 = 85Hz 119869 = 2Hz aromatic) 739 (119905119889 2H 119869 = 61 Hz119869 = 2Hz aromatic) 741 (119889 2H 119869 = 8Hz aromatic) 743(119904 1H aromatic) 766 (119905119889 2H 119869 = 85Hz 119869 = 13Hzaromatic) 805 (119889 2H 119869 = 64Hz aromatic) 1168 (broad119904 2H OH) ppm 13C NMR (125MHz CDCl

3) 120575 319 1021

1142 1191 1214 1237 1303 1329 1333 1358 1435 15211659 1671 ppm Anal Calcd For C

25H14Cl2O6 C 6238 H

293 Found C 6232 H 279

331015840-Bis (4-hydroxy coumarin-3yl) (4-nitrophenyl) ethanon(5a) IR (KBr) ]max 3355 3015 1696 1664 1547 1357754 cmminus1 1H NMR (500MHz CDCl

3) 120575 64 (119904 1H CH)

734 (119905119889 2H 119869 = 74Hz 119869 = 2Hz aromatic) 736 (119898 2Haromatic) 758 (119889119889 2H 119869 = 74Hz 119869 = 2Hz aromatic) 778(119898 2H aromatic) 791 (119889 2H 119869 = 8Hz aromatic) 829 (1198892H 119869 = 8Hz aromatic) 113 (broad 119904 2H OH) ppm 13CNMR (125MHz CDCl

3) 120575 802 1041 1157 1192 1217 1242

1284 1302 1329 1421 1537 1582 1629 1672 1980 ppmAnal Calcd For C

26H15NO9 C 6433 H 311 N 288 Found

C 6421 H 304 N 285

331015840-Bis (4-hydroxy coumarin-3yl) (4-bromophenyl) ethanon(5b) IR (KBr) ]max 3335 3085 1696 1648 759 cm

minus1 1HNMR (500MHz CDCl

3) 120575 631 (119904 1H CH) 724 (119889 2H

119869 = 75Hz aromatic) 727 (119889 2H 119869 = 83Hz aromatic)75 (119905 2H 119869 = 7Hz aromatic) 758 (119889 2H 119869 = 85Hzaromatic) 771 (119889 2H 119869 = 85Hz aromatic) 784 (119889 2H119869 = 75Hz aromatic) 1041 (broad 119904 2HOH) ppm 13CNMR(125MHz CDCl

3) 120575 800 1025 1167 1190 1216 1242 1247

1302 1320 1324 1531 1643 1672 1652 1965 ppm AnalCalcd For C

26H15BrO7 C 6013 H 291 Found C 6008 H

289

331015840-Bis (4-hydroxy coumarin-3yl) (phenyl) ethanon (5c) IR(KBr) ]max 3405 3015 1692 1637 764 cmminus1 1H NMR(500MHz CDCl

3) 120575 635 (119904 1H CH) 729 (119905119889 2H 119869 =

74Hz 119869 = 2Hz aromatic) 735 (119898 3H aromatic) 747 (1198892H 119869 = 78Hz aromatic) 757 (119898 2H aromatic) 771 (1198982H aromatic) 782 (119889 2H 119869 = 8Hz aromatic) 1041 (broad119904 2H OH) ppm 13C NMR (125MHz CDCl

3) 120575 803 1019

1155 1187 1210 1243 1297 1301 1318 1332 1362 15131618 1674 1942 ppm Anal Calcd For C

26H16O7 C 709

H 366 Found C 707 H 359

3 Results and Discussion

In continuation of our investigations of the application ofsolid acids in organic synthesis [12ndash16] we have investigatedthe synthesis of biscoumarin derivatives by condensationof a 4-hydroxycoumarin 1 and an aromatic aldehyde 2 orphenylglyoxals 3 in the presence of 0003 g SiO

2-OSO

3HNPs

catalystThe stable silica gel nanoparticles are easily prepared [17]

and used for preparation of catalyst (SiO2-OSO

3H NPs)

To optimize the reaction conditions the reaction ofbenzaldehyde and 4-hydroxycoumarin was used as a modelreaction Initially the catalytic activity of SiO

2-OSO

3H NPs

has been compared with other catalysts according to theobtained data and this catalyst afforded good yields howeverit has limitations of long reaction time harsh reactionconditions and often expensive catalysts (Table 1 entry 1ndash6)In order to determine the optimum quantity of SiO

2-OSO

3H

NPs model reaction was carried out at reflux in ethanolcondition (Table 1 entry 7ndash9) SiO

2-OSO

3H NPs (0003 g)

gave an excellent yield in 20min (Table 1 entry 8) Theprevious reaction was also examined in various solvents Thebest results were obtainedwhen EtOHwas used as a solvent atreflux (Table 1 entry 8) An interesting feature of this methodis that the reagent can be regenerated at the endof the reactionand can be used several times without losing its activityTo recover the catalyst after completion of the reaction themixture was filtered and catalyst was washed with CHCl

3

and then the solid residue dries This process was repeatedfor two cycles and the yield of product 4a did not changesignificantly (Table 1 entry 12 13)








2-OSO






3


4 Conclusion


2-




H

H+

+

1

1

2

3

SiO2-OSO

3H NPs

SiO2-OSO

3H NPs

Reflux EtOH 20min

Reflux EtOH 20min

Ar

Ar

O

O

OO

O

OH

OH

O

O

O OO

OHOH

O

O OO O

O

Ar

OHOHAr

5andashc

4andashn


3H

NPs as catalyst


Acknowledgment


References














2)4SO3H] [HSO




2-H2SO4)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of








2-OSO






3


4 Conclusion


2-




H

H+

+

1

1

2

3

SiO2-OSO

3H NPs

SiO2-OSO

3H NPs

Reflux EtOH 20min

Reflux EtOH 20min

Ar

Ar

O

O

OO

O

OH

OH

O

O

O OO

OHOH

O

O OO O

O

Ar

OHOHAr

5andashc

4andashn


3H

NPs as catalyst


Acknowledgment


References














2)4SO3H] [HSO




2-H2SO4)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


H

H+

+

1

1

2

3

SiO2-OSO

3H NPs

SiO2-OSO

3H NPs

Reflux EtOH 20min

Reflux EtOH 20min

Ar

Ar

O

O

OO

O

OH

OH

O

O

O OO

OHOH

O

O OO O

O

Ar

OHOHAr

5andashc

4andashn


3H

NPs as catalyst


Acknowledgment


References














2)4SO3H] [HSO




2-H2SO4)


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of













Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article a fast, highly efficient, and green protocol for … · 2020-01-17 · cient...

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