Login Register Cart 0
Generic placeholder image

Current Organocatalysis

Editor-in-Chief

ISSN (Print): 2213-3372
ISSN (Online): 2213-3380

Back
Journal Home About Journal Editorial Board Journal Insight Current Issue Volumes/Issues
Subscribe
Opinion Article

Synthesis of 1,8-Dioxo-octahydro-xanthene and Tetrahydrobenzo[b]pyran Derivatives Promoted by two Bis-imidazolium-based Ionic Liquids

Author(s): Maryam Shirzad, Mitra Nasiri, Nader Daneshvar, Farhad Shirini* and Hassan Tajik

Volume 9, Issue 2, 2022

Published on: 26 July, 2021

Page: [102 - 116] Pages: 15

DOI: 10.2174/2213337208666210726141934

Price: $65

Abstract

Aim and Objective: In this work, we have prepared two bis-dicationic ionic liquids with the same cationic core (Bis-imidazole) and different counter-anions using sulfuric acid and perchloric acids. After that, the efficiency and ability of these compounds as catalysts were investigated and compared with respect to the promotion of Knoevenagel condensation and synthesis of benzo[ b] pyran derivatives to see the effect of the anionic counter-part in the reaction.

Materials and Methods: In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-- cyclo dicarbonyl (2.0 mmol), and the desired amount of the above-mentioned acidic ionic liquids was heated at 90°C in the absence of solvent (Reaction A). In a 25 mL round-bottomed flask, a mixture of aldehyde (1.0 mmol), 1,3-cyclo dicarbonyl (1.0 mmol), malononitrile, (1.1 mmol) and calculated amounts of the ionic liquid in water (3.0 mL) was heated at 80°C (Reaction B) for the appropriated time. After the completion of the reaction which was monitored by TLC of (n-hexane: EtOAc; 3:1). 10 mL of water was added and the mixture was stirred for 2 minutes. Then, the products were separated by filtration and washed several times with water, after drying, the pure products were obtained.

Results: Comparison of the obtained results from both the ionic liquids revealed that [H2- Bisim][HSO4]2, because of its more acidic structure, had shown a more catalytic activity in the preparation of 1,8-dioxo-octahydro-xanthene derivatives but [H2-Bisim][ClO4]2 was relatively more efficient for the synthesis of tetrahydrobenzo[b]pyran derivatives. Because the stronger acidic nature of [H2-Bisim][HSO4]2 may prevent the simple activation of malononitrile in the reaction media.

Conclusion: In this study, we have introduced efficient methods for the synthesis of 1,8-dioxo-octahydro- xanthene and tetrahydrobenzo[b]pyran derivatives in the presence of catalytic amounts of [H2-Bisim][ClO4]2 and [H2-Bisim][HSO4]2. These methods have several advantages such as ease of preparation and handling of the catalysts, high reaction rates, excellent yields, eco-friendly procedures, and simple work-up.

Keywords: Bronsted acidic ionic liquids, bis-imidazolium hydrogen sulfate, bis-imidazolium perchlorate, 1, 8-Dioxo-octyahdro- xanthenes, tetrahydrobenzo[b]pyrans, bis-dicationic ionic liquids.

« Previous Next »
Graphical Abstract

[1]
Wasserscheid, P.; Keim, W. Ionic liquids-new “solutions” for transition metal catalysis. Angew. Chem. Int. Ed. Engl., 2000, 39(21), 3772-3789.
[http://dx.doi.org/10.1002/1521-3773(20001103)39:21<3772::AID-ANIE3772>3.0.CO;2-5] [PMID: 11091453]
[2]
Pârvulescu, V.I.; Hardacre, C. Catalysis in ionic liquids. Chem. Rev., 2007, 107(6), 2615-2665.
[http://dx.doi.org/10.1021/cr050948h] [PMID: 17518502]
[3]
Earle, M.J.; Katdare, S.P.; Seddon, K.R. Paradigm confirmed: the first use of ionic liquids to dramatically influence the outcome of chemical reactions. Org. Lett., 2004, 6(5), 707-710.
[http://dx.doi.org/10.1021/ol036310e] [PMID: 14986955]
[4]
Ranu, B.C.; Banerjee, S. Ionic liquid as reagent. A green procedure for the regioselective conversion of epoxides to vicinal-halohydrins using [AcMIm]X under catalyst- and solvent-free conditions. J. Org. Chem., 2005, 70(11), 4517-4519.
[http://dx.doi.org/10.1021/jo0500885] [PMID: 15903336]
[5]
Ranu, B.C.; Adak, L.; Banerjee, S. Efficient regio-and stereo-selective cleavage of aziridines and epoxides using an ionic liquid as reagent and reaction medium. Can. J. Chem., 2007, 85(5), 366-371.
[http://dx.doi.org/10.1139/v07-040]
[6]
Zolfigol, M.A.; Khazaei, A.; Moosavi-Zare, A.R.; Zare, A. 3-Methyl-1-Sulfonic acid imidazolium chloride as a new, efficient and recyclable catalyst and solvent for the preparation of N-sulfonyl imines at room temperature. J. Iran. Chem. Soc, 2010, 7(3), 646-651.
[http://dx.doi.org/10.1007/BF03246053]
[7]
Khazaei, A.; Zolfigol, M.A.; Moosavi-Zare, A.R.; Zare, A. An efficient method for the nitration of phenols with NaNO^ sub 2^ in the Presence of 3-methyl-1-sulfonic acid imidazolium chloride. Sci. Iran., 2010, 17(1), 31.
[8]
Zolfigol, M.A.; Khazaei, A.; Moosavi-Zare, A.R.; Zare, A.; Khakyzadeh, V. Rapid synthesis of 1-amidoalkyl-2-naphthols over sulfonic acid functionalized imidazolium salts. Appl. Catal. A., 2011, 400(1-2), 70-81.
[http://dx.doi.org/10.1016/j.apcata.2011.04.013]
[9]
Heravi, M.M.; Abdi Oskooie, H.; Latifi, Z.; Hamidi, H. One-Pot synthesis of tetracyanocyclopropane derivatives using hexamethylenetetramine-bromine (HMTAB). Adv. J. Chem. A, 2018, 1(1), 7-11.
[10]
Fraga-Dubreuil, J.; Bourahla, K.; Rahmouni, M.; Bazureau, J.P.; Hamelin, J. Catalysed esterifications in room temperature ionic liquids with acidic counteranion as recyclable reaction media. Catal. Commun., 2002, 3(5), 185-190.
[http://dx.doi.org/10.1016/S1566-7367(02)00087-0]
[11]
Singh, V.; Kaur, S.; Sapehiyia, V.; Singh, J.; Kad, G.L. Microwave accelerated preparation of [bmim][HSO4] ionic liquid: an acid catalyst for improved synthesis of coumarins. Catal. Commun., 2005, 6(1), 57-60.
[http://dx.doi.org/10.1016/j.catcom.2004.10.011]
[12]
Gupta, N.; Kad, G.L.; Singh, J. Acidic ionic liquid [bmim] HSO4: An efficient catalyst for acetalization and thioacetalization of carbonyl compounds and their subsequent deprotection. Catal. Commun., 2007, 8(9), 1323-1328.
[http://dx.doi.org/10.1016/j.catcom.2006.11.030]
[13]
Hajipour, A.R.; Khazdooz, L.; Ruoho, A.E. Brønsted acidic ionic liquid as an efficient catalyst for chemoselective synthesis of 1, 1- diacetates under solvent-free conditions. Catal. Commun., 2008, 9(1), 89-96.
[http://dx.doi.org/10.1016/j.catcom.2007.05.003]
[14]
Llama, E.F.; del Campo, C.; Capo, M.; Anadon, M. Synthesis and antinociceptive activity of 9-phenyl-oxy or 9-acyl-oxy derivatives of xanthene, thioxanthene and acridine. Eur. J. Med. Chem., 1989, 24(4), 391-396.
[http://dx.doi.org/10.1016/0223-5234(89)90083-4]
[15]
Lambert, R.W.; Martin, J.A.; Merrett, J.H.; Parkes, K.E.B.; Thomas, G.J. Pyrimidine nucleosides. PCT Int. Appl. WO 9706178, 1997. In Chem. Abstr. 1997, 126, 212377y
[16]
Poupelin, J.P.; Saint-Ruf, G.; Foussard-Blanpin, O.; Narcisse, G.; Uchida-Ernouf, G.; Lacroix, R.H. 4SiW12O40 catalyzed one-pot synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo [a] xanthen-11-ones under solvent-free conditions. Eur. J. Med. Chem., 1978, 13, 67-71.
[17]
Ahmad, M.; King, T.A.; Ko, D.K.; Cha, B.H.; Lee, J. Performance and photostability of xanthene and pyrromethene laser dyes in sol-gel phases. J. Phys. D Appl. Phys., 2002, 35(13), 1473-1476.
[http://dx.doi.org/10.1088/0022-3727/35/13/303]
[18]
Das, B.; Ravikanth, B.; Ramu, R.; Laxminarayana, K.; Rao, B.V. Iodine catalyzed simple and efficient synthesis of 14-aryl or alkyl-14-H-dibenzo [a, j] xanthenes. J. Mol. Catal. Chem., 2006, 255(1-2), 74-77.
[http://dx.doi.org/10.1016/j.molcata.2006.04.007]
[19]
Seyyedhamzeh, M.; Mirzaei, P.; Bazgir, A. Solvent-free synthesis of aryl-14H-dibenzo [a, j] xanthenes and 1,8-dioxo-octahydro-xanthenes using silica sulfuric acid as catalyst. Dyes Pigm, 2008, 76(3), 836-839.
[http://dx.doi.org/10.1016/j.dyepig.2007.02.001]
[20]
Shirini, F.; Abedini, M.; Pourhasan, R. N-sulfonic acid poly (4-vinylpyridinium) chloride: A novel polymeric and reusable catalyst for the preparation of xanthenes derivatives. Dyes and Pigm, 2013, 99(1), 250-255.
[http://dx.doi.org/10.1016/j.dyepig.2013.04.036]
[21]
Niknam, K.; Damya, M. 1-Butyl-3-methylimidazolium Hydrogen Sulfate [Bmim] HSO4: An Efficient Reusablen Acidic Ionic Liquid for the Synthesis of 1, 8- Dioxo-Octahydroxanthenes. J. Chin. Chem. Soc. (Taipei), 2009, 56(3), 659-665.
[http://dx.doi.org/10.1002/jccs.200900098]
[22]
Zare, A.; Moosavi-Zare, A.R.; Merajoddin, M.; Zolfigol, M.A.; Hekmat-Zadeh, T.; Hasaninejad, A.; Khazaei, A.; Mokhlesi, M.; Khakyzadeh, V.; Derakhshan-Panah, F.H.; Beyzavi, M.; Rostami, E.; Arghoon, A.; Roohandeh, R. Ionic liquid triethylamine-bonded sulfonic acid {[Et3N-SO3H] Cl} as a novel, highly efficient and homogeneous catalyst for the synthesis of β-acetamido ketones, 1, 8- dioxo- octahydroxanthenes and 14-aryl-14H-dibenzo [a, j] xanthenes. J. Mol. Liq., 2012, 167, 69-77.
[http://dx.doi.org/10.1016/j.molliq.2011.12.012]
[23]
Bigdeli, M.A.; Nemati, F.; Mahdavinia, G.H.; Doostmohammadi, H.A. series of 1,8-dioxooctahydroxanthenes are prepared using trichloroisocyanuric acid. Chin. Chem. Lett., 2009, 20(11), 1275-1278.
[http://dx.doi.org/10.1016/j.cclet.2009.06.024]
[24]
Zare, A.; Mokhlesi, M.; Hasaninejad, A.; Hekmat-Zadeh, T. Solvent-free synthesis of 1, 8-dioxo-octahydroxanthenes and 14-aryl-14H-dibenzo [a,j] xanthenes using saccharin sulfonic acid as an efficient and green catalyst. J. Chem., 2012, 9(4), 1854-1863.
[25]
Ghasemzadeh, A.M.; Safaei-Ghomi, J.; Zahedi, S. Fe3O4 nanoparticles: a highly efficient and easily reusable catalyst for the one-pot synthesis of xanthene derivatives under solvent-free conditions. J. Serb. Chem. Soc., 2013, 78(6), 769-779.
[http://dx.doi.org/10.2298/JSC120624156G]
[26]
Maghsoodlou, M.T.; Habibi-Khorassani, S.M.; Shahkarami, Z.; Maleki, N.; Rostamizadeh, M. An efficient synthesis of 2, 2′-arylmethylene bis (3-hydroxy-5, 5-dimethyl-2-cyclohexene-1-one) and 1, 8-dioxooctahydroxanthenes using ZnO and ZnO-acetyl chloride. Chin. Chem. Lett., 2010, 21(6), 686-689.
[http://dx.doi.org/10.1016/j.cclet.2010.02.005]
[27]
Karade, H.N.; Sathe, M.; Kaushik, M.P. An efficient synthesis of 1,8-dioxo-octahydroxanthenes using tetrabutylammonium hydrogen sulfate. ARKIVOC, 2007, 13, 252-258.
[http://dx.doi.org/10.3998/ark.5550190.0008.d28]
[28]
Poor Heravi, M.R. Select fluor promoted synthesis of 9-aryl-1, 8- dioxooctahydroxanthane derivatives under solvent-Free conditions. J. Iran. Chem. Soc, 2009, 6(3), 483-488.
[http://dx.doi.org/10.1007/BF03246525]
[29]
Kamat, S.R.; Mane, A.H.; Arde, S.M.; Salunkhe, R.S. β-cyclodextrin-Glycerin as a versatile green system For synthesis of 2-amino-Tetrahydro-4-H-Chromenes. Int. J. Pharm. Chem. Biol. Sci., 2014, 4(4), 1012-1021.
[30]
Rostamnia, S.; Morsali, A. Size-controlled crystalline basic nanoporous coordination polymers of Zn4O(H2N-TA)3: catalytically study of IRMOF-3 as a suitable and green catalyst for selective synthesis of tetrahydro-chromenes. Inorg. Chim. Acta, 2014, 411, 113-118.
[http://dx.doi.org/10.1016/j.ica.2013.12.002]
[31]
Hu, H.; Qiu, F.; Ying, A.; Yang, J.; Meng, H. An environmentally benign protocol for aqueous synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid. Int. J. Mol. Sci., 2014, 15(4), 6897-6909.
[http://dx.doi.org/10.3390/ijms15046897] [PMID: 24758931]
[32]
El-Rahman, N.M.A.; Borik, R.M. Eco-friendly solvent-free synthesis of tetrahydrobenzo[b]pyran derivatives under microwave irradiation. World Appl. Sci. J., 2014, 31(1), 1-6.
[33]
Behbahani, F.K. One-pot Synthesis of 2-amino-4H-pyrans and 2-amino-tetrahydro-4H-chromenes using L-proline. Gazi Univ. J. of Sci, 2015, 28(3), 387-393.
[34]
Sheikhhosseini, E.; Ghazanfari, D.; Nezamabadi, V. A new method for synthesis of tetrahydrobenzo [b] pyrans and dihydropyrano [c] chromenes using p-dodecylbenzenesulfonic acid as catalyst in water. IJC, 2013, 3(4), 197-201.
[35]
Mondal, J.; Modak, A.; Nandi, M.; Uyama, H.; Bhaumik, A. Triazine functionalized ordered mesoporous organosilica as a novel organocatalyst for the facile one-pot synthesis of 2-amino-4H-chromenes under solvent-free conditions. RSC Advances, 2012, 2(30), 11306-11317.
[http://dx.doi.org/10.1039/c2ra22291d]
[36]
Bhosale, R.S.; Magar, C.V.; Solanke, K.S.; Mane, S.B.; Choudhary, S.S.; Pawar, R.P. Molecular iodine: An efficient catalyst for the synthesis of tetrahydrobenzo [b] pyrans. Synth. Commun., 2007, 37(24), 4353-4357.
[http://dx.doi.org/10.1080/00397910701578578]
[37]
Hatamjafari, F. Glutamic acid as an environmentally friendly catalyst for one-pot synthesis of 4H-Chromene derivatives and biological activity. J. Chem. Health Risks, 2016, 6(2), 133-142.
[38]
Jin, T.; Wang, A.; Shi, F.; Han, L.; Liu, L.; Li, T. Hexadecyldimethyl benzyl ammonium bromide: an efficient catalyst for a clean one-pot synthesis of tetrahydrobenzopyran derivatives in water. ARKIVOC, 2006, 14, 78-86.
[http://dx.doi.org/10.3998/ark.5550190.0007.e11]
[39]
Mehrabi, H.; Kamali, N. Efficient and eco-friendly synthesis of 2-amino-4H-chromene derivatives using catalytic amount of tetrabutylammonium chloride (TBAC) in water and solvent-free conditions. J. Iran. Chem. Soc, 2012, 9, 599-605.
[http://dx.doi.org/10.1007/s13738-012-0073-8]
[40]
Hassanzadeh, F.; Shirini, F.; Mamaghani, M.; Daneshvar, N. Introduction of succinimide as a green and sustainable organo-catalyst for the synthesis of arylidene malononitrile and tetrahydrobenzo[b] pyran derivatives. Comb. Chem. High Throughput Screen., 2021, 24(1), 155-163.
[http://dx.doi.org/10.2174/1386207323666200709170916] [PMID: 32646356]
[41]
Daneshvar, N.; Shirini, F.; Langarudi, M.S.N.; Karimi-Chayjani, R. Taurine as a green bio-organic catalyst for the preparation of bio-active barbituric and thiobarbituric acid derivatives in water media. Bioorg. Chem., 2018, 77, 68-73.
[http://dx.doi.org/10.1016/j.bioorg.2017.12.021] [PMID: 29334621]
[42]
Daneshvar, N.; Goli-Jolodar, O.; Karimi-Chayjani, R.; Langarudi, M.S.N.; Shirini, F. Sustainable and eco-friendly method for the synthesis of some bioactive derivatives of biscoumarin and pyrano[3,2-c]chromene-3-carbonitrile using taurine, as the catalyst. ChemistrySelect, 2019, 4(5), 1562-1566.
[http://dx.doi.org/10.1002/slct.201803210]
[43]
Asadi, S.K.; Aleaba, G.; Daneshvar, N.; Shirini, F. Sustainable and green synthesis of 3-methyl-4-arylmethylene-isoxazole-5(4H)-one derivatives under mild conditions using a novel phosphoric acid-based molten salt as catalyst. Sustain. Chem. Pharm., 2021, 21, 100442.
[http://dx.doi.org/10.1016/j.scp.2021.100442]
[44]
Shirini, F.; Daneshvar, N. Introduction of taurine (2-aminoethanesulfonic acid) as a green bio-organic catalyst for the promotion of organic reactions under green conditions. RSC Advances, 2016, 6(111), 110190-110205.
[http://dx.doi.org/10.1039/C6RA15432H]
[45]
Zabihzadeh, M.; Shirini, F.; Tajik, H.; Daneshvar, N. [H-Pyrr][HSO4] as an efficient ionic liquid catalyst for the synthesis of xanthenes, tetraketones, and triazolo[2,1-b]quinazolinones. Polycycl. Aromat. Compd., 2020.
[http://dx.doi.org/10.1080/10406638.2019.1708419]
[46]
Karimi-Chayjani, R.; Daneshvar, N.; Tajik, H.; Shirini, F. Introduction of a new magnetic nanocatalyst as an organic-inorganic hybrid framework for the synthesis of pyrano [2, 3-d] pyrimidinone (thione) s and pyrido [2,3-d] pyrimidines. ChemistrySelect, 2019, 4(4), 1205-1213.
[http://dx.doi.org/10.1002/slct.201802916]
[47]
Mazloumi, M.; Shirini, F. Introduction of a new catalyst containing an ionic liquid bridge on nanoporous Na+ - montmorillonite for the synthesis of hexahydroquinolines and 1,8-dioxo-decahydroacridines via Hantzsch condensation. J. Mol. Struct., 2020, 127, 128326.
[http://dx.doi.org/10.1016/j.molstruc.2020.128326]
[48]
Fan, X.; Hu, X.; Zhang, X.; Wang, J. InCl3. 4H2O-promoted green preparation of xanthenedione derivatives in ionic liquids. Can. J. Chem., 2005, 83(1), 16-20.
[http://dx.doi.org/10.1139/v04-155]
[49]
Jin, T.S.; Zhang, J.S.; Xiao, J.C.; Wang, A.Q.; Li, T.S. Clean synthesis of 1,8-dioxo-octahydroxanthene derivatives catalyzed by p-dodecylbenezenesulfonic acid in aqueous media. Synlett, 2004, 5, 866-870.
[http://dx.doi.org/10.1055/s-2004-820022]
[50]
Li, J.J.; Tao, X.Y.; Zhang, Z.H. An effective bismuth trichloride- catalyzed synthesis of 1,8-dioxo-octahydroxanthenes. Phosphorus Sulfur Silicon Relat. Elem., 2008, 183(7), 1672-1678.
[http://dx.doi.org/10.1080/10426500701724530]
[51]
Witte, E.C.; Neubert, P.; Roesch, A. 7-(Piperazinylpropoxy)-2H-1-benzopyran-2-ones. Ger Offen DE 3427985. Chem. Abstr., 1986, 104, 224915.
[52]
Gao, S.; Tsai, C.H.; Tseng, C.; Yao, C.F. Fluoride ion catalyzed multicomponent reactions for efficient synthesis of 4H-chromene and N-arylquinoline derivatives in aqueous media. Tetrahedron, 2008, 64(38), 9143-9149.
[http://dx.doi.org/10.1016/j.tet.2008.06.061]
[53]
Balalaie, S.; Bararjanian, M.; Sheikh-Ahmadi, M.; Hekmat, S.; Salehi, P. Diammonium hydrogen phosphate: An efficient and versatile catalyst for the one-pot synthesis of tetrahydrobenzo [b] pyran derivatives in aqueous media. Synth. Commun., 2007, 37(7), 1097-1108.
[http://dx.doi.org/10.1080/00397910701196579]
[54]
Davoodnia, A.; Allameh, S.; Fazli, S.; Tavakoli-Hoseini, N. One-pot synthesis of 2-amino-3-cyano-4-arylsubstituted tetrahydrobenzo [b] pyrans catalysed by silica gel-supported polyphosphoric acid (PPA-SiO2) as an efficient and reusable catalyst. Chem. Pap., 2011, 65(5), 714-720.
[http://dx.doi.org/10.2478/s11696-011-0064-8]
[55]
Shirini, F.; Goli-Jolodar, O.; Akbari, M.; Seddighi, M. Preparation, characterization, and use of poly (vinylpyrrolidonium) hydrogen phosphate ([PVP-H] H2PO4) as a new heterogeneous catalyst for efficient synthesis of 2-amino-tetrahydro-4H-pyrans. Res. Chem. Intermed., 2016, 42(5), 4733-4749.
[http://dx.doi.org/10.1007/s11164-015-2312-y]
[56]
Fan, X.; Feng, D.; Qu, Y.; Zhang, X.; Wang, J.; Loiseau, P.M.; Andrei, G.; Snoeck, R.; De Clercq, E. Practical and efficient synthesis of pyrano[3,2-c]pyridone, pyrano[4,3-b]pyran and their hybrids with nucleoside as potential antiviral and antileishmanial agents. Bioorg. Med. Chem. Lett., 2010, 20(3), 809-813.
[http://dx.doi.org/10.1016/j.bmcl.2009.12.102] [PMID: 20064723]
[57]
Jin, T.S.; Wang, A.Q.; Shi, F.; Han, L.S.; Liu, L.B.; Li, T.S. Hexadecyldimethyl benzyl ammonium bromide: an efficient catalystfor a clean one-pot synthesis of tetrahydrobenzopyran derivatives in water. ARKIVOC, 2006, 14, 78-86.
[http://dx.doi.org/10.3998/ark.5550190.0007.e11]
[58]
Bhattacharyya, P.; Pradhan, K.; Paul, S.; Das, A.R. Nano crystalline ZnO catalyzed one pot multicomponent reaction for an easy access of fully decorated 4H-pyran scaffolds and its rearrangement to 2-pyridone nucleus in aqueous media. Tetrahedron Lett., 2012, 53(35), 4687-4691.
[http://dx.doi.org/10.1016/j.tetlet.2012.06.086]
[59]
Kumar, D.; Reddy, V.B.; Sharad, S.; Dube, U.; Kapur, S. A facile one-pot green synthesis and antibacterial activity of 2-amino-4H-pyrans and 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromenes. Eur. J. Med. Chem., 2009, 44(9), 3805-3809.
[http://dx.doi.org/10.1016/j.ejmech.2009.04.017] [PMID: 19419801]
[60]
Devi, I.; Bhuyan, P.J. Sodium bromide catalysed one-pot synthesis of tetrahydrobenzo [b] pyrans via a three-component cyclocondensation under microwave irradiation and solvent free conditions. Tetrahedron Lett., 2004, 45(47), 8625-8627.
[http://dx.doi.org/10.1016/j.tetlet.2004.09.158]
[61]
Alizadeh, A.; Khodaei, M.M.; Beygzadeh, M.; Kordestani, D.; Feyzi, M. Biguanide-functionalized Fe3O4/SiO 2 magnetic nanoparticles: an efficient heterogeneous organosuperbase catalyst for various organic transformations in aqueous media. Bull. Korean Chem. Soc., 2012, 33(8), 2546-2552.
[http://dx.doi.org/10.5012/bkcs.2012.33.8.2546]
[62]
L. Fotouhi, L.; Heravi, M.M.; Fatehi, A.; Bakhtiari, K. Electrogenerated base-promoted synthesis of tetrahydrobenzo [b] pyran derivatives. Tetrahedron Lett., 2007, 48(31), 5379-5381.
[http://dx.doi.org/10.1016/j.tetlet.2007.06.035]
[63]
Daneshvar, N.; Nasiri, M.; Shirzad, M.; Langarudi, M.S.N.; Shirini, F.; Tajik, H. The introduction of two new imidazole-based bis-dicationic Bronsted acidic ionic liquids and comparison of their catalytic activity in the synthesis of barbituric acid derivatives. New J. Chem., 2018, 42(12), 9744-9756.
[http://dx.doi.org/10.1039/C8NJ01179F]

Rights & Permissions Print Cite
Article Metrics
19
1
© 2024 Bentham Science Publishers | Privacy Policy