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Current Organic Synthesis

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ISSN (Print): 1570-1794
ISSN (Online): 1875-6271

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Research Article

L-Cysteine Catalyzed Environmentally Benign One-pot Multicomponent Approach Towards the Synthesis of Dihydropyrano[2,3-c]pyrazole Derivatives

Author(s): Sana Sikandar, Ameer Fawad Zahoor*, Sajjad Ahmad, Muhammad Naveed Anjum, Mirza Nadeem Ahmad and Muhammad Sami Ullah Shah

Volume 17, Issue 6, 2020

Page: [457 - 463] Pages: 7

DOI: 10.2174/1570179417666200511092332

Price: $65

Abstract

Background: The pyrano[2,3-c]pyrazole derivatives are important building blocks of many biologically active compounds owing to their diverse biological potential for example, anti-inflammatory, anticancer, anti-microbial and anti-oxidant properties.

Objective: Keeping in mind the wide range of applications of pyrano[2,3-c]pyrazoles, herein we intended to develop a novel synthetic methodology for dihydropyranopyrazoles. We were also interested in determining the influence of amino acids and dipeptides as a catalyst on the synthesis of pyrano[2,3-c]pyrazole derivatives.

Methods: To achieve our objectives, we used a one-pot multi-component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and several substituted benzaldehydes by using different catalysts and solvents to synthesize our desired products in the presence of various catalysts.

Results and Discussion: We found that optimal conditions for the preparation of pyrano[2,3-c]pyrazoles were L-cysteine (0.5 mol) in the presence of water:ethanol (9:1) at 90 °C. Various 1,4-dihydropyrano[2,3- c]pyrazoles were afforded by using several substituted benzaldehydes in 66-97% yields.

Conclusion: We described a green and environmentally benign method to synthesize pyrano[2,3-c]pyrazoles in a one-pot four component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and different substituted benzaldehyde in the presence of L-cysteine in aqueous ethanol (9:1) at 90 °C. Excellent yields of the products, simple work-up, easily available starting materials, use of green solvents, naturally occurring catalyst, non-toxicity, non-chromatographic purification and environmentally benign reaction conditions are some main advantages of this protocol.

Keywords: Multicomponent reaction, L-cysteine, organocatalyst, green chemistry, 1, 4-dihydropyrano[2, 3-c]pyrazole, anti-oxidant properties.

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[1]
Kalinski, C.; Umkehrer, M.; Weber, L.; Kolb, J.; Burdack, C.; Ross, G. On the industrial applications of MCRs: Molecular diversity in drug discovery and generic drug synthesis. Mol. Divers., 2010, 14(3), 513-522.
[http://dx.doi.org/10.1007/s11030-010-9225-x] [PMID: 20229364]
[2]
Weber, L. The application of multi-component reactions in drug discovery. Curr. Med. Chem., 2002, 9(23), 2085-2093.
[http://dx.doi.org/10.2174/0929867023368719] [PMID: 12470248]
[3]
Dömling, A.; Wang, W.; Wang, K. Chemistry and biology of multicomponent reactions. Chem. Rev., 2012, 112(6), 3083-3135.
[http://dx.doi.org/10.1021/cr100233r] [PMID: 22435608]
[4]
Jarvo, E.R.; Miller, S.J. Amino acids and peptides as asymmetric organocatalysts. Tetrahedron, 2002, 58(13), 2481-2495.
[http://dx.doi.org/10.1016/S0040-4020(02)00122-9]
[5]
Sakthivel, K.; Notz, W.; Bui, T.; Barbas, C.F., III Amino acid catalyzed direct asymmetric aldol reactions: A bioorganic approach to catalytic asymmetric carbon-carbon bond-forming reactions. J. Am. Chem. Soc., 2001, 123(22), 5260-5267.
[http://dx.doi.org/10.1021/ja010037z] [PMID: 11457388]
[6]
Kumar, A.; Gupta, M.K.; Kumar, M. L-Proline catalyzed multicomponent synthesis of 3-amino alkylated indoles via a Mannich-type reaction under solvent-free conditions. Green Chem., 2012, 14(2), 290-295.
[http://dx.doi.org/10.1039/C1GC16297G]
[7]
Sabitha, G.; Fatima, N.; Reddy, E.V.; Yadav, J.S. First examples of proline‐catalyzed domino knoevenagel/hetero‐diels-alder/elimination reactions. Adv. Synth. Catal., 2005, 347(10), 1353-1355.
[http://dx.doi.org/10.1002/adsc.200505144]
[8]
Ramachary, D.B.; Ramakumar, K.; Narayana, V.V. Amino acid-catalyzed cascade [3+2]-cycloaddition/hydrolysis reactions based on the push-pull dienamine platform: Synthesis of highly functionalized NH-1,2,3-triazoles. Chemistry, 2008, 14(30), 9143-9147.
[http://dx.doi.org/10.1002/chem.200801325] [PMID: 18767077]
[9]
Lewis, R.A.; Drazen, J.M.; Austen, K.F.; Clark, D.A.; Corey, E.J. Identification of the C(6)-S-conjugate of leukotriene A with cysteine as a naturally occurring slow reacting substance of anaphylaxis (SRS-A). Importance of the 11-cis-geometry for biological activity. Biochem. Biophys. Res. Commun., 1980, 96(1), 271-277.
[http://dx.doi.org/10.1016/0006-291X(80)91210-3] [PMID: 6254506]
[10]
Chen, Y.; Zhang, Z.; Jiang, W.; Zhang, M.; Li, Y. RuIII@CMC/Fe3O4 hybrid: an efficient, magnetic, retrievable, self-organized nanocatalyst for green synthesis of pyranopyrazole and polyhydroquinoline derivatives. Mol. Divers., 2019, 23(2), 421-442.
[http://dx.doi.org/10.1007/s11030-018-9887-3] [PMID: 30374813]
[11]
Kumar, A.; Lohan, P.; Aneja, D.K.; Gupta, G.K.; Kaushik, D.; Prakash, O. Design, synthesis, computational and biological evaluation of some new hydrazino derivatives of DHA and pyranopyrazoles. Eur. J. Med. Chem., 2012, 50, 81-89.
[http://dx.doi.org/10.1016/j.ejmech.2012.01.042] [PMID: 22357113]
[12]
Mandha, S.R.; Siliveri, S.; Alla, M.; Bommena, V.R.; Bommineni, M.R.; Balasubramanian, S. Eco-friendly synthesis and biological evaluation of substituted pyrano[2,3-c]pyrazoles. Bioorg. Med. Chem. Lett., 2012, 22(16), 5272-5278.
[http://dx.doi.org/10.1016/j.bmcl.2012.06.055] [PMID: 22818081]
[13]
Ramiz, M.M.; Hafiz, I.S.A.; Reheim, M.A.A.; Gaber, H.M. Pyrazolones as building blocks in heterocyclic synthesis: Synthesis of new pyrazolopyran, pyrazolopyridazine and pyrazole derivatives of expected antifungicidal activity. . J. Chin. Chem. Soc_TAIP, 2012, 59(1), 72-80.
[14]
Ahadi, S.; Yasaei, Z.; Bazgir, A. A clean and one-pot synthesis of spiroindoline-pyranopyrazoles. J. Heterocycl. Chem., 2010, 47(5), 1090-1094.
[http://dx.doi.org/10.1002/jhet.437]
[15]
Mamaghani, M.; Nia, R.H.; Shirini, F.; Tabatabaeian, K.; Rassa, M. An efficient and eco-friendly synthesis and evaluation of antibactrial activity of pyrano[2,3-c]pyrazole derivatives. Med. Chem. Res., 2015, 24(5), 1916-1926.
[http://dx.doi.org/10.1007/s00044-014-1271-y]
[16]
Nimbalkar, U.D.; Seijas, J.A.; Vazquez-Tato, M.P.; Damale, M.G.; Sangshetti, J.N.; Nikalje, A.P.G. Ionic liquid-catalyzed green protocol for multi-component synthesis of dihydropyrano[2,3-c]pyrazoles as potential anticancer scaffolds. Molecules, 2017, 22(10), 1628-1645.
[http://dx.doi.org/10.3390/molecules22101628] [PMID: 28956863]
[17]
Salama, S.K.; Mohamed, M.F.; Darweesh, A.F.; Elwahy, A.H.; Abdelhamid, I.A. Molecular docking simulation and anticancer assessment on human breast carcinoma cell line using novel bis(1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile) and bis(1,4-dihydropyrazolo[4′,3′:5,6]pyrano[2,3-b]pyridine-6-carbonitrile) derivatives. Bioorg. Chem., 2017, 71, 19-29.
[http://dx.doi.org/10.1016/j.bioorg.2017.01.009] [PMID: 28143658]
[18]
Reddy, G.M.; Chen, D.Y.; Subbaiah, M.V.; Jianyou, J.; Wen, J.C. Multicomponent one-pot synthesis of oxadiazole included pyranopyrazoles as promising antioxidant agents. J. Heterocycl. Chem., 2019, 56(6), 1806-1811.
[http://dx.doi.org/10.1002/jhet.3553]
[19]
Aliabadi, R.S.; Mahmoodi, N.O. Green and efficient synthesis of pyranopyrazoles using [bmim][OH-] as an ionic liquid catalyst in water under microwave irradiation and investigation of their antioxidant activity. RSC Advances, 2016, 6(89), 85877-85884.
[http://dx.doi.org/10.1039/C6RA17594E]
[20]
Kuo, S.C.; Huang, L.J.; Nakamura, H. Studies on heterocyclic compounds. 6. Synthesis and analgesic and antiinflammatory activities of 3,4-dimethylpyrano[2,3-c]pyrazol-6-one derivatives. J. Med. Chem., 1984, 27(4), 539-544.
[http://dx.doi.org/10.1021/jm00370a020] [PMID: 6708056]
[21]
Abdelrazek, F.M.; Metz, P.; Kataeva, O.; Jäger, A.; El-Mahrouky, S.F. Synthesis and molluscicidal activity of new chromene and pyrano[2,3-c]pyrazole derivatives. Arch. Pharm. (Weinheim), 2007, 340(10), 543-548.
[http://dx.doi.org/10.1002/ardp.200700157] [PMID: 17912679]
[22]
Abdelrazek, F.M.; Metz, P.; Metwally, N.H.; El-Mahrouky, S.F. Synthesis and molluscicidal activity of new cinnoline and pyrano [2,3-c]pyrazole derivatives. Arch. Pharm. (Weinheim), 2006, 339(8), 456-460.
[http://dx.doi.org/10.1002/ardp.200600057] [PMID: 16795107]
[23]
Ramtekkar, R.; Kumarvel, K.; Vasuki, G.; Sekar, K.; Krishna, R. Computer-aided drug design of pyranopyrazoles and related compounds for checkpoint kinase-1. Lett. Drug Des. Discov., 2009, 6(8), 579-584.
[http://dx.doi.org/10.2174/157018009789353455]
[24]
Kashtoh, H.; Muhammad, M.T.; Khan, J.J.; Rasheed, S.; Khan, A.; Perveen, S.; Javaid, K. Atia-Tul-Wahab; Khan, K.M.; Choudhary, M.I. Dihydropyrano [2,3-c] pyrazole: Novel in vitro inhibitors of yeast α-glucosidase. Bioorg. Chem., 2016, 65, 61-72.
[http://dx.doi.org/10.1016/j.bioorg.2016.01.008] [PMID: 26874344]
[25]
Derabli, C.; Boualia, I.; Abdelwahab, A.B.; Boulcina, R.; Bensouici, C.; Kirsch, G.; Debache, A. A cascade synthesis, in vitro cholinesterases inhibitory activity and docking studies of novel Tacrine-pyranopyrazole derivatives. Bioorg. Med. Chem. Lett., 2018, 28(14), 2481-2484.
[http://dx.doi.org/10.1016/j.bmcl.2018.05.063] [PMID: 29887354]
[26]
Al-Matar, H.M.; Khalil, K.D.; Adam, A.Y.; Elnagdi, M.H. Green one pot solvent-free synthesis of pyrano[2,3-c]-pyrazoles and pyrazolo[1,5-a]pyrimidines. Molecules, 2010, 15(9), 6619-6629.
[http://dx.doi.org/10.3390/molecules15096619] [PMID: 20877248]
[27]
Kanagaraj, K.; Pitchumani, K. Solvent-free multicomponent synthesis of pyranopyrazoles: per-6-amino-β-cyclodextrin as a remarkable catalyst and host. Tetrahedron Lett., 2010, 51(25), 3312-3316.
[http://dx.doi.org/10.1016/j.tetlet.2010.04.087]
[28]
Reddy, M.M.; Jayashankara, V.P.; Pasha, M.A. Glycine-catalyzed efficient synthesis of pyranopyrazoles via one-pot multicomponent reaction. Synth. Commun., 2010, 40(19), 2930-2934.
[http://dx.doi.org/10.1080/00397910903340686]
[29]
Mecadon, H.; Rohman, M.R.; Rajbangshi, M.; Myrboh, B. γ-Alumina as a recyclable catalyst for the four-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano [2,3-c] pyrazole-5-carbonitriles in aqueous medium. Tetrahedron Lett., 2011, 52(19), 2523-2525.
[http://dx.doi.org/10.1016/j.tetlet.2011.03.036]
[30]
Mecadon, H.; Rohman, M.R.; Kharbangar, I.; Laloo, B.M.; Kharkongor, I.; Rajbangshi, M.; Myrboh, B. L-Proline as an efficicent catalyst for the multi-component synthesis of 6-amino-4-alkyl/aryl-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles in water. Tetrahedron Lett., 2011, 52(25), 3228-3231.
[http://dx.doi.org/10.1016/j.tetlet.2011.04.048]
[31]
Bhosale, V.N.; Khansole, G.S.; Angulwar, J.A.; Choudhare, S.S.; Karad, A.R.; Wadwale, N.B. One pot, four-component for the synthesis of pyrano pyrazole derivatives using TBAHS as green catalyst and their biological evaluation. AJRC, 2017, 10(6), 745-749.
[http://dx.doi.org/10.5958/0974-4150.2017.00126.2]
[32]
Siddekha, A.; Nizam, A.; Pasha, M.A. An efficient and simple approach for the synthesis of pyranopyrazoles using imidazole (catalytic) in aqueous medium, and the vibrational spectroscopic studies on 6-amino-4-(4′-methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole using density functional theory. Spectrochim. Acta A Mol. Biomol. Spectrosc., 2011, 81(1), 431-440.
[http://dx.doi.org/10.1016/j.saa.2011.06.033] [PMID: 21795106]
[33]
Vasuki, G.; Kumaravel, K. Rapid four-component reactions in water: Synthesis of pyranopyrazoles. Tetrahedron Lett., 2008, 49(39), 5636-5638.
[http://dx.doi.org/10.1016/j.tetlet.2008.07.055]
[34]
Farahi, M.; Karami, B.; Sedighimehr, I.; Tanuraghaj, H.M. An environmentally friendly synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives catalyzed by tungstate sulfuric acid. Chin. Chem. Lett., 2014, 25(12), 1580-1582.
[http://dx.doi.org/10.1016/j.cclet.2014.07.012]
[35]
Moshtaghi Zonouz, A.; Moghani, D. Green and highly efficient synthesis of pyranopyrazoles in choline chloride/urea deep eutectic solvent. Synth. Commun., 2016, 46(3), 220-225.
[http://dx.doi.org/10.1080/00397911.2015.1129668]
[36]
Guo, R.Y.; An, Z.M.; Mo, L.P.; Yang, S.T.; Liu, H.X.; Wang, S.X.; Zhang, Z.H. Meglumine promoted one-pot, four-component synthesis of pyranopyrazole derivatives. Tetrahedron, 2013, 69(47), 9931-9938.
[http://dx.doi.org/10.1016/j.tet.2013.09.082]
[37]
Waghmare, A.S.; Pandit, S.S. DABCO catalyzed rapid one-pot synthesis of 1,4-dihydropyrano[2,3-c]pyrazole derivatives in aqueous media. J. Saudi Chem. Soc., 2017, 21(3), 286-290.
[http://dx.doi.org/10.1016/j.jscs.2015.06.010]
[38]
Zolfigol, M.A.; Tavasoli, M.; Moosavi-Zare, A.R.; Moosavi, P.; Kruger, H.G.; Shiri, M.; Khakyzadeh, V. Synthesis of pyranopyrazoles using isonicotinic acid as a dual and biological organocatalyst. RSC Advances, 2013, 3(48), 25681-25685.
[http://dx.doi.org/10.1039/c3ra45289a]
[39]
Wu, M.; Feng, Q.; Wan, D.; Ma, J. CTACl as catalyst for four-component, one-pot synthesis of pyranopyrazole derivatives in aqueous medium. Synth. Commun., 2013, 43(12), 1721-1726.
[http://dx.doi.org/10.1080/00397911.2012.666315]
[40]
Yang, S.; Shen, L.L.; Kim, Y.J.; Jeong, J.H. Effective and novel enantioselective preparation of pyranopyrazoles and pyranocoumarins that is catalyzed by a quinine-derived primary amine. Org. Biomol. Chem., 2016, 14(2), 623-630.
[http://dx.doi.org/10.1039/C5OB01656H] [PMID: 26540619]
[41]
Azzam, S.H.S.; Pasha, M.A. Simple and efficient protocol for the synthesis of novel dihydro-1H-pyrano[2,3-c]pyrazol-6-ones via a one-pot four-component reaction. Tetrahedron Lett., 2012, 53(50), 6834-6837.
[http://dx.doi.org/10.1016/j.tetlet.2012.10.025]
[42]
Khurana, J.M.; Chaudhary, A. Efficient and green synthesis of 4h-pyrans and 4h-pyrano[2,3-c]pyrazoles catalyzed by task-specific ionic liquid [bmim]OH under Solvent-free Conditions. Green Chem. Lett. Rev., 2012, 5(4), 633-638.
[http://dx.doi.org/10.1080/17518253.2012.691183]
[43]
Fatahpour, M.; Sadeh, F.N.; Hazeri, N.; Maghsoodlou, M.T.; Hadavi, M.S.; Mahnaei, S. Ag/TiO2 nano-thin films as robust heterogeneous catalyst for one-pot, multi-component synthesis of bis(pyrazol-5-ol) and dihydropyrano[2,3-c]pyrazole analogs. J. Saudi Chem. Soc., 2017, 21(8), 998-1006.
[http://dx.doi.org/10.1016/j.jscs.2017.05.009]
[44]
Tekale, S.U.; Kauthale, S.S.; Jadhav, K.M.; Pawar, R.P. Nano-ZnO catalyzed green and efficient one-pot four-component synthesis of pyranopyrazoles; J. Chem-Ny, 2013, pp. 1-8.
[45]
Atar, A.B.; Kim, J.T.; Lim, K.T.; Jeong, Y.T. Synthesis of 6-amino-2,4-dihydropyrano[2,3-c]pyrazol-5-carbonitriles catalyzed by silica-supported tetramethylguanidine under solvent-free conditions. Synth. Commun., 2014, 44(18), 2679-2691.
[http://dx.doi.org/10.1080/00397911.2014.913634]
[46]
Ali, M.A.E.A.A. Synthesis of pyranopyrazoles using magnetic Fe3O4 nanoparticles as efficient and reusable catalyst. Tetrahedron, 2014, 70(18), 2971-2975.
[http://dx.doi.org/10.1016/j.tet.2014.03.024]
[47]
Farokhian, P.; Mamaghani, M.; Mahmoodi, N.O.; Tabatabaeian, K. A green and practical method for the synthesis of novel pyrano[2,3-c]pyrazoles and bis-pyrano[2,3-c]pyrazoles using sulfonic acid-functionalized ionic liquid. J. Iran Chem Soc, 2018, 15(1), 11-16.
[http://dx.doi.org/10.1007/s13738-017-1203-0]
[48]
Liu, T.; Li, C.B.; Yu, Y.Q.; Xu, D.Z. An efficient four‐component reaction for the rapid synthesis of highly functionalized pyrano[2,3‐c] pyrazoles Catalyzed by [Dabco‐H][AcO] ionic liquid under mild condition. ChemistrySelect, 2017, 2(10), 2917-2921.
[http://dx.doi.org/10.1002/slct.201700168]
[49]
Bihani, M.; Bora, P.P.; Bez, G.; Askari, H. Amberlyst A21 catalyzed chromatography-free method for multicomponent synthesis of dihydropyrano[2,3-c]pyrazoles in ethanol. ACS Sustain. Chem.& Eng., 2013, 1(4), 440-447.
[http://dx.doi.org/10.1021/sc300173z]
[50]
Gujar, J.B.; Chaudhari, M.A.; Kawade, D.S.; Shingare, M.S. Molecular sieves: an efficient and reusable catalyst for multi-component synthesis of dihydropyrano[2,3-c]pyrazole derivatives. Tetrahedron Lett., 2014, 55(44), 6030-6033.
[http://dx.doi.org/10.1016/j.tetlet.2014.08.127]
[51]
Javid, A.; Khojastehnezhad, A.; Eshghi, H.; Moeinpour, F.; Bamoharram, F.F.; Ebrahimi, J. Synthesis of pyranopyrazoles using a magnetically separable modified preyssler heteropoly acid. Org. Prep. Proced. Int., 2016, 48(5), 377-384.
[http://dx.doi.org/10.1080/00304948.2016.1206424]
[52]
Nikam, M.D.; Mahajan, P.; Chate, A.V.; Dabhade, S.; Gill, C. An efficient and green protocol for the synthesis of dihydropyrano[2,3-c]pyrazoles in aqueous medium using thiamine hydrochloride as a catalyst. J. Chil. Chem. Soc., 2015, 60(1), 2847-2850.
[http://dx.doi.org/10.4067/S0717-97072015000100016]
[53]
Faiz, S.; Zahoor, A.F.; Rasool, N.; Ajmal, M.; Irfan, M. Tetra-n-Butyl ammonium iodide catalyzed ring opening of epoxides with sodium saccharin. Warasan Khana Witthayasat Maha Witthayalai Chiang Mai, 2019, 46(6), 1229-1233.
[54]
Faiz, S.; Zahoor, A.F.; Ajmal, M.; Kamal, S.; Ahmad, S.; Abdelgawad, A.M.; Elnaggar, M.E. Design, synthesis, antimicrobial evaluation, and laccase catalysis effect of novel benzofuran–oxadiazole and benzofuran–triazole hybrids. J. Heterocycl. Chem., 2019, 56(10), 2839-2852.
[http://dx.doi.org/10.1002/jhet.3674]
[55]
Akhtar, R.; Zahoor, A.F.; Rasul, A.; Ahmad, M.; Anjum, M.N.; Ajmal, M.; Raza, Z. Design, synthesis, in-silico study and anticancer potential of novel n-4- piperazinyl-ciprofloxacin-aniline hybrids Pak. J. Pharm. Sci., 2019, 32(5(Supplementary)), 2215-2222.
[PMID: 31894047]
[56]
Vekariya, R.H.; Patel, K.D.; Patel, H.D. A green and one-pot synthesis of a library of 1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile derivatives using thiourea dioxide (TUD) as an efficient and reusable organocatalyst. Res. Chem. Intermed., 2016, 42(5), 4683-4696.
[http://dx.doi.org/10.1007/s11164-015-2308-7]
[57]
Safaei-Ghomi, J.; Ziarati, A.; Tamimi, M. A novel method for the one-pot five-component synthesis of highly functionalized pyranopyrazoles catalyzed by CuI nanoparticles Acta Chim. Slov., 2013, 60(2), 403-410.
[PMID: 23878946]
[58]
Kangani, M.; Hazeri, N.; Maghsoodlou, M.T.; Khandan-Barani, K.; Kheyrollahi, M.; Nezhadshahrokhabadi, F. Green procedure for the synthesis of 1,4-dihydropyrano[2,3-c]pyrazoles using saccharose. J. Iran. Chem. Soc, 2015, 12(1), 47-50.
[http://dx.doi.org/10.1007/s13738-014-0452-4]
[59]
Khazaei, A.; Zolfigol, M.A.; Karimitabar, F.; Nikokar, I.; Moosavi-Zare, A.R.N. 2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide: an efficient and homogeneous catalyst for one-pot synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives under aqueous media. RSC Advances, 2015, 5(87), 71402-71412.
[http://dx.doi.org/10.1039/C5RA10730J]

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