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Current Microwave Chemistry


ISSN (Print): 2213-3356
ISSN (Online): 2213-3364

Review Article

Microwave-assisted Synthesis of Benzoxazoles Derivatives

Author(s): Musa Özil* and Emre Menteşe

Volume 7, Issue 3, 2020

Page: [183 - 195] Pages: 13

DOI: 10.2174/2213335607999200518094114

Price: $65


Background: Benzoxazole, containing a 1,3-oxazole system fused with a benzene ring, has a profound effect on medicinal chemistry research owing to its important pharmacological activities. On the other hand, the benzoxazole derivative has exhibited important properties in material science. Especially in recent years, microwave-assisted synthesis is a technique that can be used to increase diversity and quick research in modern chemistry. The utilization of microwave irradiation is beneficial for the synthesis of benzoxazole in recent years. In this focused review, we provide a metaanalysis of studies on benzoxazole in different reaction conditions, catalysts, and starting materials by microwave technique so far, which is different from conventional heating.

Methods: Synthesis of different kind of benzoxazole derivatives have been carried out by microwave irradiation. The most used method to obtain benzoxazoles is the condensation of 2-aminophenol or its derivatives with aldehydes, carboxylic acids, nitriles, isocyanates, and aliphatic amines.

Results: Benzoxazole system and its derivatives have exhibited a broad range of pharmacological properties. Thus, many scientists have remarked on the importance of the synthesis of different benzoxazole derivatives. Conventional heating is a relatively inefficient and slow method to convey energy in orientation to the reaction medium. However, the microwave-assisted heating technique is a more effective interior heating by straight coupling of microwave energy with the molecules.

Conclusion: In this review, different studies were presented on the recent details accessible in the microwave- assisted techniques on the synthesis of the benzoxazole ring. It presents all examples of such compounds that have been reported from 1996 to the present. Benzoxazoles showed an extensive class of chemical substances not only in pharmaceutical chemistry but also in dyestuff, polymer industries, agrochemical, and optical brighteners. Thus the development of fast and efficient achievement of benzoxazoles with a diversity of substituents in high yield is getting more noteworthy. As shown in this review, microwave-assisted synthesis of benzoxazoles is a very effective and useful technique.

Keywords: Benzoxazoles, microwave, synthesis, heterocyclic, green chemistry, solvent free, catalyst free, bioactive.

Graphical Abstract
Al-Soud, Y.A.; Al-Sa’doni, H.; Amajaour, H.A.S.; Al-Masoudi, N.A. Nitroimidazoles, Part 3. Synthesis and anti-HIV activity of new N-alkyl-4-nitroimidazoles bearing benzothiazole and benzoxazole backbones. Z. Naturforsch. B, 2007, 62(4), 523-528.
Arisoy, M.; Temiz-Arpaci, O.; Kaynak-Onurdag, F.; Ozgen, S. Novel benzoxazoles: synthesis and antibacterial, antifungal, and antitubercular activity against antibiotic-resistant and -sensitive microbes. Z. Natforsch. C J. Biosci., 2013, 68(11-12), 453-460.
[] [PMID: 24601083]
Ertan-Bolelli, T.; Yildiz, İ.; Ozgen-Ozgacar, S. Synthesis, molecular docking and antimicrobial evaluation of novel benzoxazole derivatives. Med. Chem. Res., 2016, 25(4), 553-567.
Gudipati, R.; Anreddy, R.N.; Manda, S. Synthesis, anticancer and antioxidant activities of some novel N-(benzo[d]oxazol-2-yl)-2-(7- or 5-substituted-2-oxoindolin-3-ylidene) hydrazinecarboxamide derivatives. J. Enzyme Inhib. Med. Chem., 2011, 26(6), 813-818.
[] [PMID: 21476831]
Jauhari, P.K.; Bhavani, A.; Varalwar, S.; Singhal, K.; Raj, P. Synthesis of some novel 2-substituted benzoxazoles as anticancer, antifungal, and antimicrobial agents. Med. Chem. Res., 2008, 17(2-7), 412-424.
Kim, M.; Jeon, J.; Song, J.; Suh, K.H.; Kim, Y.H.; Min, K.H.; Lee, K.O. Synthesis of proline analogues as potent and selective cathepsin S inhibitors. Bioorg. Med. Chem. Lett., 2013, 23(11), 3140-3144.
[] [PMID: 23639544]
Rida, S.M.; Ashour, F.A.; El-Hawash, S.A.; ElSemary, M.M.; Badr, M.H.; Shalaby, M.A. Synthesis of some novel benzoxazole derivatives as anticancer, anti-HIV-1 and antimicrobial agents. Eur. J. Med. Chem., 2005, 40(9), 949-959.
[] [PMID: 16040162]
Xue, N.; Zhou, Y.; Wang, G.; Miao, W.; Qu, J. Syntheses and herbicidal activity of pyrazolyl benzoxazole derivatives. J. Heterocycl. Chem., 2010, 47, 15-21.
Agag, T.; Liu, J.; Graf, R.; Spiess, H.W.; Ishida, H. Benzoxazole Resin: A novel class of thermoset polymer via smart benzoxazine resin. Macromolecules, 2012, 45(22), 8991-8997.
Smulders, E.; Sung, E. Wiley VCH Verlag GmbH & Co. KGaA, 2011. Laundry Detergents, 2. Ingredients and Products. In Ullmann's Encyclopedia of Industrial Chemistry;;
Chanda, K.; Rajasekhar, S.; Maiti, B. A decade update on benzoxazoles, a privileged scaffold in synthetic organic chemistry. Synlett, 2017, 28(05), 521-541.
Kappe, C.O.; Dallinger, D.; Murphree, S.S. Practical microwave synthesis for organic chemists: Strategies, instruments, and protocols; John Wiley & Sons, 2008.
Kahveci, B.; Mentes, E.; Ozil, M.; Ulker, S.; Erturk, M. An efficient synthesis of benzimidazoles via a microwave technique and evaluation of their biological activities. Monatsh. Chem., 2013, 144(7), 993-1001.
Özil, M.; Emirik, M.; Beldüz, A.; Ülker, S. Molecular docking studies and synthesis of novel bisbenzimidazole derivatives as inhibitors of α-glucosidase. Bioorg. Med. Chem., 2016, 24(21), 5103-5114.
[] [PMID: 27576293]
Ozil, M.; Islamoglu, F.; Mentese, E.; Kahveci, B. Microwave-assisted synthesis of novel 2,4-dihydro-5-[4-(trifluorom-ethyl)phenyl]-3h-1,2,4-triazol-3-ones and potentiometric determin-ation of their pK(a) in nonaqueous solvents. Helv. Chim. Acta, 2010, 93(10), 1967-1974.
Lidstrom, P.; Tierney, J.; Wathey, B.; Westman, J. Microwave assisted organic synthesis - a review. Tetrahedron, 2001, 57(45), 9225-9283.
Özil, M.; Parlak, C.; Baltaş, N. A simple and efficient synthesis of benzimidazoles containing piperazine or morpholine skeleton at C-6 position as glucosidase inhibitors with antioxidant activity. Bioorg. Chem., 2018, 76, 468-477.
[] [PMID: 29287256]
Antonetti, C.; Galletti, A.M.R.; Fulignati, S.; Licursi, D. Amberlyst A-70: A surprisingly active catalyst for the MW-assisted dehydration of fructose and inulin to HMF in water. Catal. Commun., 2017, 97, 146-150.
Keglevich, G. Milestones in Microwave Chemistry; Springer, 2016.
Ameta, S.C.; Punjabi, P.B.; Ameta, R.; Ameta, C. Microwave-assisted organic synthesis: a green chemical approach; CRC Press, 2014.
de la Hoz, A.; Loupy, A. Microwaves in organic synthesis; John Wiley & Sons, 2013.
Desai, K.; Kanetkar, V. Green Chemistry; Microwave synthesis; Himalaya Publishing House, 2010.
Rauf, A.; Farshori, N.N. Microwave-induced synthesis of aromatic heterocycles; Springer Science & Business Media, 2011.
Tierney, J.; Lidström, P. Microwave assisted organic synthesis; John Wiley & Sons, 2009.
Kappe, C.O.; Dallinger, D.; Murphree, S.S. Practical microwave synthesis for organic chemists; John Wiley & Sons, 2008.
Eycken, E.d.; Kappe, C.O. Microwave-assisted synthesis of heterocycles; Springer, 2006.
Bogdal, D. Microwave-assisted organic synthesis: One hundred reaction procedures; Elsevier, 2005, Vol. 25, .
Bayliss, T.; Robinson, D.A.; Smith, V.C.; Brand, S.; McElroy, S.P.; Torrie, L.S.; Mpamhanga, C.; Norval, S.; Stojanovski, L.; Brenk, R.; Frearson, J.A.; Read, K.D.; Gilbert, I.H.; Wyatt, P.G. Design and synthesis of brain penetrant trypanocidal n-myristoyltransferase inhibitors. J. Med. Chem., 2017, 60(23), 9790-9806.
[] [PMID: 29125744]
Myers, S.H.; Temps, C.; Houston, D.R.; Brunton, V.G.; Unciti-Broceta, A. Development of potent inhibitors of receptor tyrosine kinases by ligand-based drug design and target-biased phenotypic screening. J. Med. Chem., 2018, 61(5), 2104-2110.
[] [PMID: 29466002]
Sharma, P.; Reddy, T.S.; Kumar, N.P.; Senwar, K.R.; Bhargava, S.K.; Shankaraiah, N. Conventional and microwave-assisted synthesis of new 1H-benzimidazole-thiazolidinedione derivatives: A potential anticancer scaffold. Eur. J. Med. Chem., 2017, 138, 234-245.
[] [PMID: 28668476]
Xiao, M.; Ye, J.; Lian, W.; Zhang, M.; Li, B.; Liu, A.; Hu, A. Microwave-assisted synthesis, characterization and bioassay of acylhydrazone derivatives as influenza neuraminidase inhibitors. Med. Chem. Res., 2017, 26(12), 3216-3227.
Protopopov, M.V.; Ostrynska, O.V.; Starosyla, S.A.; Vodolazhenko, M.A.; Sirko, S.M.; Gorobets, N.Y.; Bdzhola, V.; Desenko, S.M.; Yarmoluk, S.M. Dihydrobenzo[4,5]imidazo[1,2-a]pyrimidine-4-ones as a new class of CK2 inhibitors. Mol. Divers., 2018, 22(4), 991-998.
[] [PMID: 29845490]
Holiyachi, M.; Samundeeswari, S.; Chougala, B.M.; Naik, N.S.; Madar, J.; Shastri, L.A.; Joshi, S.D.; Dixit, S.R.; Dodamani, S.; Jalalpure, S.; Sunagar, V.A. Design and synthesis of coumarin–imidazole hybrid and phenyl-imidazoloacrylates as potent antimicrobial and antiinflammatory agents. Monatsh. Chem., 2018, 149(3), 595-609.
Frecentese, F.; Saccone, I.; Caliendo, G.; Corvino, A.; Fiorino, F.; Magli, E.; Perissutti, E.; Severino, B.; Santagada, V. Microwave assisted organic synthesis of heterocycles in aqueous media: recent advances in medicinal chemistry. Med. Chem., 2016, 12(8), 720-732.
[] [PMID: 27140185]
de Andrade, P.; Bernardes, L.S.C.; Carvalho, I. General aspects of the microwave-assisted drug development. New Dev. Med. Chem., 2010, 1, 114-132.
Kappe, C.O.; Stadler, A.; Dallinger, D. Microwaves in organic and medicinal chemistry; John Wiley & Sons, 2012.
Zanin, L.L.; Jimenez, D.E.; Fonseca, L.P.; Meleiro Porto, A.L. Knoevenagel condensation reactions of cyano malononitrile-derivatives under microwave radiation. Curr. Org. Chem., 2018, 22(6), 519-532.
Khanna, P.; Khanna, L.; Thomas, S.J.; Asiri, A.M.; Panda, S.S. Microwave assisted synthesis of spiro heterocyclic systems: A review. Curr. Org. Chem., 2018, 22(1), 67-84.
Lukasik, N.; Wagner-Wysiecka, E. A review of amide bond formation in microwave organic synthesis. Curr. Org. Synth., 2014, 11(4), 592-604.
Takkellapati, R.S. Microwave-assisted chemical transformations. Curr. Org. Chem., 2013, 17(20), 2305-2322.
Heravi, M.M.; Ghavidel, M.; Heidari, B. Microwave-assisted Biginelli reaction: an old reaction, a new perspective. Curr. Org. Synth., 2016, 13(4), 569-600.
So, Y-H.; Heeschen, J.P. Mechanism of polyphosphoric acid and phosphorus pentoxide− methanesulfonic acid as synthetic reagents for benzoxazole formation. J. Org. Chem., 1997, 62(11), 3552-3561.
Huh, K.T.; Shim, S.C. Ruthenium complex catalyzed synthesis of 2‐substituted benzoxazoles from o‐aminophenol and alcohol with spontaneous hydrogen evolution. ChemInform, 1994, 25(12)
Blacker, A.J.; Farah, M.M.; Hall, M.I.; Marsden, S.P.; Saidi, O.; Williams, J.M. Synthesis of benzazoles by hydrogen-transfer catalysis. Org. Lett., 2009, 11(9), 2039-2042.
[] [PMID: 19354284]
Nadaf, R. Room temperature ionic liquid promoted regioselective synthesis of 2-aryl benzimidazoles, benzoxazoles and benzthiazoles under ambient conditions. J. Mol. Catal. Chem., 2004, 214(1), 155-160.
Wang, Y.; Sarris, K.; Sauer, D.R.; Djuric, S.W. A simple and efficient one step synthesis of benzoxazoles and benzimidazoles from carboxylic acids. Tetrahedron Lett., 2006, 47(28), 4823-4826.
Hein, D.; Alheim, R.J.; Leavitt, J. The use of polyphosphoric acid in the synthesis of 2-aryl-and 2-alkyl-substituted benzimidazoles, benzoxazoles and benzothiazoles. J. Am. Chem. Soc., 1957, 79(2), 427-429.
Singh, S.; Veeraswamy, G.; Bhattarai, D.; Goo, J.I.; Lee, K.; Choi, Y. Recent advances in the development of pharmacologically active compounds that contain a benzoxazole scaffold. Asian J. Org. Chem., 2015, 4(12), 1338-1361.
Lokwani, P.; Nagori, B.; Batra, N.; Goyal, A.; Gupta, S.; Singh, N. Benzoxazole: The molecule of diverse biological activities. J. Chem. Pharm. Res., 2011, 3(3), 302-311.
Kumar, R.V. Synthetic strategies towards benzoxazole ring systems: a review. Asian J. Chem., 2004, 16(3), 1241.
Gautam, M.K.; Sonal, S.N.; Priyanka, J.K. Pharmacological profile and pharmaceutical importance of substituted benzoxazoles: a comprehensive review. Inter. J. ChemTech. Res., 2012, 4(2), 640-650.
Lin, W-H.; Wu, W-C.; Selvaraju, M.; Sun, C-M. One-pot synthesis of benzazoles and quinazolinones via iron pentacarbonyl mediated carbonylation of aryl iodides under microwave irradiation. Org. Chem. Front., 2017, 4(3), 392-397.
Naeimi, H.; Rouzegar, Z.; Rahmatinejad, S. Catalyst-free microwave-promoted one pot synthesis of 2-aryl benzoxazoles using MnO2 nanoparticles as a convenient oxidant under mild condition. Res. Chem. Intermed., 2017, 43(8), 4745-4758.
Dev, D.; Chandra, J.; Palakurthy, N.B.; Thalluri, K.; Kalita, T.; Mandal, B. Benzoxazole and benzothiazole synthesis from carboxylic acids in solution and on resin by using ethyl 2-cyano-2-(2-nitrobenzenesulfonyloxyimino)acetate and para-toluenesulfonic acid. Asian J. Org. Chem., 2016, 5(5), 663-675.
Naeimi, H.; Rahmatinejad, S. Microwave assisted synthesis of two-substituted benzoxazoles in the presence of potassium cyanide under mild conditions. Synth. React. Inorg. Met.-Org. Nano-Met. Chem., 2015, 46(3), 471-476.
Sangi, D.P.; Monteiro, J.L.; Vanzolini, K.L.; Cass, Q.B.; Paixão, M.W.; Corrêa, A.G. Microwave-assisted synthesis of n-heterocycles and their evaluation using an acetylcholinesterase immobilized capillary reactor. J. Braz. Chem. Soc., 2014, 25(5), 887-889.
Eppakayala, L.; Tharigoppula, G.; Bucha, M.; Bommera, R.K.; Harkala, K. Microwave assisted synthesis and characterization of 6-substituted-N-arylbenzo[d]oxazol-2-amines. J. Pharm. Res., 2013, 7(2), 205-207.
Lee, W-L.; Liu, L-C.; Chung, M-H.; Chen, C-M.; Lin, J-S. Microwave-assisted synthesis of benazoxoazol derivatives and their applications for phosphors of white light-emitting diodes. J. Lumin., 2013, 142, 173-179.
Nieddu, G.; Giacomelli, G. A microwave assisted synthesis of benzoxazoles from carboxylic acids. Tetrahedron, 2013, 69(2), 791-795.
Kumar, N.; Dubey, P. An expeditious microwave-assisted synthesis of mercapto benzazoles, quinazolinone and oxadiazoles. Indian J. Chem., 2012, 51B, 1619-1622.
Miandji, A.M.; Ulusoy, S.; Dündar, Y.; Ozgen, S.; Onurdağ, F.K.; Boşgelmez-Tınaz, G.; Noyanalpan, N. Synthesis and biological activities of some 1,3-benzoxazol-2(3H)-one derivatives as anti-quorum sensing agents. Arzneimittelforschung, 2012, 62(7), 330-334.
[] [PMID: 22588631]
Sondhi, S.M.; Arya, S.; Rani, R. Microwave-assisted conversion of aromatic heterocyclic nitriles to various heterocyclic molecules. Green Chem. Lett. Rev., 2012, 5(3), 409-414.
Praveen, C.; Nandakumar, A.; Dheenkumar, P.; Muralidharan, D.; Perumal, P. Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents. J. Chem. Sci., 2012, 124(3), 609-624.
Pizzetti, M.; Luca, E.D.; Petricci, E.; Porcheddu, A.; Taddei, M. A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines. Adv. Synth. Catal., 2012, 354, 2453-2464.
Wen, X.; Bakali, J.E.; Deprez-Poulain, R.; Deprez, B. Efficient propylphosphonic anhydride (®T3P) mediated synthesis of benzothiazoles, benzoxazoles and benzimidazoles. Tetrahedron Lett., 2012, 53(19), 2440-2443.
Madabhushi, S.; Chinthala, N.; Vangipuram, V.S.; Godala, K.R.; Jillella, R.; Mallu, K.K.R.; Beeram, C.R. Microwave-assisted efficient one-step synthesis of amides from ketones and benzoxazoles from (2-hydroxyaryl) ketones with acetohydroxamic acid using sulfuric acid as the catalyst. Tetrahedron Lett., 2011, 52(46), 6103-6107.
Tahermansouri, H.; Chobfrosh Khoei, D.; Meskinfam, M. The chemical functionalization of carboxylated multi-wall nanotubes with 2-aminophenole via microwave irradiation. Orient. J. Chem., 2011, 27(2), 499-504.
Chanda, K.; Maiti, B.; Yellol, G.S.; Chien, M.H.; Kuo, M.L.; Sun, C.M. Polymer supported synthesis of novel benzoxazole linked benzimidazoles under microwave conditions: in vitro evaluation of VEGFR-3 kinase inhibition activity. Org. Biomol. Chem., 2011, 9(6), 1917-1926.
[] [PMID: 21283915]
Youssef, M.M.; Amin, M.A. Microwave assisted synthesis of some new heterocyclic spiro-derivatives with potential antimicrobial and antioxidant activity. Molecules, 2010, 15(12), 8827-8840.
[] [PMID: 21131902]
Nourmohammadian, F.; Gholami, M.D. Microwave-promoted one-pot syntheses of coumarin dyes. Synth. Commun., 2010, 40(6), 901-909.
Radi, M.; Saletti, S.; Botta, M. A one-pot, two-step microwave-assisted synthesis of highly functionalized benzoxazoles using solid-supported reagents (SSRs). Tetrahedron Lett., 2008, 49(29-30), 4464-4466.
Lim, H-J.; Myung, D.; Lee, I.Y.C.; Jung, M.H. Microwave-assisted synthesis of benzimidazoles, benzoxazoles, and benzothiazoles from resin-bound esters. J. Comb. Chem., 2008, 10(4), 501-503.
[] [PMID: 18547118]
Zahran, M.A.; El-Essawy, F.A.; Yassin, S.M.; Salem, T.A.; Boshta, N.M. Rapid and efficient synthesis of 4-substituted pyrazol-5-one under microwave irradiation in solvent-free conditions. Arch. Pharm. (Weinheim), 2007, 340(11), 591-598.
[] [PMID: 17924363]
Viirre, R.D.; Evindar, G.; Batey, R.A. Copper-catalyzed domino annulation approaches to the synthesis of benzoxazoles under microwave-accelerated and conventional thermal conditions. J. Org. Chem., 2008, 73(9), 3452-3459.
[] [PMID: 18376860]
Seijas, J.; Vázquez-Tato, M.; Carballido-Reboredo, M.; Crecente-Campo, J.; Romar-López, L. Lawesson’s reagent and microwaves: a new efficient access to benzoxazoles and benzothiazoles from carboxylic acids under solvent-free conditions.Synlett,2007, 2007, (2), 0313-0317.
Likhanova, N.V.; Martínez‐Palou, R.; Veloz, M.A.; Matias, D.J.; Reyes‐Cruz, V.E.; Höpfl, H.; Olivares, O. Microwave‐assisted synthesis of 2‐(2‐pyridyl) azoles. Study of their corrosion inhibiting properties. J. Heterocycl. Chem., 2007, 44(1), 145-153.
Ravindran, G.; Muthusubramanian, S.; Selvaraj, S.; Perumal, S. Solventless synthesis of 2,4,10a-triaryl-1,10a-dihydro-2H-pyrazino [2,1-b][1,3] benzoxazole. Indian J. Chem., 2007, 46B, 1047-1050.
Matloubi Moghaddam, F.; Rezanejade Bardajee, G.; Ismaili, H.; Maryam Dokht Taimoory, S. Facile and efficient one‐pot protocol for the synthesis of benzoxazole and benzothiazole derivatives using molecular iodine as catalyst. Synth. Commun., 2006, 36(17), 2543-2548.
Huxley, A. Microwave-assisted synthesis of benzoxazole-7-carboxylate esters using trifluoroacetic acid and acetic acid. Synlett, 2006, 2006(16), 2658-2660.
Dabholkar, V.V.; Mishra, S.K.J. Efficient synthesis of some novel spiro heterocycles containing thiazole, oxazole, thiadiazole and triazolo-thiadiazole moiety under microwave irradiation. Heterocycl. Commun., 2006, 12(3-4), 241-246.
Lewis, J.C.; Wu, J.Y.; Bergman, R.G.; Ellman, J.A. Microwave-promoted rhodium-catalyzed arylation of heterocycles through C--H bond activation. Angew. Chem. Int. Ed. Engl., 2006, 45(10), 1589-1591.
[] [PMID: 16444794]
Martínez-Palou, R.; Zepeda, L.G.; Höpfl, H.; Montoya, A.; Guzmán-Lucero, D.J.; Guzmán, J. Parallel and automated library synthesis of 2-long alkyl chain benzoazoles and azole[4,5-b]pyridines under microwave irradiation. Mol. Divers., 2005, 9(4), 361-369.
[] [PMID: 16311813]
Chakraborti, A.K.; Kumar, R.; Selvam, C.; Kaur, G. Microwave-assisted direct synthesis of 2-substituted benzoxazoles from carboxylic acids under catalyst and solvent-free conditions. Synlett, 2005, (9), 1401-1404.
Pottorf, R.S.; Chadha, N.K.; Katkevics, M.; Ozola, V.; Suna, E.; Ghane, H.; Regberg, T.; Player, M.R. Parallel synthesis of benzoxazoles via microwave-assisted dielectric heating. Tetrahedron Lett., 2003, 44(1), 175-178.
Rostamizadeh, S.; Derafshian, E. A simple route to the preparation of benzimidazoles and benzoxazoles. J. Chem. Res., 2001, 227-228.
Bougrin, K.; Loupy, A.; Soufiaoui, M. Trois nouvelles voies de synthèse des dérivés 1, 3-azoliques sous micro-ondes. Tetrahedron, 1998, 54(28), 8055-8064.
Villemin, D.; Hammadi, M.; Martin, B. Clay catalysis: condensation of orthoesters with O-substituted aminoaromatics into heterocycles. Synth. Commun., 1996, 26(15), 2895-2899.

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