Recent Advances in the Green Synthesis of Heterocycles: From Building
Blocks to Biologically Active Compounds

Christian      Schäfer; Hyejin       Cho; Bernadett      Vlocskó; Guoshu       Xie; Béla       Török
doi:10.2174/1570179418666210910110205
Abstract

Recent advances in the environmentally benign synthesis of common heterocycles are described. This account features three main parts; the preparation of non-aromatic heterocycles, one-ring aromatic heterocycles and their condensed analogs. Due to the great variety of and high interest in these compounds, this work focuses on providing representative examples of the preparation of the target compounds.
Keywords: Sustainable synthesis, non-aromatic heterocycles, aromatic heterocycles, condensed heterocycles, epoxides, aziridines, azetidines, pyrroles, indoles, quinolines, pyridines, pyrimidines, condensed heterocycles.
« Previous Next »
Graphical Abstract

[1] 
Gilchrist, T.L. Heterocyclic Chemistry, 3rd ed; Addison, Wesley, Longman: Harlow, 1997. 
[2] 
Török, B.; Dransfield, T. Green Chemistry: An Inclusive Approach; Elsevier: Amsterdam, Oxford, Cambridge, 2018. 
[3] 
Singh, G.S.; D’hooghe, M.; De Kimpe, N. Synthesis and reactivity of C-heteroatom-substituted aziridines. Chem. Rev.,  2007, 107(5), 2080-2135.
[http://dx.doi.org/10.1021/cr0680033] [PMID:  17488062] 
[4] 
Yudin, A.K. Aziridines and Epoxides in Organic Synthesis; Wiley-VCH: Weinheim, 2006. 
[http://dx.doi.org/10.1002/3527607862] 
[5] 
Chawla, R.; Singh, A.K.; Yadav, L.D.S. Organocatalysis in synthesis and reactions of epoxides and aziridines. RSC Advances,  2013, 13, 11385-11403.
[http://dx.doi.org/10.1039/c3ra00175j]] 
[6] 
Gomes, A.R.; Varela, C.L.; Tavares-da-Silva, E.J.; Roleira, F.M.F. Epoxide containing molecules: A good or a bad drug design approach. Eur. J. Med. Chem.,  2020, 201, 112327.
[http://dx.doi.org/10.1016/j.ejmech.2020.112327] [PMID:  32526552] 
[7] 
Moschona, F.; Savvopoulou, I.; Tsitopoulou, M.; Tataraki, D.; Rassias, G. Epoxide syntheses and ring-opening reactions in drug development. Catalysts,  2020, 10, 1117.
[http://dx.doi.org/10.3390/catal10101117] 
[8] 
Marco-Contelles, J.; Molina, M.T.; Anjum, S. Naturally occurring cyclohexane epoxides: sources, biological activities, and synthesis. Chem. Rev.,  2004, 104(6), 2857-2899.
[http://dx.doi.org/10.1021/cr980013j] [PMID:  15186183] 
[9] 
Grigoropoulou, G.; Clark, J.H.; Elings, J.A. Recent developments on the epoxidation of alkenes using hydrogen peroxide as an oxidant. Green Chem.,  2003, 5, 1-7.
[http://dx.doi.org/10.1039/b208925b] 
[10] 
Tebandeke, E.; Coman, C.; Guillois, K.; Canning, G.; Ataman, E.; Knudsen, J.; Wallenberg, L.R.; Ssekaalo, H.; Schnadt, J.; Wendt, O.F. Epoxidation of olefins with molecular oxygen as the oxidant using gold catalysts supported on polyoxometalates. Green Chem.,  2014, 16, 1586-1593.
[http://dx.doi.org/10.1039/c3gc42198h] 
[11] 
Tang, B.; Dai, W.; Sun, X.; Guan, N.; Li, L.; Hunger, M. A procedure for the preparation of Ti-Beta zeolites for catalytic epoxidation with hydrogen peroxide. Green Chem.,  2014, 16, 2281-2291.
[http://dx.doi.org/10.1039/C3GC42534G] 
[12] 
Bawaked, S.; Dummer, N.F.; Bethell, D.; Knight, D.W.; Hutchings, G.J. Solvent-free selective epoxidation of cyclooctene using supported gold catalysts: an investigation of catalyst re-use. Green Chem.,  2011, 13, 127-134.
[http://dx.doi.org/10.1039/C0GC00550A] 
[13] 
Doherty, S.; Knight, J.G.; Ellison, J.R.; Weekes, D.; Harrington, R.W.; Hardacre, C.; Manyar, H. An efficient recyclable peroxometalate-based polymer-immobilised ionic liquid phase (PIILP) catalyst for hydrogen peroxide-mediated oxidation. Green Chem.,  2012, 14, 925-929.
[http://dx.doi.org/10.1039/c2gc16679h] 
[14] 
Qiao, Y.; Hou, Z.; Li, H.; Hu, Y.; Feng, B.; Wang, X.; Hua, L.; Huang, Q. Polyoxometalate-based protic alkylimidazolium salts as reaction-induced phase-separation catalysts for olefin epoxidation. Green Chem.,  2009, 11, 1955-1960.
[http://dx.doi.org/10.1039/b916766h] 
[15] 
Hasan, K.; Brown, N.; Kozak, C.M. Iron-catalyzed epoxidation of olefins using hydrogen peroxide. Green Chem.,  2011, 13, 1230-1237.
[http://dx.doi.org/10.1039/c0gc00943a] 
[16] 
Chen, Q.; Beckman, E.J. One-pot green synthesis of propylene oxide using in situ generated hydrogen peroxide in carbon dioxide. Green Chem.,  2008, 10, 934-938.
[http://dx.doi.org/10.1039/b803847c] 
[17] 
Katsuki, T.; Sharpless, K.B. The First Practical Method for Asymmetric Epoxidation. J. Am. Chem. Soc.,  1980, 102, 5974-5976.
[http://dx.doi.org/10.1021/ja00538a077] 
[18] 
Sharpless, K.B. Searching for new reactivity (Nobel lecture). Angew. Chem. Int. Ed.,  2002, 41(12), 2024-2032.
[http://dx.doi.org/10.1002/1521-3773(20020617)41:12<2024:AID-ANIE2024>3.0.CO;2-O] [PMID:  19746596] 
[19] 
De Faveri, G.; Ilyashenko, G.; Watkinson, M. Recent advances in catalytic asymmetric epoxidation using the environmentally benign oxidant hydrogen peroxide and its derivatives. Chem. Soc. Rev.,  2011, 40(3), 1722-1760.
[http://dx.doi.org/10.1039/C0CS00077A] [PMID:  21079863] 
[20] 
Meninno, S.; Lattanzi, A. Asymmetric organocatalytic journey into the world of three-membered rings. Catal. Today,  2017, 285, 39-48.
[http://dx.doi.org/10.1016/j.cattod.2017.02.007] 
[21] 
Kawai, H.; Okusu, S.; Yuan, Z.; Tokunaga, E.; Yamano, A.; Shiro, M.; Shibata, N. Enantioselective synthesis of epoxides having a tetrasubstituted trifluoromethylated carbon center: methylhydrazine-induced aerobic epoxidation of β,β-disubstituted enones. Angew. Chem. Int. Ed. Engl.,  2013, 52(8), 2221-2225.
[http://dx.doi.org/10.1002/anie.201209355] [PMID:  23339133] 
[22] 
Majdecki, M.; Tyszka-Gumkowska, A.; Jurczak, J. Highly enantioselective epoxidation of α,β-unsaturated ketones using amide-based cinchona alkaloids as hybrid phase-transfer catalysts. Org. Lett.,  2020, 22(21), 8687-8691.
[http://dx.doi.org/10.1021/acs.orglett.0c03272] [PMID:  33112627] 
[23] 
Devi, E.S.; Pavithra, T.; Tamilselvi, A.; Nagarajan, S.; Sridharan, V.; Maheswari, C.U. N-heterocyclic carbene catalyzed synthesis of trisubstituted epoxides via tandem amidation/epoxidation sequence. Org. Lett.,  2020, 22(9), 3576-3580.
[http://dx.doi.org/10.1021/acs.orglett.0c01017] [PMID:  32271025] 
[24] 
Zhang, Y.; Pan, H.; Liu, W.; Cao, W.; Feng, X. Asymmetric catalytic synthesis of epoxides via three-component reaction of diazoacetates, 2-Oxo-3-ynoates, and nitrosoarenes. Org. Lett.,  2020, 22(17), 6744-6749.
[http://dx.doi.org/10.1021/acs.orglett.0c02108] [PMID:  32818380] 
[25] 
Aouf, C.; Durand, E.; Lecomte, J.; Figueroa-Espinoza, M-C.; Dubreucq, E.; Fulcrand, H.; Villeneuve, P. The use of lipases as biocatalysts for the epoxidation of fatty acids and phenolic compounds. Green Chem.,  2014, 16, 1740-1754.
[http://dx.doi.org/10.1039/C3GC42143K] 
[26] 
Kluge, M.; Ullrich, R.; Scheibner, K.; Hofrichter, M. Stereoselective benzylic hydroxylation of alkylbenzenes and epoxidation of styrene derivatives catalyzed by the peroxygenase of Agrocybe aegerita. Green Chem.,  2012, 14, 440-446.
[http://dx.doi.org/10.1039/C1GC16173C] 
[27] 
Thibodeaux, C.J.; Chang, W.C.; Liu, H.W. Enzymatic chemistry of cyclopropane, epoxide, and aziridine biosynthesis. Chem. Rev.,  2012, 112(3), 1681-1709.
[http://dx.doi.org/10.1021/cr200073d] [PMID:  22017381] 
[28] 
Chavan, V.P.; Pathwardan, A.V.; Gogate, P.R. Intensification of epoxidation of soybean oil using sonochemical reactors. Chem. Eng. Process.,  2012, 54, 22-28.
[http://dx.doi.org/10.1016/j.cep.2012.01.006] 
[29] 
Sato, K.; Aoki, M.; Ogawa, M.; Hashimoto, T.; Noyori, R. A practical method for epoxidation of terminal olefins with 30 hydrogen peroxide under halide-free conditions. J. Org. Chem.,  1996, 61(23), 8310-8311.
[http://dx.doi.org/10.1021/jo961287e] [PMID:  11667823] 
[30] 
Sato, K.; Aoki, M.; Ogawa, M.; Hashimoto, T.; Panyella, D.; Noyori, R. A halide free method for olefin epoxidation with 30% hydrogen peroxide. Bull. Chem. Soc. Jpn.,  1997, 70, 905-915.
[http://dx.doi.org/10.1246/bcsj.70.905] 
[31] 
Wang, C.; Yamamoto, H. Tungsten-catalyzed asymmetric epoxidation of allylic and homoallylic alcohols with hydrogen peroxide. J. Am. Chem. Soc.,  2014, 136(4), 1222-1225.
[http://dx.doi.org/10.1021/ja411379e] [PMID:  24422626] 
[32] 
Salvadori, P.; Pini, D.; Petri, A.; Mandoli, A. Catalytic heterogeneous enantioselective dihydroxylation and epoxidation. In: Chiral Catalvst Immobilization and Recycling; DeVos, D.E.; Vankelecom, I.F.J.; Jacobs, P.A., Eds.; Wiley-VCH Verlag, 2000; 11, pp. 239-259.
[http://dx.doi.org/10.1002/9783527613144.ch10] 
[33] 
Wang, R.; Liu, X.; Yang, F.; Gao, S.; Zhou, S.; Kong, Y. Neighboring Cu toward Mn site in confined mesopore to trigger strong interplay for boosting catalytic epoxidation of styrene. Appl. Surf. Sci.,  2021, 537, 148100.
[http://dx.doi.org/10.1016/j.apsusc.2020.148100] 
[34] 
Török, B.; Schäfer, C.; Kokel, A. Heterogeneous Catalysis in Green and Sustainable Synthesis, 1st ed; Elsevier: Oxford, Cambridge, MA, 2021. 
[http://dx.doi.org/10.1016/b978-0-12-817825-6.00009-4] 
[35] 
Otake, K-I.; Ahn, S.; Knapp, J.; Hupp, J.T.; Notestein, J.M.; Farha, O.K. Vapor-Phase Cyclohexene Epoxidation by Single-Ion Fe(III) Sites in Metal-Organic Frameworks. Inorg. Chem.,  2021, 60(4), 2457-2463.
[http://dx.doi.org/10.1021/acs.inorgchem.0c03364] [PMID:  33497212] 
[36] 
Escande, V.; Petit, E.; Garoux, L.; Boulanger, C.; Grison, C. Switchable alkene epoxidation/oxidative cleavage with H2O2/NaHCO3: efficient heterogeneous catalysis derived from biosourced Eco-Mn. ACS Sustain. Chem.& Eng.,  2015, 3, 2704-2715.
[http://dx.doi.org/10.1021/acssuschemeng.5b00561] 
[37] 
Lueangchaichaweng, W.; Brooks, N.R.; Fiorilli, S.; Gobechiya, E.; Lin, K.; Li, L. Parres-Esclapez, S.; Javon, E.; Bals, S.; Van Tendeloo, G.; Martens, J. A.; Kirschhock, C. E. A.; Jacobs, P. A.; Pescarmona, P. P. Gallium oxide nanorods: novel, template-free synthesis and high catalytic activity in epoxidation reactions. Angew. Chem. Int. Ed.,  2014, 53, 1585-1589.
[http://dx.doi.org/10.1002/anie.201308384] 
[38] 
Sweeney, J.B. Aziridines: epoxides’ ugly cousins? Chem. Soc. Rev.,  2002, 31(5), 247-258.
[http://dx.doi.org/10.1039/B006015L] [PMID:  12357722] 
[39] 
Müller, P.; Fruit, C. Enantioselective catalytic aziridinations and asymmetric nitrene insertions into CH bonds. Chem. Rev.,  2003, 103(8), 2905-2920.
[http://dx.doi.org/10.1021/cr020043t] [PMID:  12914485] 
[40] 
Degennaro, L.; Trinchera, P.; Luisi, R. Recent advances in the stereoselective synthesis of aziridines. Chem. Rev.,  2014, 114(16), 7881-7929.
[http://dx.doi.org/10.1021/cr400553c] [PMID:  24823261] 
[41] 
Jin, L.M.; Xu, X.; Lu, H.; Cui, X.; Wojtas, L.; Zhang, X.P. Effective synthesis of chiral N-fluoroaryl aziridines through enantioselective aziridination of alkenes with fluoroaryl azides. Angew. Chem. Int. Ed. Engl.,  2013, 52(20), 5309-5313.
[http://dx.doi.org/10.1002/anie.201209599] [PMID:  23589338] 
[42] 
Jenkins, D.M. Atom-economical C2 + N1 aziridination: progress towards catalytic intermolecular reactions using alkenes and aryl azides. Synlett,  2012, 23, 1267-1270.
[http://dx.doi.org/10.1055/s-0031-1290977] 
[43] 
Cramer, S.A.; Jenkins, D.M. Synthesis of aziridines from alkenes and aryl azides with a reusable macrocyclic tetracarbene iron catalyst. J. Am. Chem. Soc.,  2011, 133(48), 19342-19345.
[http://dx.doi.org/10.1021/ja2090965] [PMID:  22081884] 
[44] 
Jung, N.; Bräse, S. New catalysts for the transition-metal-catalyzed synthesis of aziridines. Angew. Chem. Int. Ed. Engl.,  2012, 51(23), 5538-5540.
[http://dx.doi.org/10.1002/anie.201200966] [PMID:  22565642] 
[45] 
Munnuri, S.; Anugu, R.R.; Falck, J.R. Cu(II)-Mediated N-H and N-alkyl aryl amination and olefin aziridination. Org. Lett.,  2019, 21(6), 1926-1929.
[http://dx.doi.org/10.1021/acs.orglett.9b00586] [PMID:  30821980] 
[46] 
Dos Santos, D.A.; da Silva, A.R.; Ellena, J.; da Silva, C.C.P.; Paixão, M.W.; Corrêa, A.G. Green one-pot asymmetric synthesis of peptidomimetics via sequential organocatalyzed aziridination and passerini multicomponent reaction. Synthesis,  2020, 52, 1076-1086.
[http://dx.doi.org/10.1055/s-0039-1690774] 
[47] 
Borkin, D.; Carlson, A.; Török, B. K-10-catalyzed highly diastereoselective synthesis of aziridines. Synlett,  2010, 12(5), 745-748.
[48] 
Luo, H.; Hu, G.; Li, P. Sulfur-mediated allylic C-H arylation, epoxidation, and aziridination. J. Org. Chem.,  2019, 84(17), 10569-10578.
[http://dx.doi.org/10.1021/acs.joc.9b01438] [PMID:  31287687] 
[49] 
Liu, X-X.; Jia, J.; Wang, Z.; Zhang, Y-T.; Chen, J.; Yang, K.; He, C-J.; Zhao, L. Catalyst-free and visible light promoted aminofluor-oalkylation of unactivated alkenes: an access to fluorinated aziridines. Adv. Synth. Catal.,  2020, 362, 2604-2608.
[http://dx.doi.org/10.1002/adsc.202000342] 
[50] 
Abe, M. Formation of a four-membered ring: oxetanes. In: Handbook of Synthetic Photochemistry; Albini, A.; Fagnoni, M., Eds.; Wiley-VCH: Weinheim, 2010; pp. 217-239.
[51] 
Adam, W.; Stegmann, V.R. Hydroxy-group directivity in the regioselective and diastereoselective [2+2] photocycloaddition (Paterno-Buechi reaction) of aromatic carbonyl compounds to chiral and achiral allylic substrates: the preparation of oxetanes with up to three stereogenic centers as synthetic building blocks. Synthesis,  2011, 112(8), 1203-1214.
[52] 
Bull, J.A.; Croft, R.A.; Davis, O.A.; Doran, R.; Morgan, K.F. Oxetanes: Recent advances in synthesis, reactivity, and medicinal chemistry. Chem. Rev.,  2016, 116(19), 12150-12233.
[http://dx.doi.org/10.1021/acs.chemrev.6b00274] [PMID:  27631342] 
[53] 
Christlieb, M.; Davies, J.E.; Eames, J.; Hooley, R.; Warren, S. The stereoselective synthesis of oxetanes; exploration of a new, Mitsunobu-style procedure for the cyclization of 1,3- diols. J. Chem. Soc., Perkin Trans. 1,  2001, 2983-2996.
[http://dx.doi.org/10.1039/b106851b] 
[54] 
Rykaczewski, K.A.; Schindler, C.S. Visible-light-enabled paternò-büchi reaction via triplet energy transfer for the synthesis of oxetanes. Org. Lett.,  2020, 22(16), 6516-6519.
[http://dx.doi.org/10.1021/acs.orglett.0c02316] [PMID:  32806149] 
[55] 
Richardson, A.D.; Becker, M.R.; Schindler, C.S. Synthesis of azetidines by aza Paternò-Büchi reactions. Chem. Sci. (Camb.),  2020, 11(29), 7553-7561.
[http://dx.doi.org/10.1039/D0SC01017K] [PMID:  32832061] 
[56] 
Becker, M.R.; Wearing, E.R.; Schindler, C.S. Synthesis of azetidines via visible-light-mediated intermolecular [2+2] photocycloadditions. Nat. Chem.,  2020, 12(10), 898-905.
[http://dx.doi.org/10.1038/s41557-020-0541-1] [PMID:  32968230] 
[57] 
Reidl, T.W.; Son, J.; Wink, D.J.; Anderson, L.L. Facile synthesis of azetidine nitrones and diastereoselective conversion into densely substituted azetidines. Angew. Chem. Int. Ed. Engl.,  2017, 56(38), 11579-11583.
[http://dx.doi.org/10.1002/anie.201705681] [PMID:  28707372] 
[58] 
Wu, Z-J.; Li, S-R.; Xu, H-C. Synthesis of N-heterocycles by dehydrogenative annulation of N-allyl amides with 1,3-dicarbonyl compounds. Angew. Chem. Int. Ed. Engl.,  2018, 57(43), 14070-14074.
[http://dx.doi.org/10.1002/anie.201807683] [PMID:  30184314] 
[59] 
Zalomaeva, O.V.; Chibiryaev, A.M.; Kovalenko, K.A.; Kholdeeva, O.A.; Balzhinimaev, B.S.; Fedin, V.P. Cyclic carbonates synthesis from epoxides and CO2 over metal–organic framework Cr-MIL-101. J. Catal.,  2013, 298, 179-185.
[http://dx.doi.org/10.1016/j.jcat.2012.11.029] 
[60] 
Yang, Y.; Hayashi, Y.; Fujii, Y.; Nagano, T.; Kita, Y.; Ohshima, T.; Okuda, J.; Mashima, K. Efficient cyclic carbonate synthesis catalyzed by zinc cluster systems under mild conditions. Catal. Sci. Technol.,  2012, 2, 509-513.
[http://dx.doi.org/10.1039/C1CY00404B] 
[61] 
Yang, Z.Z.; Li, Y.N.; Wei, Y.Y.; He, L.N. Protic onium salts-catalyzed synthesis of 5-aryl-2-oxazolidinones from aziridines and CO2 under mild conditions. Green Chem.,  2011, 13, 2351-2353.
[http://dx.doi.org/10.1039/c1gc15581d] 
[62] 
Schäfer, C. Béla TörökIn, B. Application of nontraditional activation methods in green and sustainable chemistry: Microwaves, ultrasounds, electro-, photo-, and mechanochemistry, and high hydrostatic pressure. In: Nontraditional Activation Methods in Green and Sustainable Applications; Béla, Török; Christian, Schäfer, Eds.; Elsevier Science B. V: Amsterdam, 2021; pp. 1-26.
[63] 
Phung, C.; Ulrich, R.M.; Ibrahim, M.; Tighe, N.T.G.; Lieberman, D.L.; Pinhas, A.R. The solvent-free and catalyst-free conversion of an aziridine to an oxazolidinone using only carbon dioxide. Green Chem.,  2011, 13, 3224-3229.
[http://dx.doi.org/10.1039/c1gc15850c] 
[64] 
Zhou, H.; Mu, S.; Ren, B-H.; Zhang, R.; Lu, X-B. Organocatalyzed carboxylative cyclization of propargylic amides with atmospheric CO2 towards oxazolidine-2,4-diones. Green Chem.,  2019, 21, 991-994.
[http://dx.doi.org/10.1039/C8GC03929A] 
[65] 
Yang, X.; Zhu, Y.; Xie, Z.; Li, Y.; Zhang, Y. Visible-light-induced charge transfer enables Csp3-H functionalization of glycine derivatives: access to 1,3-oxazolidines. Org. Lett.,  2020, 22(4), 1638-1643.
[http://dx.doi.org/10.1021/acs.orglett.0c00234] [PMID:  32037834] 
[66] 
Han, M.Y.; Jia, J.Y.; Wang, W. Recent advances in organocatalytic asymmetric synthesis of polysubstituted pyrrolidines. Tetrahedron Lett.,  2014, 55, 784-794.
[http://dx.doi.org/10.1016/j.tetlet.2013.11.048] 
[67] 
Brown, A.R.; Uyeda, C.; Brotherton, C.A.; Jacobsen, E.N. Enantioselective thiourea-catalyzed intramolecular cope-type hydroamination. J. Am. Chem. Soc.,  2013, 135(18), 6747-6749.
[http://dx.doi.org/10.1021/ja402893z] [PMID:  23597402] 
[68] 
Chapurina, Y.; Ibrahim, H.; Guillot, R.; Kolodziej, E.; Collin, J.; Trifonov, A.; Schulz, E.; Hannedouche, J. Catalytic, enantioselective intramolecular hydroamination of primary amines tethered to di- and trisubstituted alkenes. J. Org. Chem.,  2011, 76(24), 10163-10172.
[http://dx.doi.org/10.1021/jo202009q] [PMID:  22059438] 
[69] 
Tarannum, S.; Sk, S.; Das, S.; Wani, I.A.; Ghorai, M.K. Stereoselective syntheses of highly functionalized imidazolidines and oxazolidines via ring-opening cyclization of activated aziridines and epoxides with amines and aldehydes. J. Org. Chem.,  2020, 85(2), 367-379.
[http://dx.doi.org/10.1021/acs.joc.9b02278] [PMID:  31782305] 
[70] 
Zhang, H.; Muñiz, K. Selective piperidine synthesis exploiting iodine-catalyzed Csp3−H amination under visible light. ACS Catal.,  2017, 7, 4122-4125.
[http://dx.doi.org/10.1021/acscatal.7b00928] 
[71] 
Burtea, A.; DeForest, J.; Li, X.; Rychnovsky, S.D. Total Synthesis of. Himeradine A. Angew. Chem. Int. Ed.,  2019, 131, 16339-16343.
[72] 
Guérinot, A.; Serra-Muns, A.; Gnamm, C.; Bensoussan, C.; Reymond, S.; Cossy, J. FeCl(3)-Catalyzed highly diastereoselective synthesis of substituted piperidines and tetrahydropyrans. Org. Lett.,  2010, 12(8), 1808-1811.
[http://dx.doi.org/10.1021/ol100422d] [PMID:  20337417] 
[73] 
Sun, Z.; Winschel, G.A.; Zimmerman, P.M.; Nagorny, P. Enantioselective synthesis of piperidines through the formation of chiral mixed phosphoric acid acetals: experimental and theoretical studies. Angew. Chem. Int. Ed. Engl.,  2014, 53(42), 11194-11198.
[http://dx.doi.org/10.1002/anie.201405128] [PMID:  25196818] 
[74] 
Balakrishna, A.; Aguiar, A.; Sobral, P.J.M.; Wani, M.Y.; Almeida, J.; Sobral, S.A.J.N.F. Paal–Knorr synthesis of pyrroles: from conventional to green synthesis. Catal. Rev., Sci. Eng.,  2019, 61, 84-110.
[http://dx.doi.org/10.1080/01614940.2018.1529932] 
[75] 
Akbaslar, D.; Demirkol, O.; Giray, S. Paal-Knorr pyrrole synthesis in water. Synth. Commun.,  2014, 44, 1323-1332.
[http://dx.doi.org/10.1080/00397911.2013.857691] 
[76] 
Cho, H.; Madden, R.; Nisanci, B.; Török, B. The Paal-Knorr reaction revisited. A catalyst and solvent-free synthesis of underivatized and N-substituted pyrroles. Green Chem.,  2015, 17, 1088-1099.
[http://dx.doi.org/10.1039/C4GC01523A] 
[77] 
Guan, Z-H.; Li, L.; Ren, Z-H.; Li, J.; Zhao, M.N. A facile and efficient synthesis of multisubstituted pyrroles from enaminoesters and nitroolefins. Green Chem.,  2011, 13, 1664-1668.
[http://dx.doi.org/10.1039/c1gc15278e] 
[78] 
Xu, J.; Green, A.P.; Turner, N.J. Chemo-enzymatic synthesis of pyrazines and pyrroles. Angew. Chem. Int. Ed. Engl.,  2018, 57(51), 16760-16763.
[http://dx.doi.org/10.1002/anie.201810555] [PMID:  30335228] 
[79] 
Yasukawa, N.; Kuwata, M.; Imai, T.; Monguchi, Y.; Sajiki, H.; Sawama, Y. Copper-catalyzed pyrrole synthesis from 3,6-dihydro-1,2-oxazines. Green Chem.,  2018, 20, 4409-4413.
[http://dx.doi.org/10.1039/C8GC01373J] 
[80] 
Wang, P.; Ma, F-P.; Zhang, Z-H. L-(+)-Tartaric acid and choline chloride based deep eutectic solvent: An efficient and reusable medium for synthesis of N-substituted pyrroles via Clauson-Kaas reaction. J. Mol. Liq.,  2014, 198, 259-262.
[http://dx.doi.org/10.1016/j.molliq.2014.07.015] 
[81] 
Abid, M.; Landge, S.M.; Török, B. An efficient and rapid synthesis of N-substituted pyrroles by microwave assisted solid acid catalysis. Org. Prep. Proced. Int.,  2006, 38, 495-500.
[http://dx.doi.org/10.1080/00304940609356444] 
[82] 
Naeimi, H.; Dadaei, M. Efficient and Green Synthesis of N-aryl Pyrroles Catalyzed by Ionic Liquid [H-NMP][HSO4] in Water at Room Temperature. J. Chin. Chem. Soc. (Taipei),  2014, 61, 1127-1132.
[http://dx.doi.org/10.1002/jccs.201400039] 
[83] 
Singh, S.B.; Verma, P.K.; Tiwari, K.; Srivastava, M.; Ankit, P.; Singh, M.; Singh, J.; Tiwari, K.P. Supramolecular catalysis in the synthesis of polyfunctionalised pyrroles. Supramol. Chem.,  2014, 26, 882-889.
[http://dx.doi.org/10.1080/10610278.2013.877136] 
[84] 
Leonardi, M.; Estévez, V.; Villacampa, M.; Menéndez, J.C. The hantzsch pyrrole synthesis: non-conventional variations and applications of a neglected classical reaction. Synthesis,  2019, 51, 816-828.
[http://dx.doi.org/10.1055/s-0037-1610320] 
[85] 
Guchhait, S.K.; Sisodiya, S.; Saini, M.; Shah, Y.V.; Kumar, G.; Daniel, D.P.; Hura, N.; Chaudhary, V. Synthesis of polyfunc-tionalized pyrroles via a tandem reaction of michael addition and intramolecular cyanide-mediated nitrile-to-nitrile condensation. J. Org. Chem.,  2018, 83(10), 5807-5815.
[http://dx.doi.org/10.1021/acs.joc.8b00465] [PMID:  29671317] 
[86] 
Gui, Q-W.; He, X.; Wang, W.; Zhou, H.; Dong, Y.; Wang, N.; Tang, J-X.; Cao, Z.; He, W-M. The clean preparation of multisubstituted pyrroles under metal- and solvent-free conditions. Green Chem.,  2020, 22, 118-122.
[http://dx.doi.org/10.1039/C9GC02657F] 
[87] 
Zhou, Y.; Zhou, L.; Jesikiewicz, L.T.; Liu, P.; Buchwald, S.L. Synthesis of pyrroles through the CuH-catalyzed coupling of enynes and nitriles. J. Am. Chem. Soc.,  2020, 142(22), 9908-9914.
[http://dx.doi.org/10.1021/jacs.0c03859] [PMID:  32395998] 
[88] 
Chen, J-R.; Hu, X-Q.; Lu, L-Q.; Xiao, W-J. Exploration of visible-light photocatalysis in heterocycle synthesis and functionalization: reaction design and beyond. Acc. Chem. Res.,  2016, 49(9), 1911-1923.
[http://dx.doi.org/10.1021/acs.accounts.6b00254] [PMID:  27551740] 
[89] 
Cao, H.; Tang, X.; Tang, H.; Yuan, Y.; Wu, J. Photoinduced intermolecular hydrogen atom transfer reactions in organic synthesis. Chem. Catal.,  2021, 1, 1-76.
[90] 
Lenardon, G.V.A.; Nicchio, L.; Fagnoni, M. Photogenerated electrophilic radicals for the umpolung of enolate chemistry. J. Photochem. Photobiol. Photochem. Rev.,  2021, 46, 100387.
[http://dx.doi.org/10.1016/j.jphotochemrev.2020.100387] 
[91] 
Pawlowski, R.; Stanek, F.; Stodulski, M. Recent advances on metal-free, visible-light- induced catalysis for assembling nitrogen- and oxygen-based heterocyclic scaffolds. Molecules,  2019, 24(8), 1533.
[http://dx.doi.org/10.3390/molecules24081533] [PMID:  31003464] 
[92] 
Xuan, J.; Xia, X-D.; Zeng, T-T.; Feng, Z-J.; Chen, J-R.; Lu, L-Q.; Xiao, W-J. Visible-light-induced formal [3+2] cycloaddition for pyrrole synthesis under metal-free conditions. Angew. Chem. Int. Ed. Engl.,  2014, 53(22), 5653-5656.
[http://dx.doi.org/10.1002/anie.201400602] [PMID:  24729379] 
[93] 
Li, X.T.; Liu, Y.H.; Liu, X.; Zhang, Z.H. Meglumine catalyzed one-pot, three-component combinatorial synthesis of pyrazoles bearing a coumarin unit. RSC Advances,  2015, 5, 25625-25633.
[http://dx.doi.org/10.1039/C5RA01677K] 
[94] 
Schmitt, D.C.; Taylor, A.P.; Flick, A.C.; Kyne, R.E., Jr Synthesis of pyrazoles from 1,3-diols via hydrogen transfer catalysis. Org. Lett.,  2015, 17(6), 1405-1408.
[http://dx.doi.org/10.1021/acs.orglett.5b00266] [PMID:  25719568] 
[95] 
Matcha, K.; Antonchick, A.P. Cascade multicomponent synthesis of indoles, pyrazoles and pyridazinones by functionalization of alkenes. Angew. Chem. Int. Ed.,  2014, 53, 11960-11964.
[96] 
Dias, D.; Pacheco, B.S.; Cunico, W.; Pizzuti, L.; Pereira, C.M.P. Recent advances on the green synthesis and antioxidant activities of pyrazoles. Mini Rev. Med. Chem.,  2015, 14(13), 1078-1092.
[http://dx.doi.org/10.2174/1389557515666150101102606] [PMID:  25553424] 
[97] 
Fustero, S.; Sánchez-Roselló, M.; Barrio, P.; Simón-Fuentes, A. From 2000 to mid-2010: a fruitful decade for the synthesis of pyrazoles. Chem. Rev.,  2011, 111(11), 6984-7034.
[http://dx.doi.org/10.1021/cr2000459] [PMID:  21806021] 
[98] 
Landge, S.M.; Schmidt, A.; Outerbridge, V.; Török, B. Synthesis of pyrazoles by a one-pot tandem cyclization-dehydrogenation approach on Pd/C/K-10 catalyst. Synlett,  2007, 1600-1604.
[99] 
Borkin, D.A.; Puscau, M.; Carlson, A.; Solan, A.; Wheeler, K.A.; Török, B.; Dembinski, R. Synthesis of diversely 1,3,5-trisubstituted pyrazoles via 5-exo-dig cyclization. Org. Biomol. Chem.,  2012, 10(23), 4505-4508.
[http://dx.doi.org/10.1039/c2ob25580d] [PMID:  22575899] 
[100] 
Guo, Y.; Wang, G.; Wei, L.; Wan, J-P. Domino C-H sulfonylation and pyrazole annulation for fully substituted pyrazole synthesis in water using hydrophilic enaminones. J. Org. Chem.,  2019, 84(5), 2984-2990.
[http://dx.doi.org/10.1021/acs.joc.8b02897] [PMID:  30714367] 
[101] 
Vuluga, D.; Legros, J.; Crousse, B.; Bonnet-Delpon, D. Synthesis of pyrazoles through catalyst-free cycloaddition of diazo compounds to alkynes. Green Chem.,  2009, 11, 156-159.
[http://dx.doi.org/10.1039/B812242C] 
[102] 
Deng, Q-H.; Zou, Y-Q.; Lu, L.Q.; Tang, Z.L.; Chen, J.R.; Xiao, W.J. De novo synthesis of imidazoles by visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade. Chem. Asian J.,  2014, 9(9), 2432-2435.
[http://dx.doi.org/10.1002/asia.201402443] [PMID:  24986800] 
[103] 
Yao. C., Yu, C., Lu, J., Li, T., Wang, D., Qin, B., Zhang, H. A NHC-involved, cascade, metal-free, and three-component synthesis of 2,3-diarylated fully substituted furans under solvent-free conditions. Synlett,  2011, 2420-2424.
[104] 
Reddy, B.V.S.; Somashekar, D.; Reddy, A.M.; Yadav, J.S.; Sridhar, B. PEG 400 as a Reusable solvent for 1,4-dipolar cycloadditions via a three-component reaction. Synthesis,  2010, 2069-2074.
[http://dx.doi.org/10.1055/s-0029-1218762] 
[105] 
Yadav, J.S.; Reddy, B.V.S.; Shubashree, S.; Sadashiv, K.; Rao, D.K. Organic synthesis in water: Green protocol for the synthesis of 2-amino furan derivatives. J. Mol. Catal. Chem.,  2007, 272, 128-131.
[http://dx.doi.org/10.1016/j.molcata.2007.02.032] 
[106] 
Azizian, J.; Mohammadizadeh, M.R.; Mohammadi, A.A.; Karimi, A.R. A modified and green methodology for preparation of polysubstituted furans. Heteroatom Chem.,  2005, 16, 259-262.
[http://dx.doi.org/10.1002/hc.20086] 
[107] 
Allais, C.; Grassot, J-M.; Rodriguez, J.; Constantieux, T. Metal-free multicomponent syntheses of pyridines. Chem. Rev.,  2014, 114(21), 10829-10868.
[http://dx.doi.org/10.1021/cr500099b] [PMID:  25302420] 
[108] 
Xu, F.; Wang, C.; Wang, H.; Li, X.; Wan, B. Eco-friendly synthesis of pyridines via rhodium-catalyzed cyclization of diynes with oximes. Green Chem.,  2015, 17, 799-803.
[http://dx.doi.org/10.1039/C4GC01756K] 
[109] 
Kidwai, M.; Chauhan, R. K2CO3 catalyzed green and rapid access to 2-amino-3,5-dicarbonitrile-6-thio-pyridines. J. Iran. Chem. Soc.,  2014, 11, 1005-1013.
[http://dx.doi.org/10.1007/s13738-013-0368-4] 
[110] 
Shaikh, Y.I.; Shaikh, A.A.; Nazeruddin, G.M. Ammonia solution catalyzed one-pot synthesis of highly functionalized pyridine derivatives. J. Chem. Pharm. Res.,  2012, 4, 4953-4956.
[111] 
Yang, X-H.; Zhou, Y-H.; Zhang, P-H.; Zhang, L.Y. An effective, one-pot synthesis of fully substituted pyridines under microwave irradiation in the absence of solvent. J. Heterocycl. Chem.,  2013, 50, 1346-1350.
[http://dx.doi.org/10.1002/jhet.1035] 
[112] 
Yin, G.; Liu, Q.; Ma, J. Solvent- and catalyst-free synthesis of new hydroxylated trisubstituted pyridines under microwave irradiation. Green Chem.,  2012, 14, 1796-1798.
[http://dx.doi.org/10.1039/c2gc35243e] 
[113] 
De Paolis, O.; Baffoe, J.; Landge, S.M.; Török, B. Multicomponent domino cyclization-oxidative aromatization on a bifunctional Pd/C/K-10 catalyst: an environmentally benign approach toward the synthesis of pyridines. Synthesis,  2008, 21, 3423-3428.
[114] 
Wang, Q.; Wan, C.; Gu, Y.; Zhang, J.; Gao, L.; Wang, Z. A metal-free decarboxylative cyclization from natural α-amino acids to construct pyridine derivatives. Green Chem.,  2011, 13, 578-581.
[http://dx.doi.org/10.1039/c0gc00753f] 
[115] 
Wang, Y.F.; Chiba, S. Mn(III)-mediated reactions of cyclopropanols with vinyl azides: synthesis of pyridine and 2-azabicyclo[3.3.1]non-2-en-1-ol derivatives. J. Am. Chem. Soc.,  2009, 131(35), 12570-12572.
[http://dx.doi.org/10.1021/ja905110c] [PMID:  19722716] 
[116] 
Yi, Y.K.; Zhao, M.N.; Ren, Z.H.; Wang, Y.Y.; Guan, Z.H. Synthesis of symmetrical pyridines by iron-catalyzed cyclization of ketoxime acetates and aldehydes. Green Chem.,  2017, 19, 1023-1027.
[http://dx.doi.org/10.1039/C6GC03137D] 
[117] 
Tan, J.F.; Bormann, C.T.; Perrin, F.G.; Chadwick, F.M.; Severin, K.; Cramer, N. Divergent synthesis of densely substituted arenes and pyridines via cyclotrimerization reactions of alkynyl triazenes. J. Am. Chem. Soc.,  2019, 141(26), 10372-10383.
[http://dx.doi.org/10.1021/jacs.9b04111] [PMID:  31244170] 
[118] 
Zhan, J.L.; Wu, M.W.; Han, B.; Wei, B.Y.; Jiang, Y.; Yu, W.; Han, B. 4-HO-TEMPO-catalyzed redox annulation of cyclopropanols with oxime acetates toward pyridine derivatives. ACS Catal.,  2019, 9, 4179-4188.
[http://dx.doi.org/10.1021/acscatal.9b00832] 
[119] 
Erhardt, H.; Kunz, K.A.; Kirsch, S.F. Thermolysis of geminal diazides: reagent-free synthesis of 3-Hydroxypyridines. Org. Lett.,  2017, 19(1), 178-181.
[http://dx.doi.org/10.1021/acs.orglett.6b03475] [PMID:  27982590] 
[120] 
Mao, Z.Y.; Liao, X.Y.; Wang, H.S.; Wang, C.G.; Huang, K.B.; Pan, Y.M. Acid-catalyzed tandem reaction for the synthesis of pyridine derivatives via C=C/C(sp3)–N bond cleavage of enones and primary amines. RSC Advances,  2017, 7, 13123-13129.
[http://dx.doi.org/10.1039/C7RA00780A] 
[121] 
Wang, K.; Meng, L.G.; Wang, L. Visible-Light-Promoted [2 + 2 + 2] cyclization of alkynes with nitriles to pyridines using pyrylium salts as photoredox catalysts. Org. Lett.,  2017, 19(8), 1958-1961.
[http://dx.doi.org/10.1021/acs.orglett.7b00292] [PMID:  28368617] 
[122] 
(a)Lou, S.; Zhang, J. Pyrimidines. In: Heterocyclic Chemistry in Drug Discovery; Jie, J.L., Ed.; John Wiley & Sons, Inc., 2013; pp. 569-613.
(b)Gore, R.P.; Rajput, A.P. A review on recent progress in multicomponent reactions of pyrimidine synthesis. Drug Invent. Today,  2013, 5, 148-152.
[http://dx.doi.org/10.1016/j.dit.2013.05.010] 
[123] 
Sivagamisundari, G.; Pushpalatha, A.M.; Ranee, S.J. Silica bonded S-sulphonic acid as a green catalyst in the synthesis of functionalized pyrimidine under solvent-free microwave irradiation conditions. Int. J. Sci. Eng. Technol.,  2014, 3, 852-855.
[124] 
Khan, S.A.; Asiri, A.M.; Kumar, S.; Sharma, K. Green synthesis, antibacterial activity and computational study of pyrazoline and pyrimidine derivatives from 3-(3,4-dimethoxy-phenyl-1-(2,5-dimethylthiophen-3-yl)-propenone. Eur. J. Chem.,  2014, 5, 85-90.
[http://dx.doi.org/10.5155/eurjchem.5.1.85-90.789] 
[125] 
Ezhilarasi, M.R.; Prabha, B.; Prabakaran, S. Microwave assisted synthesis and spectral studies of thiophenyl pyrimidine derivatives. J. Appl. Chem.,  2014, 3, 1929-1935.
[126] 
Babu, K.R.; Paul, V.L.; Rao, V.M. Substituted pyridine catalysed domino synthesis of pyrazolines and pyrimidines. World J. Pharm. Res.,  2014, 3, 389-398.
[127] 
Xie, L.G.; Niyomchon, S.; Mota, A.J.; González, L.; Maulide, N. Metal-free intermolecular formal cycloadditions enable an orthogonal access to nitrogen heterocycles. Nat. Commun.,  2016, 7, 10914.
[http://dx.doi.org/10.1038/ncomms10914] [PMID:  26975182] 
[128] 
Deibl, N.; Ament, K.; Kempe, R. A Sustainable Multicomponent Pyrimidine Synthesis. J. Am. Chem. Soc.,  2015, 137(40), 12804-12807.
[http://dx.doi.org/10.1021/jacs.5b09510] [PMID:  26414993] 
[129] 
Chen, J.J.; Meng, H.X.; Zhang, F.; Xiao, F.H.; Deng, G.J. Transition-metal-free selective pyrimidines and pyridines formation from aromatic ketones, aldehydes and ammonium salts. Green Chem.,  2019, 21, 5201-5206.
[http://dx.doi.org/10.1039/C9GC02077B] 
[130] 
Yamaguchi, T.; Sugiura, Y.; Yamaguchi, E.; Tada, N.; Itoh, A. Synthetic Method for the Preparation of Quinazolines by the Oxidation of Amines Using Singlet Oxygen. Asian J. Org. Chem.,  2017, 6, 432-435.
[http://dx.doi.org/10.1002/ajoc.201600431] 
[131] 
Liu, K.; Song, C.; Wu, J. Electrochemical Oxidation Synergizing with Brønsted-Acid Cataly-sis Leads to [4+2] Annulation for the Synthesis of Pyrazines. Green Chem.,  2019, 21, 765-769.
[http://dx.doi.org/10.1039/C8GC03786H] 
[132] 
Daw, P.; Ben-David, Y.; Milstein, D. Acceptorless dehydrogenative coupling using ammonia: direct synthesis of N-heteroaromatics from diols catalyzed by ruthenium. J. Am. Chem. Soc.,  2018, 140(38), 11931-11934.
[http://dx.doi.org/10.1021/jacs.8b08385] [PMID:  30205675] 
[133] 
Abid, M.; Spaeth, A.; Török, B. Solvent-free solid acid-catalyzed electrophilic annelations: a new green approach for the synthesis of substituted five-membered N-heterocycles. Adv. Synth. Catal.,  2006, 348, 2191-2196.
[http://dx.doi.org/10.1002/adsc.200606200] 
[134] 
Xu, D.; Yang, W.; Luo, S.; Wang, B.; Wu, J.; Xu, Z. Fischer indole synthesis in Brønsted acidic ionic liquids: a green, mild, and regiospecific reaction system. Eur. J. Org. Chem.,  2007, 1007-1012.
[http://dx.doi.org/10.1002/ejoc.200600886] 
[135] 
Xu, D.; Wu, J.; Luo, S.; Zhang, J.; Wu, J.; Du, X.; Xu, Z. Fischer indole synthesis catalyzed by novel SO3H-functionalized ionic liquids in water. Green Chem.,  2009, 11, 1239-1246.
[http://dx.doi.org/10.1039/b901010f] 
[136] 
Shan, X.H.; Zheng, H.X.; Yang, B.; Tie, L.; Fu, J.L.; Qu, J.P.; Kang, Y.B. Copper-catalyzed oxidative benzylic C-H cyclization via iminyl radical from intermolecular anion-radical redox relay. Nat. Commun.,  2019, 10(1), 908.
[http://dx.doi.org/10.1038/s41467-019-08849-z] [PMID:  30796224] 
[137] 
Sha, Q.; Arman, H.; Doyle, M.P. Three-component cascade reactions with 2,3-diketoesters: a novel metal-free synthesis of 5-vinyl-pyrrole and 4-hydroxy-indole derivatives. Org. Lett.,  2015, 17(15), 3876-3879.
[http://dx.doi.org/10.1021/acs.orglett.5b01855] [PMID:  26185966] 
[138] 
Yu, S.; Qi, L.; Hu, K.; Gong, J.; Cheng, T.; Wang, Q.; Chen, J.; Wu, H. The development of a palladium-catalyzed tandem addition/cyclization for the construction of indole skeletons. J. Org. Chem.,  2017, 82(7), 3631-3638.
[http://dx.doi.org/10.1021/acs.joc.7b00148] [PMID:  28288278] 
[139] 
Lin, W.; Zheng, Y.X.; Xun, Z.; Huang, Z.B.; Shi, D.Q. Microwave-assisted regioselective synthesis of 3-functionalized indole derivatives via three-vomponent fomino teaction. ACS Comb. Sci.,  2017, 19(11), 708-713.
[http://dx.doi.org/10.1021/acscombsci.7b00126] [PMID:  28985045] 
[140] 
Tambe, S.D.; Rohokale, R.S.; Kshirsagar, U.A. Visible-light-mediated eosin Y photoredox-catalyzed vicinal thioamination of slkynes: tadical vascade snnulation dtrategy for 2-dubstituted-3-sulfenylindoles. Eur. J. Org. Chem.,  2018, 2117-2121.
[http://dx.doi.org/10.1002/ejoc.201800287] 
[141] 
Jana, S.; Verma, A.; Kadu, R.; Kumar, S. Visible-light-induced oxidant and metal-free dehydrogenative cascade trifluoromethylation and oxidation of 1,6-enynes with water. Chem. Sci. (Camb.),  2017, 8(9), 6633-6644.
[http://dx.doi.org/10.1039/C7SC02556D] [PMID:  28989690] 
[142] 
Dinica, R.M.; Furdui, B.; Ghinea, I.O.; Bahrim, G.; Bonte, S.; Demeunynck, M. Novel one-pot green synthesis of indolizines biocatalysed by Candida antarctica Lipases. Mar. Drugs,  2013, 11(2), 431-439.
[http://dx.doi.org/10.3390/md11020431] [PMID:  23389089] 
[143] 
Li, J.; Liu, X.; Deng, J.; Huang, Y.; Pan, Z.; Yu, Y.; Cao, H. Electrochemical diselenylation of indolizines via intermolecular C-Se formation with 2-methylpyridines, α-bromoketones and diselenides. Chem. Commun. (Camb.),  2020, 56(5), 735-738.
[http://dx.doi.org/10.1039/C9CC08784B] [PMID:  31840710] 
[144] 
Yang, D.; Yu, Y.; Wu, Y.; Feng, H.; Li, X.; Cao, H. One-pot regiospecific synthesis of indolizines: a solvent-free, metal-free, three-component reaction of 2-(pyridin-2-yl)acetates, ynals, and alcohols or thiols. Org. Lett.,  2018, 20(8), 2477-2480.
[http://dx.doi.org/10.1021/acs.orglett.8b00835] [PMID:  29613809] 
[145] 
Cheng, C.C.; Yan, S.J. The Friedländer Synthesis of Quinolines. In: Organic Reactions; Jie Jack Li, Ed.; Wiley: New York, 2005; pp. 264-265.
[146] 
Arcadi, A.; Chiarini, M.; Giuseppe, S.D.; Marinelli, F. A new approach to the Friedländer synthesis of quinolines. Synlett,  2003, 203-206.
[http://dx.doi.org/10.1055/s-2003-36798] 
[147] 
Sels, B.F.; De Vos, D.E.; Jacobs, P.A. Hydrotalcite-like anionic clays in catalytic organic reactions. Catal. Rev.,  2001, 43, 443-448.
[http://dx.doi.org/10.1081/CR-120001809] 
[148] 
Motokura, K.; Mizugaki, T.; Ebitani, K.; Kaneda, K. Multifunctional catalysis of a ruthenium-grafted hydrotalcite: one-pot synthesis of quinolines from 2-aminobenzyl alcohol and various carbonyl compounds via aerobic oxidation and aldol reaction. Tetrahedron Lett.,  2004, 45, 6029-6032.
[http://dx.doi.org/10.1016/j.tetlet.2004.06.023] 
[149] 
Wang, J.; Fan, X.; Zhang, X.; Han, L. Green preparation of quinoline derivatives through FeCl3·6H2O catalyzed Friedländer reaction in ionic liquids. Can. J. Chem.,  2004, 82, 1192-1196.
[http://dx.doi.org/10.1139/v04-066] 
[150] 
Akbari, J.; Heydari, A.; Reza Kalhor, H.; Kohan, S.A. Sulfonic acid functionalized ionic liquid in combinatorial approach, a recyclable and water tolerant-acidic catalyst for one-pot Friedlander quinoline synthesis. J. Comb. Chem.,  2010, 12(1), 137-140.
[http://dx.doi.org/10.1021/cc9001313] [PMID:  19883051] 
[151] 
Kulkarni, A.; Török, B. Microwave-assisted multicomponent domino cyclization–aromatization: an efficient approach for the synthesis of substituted quinolines. Green Chem.,  2010, 12, 875-878.
[http://dx.doi.org/10.1039/c001076f] 
[152] 
Reddy, T.R.; Reddy, L.S.; Reddy, G.R.; Yarbagi, K.; Lingappa, Y.; Rambabu, D.; Krishna, G.R.; Reddy, C.M.; Kumar, K.S.; Pal, M. Construction of quinoline ring via a 3-component reaction in water: crystal structure analysis and H-bonding patterns of a 2-aryl quinoline. Green Chem.,  2012, 14, 1870-1872.
[http://dx.doi.org/10.1039/c2gc35256g] 
[153] 
Shee, S.; Ganguli, K.; Jana, K.; Kundu, S. Cobalt complex catalyzed atom-economical synthesis of quinoxaline, quinoline and 2-alkylaminoquinoline derivatives. Chem. Commun. (Camb.),  2018, 54(50), 6883-6886.
[http://dx.doi.org/10.1039/C8CC02366B] [PMID:  29790492] 
[154] 
He, L.; Wang, J.Q.; Gong, Y.; Liu, Y.M.; Cao, Y.; He, H.Y.; Fan, K.N. Titania-supported iridium subnanoclusters as an efficient heterogeneous catalyst for direct synthesis of quinolines from nitroarenes and aliphatic alcohols. Angew. Chem. Int. Ed. Engl.,  2011, 50(43), 10216-10220.
[http://dx.doi.org/10.1002/anie.201104089] [PMID:  21990251] 
[155] 
Ahmed, W.; Zhang, S.; Yu, X.; Yamamoto, Y.; Bao, M. Brønsted acid-catalyzed metal- and solvent-free quinoline synthesis from N-alkyl anilines and alkynes or alkenes. Green Chem.,  2018, 20, 261-265.
[http://dx.doi.org/10.1039/C7GC03175K] 
[156] 
Sun, D.; Yin, K.; Zhang, R. Visible-light-induced multicomponent cascade cycloaddition involving N-propargyl aromatic amines, diaryliodonium salts and sulfur dioxide: rapid access to 3-arylsulfonylquinolines. Chem. Commun. (Camb.),  2018, 54(11), 1335-1338.
[http://dx.doi.org/10.1039/C7CC09410H] [PMID:  29350225] 
[157] 
Mishra, M.; Twardy, D.; Ellstrom, C.; Wheeler, K.A.; Dembinski, R.; Török, B. Catalyst-free ambient temperature synthesis of isoquinoline-fused benzimidazoles from 2-alkynylbenzaldehydes via alkyne hydroamination. Green Chem.,  2019, 21, 99-108.
[http://dx.doi.org/10.1039/C8GC02520G] 
[158] 
Liu, X.; Qing, Z.; Cheng, P.; Zheng, X.; Zeng, J.; Xie, H. Metal-free photoredox catalyzed cyclization of O-(2,4-dinitrophenyl)oximes to phenanthridines. Molecules,  2016, 21(12), 1690.
[http://dx.doi.org/10.3390/molecules21121690] [PMID:  27941654] 
[159] 
Ishida, T.; Tsunoda, R.; Zhang, Z.; Hamasaki, A.; Honma, T.; Ohashi, H.; Yokoyama, T.; Tokunaga, M. Supported palladium hydroxide-catalyzed intramolecular double C-H bond functionalization for synthesis of carbazoles and dibenzofurans. Appl. Catal. B,  2014, 150-151, 523-531.
[http://dx.doi.org/10.1016/j.apcatb.2013.12.051] 
[160] 
Xiao, F.; Liao, Y.; Wu, M.; Deng, G.J. One-pot synthesis of carbazoles from cyclohexanones and arylhydrazine hydrochlorides under metal-free conditions. Green Chem.,  2012, 14, 3277-3280.
[http://dx.doi.org/10.1039/c2gc36473e] 
[161] 
Yang, L.; Zhang, Y.; Zou, X.; Lu, H.J.; Li, G.G. Visible-light-promoted intramolecular C–H amination in aqueous solution: synthesis of carbazoles. Green Chem.,  2018, 20, 1362-1366.
[http://dx.doi.org/10.1039/C7GC03392C] 
[162] 
Kulkarni, A.; Abid, M.; Török, B.; Huang, X. A direct synthesis of b-carbolines via a three-step one-pot domino approach with a bifunctional Pd/C/K-10 catalyst. Tetrahedron Lett.,  2009, 50, 1791-1794.
[http://dx.doi.org/10.1016/j.tetlet.2009.01.143] 
Rights & Permissions Print Cite
Article Metrics
31
1
Journal Information
For Authors
For Editors
For Reviewers
Explore Articles
Open Access
Open Access Articles
For Visitors
DOI https://dx.doi.org/10.2174/1570179418666210910110205	Print ISSN 1570-1794
Publisher Name Bentham Science Publisher	Online ISSN 1875-6271
Current Organic Synthesis

Recent Advances in the Green Synthesis of Heterocycles: From Building Blocks to Biologically Active Compounds

Abstract Play Pause

Graphical Abstract

Related Journals

Related Books

Abstract
