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Current Organic Chemistry


ISSN (Print): 1385-2728
ISSN (Online): 1875-5348

Review Article

The Double and Triple Role of L-(+)-tartaric Acid and Dimethyl Urea: A Prevailing Green Approach in Organic Synthesis

Author(s): Rashid Ali*, Ajay Kumar Chinnam and Vikas R. Aswar

Volume 25 , Issue 5 , 2021

Published on: 10 January, 2021

Page: [554 - 579] Pages: 26

DOI: 10.2174/1385272825666210111111313

Price: $65


The deep eutectic mixtures (DESs), introduced as a novel alternative to usual volatile organic solvents for organic transformations, have attracted tremendous attention of the research community because of their low cost, negligible vapour pressure, low toxicity, biodegradability, recyclability, insensitivity towards moisture, and ready availability from bulk renewable resources. Although the low melting mixture of dimethyl urea (DMU)/L-(+)- tartaric acid (TA) is still in infancy, it is very effective as it plays multiple roles such as solvent, catalyst and/or reagent in the same pot for many crucial organic transformations. These unique properties of the DMU/TA mixture prompted us to provide a quick overview of where the field stands presently and where it might be going in the near future. To our best knowledge, no review dealing with the applications of a low melting mixture of DMU/TA appeared in the literature except the one published in 2017, describing only the chemistry of indole systems. Therefore, we intended to reveal the developments of this versatile, low melting mixture in the modern organic synthesis since its first report in 2011 by Köenig’s team to date. Hopefully, the present review article will be useful to the researcher working not only in the arena of synthetic organic chemistry but also to the scientists working in other branches of science and technology.

Keywords: Catalysis, dimethyl urea, green synthesis, low melting mixture, tartaric acid, organic synthesis.

Graphical Abstract
Abbott, A.P.; Capper, G.; Davies, D.L.; Rasheed, R.K.; Tambyrajah, V. Novel solvent properties of choline chloride/urea mixtures. Chem. Commun. (Camb.), 2003, 2003(1), 70-71.
[] [PMID: 12610970]
Abbott, A.P.; Boothby, D.; Capper, G.; Davies, D.L.; Rasheed, R.K. Deep eutectic solvents formed between choline chloride and carboxylic acids: versatile alternatives to ionic liquids. J. Am. Chem. Soc., 2004, 126(29), 9142-9147.
[] [PMID: 15264850]
Abbott, A.P.; Capper, G.; Davies, D.L.; Rasheed, R. Ionic liquids based upon metal halide/substituted quaternary ammonium salt mixtures. Inorg. Chem., 2004, 43(11), 3447-3452.
[] [PMID: 15154807]
Abbott, A.P.; Harris, R.C.; Ryder, K.S. Application of hole theory to define ionic liquids by their transport properties. J. Phys. Chem. B, 2007, 111(18), 4910-4913.
[] [PMID: 17388488]
Francisco, M.; van den Bruinhorst, A.; Kroon, M.C. Low-transition-Temperature Mixtures (LTTMs): a new generation of designer solvents. Angew. Chem. Int. Ed., 2013, 52, 3074-3085.
Abbott, A.P.; Harris, R.C.; Ryder, K.S.; D’Agostino, C.; Gladden, L.F.; Mantle, M.D. Glycerol eutectics as sustainable solvent systems. Green Chem., 2011, 13, 82-90.
Hallett, J.P.; Welton, T. Room-temperature ionic liquids: solvents for synthesis and catalysis. 2. Chem. Rev., 2011, 111(5), 3508-3576.
[] [PMID: 21469639]
Paiva, A.; Craveiro, R.; Aroso, I.; Martins, M.; Reis, R.L.; Duarte, A.R.C. Natural deep eutectic solvents–solvents for the 21st century. ACS Sustain. Chem.& Eng., 2014, 2, 1063-1071.
Alonso, D.A.; Baeza, A.; Chinchilla, R.; Guillena, G.; Pastor, I.M.; Ramon, D.J. Deep eutectic solvents: the organic reaction medium of the century. Eur. J. Org. Chem., 2016, 4, 612-632.
Tang, N.; Zhong, J.; Yan, W. Solubilities of three flavonoids in different natural deep eutectic solvents at T = (288.15 to 328.15). K. J. Chem. Eng. Data, 2016, 61, 4203-4208.
Jiang, W.; Li, H.; Wang, C.; Liu, W.; Guo, T.; Liu, H.; Zhu, W.; Li, H. Synthesis of ionic-liquid-based deep eutectic solvents for extractive desulfurization of fuel. Energy Fuels, 2016, 30, 8164-8170.
Bangde, P.S.; Jain, R.; Dandekar, P. Alternative approach to synthesize methylated chitosan using deep eutectic solvents, biocatalyst and “green” methylating agents. ACS Sustain. Chem.& Eng., 2016, 4, 3552-3557.
Sun, Y.; Wei, G.; Tantai, X.; Huang, Z.; Yang, H.; Zhang, L. Highly efficient nitric oxide absorption by environmentally friendly deep eutectic solvents based on 1, 3-dimethylthiourea. Energy Fuels, 2017, 31, 12439-12445.
Ramón, D.J.; Guillena, G. Deep Eutectic Solvents: Synthesis, Properties, and Applications; Wiley-VCH, 2019.
Marullo, S.; Rizzo, C.; D’Anna, F. Activity of a heterogeneous catalyst in deep eutectic solvents: the case of carbohydrate conversion into 5-hydroxymethylfurfural. ACS Sustain. Chem.& Eng., 2019, 7, 13359-13368.
Li, Z-L.; Zhong, F-Y.; Huang, J-Y.; Peng, H-L.; Huang, K. Sugar-based natural deep eutectic solvents as potential absorbents for NH3 capture at elevated temperatures and reduced pressures. J. Mol. Liq., 2020, 317113992
Morais, E.S.; da Costa Lopes, A.M.; Freire, M.G.; Freire, C.S.R.; Coutinho, J.A.P.; Silvestre, A.J.D. Use of ionic liquids and deep eutectic solvents in polysaccharides dissolution and extraction processes towards sustainable biomass valorization. Molecules, 2020, 25, 3652.
Mahajan, T.; Bangde, P.; Dandekar, P.; Jain, R. Greener approach for synthesis of N,N,N-trimethyl chitosan (TMC) using ternary deep eutectic solvents (TDESs). Carbohydr. Res., 2020, 493108033
[] [PMID: 32505997]
Lončarić, M.; Sušjenka, M.; Molnar, M. An extensive study of coumarin synthesis via Knoevenagel condensation in choline chloride based deep eutectic solvents. Curr. Org. Synth., 2020, 17(2), 98-108.
[] [PMID: 32418515]
Liu, L.; Wei, Q.; Zhou, Y.; Ren, X. Using dialkyl amide via forming hydrophobic deep eutectic solvents to separate citric acid from fermentation broth. Green Chem., 2020, 22, 2526-2533.
Kitanosono, T.; Masuda, K.; Xu, P.; Kobayashi, S. Catalytic organic reactions in water toward sustainable society. Chem. Rev., 2018, 118, 679-746.
Kumari, K.; Singh, P.; Mehrotra, G.K. Ionic liquid: best alternate to organic solvent to carry out organic synthesis. Int. J. Green Nanotechnol. Biomed., 2012, 4, 262-276.
Welton, T. Room-temperature ionic liquids. Solvents for synthesis and catalysis. Chem. Rev., 1999, 99(8), 2071-2084.
[] [PMID: 11849019]
Li, C.; Liu, W.; Zhao, Z. Efficient synthesis of benzophenone derivatives in Lewis acid ionic liquids. Catal. Commun., 2007, 8, 1834-1837.
Butler, R.N.; Coyne, A.G. Water: nature’s reaction enforcer--comparative effects for organic synthesis “in-water” and “on-water”. Chem. Rev., 2010, 110(10), 6302-6337.
[] [PMID: 20815348]
Jessop, P.G.; Ikariya, T.; Noyori, R. Homogeneous catalysis in supercritical fluids. Chem. Rev., 1999, 99(2), 475-494.
[] [PMID: 11848990]
Jutz, F.; Andanson, J-M.; Baiker, A. Ionic liquids and dense carbon dioxide: a beneficial biphasic system for catalysis. Chem. Rev., 2011, 111(2), 322-353.
[] [PMID: 21053968]
Zhu, Z.; Liu, C.; Jiang, Q.; Shi, H.; Xu, J.; Jiang, F.; Xiong, J.; Liu, E. Green DES mixture as a surface treatment recipe for improving the thermoelectric properties of PEDOT: PSS films. Synth. Met., 2015, 209, 313-318.
Craveiro, R.; Aroso, I.; Flammia, V.; Carvalho, T.; Viciosa, M.T.; Dionísio, M.; Barreiros, S.; Reis, R.L.; Duarte, A.R.C.; Paiva, A. Properties and thermal behavior of natural deep eutectic solvents. J. Mol. Liq., 2016, 215, 534-540.
Chemat, F.; Anjum, H.; Shariff, A.M.; Kumar, P.; Murugesan, T. Thermal and physical properties of (Choline chloride+ urea+ l-arginine) deep eutectic solvents. J. Mol. Liq., 2016, 218, 301-308.
Dietz, C.H.J.T.; Kroon, M.C.; van Sint Annaland, M.; Gallucci, F. Thermophysical properties and solubility of different sugar-derived molecules in deep eutectic solvents. J. Chem. Eng. Data, 2017, 62, 3633-3641.
Hammond, O.S.; Eslava, S.; Smith, A.J.; Zhang, J.; Edler, K.J. Microwave-assisted deep eutectic-solvothermal preparation of iron oxide nanoparticles for photoelectrochemical solar water splitting. J. Mater. Chem. A Mater. Energy Sustain., 2017, 5, 16189-16199.
Pal, S.; Roy, R.; Paul, S. Potential of a natural deep eutectic solvent, glyceline, in the thermal stability of the trp-cage mini-protein. J. Phys. Chem. B, 2020, 124(35), 7598-7610.
[] [PMID: 32790388]
Kow, K-K.; Sirat, K. Novel manganese (II)-based deep eutectic solvents: synthesis and physical properties analysis. Chin. Chem. Lett., 2015, 26, 1311-1314.
Protsenko, V.; Kityk, A.; Shaiderov, D.; Danilov, F. Effect of water content on physicochemical properties and electrochemical behavior of ionic liquids containing choline chloride, ethylene glycol and hydrated nickel chloride. J. Mol. Liq., 2015, 212, 716-722.
Yuan, C.; Zhang, X.; Ren, Y.; Feng, S.; Liu, J.; Wang, J.; Su, L. Temperature-and pressure-induced phase transitions of choline chloride-urea deep eutectic solvent. J. Mol. Liq., 2019, 291111343
Perna, M.P.; Vitale, P.; Capriati, V. Deep eutectic solvents and their applications as green solvents. Curr. Opin. Green Sustain. Chem., 2020, 21, 27-33.
Cardellini, F.; Tiecco, M.; Germani, R.; Cardinali, G.; Corte, L.; Roscini, L.; Spreti, N. Novel zwitterionic deep eutectic solvents from trimethylglycine and carboxylic acids: characterization of their properties and their toxicity. RSC Adv., 2014, 4, 55990-56002.
Kudłak, B.; Owczarek, K.; Namieśnik, J. Selected issues related to the toxicity of ionic liquids and deep eutectic solvents--a review. Environ. Sci. Pollut. Res. Int., 2015, 22(16), 11975-11992.
[] [PMID: 26040266]
Bubalo, M.C.; Radošević, K.; Redovniković, I.R.; Slivac, I.; Srček, V.G. Toxicity mechanisms of ionic liquids. Arc. Ind. Hyg. Toxi., 2017, 68, 171-179.
[ ]
Halder, A.K.; Cordeiro, M.N.D.S. Probing the environmental toxicity of deep eutectic solvents and their components: an in silico modeling approach. ACS Sustain. Chem. Eng., 2019, 7, 10649-10660.
Wen, Q.; Chen, J.X.; Tang, Y.L.; Wang, J.; Yang, Z. Assessing the toxicity and biodegradability of deep eutectic solvents. Chemosphere, 2015, 132, 63-69.
[] [PMID: 25800513]
Padvi, S.A.; Dalal, D.S. Choline chloride–ZnCl2: recyclable and efficient deep eutectic solvent for the [2+3] cycloaddition reaction of organic nitriles with sodium azide. Synth. Commun., 2017, 47, 779.
Inaloo, I.D.; Majnooni, S. Ureas as safe carbonyl sources for the synthesis of carbamates with Deep Eutectic Solvents (DESs) as efficient and recyclable solvent/catalyst systems. New J. Chem., 2018, 42, 13249-13255.
Inaloo, I.D.; Majnooni, S.; Esmaeilpour, M. Superparamagnetic Fe3O4 nanoparticles in a deep eutectic solvent: an efficient and recyclable catalytic system for the synthesis of primary carbamates and monosubstituted ureas. Eur. J. Org. Chem., 2018, 3481-3488.
Li, P.; Sirviö, J.A.; Asante, B.; Liimatainen, H. Recyclable deep eutectic solvent for the production of cationic nanocelluloses. Carbohydr. Polym., 2018, 199, 219-227.
[] [PMID: 30143124]
Heidari, B.; Heravi, M.M.; Nabid, M.R.; Sedghi, R.; Hooshmand, S.E. Novel palladium nanoparticles supported on β-cyclodextrin@ graphene oxide as magnetically recyclable catalyst for Suzuki–Miyaura cross-coupling reaction with two different approaches in bio-based solvents. Appl. Organomet. Chem., 2019, 33e4632
Quirós-Montes, L.; Carriedo, G.A.; García-Álvarez, J.; Soto, A.P. Deep eutectic solvents for Cu-catalysed ARGET ATRP under an air atmosphere: a sustainable and efficient route to poly (methyl methacrylate) using a recyclable Cu (II) metal–organic framework. Green Chem., 2019, 21, 5865-5875.
Wang, L-T.; Yang, Q.; Cui, Q.; Fan, X-H.; Dong, M-Z.; Gao, M-Z.; Lv, M-J.; An, J-Y.; Meng, D.; Zhao, X-H.; Fu, Y-J. Recyclable menthol-based deep eutectic solvent micellar system for extracting phytochemicals from Ginkgo biloba leaves. J. Clean. Prod., 2020, 244118648
Smith, E.L.; Abbott, A.P.; Ryder, K.S. Deep Eutectic Solvents (DESs) and their applications. Chem. Rev., 2014, 114, 11060-11082.
[] [PMID: 25300631]
Liu, P.; Hao, J-W.; Mo, L-P.; Zhang, Z-H. Recent advances in the application of deep eutectic solvents as sustainable media as well as catalysts in organic reactions. RSC Adv., 2015, 5, 48675-48704.
Imperato, G.; Eibler, E.; Niedermaier, J.; König, B. Low-melting sugar-urea-salt mixtures as solvents for Diels-Alder reactions. Chem. Commun. (Camb.), 2005, 2005(9), 1170-1172.
[] [PMID: 15726181]
Imperato, G.; Hoger, S.; Lenoir, D.; König, B. Low melting sugar–urea–salt mixtures as solvents for organic reactions-estimation of polarity and use in catalysis. Green Chem., 2006, 8, 1051-1055.
Catarina, F.; Branco, L.C.; Marrucho, I.M. Quest for green-solvent design: from hydrophilic to hydrophobic (deep) eutectic solvents. ChemSusChem, 2019, 12, 1549-1559.
[] [PMID: 30811105]
Hooshmand, S.E.; Afshari, R.; Ramón, D.J.; Varma, R.S. Deep eutectic solvents: cutting-edge applications in cross-coupling reactions. Green Chem., 2020, 22, 3668-3692.
Gore, S.; Baskaran, S.; König, B. Fischer indole synthesis in low melting mixtures. Org. Lett., 2012, 14(17), 4568-4571.
[] [PMID: 22905733]
Kotha, S.; Chakkapalli, C. Application of Fischer indolization under green conditions using deep eutectic solvents. Chem. Rec., 2017, 17(10), 1039-1058.
[] [PMID: 28378920]
Robinson, B. The Fischer Indole Synthesis; Wiley-Interscience: New York, 1982.
Sarmah, D.; Bora, U. Methylene surrogates for the synthesis of 3,3′-diindolylmethanes. Chem. Select, 2020, 5, 8577-8603.
Pike, R.A.S.; Sapkota, R.R.; Shrestha, B.; Dhungana, R.K.; Shekhar, K.C.; Dickie, D.A.; Giri, R. K2CO3-Catalyzed synthesis of 2,5-dialkyl-4,6,7-tricyano-decorated indoles via carbon–carbon bond cleavage. Org. Lett., 2020, 22(8), 3268-3272.
Gervais, S.B.; Scattolin, T.; Schoenebeck, F. N-Trifluoromethyl hydrazines, indoles and their derivatives. Angew. Chem. Int. Ed., 2020, 59, 11908-11912.
Roy, S.K.; Purkait, A.; Aziz, S.M.T.; Jana, C.K. Acid mediated coupling of aliphatic amines and nitrosoarenes to indoles. Chem. Commun. (Camb.), 2020, 56(21), 3167-3170.
[] [PMID: 32065174]
Roque, J.B.; Mercado-Marin, E.V.; Richter, S.C.; de Sant’Ana, D.P.; Mukai, K.; Ye, Y.; Sarpong, R. A unified strategy to reverse-prenylated indole alkaloids: total syntheses of preparaherquamide, premalbrancheamide, and (+)-VM-55599. Chem. Sci. (Camb.), 2020, 11, 5929-5934.
Van Order, R.B.; Lindwall, H.G. Indole. Chem. Rev., 1942, 30, 69-96.
Robinson, B. The Fischer indole synthesis. Chem. Rev., 1963, 63(4), 373-401.
Robinson, B. Studies on the Fischer indole synthesis. Chem. Rev., 1969, 69, 227-250.
Przheval’skii, N.M.; Kostromina, L.Y.U.; Grandberg, I.I. New data on the mechanism of the Fischer indole synthesis. Chem. Heterocycl. Compd., 1988, 24, 709-721.
Humphrey, G.R.; Kuethe, J.T. Practical methodologies for the synthesis of indoles. Chem. Rev., 2006, 106(7), 2875-2911.
[] [PMID: 16836303]
Haag, B.A.; Zhang, Z-G.; Li, J-S.; Knochel, P. Fischer indole synthesis with organozinc reagents. Angew. Chem. Int. Ed., 2010, 49, 9513-9516.
Li, B.L.; Xu, D-Q.; Zhong, A.G. Novel SO3H-functionalized ionic liquids catalyzed a simple, green and efficient procedure for Fischer indole synthesis in water under microwave irradiation. J. Fluor. Chem., 2012, 144, 45-50.
Li, C.; Chan, C.; Heimann, A.C.; Danishefsky, S.J. On the rearrangement of an azaspiroindolenine to a precursor to phalarine: mechanistic insights. Angew. Chem. Int. Ed., 2007, 46, 1444-1447.
Sapi, J.; Dridi, S.; Laronze, J.; Sigaut, F.; Patigny, D.; Laronze, J-Y.; Levy, J. Indole as a tool in synthesis. Indolenine approach to 4, 5-epoxy-10-normorphinans. Tetrahedron, 1996, 52, 8209-8222.
Limaa, E.; Ferreirab, O.; Gomesa, V.S.D.; Santosb, A.O.; Botob, R.E.; Fernandesa, J.R.; Almeidab, P.; Silvestreb, S.M.; Reisa, L.V. Synthesis and in vitro evaluation of the antitumoral phototherapeutic potential of squaraine cyanine dyes derived from indolenine. Dyes Pigm, 2019, 167, 98-108.
Kotha, S.; Chinnam, A.K. Anomalous behaviour of cis-bicyclo [3.3. 0] octane-3, 7-dione and its derivatives during twofold Fischer indole cyclization using low-melting mixtures. Synthesis, 2014, 46, 301-306.
Kotha, S.; Chinnam, A.K.; Ali, R. Hybrid macrocycle formation and spiro annulation on cis-syn-cis-tricyclo[,6)]undeca-3,11-dione and its congeners via ring-closing metathesis. Beilstein J. Org. Chem., 2015, 11, 1123-1128.
[] [PMID: 26199668]
Kotha, S.; Chinnam, A.K. Design of aza-polyquinanes via Fischer indole cyclization under green conditions. Heterocycles, 2015, 90, 690-697.
Kotha, S.; Chinnam, A.K.; Sreenivasachary, N.; Ali, R. Design and synthesis of polycyclic indoles under green conditions via Fischer indolization. Indian J. Chem., 2016, 57(50), 5605-5607.
Kotha, S.; Ali, R. A simple approach to bis-spirocycles and spiroindole derivatives via green methods such as Fischer indolization, ring-closing metathesis, and Suzuki--Miyaura cross-coupling. Turk. J. Chem., 2015, 39, 1190-1198.
Kotha, S.; Ali, R.; Srinivas, V.; Krishna, N.G. Diversity-oriented approach to spirocycles with indole moiety via Fischer indole cyclization, olefin metathesis and Suzuki–Miyaura cross-coupling reactions. Tetrahedron, 2015, 71, 129-138.
Kotha, S.; Saifuddin, M.; Aswar, V.R. A diversity-oriented approach to indolocarbazoles via Fischer indolization and olefin metathesis: total synthesis of tjipanazole D and I. Org. Biomol. Chem., 2016, 14(41), 9868-9873.
[] [PMID: 27714197]
Kotha, S.; Chinnam, A.K.; Shirbhate, M.E. Diversity-oriented approach to cyclophanes via Fischer indolization and ring-closing metathesis: substrate-controlled stereochemical outcome in RCM. J. Org. Chem., 2015, 80(18), 9141-9146.
[] [PMID: 26317873]
Kotha, S.; Chinnam, A.K.; Shirbhate, M.E. Design and synthesis of hybrid cyclophanes containing thiophene and indole units via Grignard reaction, Fischer indolization and ring-closing metathesis as key steps. Beilstein J. Org. Chem., 2015, 11, 1514-1519.
[] [PMID: 26425209]
Kotha, S.; Shirbhate, M.E.; Chinnam, A.K.; Sreevani, G. Synthesis of phenanthroline and indole based hybrid cyclophane derivatives via ring-closing metathesis. Heterocycles, 2016, 93, 399-405.
Kotha, S.; Todeti, S.; Das, T.; Datta, A. Synthesis and photophysical properties of C3-symmetric star-shaped molecules containing heterocycles: a new tactics for multiple Fischer indolization. ChemistrySelect, 2018, 3, 136-141.
Jella, R.R.; Nagarajan, R. Synthesis of indole alkaloids arsindoline A, arsindoline B and their analogues in low melting mixture. Tetrahedron, 2013, 69, 10249-10253.
Kotha, S.; Aswar, V.R.; Chinnam, A.K. One-pot synthesis of carbazoles from indoles via a metal free benzannulation. Tetrahedron Lett., 2017, 58, 4360-4362.
Kotha, S.; Ali, R.; Saifuddin, M. Diversity-oriented approach to natural product inspired pyrano-carbazole derivatives: strategic utilization of hetero-Diels–Alder reaction, Fischer indolization and the Suzuki–Miyaura cross-coupling reaction. Tetrahedron, 2015, 71, 9003-9011.
Kotha, S.; Ravikumar, O. Diversity−oriented approach to carbocycles and heterocycles through ring−rearrangement metathesis, fischer indole cyclization, and Diels−Alder reaction as key steps. Eur. J. Org. Chem., 2014, 5582.
Kotha, S.; Keesari, R.R.; Ansari, S. Synthesis of aza-polyquinanes via Fischer indolization and ring-rearrangement metathesis as key steps. Synthesis, 2019, 51, 3989-3997.
Kotha, S.; Cheekatla, S.R.; Chinnam, A.K.; Jain, T. Design and synthesis of polycyclic bisindoles via Fischer indolization and ring-closing metathesis as key steps. Tetrahedron Lett., 2016, 57, 5605-5607.
Kotha, S.; Aswar, V.R.; Singhal, G. Synthesis of tricyclic units of indole alkaloids: application of Fischer indolization and olefin metathesis. Tetrahedron, 2017, 73, 6436-6442.
Kotha, S.; Aswar, V.R.; Ansari, S. Selectivity in ring-closing metathesis: synthesis of propellanes and angular aza-tricycles. Adv. Synth. Catal., 2019, 361, 1376-1382.
Zhou, J.; Tan, D-X.; Han, F-S. A divergent enantioselective total synthesis of post-iboga indole alkaloids. Angew. Chem. Int. Ed., 2020, 59, 18731-18740.
Tan, D-X.; Han, F-S. Synthetic studies towards the total synthesis of indole alkaloids containing indolyl lactam frameworks. Synlett, 2020, 2020, 1.
[ ]
Xia, Z.; Hu, J.; Gao, Y-Q.; Yao, Q.; Xie, W. Facile access to 2,2-disubstituted indolin-3-ones via a cascade Fischer indolization/Claisen rearrangement reaction. Chem. Commun. (Camb.), 2017, 53(54), 7485-7488.
[] [PMID: 28627577]
Ma, F-P.; Cheng, G-T.; He, Z-G.; Zhang, Z-H. A new and efficient procedure for Friedländer synthesis of quinolines in low melting tartaric acid-urea mixtures. Aust. J. Chem., 2012, 65, 409-416.
Gore, S.; Baskaran, S.; Köenig, B. Efficient synthesis of 3,4-dihydro-pyrimidin-2-ones in low melting tartaric acid–urea mixtures. Green Chem., 2011, 13, 1009-1013.
Gore, S.; Baskaran, S.; Köenig, B. Synthesis of pyrimidopyrimidinediones in a deep eutectic reaction mixture. Adv. Synth. Catal., 2012, 354, 2368-2372.
Krishnakumar, V.; Vindhya, N.G.; Mandal, B.K.; Khan, F-R.N. Green chemical approach: low-melting mixture as a green solvent for efficient Michael addition of homophthalimides with chalcones. Ind. Eng. Chem. Res., 2014, 53, 10814-10819.
Gore, S.; Chinthapally, K.; Baskaran, S.; König, B. Synthesis of substituted hydantoins in low melting mixtures. Chem. Commun. (Camb.), 2013, 49(44), 5052-5054.
[] [PMID: 23625044]
Kotha, S.; Gupta, N.K.; Aswar, V.R. Multicomponent approach to hydantoins and thiohydantoins involving a deep eutectic solvent. Chem. Asian J., 2019, 14(18), 3188-3197.
[] [PMID: 31386259]
Devi, P.; Lambu, M.R.; Baskaran, S. A novel one-pot method for the stereoselective synthesis of tetrahydropyrimidinones in a low melting mixture. Org. Biomol. Chem., 2020, 18, 4164-4168.
[] [PMID: 32436516]
Zhang, Z-H.; Zhang, X-N. Mo, L.-P. Li, Y.-X.; Ma, F.-P. Catalyst-free synthesis of quinazoline derivatives using low melting sugar–urea–salt mixture as a solvent. Green Chem., 2012, 14, 1502-1506.

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