Open access peer-reviewed chapter - ONLINE FIRST

Green Synthesis of Chalcone Derivatives Using Chalcones as Precursor

Written By

Surbhi Dhadda, Prakash Giri Goswami and Himanshu Sharma

Submitted: January 26th, 2022 Reviewed: February 27th, 2022 Published: April 26th, 2022

DOI: 10.5772/intechopen.103959

IntechOpen
Green Chemistry - New Perspectives Edited by Brajesh Kumar

From the Edited Volume

Green Chemistry - New Perspectives [Working Title]

Dr. Brajesh Kumar and Dr. Alexis Debut

Chapter metrics overview

17 Chapter Downloads

View Full Metrics

Abstract

Recently, the use of green methodologies like sonication, use of ionic liquids, etc. attracted the attention of researchers in the field of organic synthesis as they have advantages such as mild reaction conditions, environmentally benign procedures, etc. Herein, this chapter highlights some recyclable ionic liquids (ILs) catalyzed ring closure reactions of chalcones to obtain several heterocyclic rings viz.; pyrazoles, pyrans, pyrimidines under ultrasonification. These reactions have very important features i.e., short routine, high yields, being environmentally friendly, high functional group tolerance, formation of a single product, high atom economy, high yielding, no need for column purification, etc. The various synthesized compounds were prepared in optimized reaction conditions in good to efficient yields. Analytical and spectral (FTIR, 1H, and 13C NMR) techniques were employed for the structural elucidation of the synthesized compounds. The ionic liquids used in the synthesis are recycled and reused several times.

Keywords

  • Chalcones
  • green synthesis
  • ionic liquid
  • ring closure reactions
  • sonication

1. Introduction

In recent years, the emphasis of science and technology has shifted more toward environmental benign and sustainable resources and progress. Green Chemistry is paramount concept in chemistry for sustainability, which is the implementation of a set of principles that minimize or get rid of the utilization or generation of hazardous substances in the design, manufacture, and applications of chemical products [1]. Presently, Sonochemistry is a simplistic pathway for a huge variety of syntheses in organic chemistry. Hence, significant features of the ultrasound approach compared with traditional methods are in higher yields, milder conditions, lesser reaction times, improved reaction rates, formation of purer products, easier manipulation and a role in waste minimization and energy protection [2, 3, 4, 5].

Multicomponent reactions [6] leading to facinating heterocyclic scaffolds must appear as Potent tools for delivering the molecular diversity required in combinatorial approaches for the synthesis of bioactive compounds and producing varied chemical libraries of drug-like molecules for biological screening [7, 8]. Chalcones, or 1,3-diphenyl-2-propen-1-ones, are commonly occurring heterocyclic ring systems and are important structural motifs found in many natural products and pharmaceuticals. It is also known as benzalacetophenone and benzylidene acetophenone. Chalcones are one of the most important classes of flavonoids [9, 10]. Further ring closure reactions of Chalcones can be used to obtain various heterocyclic rings viz.; Pyrazoles, Pyrans, Cyanopyridines, isoxazoles and pyrimidines having different hetero-cyclic ring systems and multiple derivatives can be synthesized using chalcones [11, 12, 13, 14, 15].

The increased environmental concerns needed the replacement of present methods with new more sustainable processes which used the ionic liquids in place of organic catalysts and solvents [16, 17, 18, 19, 20, 21, 22, 23, 24, 25]. Ionic Liquids (ILs), as a class of molten salts, are composed entirely of ions and their melting point is around or below 100°C [26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36]. Due to short reaction times, mild reaction conditions, better yields, easy recyclability thermally stable, non-flammable character with negligible vapor pressure, adjustable miscibility with organic substrates and tunable solvating ability ionic liquids (ILs) have attracted the attention of organic chemists [37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49]. Furthermore, unique physiochemical properties that make them potential candidates for many applications in pharmaceuticals, industry and academia [50, 51, 52].

There are several varieties of ionic liquids being studied, out of them a few Simple functionalized ILs have created unparalleled fascination as they display some benefits for certain base-catalyzed processes, like easy recycling and better catalytic performance [53]. The environmentally benign basic ionic liquids are used as reaction media as well as catalysts in the development of multicomponent reactions (MCRs). Among all such basic ionic ILs [DBU][OAc] has shown the desired results. Some of the key benefits that can be highlighted for utilization of this IL as catalyst are, the desired product obtained without any further purification and the recyclability of the catalyst was found to be up to 5 cycles. The investigation of alternatives with the help of ionic liquids to conventional organic solvents is a developing research area due to increased environmental concerns.

Herein, we are especially interested in developing the potential use of efficient, simple methodology for the ring closure reactions of chalcones using [DBU][OAc] as ionic liquids as a solvent and catalyst. Chalcones can be used to obtain various heterocyclic rings through ring closure reactions (Figure 1).

Figure 1.

General scheme of ring closure reactions of chalcones.

Advertisement

2. Experimental section

2.1 Materials and methods

Melting points were recorded in open glass capillary tube using Gallenkamp melting point apparatus and are uncorrected. Checked by Thin layer chromatography (TLC) was applied to check the purity of synthesized compounds and Spots were visualized by irradiation with UV lights (254 nm) or by staining with iodine vapors. The Fourier-transform infrared (FT-IR) spectra were recorded on SHIMADZU 8400S FT-IR spectrophotometer and wave number is given in cm−1. The 1H NMR spectra and 13C NMR (by broad band proton decoupling technique) were recorded on JEOL AL spectrometer in CDCl3/DMSO-d6 solvents at 400 and 100 MHz and chemical shift were measured in δ ppm relative to TMS as an internal standard. The Mass (HRMS) spectra were recorded on JEOL SX 102/DA-600 using Argon/Xenon gas. The elemental analysis (C, H and N) were performed using vario-III analyzer at CDRI Lucknow.

2.2 General procedure for preparation of DBU based ionic liquid

According to the reported literature [DBUH][OAc] ILs [54] and [DBUH][Cl] ILs [55] were synthesized by the reaction of 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (DBU) and acetic acid or hydrochloric acid, respectively.

2.3 General procedure for preparation of chalcones (3a-c)

Chalcones were synthesized according to the reported procedure with minor modification (Figure 2), the synthesized products were characterized by 1H NMR, and physical data and compared with those reported in literature [54].

Figure 2.

General procedure of synthesis of chalcones (3a-c).

2.4 Model reaction for preparation of pyrazole derivative (4a)

Chalcone derivative (1 mmol) and methylhydrazine (1 mmol) were ultrasonicated catalyzed by [DBUH][OAc] (5 ml) at 50°C for about 4 h (Figure 3). The crude product was refrigerated overnight. The precipitate formed was filtered off and crystallized from ethanol yielding yellow crystals of the product (4a).

Figure 3.

Model reaction for preparation of pyrazole derivative (4a).

2.4.1 Spectroscopic data of (4a)

1H NMR (400 MHz, DMSO-d6) δ 8.81, 7.94, 7.59, 7.47, 7.44, 7.38, 3.96; 13C NMR (100.15 MHz, DMSO-d6) δ 145.51, 133.32, 131.99, 130.37, 129.66, 128.69, 128.34, 126.78, 125.67, 123.12, 122.13, 40.57; HRMS; m/z312.04 (M+); C16H13BrN2: calcd. C, 61.36; H, 4.18; N, 8.94; found C, 61.34; H, 4.20; N, 8.97.

2.5 Model reaction for preparation of pyran derivative (5a)

Chalcone derivative (1 mmol) mixed with α,β-diketone (1 mmol) was ultrasonicated in [DBUH][OAc] (5 mL) for about 45 minutes. The mixture was heated to 60°C for 2 h to complete the reaction which was monitored by TLC. The organic layer was extracted with ethyl acetate, washed with water and then dried over Na2SO4 which was followed by filtration and concentration. The crude was recrystallized from ethyl acetate and hexane mixture to give pure product (5a). The catalyst remained in the aqueous phase was reused in other reactions (Figure 4).

Figure 4.

Model reaction for preparation of pyran derivative (5a).

2.5.1 Spectroscopic data of (5a)

1H NMR (400 MHz, DMSO-d6) δ 7.45, 7.32, 7.28, 7.25, 7.01, 5.27, 3.60, 2.28, 2.21, 2.12, 2.05; 13C NMR (100.15 MHz, DMSO-d6) δ 195.02, 164.92, 142.45, 138.87, 131.92, 129.14, 128.97, 128.27, 128.12, 122.84, 107.13, 76.87, 35.62, 35.14, 27.61, 16.76; HRMS; m/z370.01 (M+); C20H19BrO2: calcd. C, 64.72; H, 5.17; found C, 64.75; H, 5.21.

2.6 Model reaction for preparation of cyanopyridine derivative (6a)

A mixture of chalcone derivative (2 mmol) with malononitrile (2 mmol) in 5 mL of [DBUH][OAc] was ultrasonicated at atmospheric pressure at 65°C for 3 h (Figure 5). After completion of the reaction, the mixture was cooled to room temperature and the organic layer was concentrated. The pure product was obtained by column chromatography (n-hexane:ethyl acetate = 80:20) to afford the preferred product (6a).

Figure 5.

Model reaction for preparation of cyanopyridine derivative (6a).

2.6.1 Spectroscopic data of (6a)

1H NMR (400 MHz, DMSO-d6) δ 9.21, 8.40, 7.95, 7.62, 7.51, 7.44, 7.46; 13C NMR (100.15 MHz, DMSO-d6) δ 160.21, 152.79, 151.01, 138.51, 138.45, 131.34, 130.03, 129.67, 128.99, 127.91, 121.91, 120.71, 117.22, 110.19; HRMS; m/z334.06 (M+); C18H11BrN2: calcd. C, 64.52; H, 3.35; N, 8.37; found C, 64.49; H, 3.33; N, 8.36.

2.7 Model reaction for preparation of isoxazole derivative (7a)

Chalcone derivative (1 mmol) was ultrasonicated with hydroxylamine hydrochloride (1 mmol) in catalytic influence of [DBUH][OAc] ILs (5 mL) at 70°C for 1 h (Figure 6). The formation of product was monitored by TLC. Isoxazole derivative was obtained by keeping the reaction mixture on ice bath, then the desired product was isolated, washed with water, and dried (7a).

Figure 6.

Model reaction for preparation of isoxazole derivative (7a).

2.7.1 Spectroscopic data of (7a)

1H NMR (400 MHz, DMSO-d6) δ 8.66, 7.69, 7.57, 7.50, 7.41, 7.32; 13C NMR (100.15 MHz, DMSO-d6) δ 170.26, 154.95, 131.82, 130.67, 128.61, 128.30, 128.07, 127.55, 126.73, 125.41, 116.74; HRMS; m/z299.04 (M+); C15H10BrNO: calcd. C, 60.01; H, 3.37; N, 4.69; found C, 60.03; H, 3.39; N, 4.71.

2.8 Model reaction for preparation of pyrimidine derivative (8a)

To the mixture of chalcone derivative (1 mmol), guanidine hydrochloride (2 mmol) was added with [DBUH][OAc] ILs was heated under ultrasonication for 2 h at 55°C. The completion of the reaction was checked by TLC (Figure 7). The reaction mixture poured into ice water and formed product was filtered and recrystallized from ethanol (8a).

Figure 7.

Model reaction for preparation of pyrimidine derivative (8a).

2.8.1 Spectroscopic data of (8a)

1H NMR (400 MHz, DMSO) δ 7.77, 7.64, 7.47, 7.41, 7.15, 2.29; 13C NMR (100.15 MHz, DMSO-d6) δ 160.02, 158.70, 138.09, 136.17, 132.01, 131.05, 130.28, 129.20, 128.35, 125.47, 112.89; HRMS; m/z325.05 (M+); C16H12BrN3: calcd. C, 58.93; H, 3.72; N, 12.90; found C, 58.97; H, 3.70; N, 12.91 (see Figure 8).

Figure 8.

General representation of preparation of chalcone derivatives (4-8a-c).

Advertisement

3. Results and discussion

In this chapter, the ring closure reaction of chalcone derivatives in the presence of basic ionic liquid [DBUH]OAc to afford the several derivatives like pyrazoles, pyrans, pyrimidines, isoxazoles, and cyanopyridines. Different catalytic systems were used to optimize the reaction conditions on the set of model reactions.

3.1 Optimization of reaction conditions

The reaction conditions were optimized on the respective model reactions, further these optimized reaction conditions were used to produce corresponding derivatives of chalcones (Table 1).

Table 1.

% yield of desired products (4-8a,b,c).

We have carried out the synthesis of a number of chalcone derivatives (4-8a,b,c) under different reaction conditions. The optimized conditions for all the ring closure reactions of chalcones involved use of [DBUH]OAc ILs as catalyst under sonication for appropriate time at adequate temperature (Table 2, Entry 6).

S. No.Catalyst / SolventReaction ConditionPyrazole Derivative (4a)Pyran Derivative (5a)Cyanopyridine Derivative (6a)Isoxazole Derivative (7a)Pyrimidine Derivative (8a)
Temp
(°C)
% YieldTemp
(°C)
% YieldTemp
(°C)
% YieldTemp
(°C)
% YieldTemp
(°C)
% Yield
1.No catalyst / DCMReflux120<5120<5120<5120<5120<5
2.NaOH / DCMSonication100>15100>15100>15100>15100>15
3.[MIM]BF4 ILSonication1004010035100421004510038
4.[MIM]OH ILSonication90489042905190559044
5.[DBUH]Cl ILSonication90629065906890629060
6.[DBUH]OAc ILSonication50976095659370945596

Table 2.

Optimization of reaction conditions.

3.2 Reusability of ionic liquids

The catalytic reusability of ILs was observed during optimized reaction conditions. The ILs were easily recovered as filtration after the completion of reaction. The recovered ILs were used four times without remarkable loss in activity but after that there is sudden decrease (Figure 9) in yield of products.

Figure 9.

Reusability and recyclability of [DBUH]OAc ILs.

Advertisement

4. Conclusion

In Summary, we developed a simple and efficient catalytic system that can effectively promote the conversion of chalcones into different derivatives viz.; Pyrazoles, Pyrans, Cyanopyridines, isoxazoles and pyrimidines via[DBU][OAc] IL catalyzed ring closure reactions under mild conditions. A series of functional ILs was screened and [DBU][OAc] was determined as the optimal catalyst. This mild and environmental friendly synthetic methodology permitted us to synthesize products in good to excellent yields. There are many merits of the used protocol like, low cost of green catalyst, operational simplicity, obtaining products in high yield, and the catalyst can be reused without any significant loss of catalytic property up to five catalytic cycles.

References

  1. 1. Hua Y, Zou Y, Wu H, Shi D. A facile and efficient ultrasound-assisted synthesis of novel dispiroheterocycles through 1, 3-dipolar cycloaddition reactions. Ultrasonics Sonochemistry. 2012;19:264-269
  2. 2. Zbancioc G, Florea O, Jones PG, Mangalagiu II. An efficient and selective way to new highly functionalized coronands or spiro derivatives using ultrasonic irradiation. Ultrasonics Sonochemistry. 2012;19:399-403
  3. 3. Wang SY, Ji SJ, Loh TP. The Michael addition of indole to α,β-unsaturated ketones catalyzed by iodine at room temperature. Synlett. 2003;15:2377-2379
  4. 4. Dandia H, Singh R, Bhaskaran S. Ultrasound promoted greener synthesis of spiro[indole-3,5′-[1,3]oxathiolanes] in water. Ultrasonics Sonochemistry. 2010;17:399-402
  5. 5. Nair V, Rajesh C, Vinod AU, Bindu S, Sreekanth AR, Mathen JS, et al. Strategies for heterocyclic construction via novel multicomponent reactions based on isocyanides and nucleophilic carbenes. Accounts of Chemical Research. 2003;36:899-907
  6. 6. Dömling A. Recent advances in isocyanide-based multicomponent chemistry. Current Opinion in Chemical Biology. 2002;6(3):306-313
  7. 7. Babu AS, Raghunathan R. Ultrasonic assisted-silica mediated [3+ 2] cycloaddition of azomethine ylides—A facile multicomponent one-pot synthesis of novel dispiroheterocycles. Tetrahedron Letters. 2007;48(38):6809-6813
  8. 8. Ni L, Meng CQ, Sikorski JA. Recent advances in therapeutic chalcones. Expert Opinion on Therapeutic Patents. 2004;14(12):1669-1691
  9. 9. Sahu NK, Balbhadra SS, Choudhary J, Kohli DV. Exploring pharmacological significance of chalcone scaffold: A review. Current Medicinal Chemistry. 2012;19:209-225
  10. 10. El-Hashah MA, El-Kady M, Saiyed MA, Elaswy AA. Arylidene derivatives as synthons heterocyclic synthesis. Egyptian Journal of Chemistry. 1985;27:715
  11. 11. Crawley LS, Fanshawe WJ. Neighboring group participation in cyclodehydration. A regiospecific isoxazole synthesis. Journal of Heterocyclic Chemistry. 1977;14(3):531-534
  12. 12. Taylor EC, Morrison RW Jr. An unusual molecular rearrangement of an N-aminopyrimidine. The Journal of Organic Chemistry. 1967;32(8):2379-2382
  13. 13. Utale PS, Raghuwanshi PB, Doshi AG. Synthesis of some new 1-Carboxamido-3-(substituted-2-hydroxy phenyl)-5-aryl-[delta] 2-pyrazolines. Asian Journal of Chemistry. 1998;10(3):597-599
  14. 14. Kidwai M, Misra P. Ring closure reactions of chalcones using microwave technology. Synthetic Communications. 1999;29(18):3237-3250
  15. 15. Le ZG, Chen ZC, Hu Y, Zheng QG. Organic reactions in ionic liquids: A simple and highly regioselective N-substitution of pyrrole. Synthesis. 2004;12:1951-1954
  16. 16. Nara SJ, Naik PU, Harjani JR, Salunkhe MM. Potential of ionic liquids in greener methodologies involving biocatalysis and other synthetically important transformations. Indian Journal of Chemistry. 2006;45B:2257-2269
  17. 17. Catal KN. Rev. synthesis of five-membered N-heterocycles fused with other heterocycles. Catalysis Reviews. 2015;57(1):1-78
  18. 18. Kaur N, Kishore D, Kaur N, Kishore D. Microwave-assisted synthesis of six-membered O-heterocycles. Synthetic Communications. 2014;44(21):3047-3081
  19. 19. Kaur N, Dwivedi J, Kishore D, Kaur N, Dwivedi J, Kishore D. Solid-phase synthesis of nitrogen-containing five-membered heterocycles. Synthetic Communications. 2014;44(12):1671-1729
  20. 20. Nair V, Vellalath S, Poonoth M, Suresh E, Viji S. N-heterocyclic carbene catalyzed reaction of enals and diaryl-1, 2 diones via homoenolate: Synthesis of 4, 5, 5-trisubstituted γ-butyrolactones. Synthesis. 2007;20:3195-3200
  21. 21. Potewar TM, Siddiqui SA, Lahoti RJ, Srinivasan KV. Efficient and rapid synthesis of 1-substituted-1H-1, 2, 3, 4-tetrazoles in the acidic ionic liquid 1-n-butylimidazolium tetrafluoroborate. Tetrahedron Letters. 2007;48(10):1721-1724
  22. 22. Xu JM, Qian C, Liu BK, Wu Q, Lin XF. A fast and highly efficient protocol for Michael addition of N-heterocycles to α, β-unsaturated compound using basic ionic liquid [bmIm] OH as catalyst and green solvent. Tetrahedron. 2007;63(4):986-990
  23. 23. Hutka M, Toma S. Hydrogen-transfer reduction of aromatic ketones in basic ionic liquids. Monatshefte für Chemie-Chemical Monthly. 2009;140(10):1189-1194
  24. 24. Syamala M. Recent progress in three-component reactions. An update. Organic Preparations and Procedures International. 2009;41(1):1-68
  25. 25. Wasserscheid P, Keim W. Ionic liquids—New “solutions” for transition metal catalysis. Angewandte Chemie International Edition. 2000;39:3772-3789
  26. 26. Frizzo CP, Tier AZ, Bender CR, Gindri IM, Villetti MA, Zanatta N, et al. Structural and Physical Aspects of Ionic Liquid Aggregates in Solution. InIonic Liquids-Current State of the Art Rijeka. London, UK: InTech; 2015. pp. 161-198
  27. 27. Berthod A, Ruiz-Angel MJ, Carda-Broch S. Recent advances on ionic liquid uses in separation techniques. Journal of Chromatography A. 2018;1559:2-16
  28. 28. Javed MN, Muhammad S, Hashmi IA, Bari A, Musharraf SG, Ali FI. Newly designed pyridine and piperidine based ionic liquids: Aggregation behavior in ESI-MS and catalytic activity in CC bond formation reactions. Journal of Molecular Liquids. 2018;272:84-91
  29. 29. Kaur N. Environmentally benign synthesis of five-membered 1, 3-N, N-heterocycles by microwave irradiation. Synthetic Communications. 2015;45(8):909-943
  30. 30. Kaur N. Advances in microwave-assisted synthesis for five-membered N-heterocycle synthesis. Synthetic Communications. 2015;45(4):432-457
  31. 31. Kaur N. Microwave-assisted synthesis of five-membered S-heterocycles. Journal of the Iranian Chemical Society. 2014;11(2):523-564
  32. 32. Kaur N. Review on the synthesis of six-membered N, N-heterocycles by microwave irradiation. Synthetic Communications. 2015;45(10):1145-1182
  33. 33. Kaur N. Greener and expeditious synthesis of fused six-membered N, N-heterocycles using microwave irradiation. Synthetic Communications. 2015;45(13):1493-1519
  34. 34. Kaur N. Applications of microwaves in the synthesis of polycyclic six-membered N. N-heterocycles. Synthetic Communications. 2015;45(14):1599-1631
  35. 35. Kaur N. Synthesis of five-membered N, N, N-and N, N, N, N-heterocyclic compounds: Applications of microwaves. Synthetic Communications. 2015;45(15):1711-1742
  36. 36. Bao Q, Qiao K, Tomida D, Yokoyama C. Preparation of 5-hydroymethylfurfural by dehydration of fructose in the presence of acidic ionic liquid. Catalysis Communications. 2008;9(6):1383-1388
  37. 37. Shen J, Wang H, Liu H, Sun Y, Liu Z. Brønsted acidic ionic liquids as dual catalyst and solvent for environmentally friendly synthesis of chalcone. Journal of Molecular Catalysis A: Chemical. 2008;280(1–2):24-28
  38. 38. Wang W, Shao L, Cheng W, Yang J, He M. Brønsted acidic ionic liquids as novel catalysts for Prins reaction. Catalysis Communications. 2008;9(3):337-341
  39. 39. Kaur N. Role of microwaves in the synthesis of fused five-membered heterocycles with three N-heteroatoms. Synthetic Communications. 2015;45(4):403-431
  40. 40. Kaur N. Recent impact of microwave-assisted synthesis on benzo derivatives of five-membered N-heterocycles. Synthetic Communications. 2015;45(5):539-568
  41. 41. Kaur N, Kishore D. Microwave-assisted synthesis of seven-and higher-membered N-heterocycles. Synthetic Communications. 2014;44(18):2577-2614
  42. 42. Kaur N, Kishore D. Microwave-assisted synthesis of six-membered S-heterocycles. Synthetic Communications. 2014;44(18):2615-2644
  43. 43. Kaur N, Kishore D. Microwave-assisted synthesis of seven-and higher-membered O-heterocycles. Synthetic Communications. 2014;44(19):2739-2755
  44. 44. Luo S, Mi X, Zhang L, Liu S, Xu H, Cheng JP. Functionalized ionic liquids catalyzed direct aldol reactions. Tetrahedron. 2007;63(9):1923-1930
  45. 45. Carvalho PJ, Álvarez VH, Marrucho IM, Aznar M, Coutinho JA. High pressure phase behavior of carbon dioxide in 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide and 1-butyl-3- methylimidazolium dicyanamide ionic liquids. The Journal of Supercritical Fluids. 2009;50(2):105-111
  46. 46. Holbrey JD, Reichert WM, Reddy R, Rogers R. Ionic Liquids as Green Solvents: Progress and Prospects, ACS Symposium Series. Washington, DC: American Chemical Society; 2003. pp. 121-133
  47. 47. Cevasco G, Chiappe C. Are ionic liquids a proper solution to current environmental challenges. Green Chemistry. 2014;16:2375-2385
  48. 48. Yang Z, Pan W. Ionic liquids: Green solvents for nonaqueous biocatalysis. Enzyme and Microbial Technology. 2005;37(1):19-28
  49. 49. Mecerreyes D. Polymeric ionic liquids: Broadening the properties and applications of polyelectrolytes. Progress in Polymer Science. 2011;36(12):1629-1648
  50. 50. Mishra N, Arora P, Kumar B, Mishra LC, Bhattacharya A, Awasthi SK, et al. Synthesis of novel substituted 1, 3-diaryl propenone derivatives and their antimalarial activity in vitro. European Journal of Medicinal Chemistry. 2008;43(7):1530-1535
  51. 51. Awasthi SK, Mishra N, Kumar B, Sharma M, Bhattacharya A, Mishra LC, et al. Potent antimalarial activity of newly synthesized substituted chalcone analogs in vitro. Medicinal Chemistry Research. 2009;18(6):407-420
  52. 52. Hajipour AR, Rafiee F. Basic ionic liquids. A short review. Journal of the Iranian Chemical Society. 2009;6(4):647-678
  53. 53. Ying AG, Liu L, Wu GF, Chen G, Chen XZ, Ye WD. Aza-Michael addition of aliphatic or aromatic amines to α, β-unsaturated compounds catalyzed by a DBU-derived ionic liquid under solvent-free conditions. Tetrahedron Letters. 2009;50(14):1653-1657
  54. 54. Tolstikova LL, Shainyan BA. Ionic liquids on the basis of 2, 3, 4, 6, 7, 8, 9, 10-octahydropyrimido-[1, 2-a] azepine (1, 8-diazabicyclo [5.4. 0] undec-7-ene). Russian Journal of Organic Chemistry. 2006;42:1068-1074
  55. 55. Li J, Zhuang R, Qian Y. Synthesis of novel Chalcone derivatives by organic catalysis. Materials Physics and Chemistry. 2019;1(1):1-564

Written By

Surbhi Dhadda, Prakash Giri Goswami and Himanshu Sharma

Submitted: January 26th, 2022 Reviewed: February 27th, 2022 Published: April 26th, 2022