For verification of this paper, please visit on http://www.socialresearchfoundation.com/innovation.php#8

Chalcones are natural pigments have a wide spectrum of biological activities, which are of great interest in many fields. The presence of a reactive α,β-unsaturated carbonyl function in chalcones and its derivatives is the reason for their pharmacological activities. Chalcones can be synthesized by claisen-schmidts condensation, aldol condensation and using microwave irradiation.

Chalcones are open chain flavonoids containing an enone system. In the enone system the carbonyl group [electron attracting group] is in conjugation with carbon-carbon double bond, which activates the α-carbon atom towards nucleophilic reagents. The nucleophilic addition in chalcone system takes place by following mechanism.

The term chalcone was coined by Kostanecki and Tamber. Chemically chalcones are named as benzylidine acetophenones, α-phenyl, β-benzolethylene, phenyl styryl ketones, β-phenyl acrylophenone, 1,3-diphenylprop-2-en-1-one.

The chalcones are important Michael acceptors having enone system, whose polar character increases due to introducing aromatic substituents and enhance their tendency to undergo Michael condensation. Besides their synthetic utility a wide spectrum of biological activities of chalcones have been reported due to the presence of heterocyclic nuclei in the enone system. Chalcones and their derivatives possess antibacterial[11,12], anticancer[13], anti-inflammatory, analgesic, antituburcular[14-16], anti-HIV[17] activities.

 Synthesis of chalcones

 Claisen- Schmidt condensation

The chalcones are synthesized by Claisen Schmidt Condensation[18, 19] of ketone with aldehyde in the presence of  alkali base or in the presence of alcoholic alkali.

 Aldol Condensation

The reaction of acetophenone and benzaldehyde in the presence of KOH give chalcone as a product.

Microwave Assisted Synthesis of Chalcones

In the last decade, Microwave Irradiation[20, 21] have been used more and more often in organic synthesis. Heterogeneous catalyst such as K₂CO₃, Ba(OH)₂, piperidine and aqueous alkali are used to synthesize chalcones and their derivatives using microwave.

Synthetic application of chalcones

Cyclic system

Chalcones react with cyclopentanone in the presence of Ba(OH)₂ and give complex domino products.[22]

Heterocyclic systems

Substituted and unsubstituted 2,4-di-5-oxo-5,6,7,8-tetrahydro-2-chromones have been synthesized using anhydrous zinc chloride as catalyst.[23]

Oxidation of 2’-hydroxy chalcones with molar amount of mercury (II) acetate in presence of pyridine and with catalytic amount of CuBr2 in DMSO has been reported to afford aurones in excellent yields.[24]

Synthesis of 2,4,6-triaryl pyridine has been achieved using a novel reaction between chalcones and ammonium acetate under solvent free condensation.[25]

Microwave Induced Synthesis of Heterocycles using chalcones

A number of cyclic and heterocyclic systems using chalcones under microwave irradiation can be achieved very conveniently in excellent yields. 3- benzimidazolyl-5-aryl-2-isoxali has been synthesized using MWI by the interaction between benzimidazolyl chalcoles and hydroxylamine hydrochloride in presence of pyridine.[26]

Microwave assisted transformation

A series of new [3-(2-hydroxy phenyl)-5-aryl-2-pyrazolin-2-yl]-4-thiazolidinones has been prepared[27] by microwave induced reaction of N’-chloroacetyl-3, 5-diaryl-2-pyrazolines with ammonium thiocyanate.

Microwave assisted transformation of some benzimidazolyl chalcones into N’-substituted pyrazolines and evaluation of their antibacterial activities has been reported recently by Rajora et al.[28]

Various N- substituted pyrazoline derivatives have been synthesized by the condensation of chalcones with hydrazine hydrate using ethanol as a solvent under MWI.

From this review it can be stated that chalcones and their derivatives have a great applications in chemical fields like coordination chemistry as a legend, medical chemistry as antibacterial, anticancer, antifungal, in analytical chemistry as a reagents and other uses.

1. B.P. Bandga, S.A. Patil, B.L Korbad, S.H. Nile, C.N. Khobragade, Eur. J. Med. Chem. 45, 2629-2633 (2010). 2. N. Sunduru, A. Agarwal, S.B. Katiyar, Nishi, N. Goyal, S. Gupta, P.M.S Chauhan. Bioorg. Med. Chem. 14, 7706-7715 (2006). 3. Tatsuzaki, K.F. Bastow, K. Nakagawa-Goto, S. Nakamura, H. Itokawa, K-H. Lee, J. Net Prod. 69(10), 1445-1449, (2006). 4. J.M. Yun, M.H. Kweon, H. Kwon, J.K. Hwang, H. Muktar, Carcinogensis 27 (7), 1454-1464, (2006). 5. V. Calvino, M. Picallo, A.J. Lapoz- Peinado, R.M. Martin- Aranda, C.J. Duran – Valle. Appl. Surface Sci. 252 (17), 6071 – 6074 (2006). 6. Y. Rajendra Prasad, P. Ravikumar and B. Ramesh, Int. J. Chem. Sci. 5(2), 542-548 (2007). 7. Nidhi Mishra, Preeti Arora, Brajesh kkumar, Lokesh C. Mishra, Amit Bhattacharya, S.K. Awasthi, V.K. Bhasin, European J. Med. Chem. 43, 1530-1535 (2008). 8. A. Valla, B. Valla, D. Cartier, R.L. Guillou, R. Lalois, L. Florent, S.Charneau, J.Schrevel, Pierre Potier Eur.J. Med. Chem. 41, 142-146 (2006). 9. M.S. Cheng, R.S. Li, G. Kenjon, Chinese Chemical Letters, 11, no. 10, 857-850 (2000). 10. M. Liu, Prapon Wilariat, S.L. Craft, Biorganic and Medicinal chemistry 11, 2729 – 2738 (2003). 11. M. Mohamd, N.M. Aljamali, W.A. Shubber, S. A. Abdalrabman, New Azomethine- Azo Heterocylic ligands via cyclization of ester research J. Pharm. And Tech. 11,6 (2018). 12. H. Sawito, A.N. Kristanti and N.N.T. Paspaningsih, chalcone synthesis, structure, diversity and phamalogical aspects, journal of chemical and pharmaceutical research, 6(5), 1076-1088, (2014). 13. S.Y. Hassan, “Synthesis, antibacterial and antifungal activity of some new pyrazoline and Pyrazole derivatives.” Molecules, 18, 683 (2013). 14. V.R. Danger, K.N. Borkhataria and V.R. Shah, “Synthesis, Characterization and antimicrobial activity of pyrazoline and Amino Cyano- pyridine derivatives of with vanillin. Sci. Revs. Chem. Common, 4(1) 31-37 (2014). 15. N.M. Aljamali “Synthesis and chemical identification of macro compounds of thiazol and imidazol.” Research J. Pharm. And Tech., 8(1), 78-84 (2015). DOI: 10.5958/ 0974-360x.2015, 50016.5 16. P. Page, F. Gaggini and B. Laleu, Pyrazoline Dione Derivatives as NADPH oxidase inhibitors, Us Patent, 0172352, AL, (2012). 17. A.V. Leovezijn, W.I. Iwema and A. Stoit, Aryl sulfonyl Pyrazoline Carboxamide Derivatives as 5-HT6 Antagonists, US Patent, 0011775AI, (2014). 18. Z. Nowakowska Z., A review of anti-infective and anti-inflammatory chalcones, Eur. J. Med. Chem., 42(2), 125-135 (2007). 19. W.S.J. Liu CT, L.T. Tsao, J.R. Weng, KOHH, J.P. Wang , C.N. Lin, Synthetic chalcones as polential anti-inflammatory and cancer chemopreventive agents, Eur. J. Med Chem. 40, 103-112 (2005). 20. P. Lindstrom, J. Tierney, B. Wathey and J. Westman, Tetrahedron, 57, 9225 (2001). 21. S.S. Berdonosov, Sorosovski obrazovatel, nyi, Zhurn 12 (2001). 22. H.S. Rao, K. Jeyalakshmi, B. Bharthi, L. Pushpalatha and V. Umamaheshwari, J. Indian Chem. Soc., 78(10-12), 787 (2001). 23. M.G. Ahmed, S.A. Ahmed, U.K.R. Romman, A.S. Touchy, M.R. Badal, M.A. Hossain and M. Khabiruddin, Indian J. Chem., 44B (3), 622 (2005). 24. M.N. Agrawal and P.A. Soni, Indian J. Chem., 44B (5), 1301 (2006). 25. Adib Mehdi, Taher Mansouri, Hasan Kaloogani, Somayeh Ali, Mohammadi Bagher and Bijanzadeh Hamid Raza, Tetrahedron Lett., 47(33), 5957 (2006). 26. M. Nyati, N.S. Rao, Y.K. Srivastava and B.L. Verma, Indian J. Heterocyclic Chem., 15(1), 245 (2006). 27. B. Bajia, J. Rajora, R. Kumar, N.S. Rao, M. Nyati and Y.K. Srivastava, Heterocyclic Comm., 13(6), 397 (2007). 28. J. Rajora, J. Yadav, R. Kumar and Y.K. Srivastava, Indian J. Chem., 49B (7), 989 (2010).