Nalilu Suchetha Kumari

Synthesis of some halogen-containing 1,2,4-triazolo-1,3,4-thiadiazines and their antibacterial and anticancer screening studies--part I.

A series of 7-arylidene-6-(2,4-dichloro-5-fluorophenyl)-3-substituted-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazines (3) were prepared by the condensation of 4-amino-5-mercapto-3-substituted-1,2,4-triazoles (1) and 3-aryl-1-(2,4-dichloro-5-fluorophenyl)-2-bromo-2-propen-1-one (2). An alternative route for the synthesis of the title compound 3 has been described. The newly synthesised compounds were characterised on the basis of N-analyses, IR, 1H NMR and mass spectral data. Some of the newly synthesised compounds were tested for their antibacterial activities against Gram + ve and Gram - ve bacteria. Among the tested compounds 3n showed the highest degree of antibacterial activity against S. aureus and evaluation of the LD50 value of this compound was carried out. Some of the newly synthesised compounds were also screened for their anticancer activities. Among these, compounds 3b, 3g, 3n and 3p are found to be active against NCI-H460 (lung), MCF7 (breast), SF 268 (CNS) in the preliminary anticancer screening studies. Further, 60-cell-line anticancer studies of these compounds were carried out. The results of such studies are discussed in this paper.

Synthesis of some new 4-styryltetrazolo[1,5-a]quinoxaline and 1-substituted-4-styryl[1,2,4]triazolo[4,3-a]quinoxaline derivatives as potent anticonvulsants.

4-Methyltetrazolo[1,5-a]quinoxaline (3) was prepared by the azide cyclocondensation of 2-chloro-3-methylquinoxaline (2). The reaction of 3 with aromatic aldehydes furnished 4-styryltetrazolo[1,5-a]quinoxalines (4a-f). Compound 2, on treatment with hydrazine hydrate gave 2-hydrazino-3-methylquinoxaline (5). The ring closure of 5 was achieved by the reaction of orthoesters and trifluoroacetic acid to yield 4-methyl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (7a-c). Further, reaction of 7a-c with different aromatic aldehydes furnished the title compounds, 4-styryl-1-(substituted)[1,2,4]triazolo[4,3-a]quinoxalines (8a-i) in good yield. In another scheme, the hydrazino compound 5 was treated with different aromatic aldehydes to yield corresponding N-arylidenehydrazino quinoxalines (6a-d). Further, the oxidative cyclization of hydrazones by nitrobenzene yielded 1-aryl-4-methyl[1,2,4]triazolo[4,3-a]quinoxalines (7d-g), which on condensation with aromatic aldehydes gave the title compounds, 1-aryl-4-styryl[1,2,4]triazolo[4,3-a]quinoxalines (8j-u). The newly synthesized compounds have been characterized by FTIR, (1)H NMR, (13)C NMR and mass spectral data, followed by elemental analysis. Some of the compounds were screened for in vivo anticonvulsant activity. Few of them exhibited promising results.

β-Keto esters from ketones and ethyl chloroformate: a rapid, general, efficient synthesis of pyrazolones and their antimicrobial, in silico and in vitro cytotoxicity studies.

Background Pyrazolones are traditionally synthesized by the reaction of β-keto esters with hydrazine and its derivatives. There are methods to synthesize β-keto esters from esters and aldehydes, but these methods have main limitation in varying the substituents. Often, there are a number of methods such as acylation of enolates in which a chelating effect has been employed to lock the enolate anion using lithium and magnesium salts; however, these methods suffer from inconsistent yields in the case of aliphatic acylation. There are methods to synthesize β-keto esters from ketones like caboxylation of ketone enolates using carbon dioxide and carbon monoxide sources in the presence of palladium or transition metal catalysts. Currently, the most general and simple method to synthesize β-keto ester is the reaction of dimethyl or ethyl carbonate with ketone in the presence of strong bases which also requires long reaction time, use of excessive amount of reagent and inconsistent yield. These factors lead us to develop a simple method to synthesize β-keto esters by changing the base and reagent. Results A series of β-keto esters were synthesized from ketones and ethyl chloroformate in the presence of base which in turn are converted to pyrazolones and then subjected to cytotoxicity studies towards various cancer cell lines and antimicrobial activity studies towards various bacterial and fungal strains. Conclusion The β-keto esters from ethyl chloroformate was successfully attempted, and the developed method is simple, fast and applicable to the ketones having the alkyl halogens, protecting groups like Boc and Cbz that were tolerated and proved to be useful in the synthesis of fused bicyclic and tricyclic pyrazolones efficiently using cyclic ketones. Since this method is successful for different ketones, it can be useful for the synthesis of pharmaceutically important pyrazolones also. The synthesized pyrazolones were subjected to antimicrobial, docking and cytotoxicity assay against ACHN (human renal cell carcinoma), Panc-1 (human pancreatic adenocarcinoma) and HCT-116 (human colon cancer) cell line, and lead molecules have been identified. Some of the compounds are found to have promising activity against different bacterial and fungal strains tested.

Synthesis of Some Novel 2,4-Disubstituted Thiazoles as Possible Antimicrobial Agents

A series of 4-aryl-2-(3-methyl-7-substituted quinoxaline-2-one-1-yl)-1,3-thiazoles ( 6a–l ) and 4-substituted alkyl-2-(3-methyl-7-substituted quinoxaline-2-one-1-yl)-1,3-thiazoles ( 8a–i ) were synthesized in good yield by condensing 2-(3-methyl-7-substituted l,2-oxoquinoxalin-1(2H)-yl)ethanethioamides ( 5a–c ) with substituted phenacyl bromide and dichloroacetone followed by treatment with secondary amines, respectively. The intermediates, 5a–c were conveniently obtained by reacting phosphorus pentasulphide with 2-(3-methyl-7-substituted-2-oxoquinoxalin-1(2H)-yl) acetamides ( 4a–c ) which in turn were synthesized from ethyl (3-methyl-7-substituted-2-oxoquinoxalin-1(2H)-yl) acetates ( 3a–c ) by aqueous ammonia treatment. The newly synthesized compounds were characterized by IR, 1 H NMR, 13 C NMR, and Mass spectral and elemental analyses. These compounds were screened for in vitro antibacterial activity against five pathogenic strains and antifungal activity against four fungi. Preliminary results revealed that some of the synthesized compounds showed promising antimicrobial activity.

Synthesis, Characterization, and Biological Evaluation of Some New Functionalized Terphenyl Derivatives

New functionalized terphenyl derivatives incorporating various heterocyclic rings are prepared by using 4,4′′-difluoro-5′-hydroxy-1,1′:3′,1′′-terphenyl-4′-carbohydrazide as a key intermediate derived from 4,4′-difluoro chalcone, a versatile synthone. All the derivatives are characterized by 1H NMR, IR, and mass spectral data. All the synthesized products are screened for their in vitro antimicrobial and antioxidant properties. The majority of the tested compounds exhibited significant antioxidant activity and some of them showed good antimicrobial activity.

Synthesis, characterization, and SAR studies of new (1H-indol-3-yl)alkyl-3-(1H-indol-3-yl)propanamide derivatives as possible antimicrobial and antitubercular agents

In this article, we report herein the SAR studies of a series of (1H-indol-3-yl)alkyl-3-(1H-indol-3-yl)propanamide 10(a–j), 11(a–j). The synthesized compounds were evaluated for their preliminary in vitro antibacterial, antifungal activity and were screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain. The synthesized compounds displayed interesting antimicrobial activity.