874590-17-7Relevant academic research and scientific papers
Catalytic N-formylation for synthesis of 6-substituted-2-benzothiazolylimino-5-piperazinyl-4-thiazolidinone antimicrobial agents
Patel, Rahul V.,Park, Se Won
, p. 5599 - 5609 (2015/07/08)
A new class of piperazine-based 2-benzothiazolylimino-4-thiazolidinones has been efficiently prepared via highly accelerated N-formylation of N-isopropylpiperazine by the use of a mild heterogeneous catalyst, sulfated tungstate. Heterocyclization of N-(benzo[d]thiazol-2-yl)-2-chloroacetamides (3a-j) by use of NH4SCN in ethanol under reflux efficiently furnished the intermediates 2-benzothiazolyliminothiazolidin-4-ones (4a-j). These were treated with 4-isopropylpiperazine-1-carbaldehyde (2) to prepare the final products 5a-j. The structures of the new derivatives were confirmed by elemental analysis and use of spectroscopic data (FTIR and 1H NMR). Their pharmacological potential as promising antimicrobial agents was determined in vitro against bacteria and a fungus; the lowest minimum inhibitory concentrations (MIC) observed were in the range 4-8 μg/mL.
In vitro biological investigations of novel piperazine based heterocycles
Chhatriwala, Nirmal M.,Patel, Amit B.,Patel, Rahul V.,Kumari, Premlata
, p. 611 - 616 (2015/02/02)
Eleven N.phenyl- and 11 N.benzothiazolyl-2-(4-(2,3,4-trimethoxybenzyl)piperazin-1-yl)acetamides have been synthesised by a simple and efficient method. The 22 novel compounds were tested for their in vitro biological efficacy against two Grampositive bacteria, three Gram-negative bacteria, two fungi and Mycobacterium tuberculosis H37Rv. The bioassay results revealed that the majority of the N.benzothiazole-substituted piperazine derivatives exhibited moderate to good bioefficacies with encouraging MICs. The influence of the presence or absence of various electron-withdrawing or -donating functional groups on the aryl acetamide moiety on the different bioassay results is discussed.
Access to a new class of biologically active quinoline based 1,2,4-triazoles
Patel, Rahul V.,Park, Se Won
, p. 24 - 30 (2013/12/04)
As an aspect of our ongoing research in search of new antimicrobial armamentarium, a series of 1,2,4-triazol-3-ylthio-acetamides was constructed and in vitro analyzed for their antimicrobial activity against several bacteria and fungi. Aiming to establish an increased potency, the bioassay results were matched to those of 1,3,4-oxadiazoles, utilized previously. Remarkably, 1,2,4-triazoles were found to possess a good spectrum of antifungal potency, which eventually suggested the azole template as an essential pharmacophore to diversify the biological occupations of the attendant molecules. However, it was noticed that the potency of final analogs against each strain placed reliance on the type of substituent present on benzothiazole ring. The structures of final compounds were confirmed with the aid of IR, 1H NMR, 13C NMR spectroscopy and CHN analysis.
Synthesis of coumarin-based 1,3,4-oxadiazol-2ylthio-N-phenyl/benzothiazolyl acetamides as antimicrobial and antituberculosis agents
Patel, Rahul V.,Kumari, Premlata,Rajani, Dhanji P.,Chikhalia, Kishor H.
, p. 195 - 210 (2013/03/13)
In an attempt to find new agents to fight against microbial infections, a series of coumarin-based 1,3,4-oxadiazol-2ylthio-N-phenyl/benzothiazolyl acetamides was synthesized starting from coumarin-3-carboxylic acid ethyl ester obtained through Knoevenagel and Pinner reaction. In vitro antimicrobial activity against several bacteria (S. aureus, B. cereus, E. coli, P. aeruginosa, K. pneumoniae, S. typhi, P. vulgaris, S. flexneri), fungi (A. niger, A. fumigatus, A. clavatus, C. albicans) and antimycobacterial activity against Mycobacterium tuberculosis H37Rv strain was assessed. This study shows to what extent the presence of various electron withdrawing/donating substituents on the phenyl or benzothiazole ring affects the activity profiles of the newer molecules. The relationship between activity profiles (MICs, 3.12-25 μg/mL) and the lipophilic character (LogP) of the prepared products is also discussed and the MIC values of the active conjugates seem to correlate to some extent with the lipophilicity profiles. Two (5e and 6c) of the final analogues displayed promising antimycobacterial activity at 12.5 μg/mL of MIC, half fold potent to the standard drug pyrazinamide (6.25 μg/mL). Compounds were characterized by IR, 1H NMR, 13C NMR spectroscopy and elemental analysis.
New quinolinyl-1,3,4-oxadiazoles: Synthesis, in vitro antibacterial, antifungal and antituberculosis studies
Patel, Rahul V.,Kumari, Premlata,Chikhalia, Kishor H.
, p. 596 - 607 (2013/07/28)
In order to generate hybrid antimicrobial remedies with novel mode of action, two series of quinoline based 1,3,4-oxadiazole derivatives condensed with N-aryl/benzothiazolyl acetamides were synthesized and the MIC values of the compounds towards eight reference bacterial strains (S. aureus, B. cereus, E. coli, P. aeruginosa, K. pneumoniae, S. typhi, P. vulgaris, S. flexneri), four fungi (A. niger, A. fumigatus, A. clavatus, C. albicans) and Mycobacterium tuberculosis H37Rv were assayed in vitro. Quinoline-6-carboxlic acid was treated with thionyl chloride in refluxing methanol to obtain the corresponding ester derivative to be hydrazinolyzed by 99% hydrazine hydrate in ethanol to produce carbohydrazide intermediate. The carbohydrazide precursor underwent cyclization by carbon disulfide and ethanolic KOH to construct 5-quinolinyl-6-yl-1,3,4- oxadiazol-2-thiol. Substituted 2-chloro-N-phenyl(benzothiazolyl)aceta-mide derivatives were then condensed to 1,3,4-oxadiazole nucleus via sulphur linkage to yield the desired products. Target products bearing N-benzothiazolyl-2- chloroacetamides displayed good inhibitory potential. The biological screening identified that many final analogues exhibited a significant inhibition of the growth of microorganisms at 3.12-25 μg/mL of MIC, which were comparable to control drugs. The influence of the presence of various functional groups to the phenyl/benzothiazolyl ring on activity profiles was investigated. The proposed structures of the newly prepared products were confirmed with the aid of IR, 1H NMR, 13C NMR spectroscopy and elemental analysis. These results may provide new insights in the design of a novel pool of bioactive templates.
Synthesis of benzimidazolyl-1,3,4-oxadiazol-2ylthio-N-phenyl (benzothiazolyl) acetamides as antibacterial, antifungal and antituberculosis agents
Patel, Rahul V.,Patel, Paresh K.,Kumari, Premlata,Rajani, Dhanji P.,Chikhalia, Kishor H.
, p. 41 - 51 (2012/07/30)
To affiliate multiple bioactivities in a compact heteronuclei, two series of benzimidazole based 1,3,4-oxadiazoles were synthesized and assessed in vitro for their efficacy as antimicrobial agents against eight bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, Proteus vulgaris, Shigella flexneri), four fungi (Aspergillus niger, Aspergillus fumigatus, Aspergillus clavatus, Candida albicans) and Mycobacterium tuberculosis H37Rv and best results were observed amongst the N-benzothiazolyl aetamide series. The lipophilicity (LogP) influence on the biological profile (MICs) of the prepared products was also discussed. Upon biological screening, it was observed that the majority of the compounds were found to possess a significant broad spectrum antimicrobial (3.12-25 μg/mL of MIC) and antitubercular (6.25-25 μg/mL of MIC) potential. The structural assignments of the new products were done on the basis of IR, 1H NMR, 13C NMR spectroscopy and elemental analysis.
Combination of bioactive moieties with different heteroatom(s): Application of the Suzuki cross-coupling reaction
Patel, Rahul V.,Patel, Jigar K.,Kumari, Premlata,Chikhalia, Kishor H.
, p. 399 - 410 (2012/08/28)
Two series of thiophene/benzothiophene-linked quinolinyl oxadiazoles condensed to the substituted N-benzothiazolyl acetamides have been synthesized via the Suzuki cross-coupling reaction. The ester derivative of 6-bromo-substituted quinoline was reacted via the Suzuki cross-coupling reaction with commercially available (benzo)thiophen-2-ylboronic acid at optimized temperature in 1,2-dimethoxy ethane and water in the presence of potassium carbonate and palladium tetrakis. The resulting derivatives were then hydrazinolized using 99% hydrazine hydrate followed by cyclization using carbon disulfide in ethanolic KOH to furnish the corresponding oxadiazoles, which were then condensed with various substituted 2-chloro-N-benzothiazolyl acetamides to produce the final scaffolds involving a unique combination of four heterocycles to be examined for their antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus), three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae), and two fungal species (Aspergillus niger and Candida albicans). The investigation of biological screening data revealed that the majority of the compounds tested have demonstrated excellent activity (minimum inhibitory concentrations; 6.25-50 μg/mL) against most of the microorganisms as compared with the standard and hence they warrant more consideration as prospective antimicrobial agents. New products (9a-10i) were characterized by physicochemical, elemental, and spectral (IR, 1H NMR, and 13C NMR) data.
