Ionic liquid catalyzed one-pot multi-component synthesis of fused pyridine derivatives: A strategy for green and sustainable chemistry

The synthesis of a combinatorial library of heterocycle-fused pyridine derivatives has been achieved successfully via a one-pot four-component reaction of aromatic/aliphatic aldehyde, malononitrile, thiazolidine-2,4-dione and ammonium acetate in the presence of piperidinium acetate as the catalyst. It involved the Knoevenagel condensation of the aldehyde and malononitrile to produce arylidene malononitrile as an intermediate, which was further intramolecular cyclization through Michael type addition ketone to the electrophilic double bond of the arylidene to produce fused pyridines in high yields. Environmental friendliness, low cost, Operational simplicity, extensive reusability and applicability, and easy recovery of the catalyst using simple evaporation are the critical features of this methodology. Also, a series of pyridine based dihydrothiazolo[4,5-b] pyridine-6-carbonitrile analogs were synthesized and selected for their in vitro antifungal and antibacterial activities.     

Polyethylene glycol(PEG) mediated expeditious synthetic route to 1,3-oxazine derivatives

Various 1,3-oxazine derivatives were synthesized in high yields,within shorter reaction times using PEG-400 as a safer medium/ mediator.This synthetic route is exceedingly easy and avoids the use of acid/base catalysts.     

Development of a method for the estimation of low amount of plutonium in 200 L waste drums in presence of high amount of β γ activity due to 137Cs and 60Co

The waste drum monitoring system based on HPGe detector was used to study its performance for the estimation of low amounts of plutonium in presence of high activity of ¹³⁷Cs and ⁶⁰Co. The counting was carried out by keeping amount of plutonium constant at 100 mg level and varying the count rate for the γ rays of ¹³⁷Cs and ⁶⁰Co. Present study has shown that the estimation of low amount of ²³⁹Pu in a waste drum can be carried out using 129 keV γ ray in the presence of ¹³⁷Cs up to an activity level of 16 mCi and in the presence of ⁶⁰Co up to an activity level of 8 mCi.     

Thin film of poly(bis[2-(methacryloyloxy)ethyl]phosphate) grafted on surface of poly(ether sulfone) membrane for plutonium(IV)-selective alpha tracks registration in CR-39 detector

Journal of Radioanalytical and Nuclear Chemistry - To impart chemical selectivity in the solid state nuclear track detector based quantification of Pu(IV) ions, a thin film of polymer of...     

Bleaching earth clay (pH 12.5): a green catalyst for rapid synthesis of pyranopyrazole derivatives via a tandem three-component reaction

Efficient three-component synthesis of pyranopyrazole derivatives by reacting substituted aromatic aldehydes (1), (4-chlorophenyl)acetonitrile (2) and 3-methyl-1H-pyrazol-5(4H)-one (3) using bleaching earth clay (pH 12.5) as heterogeneous catalyst and PEG-400 as green solvent is reported in the present communication. The reaction time and product yields are excellent. Catalyst and solvent recovery and reusability are very good. This is a simple, green and rapid method for synthesis of pyranopyrazole derivatives.     

Ionic Liquid–Mediated Knoevenagel Condensation of Meldrum's Acid and Aldehydes

A simple, efficient, and green protocol for Knoevenagel condensation of Meldrum's acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.     

New synthesis of 3,5-disubstituted-5H-thiazolo[3,2-a]pyrimidine via ring annulation of 3,4-dihydropyrimidin-2(1H)-thione using alkynyl(aryl)iodonium salts

A transition metal-free protocol for the synthesis of biologically active thiazolo[3,2-a]pyrimidine derivatives has been achieved by the cyclocondensation of 3,4-dihydropyrimidin-2(1H)-thiones with alkynyl(aryl)iodonium tosylates. This reaction demonstrates another useful application of alkynyl(aryl)iodonium tosylates as synthon of alkynyl cation.     

Study of gamma irradiation effects on the etching and optical properties of CR-39 solid state nuclear track detector and its application to uranium assay in soil samples

The gamma irradiation effects in the dose range of 2.5?C43.0 Mrad on the etching and optical characteristics of CR-39 solid state nuclear track detector (SSNTD) have been studied by using etching and UV?CVisible spectroscopic techniques. From the measured bulk etch rates at different temperatures, the activation energies for bulk etching at different doses have also been determined. It is seen that the bulk etch rates increase and the activation energies for bulk etching decrease with the increase in gamma dose. The optical band gaps of the unirradiated and the gamma -irradiated detectors determined from the UV?CVisible spectra were found to decrease with the increase in gamma dose. These results have been explained on the basis of scission of the detector due to gamma irradiation. The present studies can be used for the estimation of gamma dose in the range of 2.5?C43.0 Mrad and can also be used for estimating track registration efficiency in the presence of gamma dose. The CR-39 detector has also been applied for the assay of uranium in some soil samples of Jammu city.     

Design,synthesis, evaluation,and molecular dynamic simulation of triclosan mimic diphenyl ether derivatives as antitubercular and antibacterial agents

In the present work, we have explored triclosan mimic diphenyl ether derivatives as inhibitors of Mycobacterium tuberculosis enoyl acyl carrier protein reductase (InhA) using a structure-based drug design approach. The virtual library of diphenyl ethers was designed and compounds with acceptable absorption, distribution, metabolism, excretion, and toxicity properties were docked. The compounds with higher dock score (5a-g) than triclosan were synthesized, characterized, and evaluated for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. Among the synthesized compounds, compounds 5f and 5c appeared to be the most promising with minimum inhibitory concentration of 18 μM and 36 μM respectively. The molecular dynamics simulation study of the most active compound 5f and triclosan was performed, which correlates with its activity in comparison with triclosan. All the compounds were further evaluated for cytotoxicity studies against Vero, and HepG2 were found to be safe. Furthermore, compound 5f was evaluated for in vitro cytotoxicity against mouse macrophage cell lines (RAW 264.7), and the study indicated its safety in eukaryotes at 50-μM concentration. In addition, compounds 5a-g were also screened for their in vitro antibacterial activity against two gram-positive and two gram-negative bacteria by resazurin-based microtiter dilution assay method. Among the synthesized compounds, 5f and 5b appeared to be promising, against various gram-positive and gram-negative microorganisms, indicating its broad-spectrum potential.