1131-16-4Relevant academic research and scientific papers
A green protocol for catalyst-free syntheses of pyrazole in glycerol-water solution
Min, Zhen-Li,Zhang, Qian,Hong, Xing,Cao, Xiao-Lu,Hu, Xia-Min
, p. 3205 - 3207 (2015)
An efficient green protocol for preparing pyrazole derivatives using glycerol and water as a mixture solvent is described. The advantages of the present method lie in using economic and environmentally benign solvent, no use of catalyst, mild reaction conditions and good yields.
Synthesis of Unsymmetrical 2,6-Diarylanilines by Palladium-Catalyzed C-H Bond Functionalization Methodology
Kwak, Se Hun,Gulia, Nurbey,Daugulis, Olafs
, p. 5844 - 5850 (2018)
3,5-Dimethylpyrazole was employed as a monodentate directing group for palladium-catalyzed ortho-sp2 C-H arylation with aryl iodides. The reaction shows good functional group tolerance and outstanding selectivity for mono-ortho-arylation. Ozonolysis of ortho-arylated arylpyrazoles gave acylated biphenylamines that were further arylated to afford unsymmetrically substituted 2,6-diarylacetanilides.
Translating high-temperature microwave chemistry to scalable continuous flow processes
Damm, Markus,Glasnov, Toma N.,Kappe, C. Oliver
, p. 215 - 224 (2010)
A comparison between batch microwave and conventionally heated continuous flow scale-up protocols for three selected model reactions is presented. Using high-temperature/-pressure conditions as process intensification principles, reaction times for all three transformations were reduced to a few seconds or minutes at temperatures ranging from.
Synthesis, characterization and antibacterial applications of pyrazolyl-sulfonamides and their palladium complexes
Amoah, Cephas,Obuah, Collins,Ainooson, Michael Kojo,Adokoh, Christian Kwaku,Muller, Alfred
, p. 3716 - 3726 (2021)
A series of pyrazolyl sulfonamide compounds were prepared by a multi-step procedure involving preparation of phenyl pyrazolyl compounds (C1, C2) and their chlorosulfonated derivatives (C3-C5), which were then converted to sulfonamides (L1-L6). Complexes of L1-L6 with palladium(ii) show the standard trans square-planar coordination environment for the six complexes (1-6). All products were prepared in moderate to high yield (61-81%). All compounds were successfully characterized by NMR spectroscopy, IR spectroscopy, mass spectrometry and in one case single X-ray crystallography. Conversion of C1 and C2 to C3-C5 is governed by steric hindrance on the pyrazolyl group as sulfonation of the phenyl only is observed for tBu groups (C4), whereas for Me groups sulfonation of the pyrazolyl is observed C3 as well as phenyl ring for C5. Antimicrobial screening was carried out on the compounds using the agar-well diffusion method at varying concentrations of (62.5, 125, 250, 500 and 1000 μg mL-1) on ten (10) bacteria strains. The zone of inhibition for all the compounds are within the ranges of 9.5 mm to 25 mm compared to the control antibiotic, gentamicin that was between 16.5 mm to 36 mm. The compounds L1-L6 generally showed mild to strong antibacterial activity in the zones of inhibition against most Gram negative bacteria strains tested, but no activity against Gram positive bacteria strains Staphylococcus aureus and Enterococcus faecalis, except L4 which showed activity towards Staphylococcus. The palladium(ii) complexes generally showed improved activities for all the bacteria strains studied with 4 exhibiting the most potent in vitro anti-bacterial activity with MICs of 1.046 μg mL-1 and 0.237 μg mL-1 against Staphylococcus epidermidis and Proteus mirabilis respectively. Theoretical Log P calculation show values between 3.06 and 5.95 for the ligands and between 6.67 and 12.36 for complexes. Suggesting high affinity of these compounds to the lipophilic medium. However, the experimental Log P value gave a different trend, which shows that compounds with sulfonation only on the phenyl ring (L3 (-0.83), L4 (-0.53), 3 (-0.96) and 4 (-0.72)) have high affinity for the hydrophilic medium. This journal is
Highly reusable support-free copper(II) complex of para-hydroxy-substituted salen: Novel, efficient and versatile catalyst for C─N bond forming reactions
Sharghi, Hashem,Aberi, Mahdi,Shiri, Pezhman
, (2017)
An air-stable, highly active and versatile method for C─N bond forming reactions is reported. Under mild conditions using a highly reusable support-free Cu(II)–salen complex, structurally diverse N-aryl-substituted compounds were obtained via direct C─N bond forming reaction of HN-heterocycles with aryl iodides or three-component C─N bond forming reaction of 2-bromobenzaldehyde, aniline derivatives and sodium azide in good to excellent yields. C─N bond forming reaction for benzimidazole derivatives was also performed in the presence of the catalyst under ambient conditions. A series of hybrid benzimidazoles bearing morpholine, tetrazole and quinoxaline backbones were produced using this method. All reactions were performed in short times under air. The Cu(II) catalyst could be reused up to eight times in the direct cross-coupling reaction of 9H–carbazole with iodobenzene without any decrease in its catalytic activity.
NSC 18725, a Pyrazole Derivative Inhibits Growth of Intracellular Mycobacterium tuberculosis by Induction of Autophagy
Arora, Garima,Behura, Assirbad,Dhiman, Rohan,Gagandeep, Garima,Gosain, Tannu Priya,Kandi, Shamseer Kulangara,Kidwai, Saqib,Rawat, Diwan S.,Shaliwal, Ravi P.,Singh, Padam,Singh, Ramandeep
, (2020)
The increasing incident rates of drug-resistant tuberculosis (DR-TB) is a global health concern and has been further complicated by the emergence of extensive and total drug-resistant strains. Identification of new chemical entities which are compatible with first-line TB drugs, possess activity against DR-, and metabolically less active bacteria is required to tackle this epidemic. Here, we have performed phenotypic screening of a small molecule library against Mycobacterium bovis BCG and identified 24 scaffolds that exhibited MIC99 values of at least 2.5 μM. The most potent small molecule identified in our study was a nitroso containing pyrazole derivative, NSC 18725. We observed a significant reduction in viable bacilli load of starved Mycobacterium tuberculosis upon exposure to NSC 18725. The action of NSC 18725 was “synergistic” with isoniazid (INH) and “additive” with other drugs in our checkerboard assays. Structure-activity relationship (SAR) studies of the parent compound revealed that pyrazole derivatives without a functional group at fourth position lacked anti-mycobacterial activity in vitro. The derivative with para-chlorophenyl substitution at the first position of the pyrazole ring was the most active scaffold. We also demonstrate that NSC 18725 is able to induce autophagy in differentiated THP-1 macrophages. The induction of autophagy by NSC 18725 is the major mechanism for the killing of intracellular slow and fast-growing mycobacteria. Taken together, these observations support the identification of NSC 18725 as an antimycobacterial compound, which synergizes with INH, is active against non-replicative mycobacteria and induces autophagy in macrophages.
Synthesis of 1,3,5-Trisubstituted Pyrazoles and Hydrazones Using Fe3O4?CeO2 Nanocomposite as an Efficient Heterogeneous Nanocatalyst
Hassani, H.,Jahani, Z.
, p. 485 - 490 (2020)
Abstract: Pyrazoles and hydrazones, as two significant kinds of potentially bioactivecompounds, were produced with good to excellent yields by condensation ofβ-dicarbonyl compounds with hydrazines in aqueous media in the presence ofFe3O4?CeO2nanocomposite as an efficient heterogeneous nanocatalyst. The magneticnanocatalyst can readily be separated using an external magnet and reused atleast six times without significant loss in activity. The products werecharacterized by IR and 1H and13C NMR spectra.
Magnetic nanoparticle-supported glutathione: A conceptually sustainable organocatalyst
Polshettiwar, Vivek,Baruwati, Babita,Varma, Rajender S.
, p. 1837 - 1839 (2009)
A conceptually novel nanoparticle-supported and magnetically recoverable organocatalyst has been developed, which is readily prepared from inexpensive starting materials in a truly sustainable manner; which catalyzes the Paal-Knorr reaction with high yield in pure aqueous medium that avoids the use of toxic organic solvents, even in the workup step.
Interconversion of nicotine enantiomers during heating and implications for smoke from combustible cigarettes, heated tobacco products, and electronic cigarettes
Moldoveanu, Serban C.
, p. 667 - 677 (2022/02/02)
Physiological properties of (R)-nicotine have differences compared with (S)-nicotine, and the subject of (S)- and (R)-nicotine ratio in smoking or vaping related items is of considerable interest. A Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) method for the analysis of (S)- and (R)-nicotine has been developed and applied to samples of nicotine from different sources, nicotine pyrolyzates, several types of tobacco, smoke from combustible cigarettes, smoke from heated tobacco products, e-liquids, and particulate matter obtained from e-cigarettes aerosol. The separation was achieved on a Chiracel OJ-3 column, 250 × 4.6 mm with 3-μm particles using a nonaqueous mobile phase. The detection was performed using atmospheric pressure chemical ionization (APCI) in positive mode. The only transition measured for the analysis of nicotine was 163.1 → 84.0. The method has been summarily validated. For the analysis, the samples of tobacco and smoke from combustible cigarettes were subject to a cleanup procedure using solid phase extraction (SPE). It was demonstrated that nicotine upon heating above 450°C for several minutes starts decomposing, and some formation of (R)-enantiomer from a sample of 99% (S)-nicotine is observed. An analogous process takes place when a 99% (R)-nicotine is heated and forms low levels of (S)-nicotine. This interconversion has the effect of slightly increasing the content of (R)-nicotine in smoke compared with the level in tobacco for combustible cigarettes and for heated tobacco products. The (S)/(R) ratio of nicotine enantiomers in e-liquids was identical with the ratio for the particulate phase of aerosols generated by e-cigarette vaping.
Predicting the catalytic activity of azolium-based halogen bond donors: an experimentally-verified theoretical study
Bolotin, Dmitrii S.,Il'in, Mikhail V.,Novikov, Alexander S.,Suslonov, Vitalii V.,Sysoeva, Alexandra A.
, p. 7611 - 7620 (2021/09/22)
This report demonstrates the successful application of electrostatic surface potential distribution analysis for evaluating the relative catalytic activity of a series of azolium-based halogen bond donors. A strong correlation (R2> 0.97) was observed between the positive electrostatic potential of the σ-hole on the halogen atom and the Gibbs free energy of activation of the model reactions (i.e., halogen abstraction and carbonyl activation). The predictive ability of the applied approach was confirmed experimentally. It was also determined that the catalytic activity of azolium-based halogen bond donors was generally governed by the structure of the azolium cycle, whereas the substituents on the heterocycle had a limited impact on the activity. Ultimately, this study highlighted four of the most promising azolium halogen bond donors, which are expected to exhibit high catalytic activity.
