Showing papers on "Pyrazole published in 2017"

Review: biologically active pyrazole derivatives

Abstract: Nitrogen-containing heterocyclic compounds and their derivatives have historically been invaluable as a source of therapeutic agents. Pyrazole, which has two nitrogen atoms and aromatic character, provides diverse functionality and stereochemical complexity in a five-membered ring structure. In the past decade, studies have reported a growing body of data on different pyrazole derivatives and their innumerable physiological and pharmacological activities. In part, such studies attempted to reveal the wide range of drug-like properties of pyrazole derivatives along with their structure–activity relationships in order to create opportunities to harness the full potentials of these compounds. Here, we summarize strategies to synthesize pyrazole derivatives and demonstrate that this class of compounds can be targeted for the discovery of new drugs and can be readily prepared owing to recent advances in synthetic medicinal chemistry.

Palladium-Catalyzed Pyrazole-Directed sp3 C−H Bond Arylation for the Synthesis of β-Phenethylamines

Abstract: We have developed a method for palladium-catalyzed, pyrazole-directed sp3 C−H bond arylation by aryl iodides. The reaction employs a Pd(OAc)2 catalyst at 5–10 mol % loading and silver(I) oxide as a halide-removal agent, and it proceeds in acetic acid or acetic acid/hexafluoroisopropanol solvent. Ozonolysis of the pyrazole moiety affords pharmaceutically important β-phenethylamines.

Synthesis of novel inhibitors of α-amylase based on the thiazolidine-4-one skeleton containing a pyrazole moiety and their configurational studies

Abstract: Postprandial hyperglycemia can be controlled by delaying the absorption of glucose resulting from carbohydrate digestion α-Amylase is the initiator of the hydrolysis of polysaccharides, and therefore developing α-amylase inhibitors can lead to development of new treatments for metabolic disorders like diabetes mellitus In the present work, we set out to rationally develop α-amylase inhibitors based on the thiazolidine-4-one scaffold The structures of all these newly synthesized hybrids were confirmed by spectroscopic analysis (IR, 1H-NMR, MS) The appearance of two sets of signals for some protons in 1H NMR revealed the existence of a mixture of 2E,5Z (371–420%) and 2Z,5Z isomers (584–628%), which was further supported by DFT studies All the newly synthesized compounds have potential inhibitory properties as revealed through in vitro α-amylase inhibition activity Compound 5a at 100 μg mL−1 concentration showed a remarkable inhibition of 9004% In vitro α-amylase inhibition was further supported by docking studies of compound 5a against the active site of human pancreatic α-amylase (PDB ID: 2QV4) The docking studies revealed that the bonding interactions found between 5a and human pancreatic α-amylase are similar to those responsible for α-amylase inhibition by acarbose

Design, Synthesis, and Fungicidal Evaluation of Novel Pyrazole-furan and Pyrazole-pyrrole Carboxamide as Succinate Dehydrogenase Inhibitors

Abstract: The identification of novel succinate dehydrogenase (SDH) inhibitors represents one of the most attractive directions in the field of fungicide research and development. During our continuous efforts to pursue inhibitors belonging to this class, some structurally novel pyrazole-furan carboxamide and pyrazole-pyrrole carboxamide derivatives have been discovered via the introduction of scaffold hopping and bioisosterism to compound 1, a remarkably potent lead obtained by pharmacophore-based virtual screening. As a result of the evaluation against three destructive fungi, including Sclerotinia sclerotiorum, Rhizoctonia solani, and Pyricularia grisea, a majority of them displayed potent fungicidal activities. In particular, compounds 12I-i, 12III-f, and 12III-o exhibited excellent fungicidal activity against S. sclerotiorum and R. solani comparable to that of commercial SDHI thifluzamide and 1.

Morita-Baylis-Hillman (MBH) Reaction Derived Nitroallylic Alcohols, Acetates and Amines as Synthons in Organocatalysis and Heterocycle Synthesis.

Abstract: The Morita–Baylis–Hillman (MBH) reaction is one of the most useful and efficient protocols for constructing new carbon–carbon bonds between an activated olefin and electrophiles in the presence of a tertiary amine/phosphine. Herein, we present the use of MBH alcohols, which are obtained from the reaction of nitrostyrenes with aldehydes, as well as acetates and amines derived thereof in several organocatalytic transformations. Densely functionalised MBH adducts can also be used to synthesise substituted heteroaromatic compounds, such as furan, pyrrole, pyrazole and imidazole derivatives.

Design and Synthesis of Novel Pyrazole-Substituted Different Nitrogenous Heterocyclic Ring Systems as Potential Anti-Inflammatory Agents

Abstract: With the aim of developing novel anti-inflammatory scaffolds, a new series of pyrazole-substituted various nitrogenous heterocyclic ring systems at C-4 position were synthesized through different chemical reactions and validated by means of spectral and elemental data. The new obtained compounds were investigated for their anti-inflammatory activity using the carrageenan-induced paw edema standard technique and revealed that, compound 6b showed increased potency with % inhibition of edema 85.23 ± 1.92 and 85.78 ± 0.99, respectively, higher than the standard reference drugs indomethacin and celebrex (72.99% and 83.76%). Molecular modeling studies were initiated herein to validate the attained pharmacological data and provide understandable evidence for the observed anti-inflammatory behavior.

Copper(II)-Mediated Chelation-Assisted Regioselective N-Naphthylation of Indoles, Pyrazoles and Pyrrole through Dehydrogenative Cross-Coupling.

Abstract: A copper-mediated picolinamide directed regioselective cross-coupling of naphthylamines with azoles is developed via C–H functionalization and C–N bond formation. The reaction of indoles leads to the formation of chiral C–N cross-coupled products with functional group tolerance. These reaction conditions can also be extended to the cross-coupling of pyrazole and pyrrole scaffolds.

Design, synthesis, conformational and molecular docking study of some novel acyl hydrazone based molecular hybrids as antimalarial and antimicrobial agents

Abstract: Acyl hydrazones are an important class of heterocyclic compounds promising pharmacological characteristics. Malaria is a life-threatening mosquito-borne blood disease caused by a plasmodium parasite. In some places, malaria can be treated and controlled with early diagnosis. However, some countries lack the resources to do this effectively. The present work involves the design and synthesis of some novel acyl hydrazone based molecular hybrids of 1,4-dihydropyridine and pyrazole (5a–g). These molecular hybrids were synthesised by condensation of 1,4-dihydropyridin-4-yl-phenoxyacetohydrazides with differently substituted pyrazole carbaldehyde. The final compound (5) showed two conformations (the major, E, s-cis and the minor, E, s-trans) as revealed by NMR spectral data and further supported by the energy calculations (MOPAC2016 using PM7 method). All the synthesised compounds were screened for their in vitro antimalarial activities against chloroquine-sensitive malaria parasite Plasmodium falciparum (3D7) and antimicrobial activity against Gram positive bacteria i.e. Bacillus cereus, Gram negative bacteria i.e. Escherichia coli and antifungal activity against one fungus i.e. Aspergillus niger. All these compounds were found more potent than chloroquine and clotrimazole, the standard drugs. In vitro antiplasmodial IC50 value of the most potent compound 5d was found to be 4.40 nM which is even less than all the three reference drugs chloroquine (18.7 nM), pyrimethamine (11 nM) and artimisinin (6 nM). In silico binding study of compound 5d with plasmodial cysteine protease falcipain-2 indicated the inhibition of falcipain-2 as the probable reason for the antimalarial potency of compound 5d. All the compounds had shown good to excellent antimicrobial and antifungal activities.

A furazan-fused pyrazole N-oxide via unusual cyclization

Abstract: 6-Nitro-pyrazolo[3,4-c]furazanate 5-oxide, a new fused anion with high energy, was designed and synthesized via an unusual intramolecular cyclization reaction of 3 by using a mixture of 100% nitric acid and trifluoroacetic anhydride followed by KI reduction. The potassium (6) and nitrogen-rich energetic (9–16) salts were prepared, and fully characterized by IR and multinuclear NMR spectroscopy, elemental analysis, and single-crystal X-ray structuring, 6, 9 and 16. Hydroxylammonium salt (10) has excellent detonation performance but high sensitivity, while 13 and 16 have detonation velocities comparable to 1,3,5-trinitro-1,3,5-triazinane (RDX), which suggests they may have potential application as green primary or secondary explosives.

New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity.

Abstract: The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety (L1–L6) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6–31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds (L1–L6), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

Microwave-assisted one pot three-component synthesis of some novel pyrazole scaffolds as potent anticancer agents.

Abstract: Pyrazoles, thiazoles and 1,3,4-thiadiazoles have been reported to possess various pharmacological activities. An efficient and a novel approach for the synthesis of some novel pyrazole based-azoles are described via multi-component reaction under controlled microwave heating conditions. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, 1H NMR and mass spectral data. All the synthesized compounds were tested for in vitro activities against two antitumor cell lines, human lung cancer and human hepatocellular carcinoma compared with the employed standard antitumor drug (cisplatin). All the newly synthesized compounds were evaluated for their anticancer activity against human lung cancer and human hepatocellular carcinoma cell lines using MTT assay. The results obtained exploring the high potency of six of the tested compounds compared with cisplatin. Graphical abstract Microwave-assisted one pot three-component synthesis of some novel pyrazole scaffolds as potent anticancer agents

Cobalt-Catalyzed Annulation of Amides with Isocyanides via C(sp2)–H Activation

Abstract: A cobalt-catalyzed [4 + 1] cycloaddition of easily accessible amides with isocyanides for the efficient synthesis of 3-iminoisoindolinone derivatives in high yield under mild conditions via intramolecular C(sp2)–H activation and isocyanide insertion is reported. The annulation was found to be applicable to a broad range of substrates, including arylamides, heteroarylamides, and acrylamide derivatives. Strongly coordinating N-heterocyclic directing groups such as pyridine, pyrimidine, and even pyrazole were fully tolerated in this cobalt-catalyzed C–H activation reaction.

Synthesis, Anti‐Inflammatory Activity, and COX‐1/2 Inhibition Profile of Some Novel Non‐Acidic Polysubstituted Pyrazoles and Pyrano[2,3‐c]pyrazoles

Abstract: The synthesis and evaluation of the anti-inflammatory activity of some structure hybrids comprising basically the 5-hydroxy-3-methyl-1-phenyl-4-substituted-1H-pyrazole scaffold directly linked to a variety of heterocycles and functionalities, or annulated as pyrano[2,3-c]pyrazoles, is described. According to the in vivo results and a comprehensive structure-activity relationship study, five analogs (5, 10, 17, 19, and 27) displayed remarkable anti-inflammatory profiles showing distinctive % protection and ED50 values, especially 10 and 27 (ED50 35.7 and 38.7 μmol/kg, respectively) which were nearly equiactive to celecoxib (ED50 32.1 μmol/kg). Compounds 10, 17, and 27 exhibited distinctive COX-2 inhibition with a noticeable COX-2 selectivity (SI values 7.83, 6.87, and 7.16, respectively), close to that of celecoxib (SI 8.68). Additionally, 5, 10, 17, 19, and 27 proved to be gastrointestinal tract safe (0-20% ulceration) and non-toxic, being well tolerated by the experimental animals up to 250 mg/kg orally and 80 mg/kg parenterally. Collectively, the in vivo ED50 values for the most potent five derivatives agree with their in vitro COX-2 selectivity indices, suggesting their usefulness as selective anti-inflammatory COX-2 inhibitors. The bipyrazole 10 and the pyranopyrazole 27 could be considered as the most active members in this study, being nearly equiactive to celecoxib, besides their obvious selective COX-2 inhibition, high safety margin, and predicted pharmacokinetic (ADME-T) suitability for oral use.