Perspective: the potential of pyrazole-based compounds in medicine

Fluoroalkyl-Substituted Diazomethanes and Their Application in a General Synthesis of Pyrazoles and Pyrazolines

A novel continuous-flow approach for the synthesis of fluoroalkyl-substituted diazomethanes has been developed. Utilizing a cheap, self-made microreactor fluoroalkyl-substituted amines were transformed into the corresponding diazomethanes using tert-butyl nitrite and acetic acid as catalyst. These diazomethanes were employed in [2+3] cycloaddition reactions with olefins and alkynes, yielding valuable pyrazolines and pyrazoles in good to excellent yields.

Coordination compounds of a hydrazone derivative with Co(iii), Ni(ii), Cu(ii) and Zn(ii): synthesis, characterization, reactivity assessment and biological evaluation

Increasing inhibitory effect of Zn-Hp2DAP < Hp2DAP < Co-Hp2DAP on ABC transporter MDR1 drug efflux pump.

Design and synthesis of pyridine-pyrazole-sulfonate derivatives as potential anti-HBV agents

Hepatitis B virus (HBV) is an infectious disease, which can cause acute and chronic infections.

[3 + 2] cycloaddition and subsequent oxidative dehydrogenation between alkenes and diazo compounds: a simple and direct approach to pyrazoles using TBAI/TBHP

Herein, an efficient [3 + 2] cycloaddition and oxidative dehydrogenation reaction of diazo compounds and alkenes was well developed using TBAI/TBHP, leading to pyrazoles with moderate to high yields.

Fluorescence quenching study of 2,6-bis(5-(4-methylphenyl)-1-H-pyrazol-3-yl)pyridine with metal ions

A novel bispyrazole derivative 2,6-bis(5-(4-methylphenyl)-1-H-pyrazol-3-yl)pyridine was synthesized and its structure was confirmed by (1)H NMR, FTIR, MS techniques and elemental analysis. The binding interactions of BMPP with Cd(2+), Co(2+), Pb(2+) and Cu(2+) ions were investigated in MeOH-H2O solution by fluorescence quenching technique at two temperatures (25 and 35°C). Their quenching constants KSV, binding constants K, binding sites n and thermodynamic parameters (ΔH, ΔG and ΔS) were determined. The results indicated that the metal ions quenched the intrinsic fluorescence of the bispyrazole by forming the bispyrazole-metal complexes and their quenching process was a static quenching mechanism. In addition, the process of interaction was spontaneous and mainly ΔS-driven.

Green protection of pyrazole, thermal isomerization and deprotection of tetrahydropyranylpyrazoles, and high-yield, one-pot synthesis of 3(5)-alkylpyrazoles

3(5)-Alkylpyrazoles are obtained in high yield from pyrazole by a one-pot procedure.

Metal-free synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles from 1,3-diyne-indole derivatives employing two successive hydroaminations

The uncatalyzed synthesis of 3,5-disubstituted 1H- and 1-aryl-1H-pyrazoles derived from 1,3-diyne indoles was successfully carried out in PEG 400. The scope and limitations of the reaction were studied.

I2-mediated oxidative C-N bond formation for metal-free one-pot synthesis of di-, tri-, and tetrasubstituted pyrazoles from α,β-unsaturated aldehydes/ketones and hydrazines

An I2-mediated metal-free oxidative C-N bond formation methodology has been established for the regioselective pyrazole synthesis. This practical and eco-friendly one-pot protocol requires no isolation of the less stable intermediates hydrazones and provides a facile access to a variety of di-, tri-, and tetrasubstituted (aryl, alkyl, and/or vinyl) pyrazoles from readily available α,β-unsaturated aldehydes/ketones and hydrazine salts.

Phosphinogold(I) dithiocarbamate complexes: effect of the nature of phosphine ligand on anticancer properties

The reactions of potassium salts of the dithiocarbamates L {where L = pyrazolyldithiocarbamate (L1), 3,5-dimethylpyrazolyldithiocarbamate (L2), or indazolyldithiocarbamate (L3)} with the gold precursors [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)], or [Au2Cl2(dpph)] lead to the new gold(I) complexes [AuL(PPh3)] (1-3), [Au2L2(dppe)] (4-6), [(Au2L2)(dppp)] (7-9), and [Au2(L)2(dpph)] (10-12) {where dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, and dpph = 1,6-bis(diphenylphosphino)hexane}. These gold compounds were characterized by a combination of NMR and infrared spectroscopy, microanalysis, and mass spectrometry; and in selected cases by single-crystal X-ray crystallography. Compounds 4-6, which have dppe ligands, are unstable in solution for prolonged periods, with 4 readily transforming to the Au18 cluster [Au18S8(dppe)6]Cl2 (4a) in dichloromethane. Compounds 1-3 and 7-12 are all active against human cervical epithelioid carcinoma (HeLa) cells, but the most active compounds are 10 and 11, with IC50 values of 0.51 μM and 0.14 μM, respectively. Compounds 10 and 11 are more selective toward HeLa cells than they are toward normal cells, with selectivities of 25.0 and 70.5, respectively. Further tests, utilizing the 60-cell-line Developmental Therapeutics Program at the National Cancer Institute (U.S.A.), showed 10 and 11 to be active against nine other types of cancers.

Cobalt complexes with pyrazole ligands as catalyst precursors for the peroxidative oxidation of cyclohexane: X-ray absorption spectroscopy studies and biological applications

[CoCl(μ-Cl)(Hpz(Ph))3]2 (1) and [CoCl2(Hpz(Ph))4] (2) were obtained by reaction of CoCl2 with HC(pz(Ph))3 and Hpz(Ph), respectively (Hpz(Ph)=3-phenylpyrazole). The compounds were isolated as air-stable solids and fully characterized by IR and far-IR spectroscopy, MS(ESI+/-), elemental analysis, cyclic voltammetry (CV), controlled potential electrolysis, and single-crystal X-ray diffraction. Electrochemical studies showed that 1 and 2 undergo single-electron irreversible Co(II)→Co(III) oxidations and Co(II)→Co(I) reductions at potentials measured by CV, which also allowed, in the case of dinuclear complex 1, the detection of electronic communication between the Co centers through the chloride bridging ligands. The electrochemical behavior of models of 1 and 2 were also investigated by density functional theory (DFT) methods, which indicated that the vertical oxidation of 1 and 2 (that before structural relaxation) affects mostly the chloride and pyrazolyl ligands, whereas adiabatic oxidation (that after the geometry relaxation) and reduction are mostly metal centered. Compounds 1 and 2 and, for comparative purposes, other related scorpionate and pyrazole cobalt complexes, exhibit catalytic activity for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions (room temperature, aqueous H2O2). In situ X-ray absorption spectroscopy studies indicated that the species derived from complexes 1 and 2 during the oxidation of cyclohexane (i.e., Ox-1 and Ox-2, respectively) are analogous and contain a Co(III) site. Complex 2 showed low in vitro cytotoxicity toward the HCT116 colorectal carcinoma and MCF7 breast adenocarcinoma cell lines.

Ferrocenylpyrazolyl palladium complexes as catalysts for the polymerisation of 1-heptene and 1-octene to highly branched polyolefins

(Ferrocenylpyrazolyl)palladium complexes that catalyse the polymerization of 1-heptene and 1-octene to highly branched polyolefins are reported.

Comprehensive review in current developments of imidazole-based medicinal chemistry

Imidazole ring is an important five-membered aromatic heterocycle widely present in natural products and synthetic molecules. The unique structural feature of imidazole ring with desirable electron-rich characteristic is beneficial for imidazole derivatives to readily bind with a variety of enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. The related research and developments of imidazole-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous imidazole-based compounds as clinical drugs have been extensively used in the clinic to treat various types of diseases with high therapeutic potency, which have shown the enormous development value. This work systematically gives a comprehensive review in current developments of imidazole-based compounds in the whole range of medicinal chemistry as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents, together with their potential applications in diagnostics and pathology. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic imidazole-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.

Assembling novel Cd(II) complexes with multidentate nitrogen donor ligands obtained in situ from the system: zerovalent copper, cadmium oxide, 1-hydroxymethyl-3,5-dimethylpyrazole and ammonium thiocyanate

A novel 3D coordination polymer [Cd2(L(1))(2)(SCN)(4)(MeOH)(2)](n) (1) and monomeric [Cd(NCS)(2)L(2)] (2) (L(1) = urotropine, L(2) = tris(1-(3,5-dimethylpyrazolylmethyl))amine) have been prepared in a one-pot synthesis using 1-hydroxymethyl-3,5-dimethylpyrazole as the starting ligand. The most prominent feature is the formation in situ of the organic compounds: urotropine and scorpionate-tripodal ligands.