Showing papers on "Pyrazole published in 1990"

2,6-bis(N-pyrazolyl)pyridines: the convenient synthesis of a family of planar tridentate N3 ligands that are terpyridine analogs

Abstract: A series of four symmetric 2,6-bis(N-pyrazolyl)pyridines were prepared in good yields by the reaction of an excess of potassium pyrazolate with 2,6-dihalopyridines in the solvent diglyme. Pyrazoles bearing bulky substituents react at the less sterically hindered nitrogen to give only a single regioisomer. The second bromide of 2,6-dibromopyridine is displaced rather sluggishly; thus, the monosubstituted 2-bromo-6-(N-pyrazolyl)pyridine can be readily isolated. Treatment of this intermediate with the potassium salt of a substituted pyrazole gives rise to three unsymmetrically substituted bis(N-pyrazolyl)pyridines

Pyrazole derivatives, and pharmaceutical composition comprising the same

Abstract: The present invention concerns pyrazole derivatives of formula: ##STR1## used for the treatment of inflammation, pain, thrombosis and rheumatism.

Estrogen synthetase inhibitors. 2. Comparison of the in vitro aromatase inhibitory activity for a variety of nitrogen heterocycles substituted with diarylmethane or diarylmethanol groups.

Abstract: The preparation and in vitro aromatase inhibitory activity of a wide variety of heterocyclic (4,4'-dichlorodiphenyl)methanes and -methanols are described. The choice of the two diaryl-bearing moieties as a vehicle for the evaluation of the heterocycles was made by the comparison of series of imidazole and pyridine-derived compounds with similar pyrimidine compounds reported previously. A structural model for the most active compounds is also presented. The activity of a related series of the compounds which contain two heterocyclic moieties was found to be consistent with the model. Many of the compounds evaluated, including representatives of the pyridine, imidazole, pyrimidine, pyrazole, triazole, thiazole, and isothiazole classes, exhibit EC50 potencies for aromatase inhibition at low nanomolar levels. These compounds are at least as potent as other nonsteroidal aromatase inhibitors reported previously.

Inhibitors of cholesterol biosynthesis. 2. 1,3,5-trisubstituted [2-(tetrahydro-4-hydroxy-2-oxopyran-6-yl)ethyl]pyrazoles.

Abstract: A series of 1,3,5-trisubstituted pyrazole mevalonolactones were prepared and evaluated for their ability to inhibit the enzyme HMG-CoA reductase in vitro. Since previous studies suggested that the 5-(4-fluorophenyl) and 3-(1-methylethyl) substituents afforded optimum potency, attention was focused on variations in position 1 of the pyrazole ring. Biological evaluation of analogues bearing a variety of 1-substituents suggested that, although most substituents were tolerated, none afforded an advantage over phenyl, which exhibited potency comparable to that of compactin in vitro.

Multiple Bonds between Main Group Elements and Transition Metals, LXXXIII. Trioxo(pyrazolyl)rhenium(VII) and [Hydridotris(1‐pyrazolyl)borato‐N,N′,N″]trioxorhenium(VII)

Abstract: The syntheses of the rhenium(VII) title compounds (pz)ReO3 (1) and [HB(pz)3]ReO3 (2) (pz = pyrazolyl) are described. An X-ray crystallographic study of 2 shows, that it has a monomeric structure.

Synthesis, spectroscopy, and electrochemistry of homo- and hetero-leptic ruthenium(II) complexes of new pyrazole-containing bidentate ligands

Abstract: Heteroleptic [Ru(bipy)2(L–L′)]2+ and homoleptic [Ru(L–L′)3]2+ complexes, where bipy = 2,2′-bipyridine and L–L′ is one of nine new pyrazole-containing bidentate ligands, have been prepared. Full assignments have been made for the 1H and 13C n.m.r. spectra of the complexes in CD3CN and the origins of the co-ordination-induced shifts are discussed. The absorption spectra and redox properties of the complexes are also discussed.

Synthesis and dioxygen reactivity of dinuclear copper-phenolate and copper-phenol complexes with pyrazole and pyridine donors

Abstract: New hybrid ligands containing pyrazole and pyridine have been prepared; and the reaction chemistry of their copper(I) derivatives has been studied. These dinucleating ligands provide three nitrogen donors to each metal ion, and a phenol or phenolate group to bridge between the metals. The reaction of the different dicopper(I) species with dioxygen follows patterns established previously for analogous pyridyl ligands; and peroxo and hydroperoxo adducts can be generated at low temperature

New tetraheterocyclic macrocycles containing triazole, pyrazole, pyridine, and/or furan subunits. Synthesis and cation-binding properties

Abstract: Ten new tetraheterocyclic macrocyclic ligands 2-4 in the porphyrinogen series were prepared. The rigid dipyrazole ditriazole macrocycles 3 extract Na + selectively, whereas the more flexible dipyrazole monotriazole monopyridine macrocycles 2 have the best transport selectivity for Na +

Synthesis, structure, and magnetism of binuclear copper(II) complexes of pyrazole ligands with nitrogen-containing chelating arms. First example of di-µ-pyrazolato-dicopper(II,II) complexes

Abstract: The preparation of new dinucleating pyrazole ligands, 3,5-bis[(2-diethylamino)ethylaminomethyl]pyrazole (HL1) and 3,5-bis[(3-dimethylamino)propylaminomethyl]pyrazole (HL2), has been accomplished. They afford binuclear copper(II) complexes of the formula [Cu2L2][BPh4]2(L = L1 or L2). The structure of [Cu2L12][BPh4]2 was determined by single-crystal X-ray analysis. It crystallizes in the triclinic space group P with a= 13.437(4), b= 15.192(5), c= 12.364(4)A, α= 116.38(3), β= 113.71(3), γ= 60.48(2)°, and Z= 1. The complex has a binuclear structure doubly bridged by the pyrazolate groups with the Cu ⋯ Cu separation 3.903(2)A. The configuration geometry of each copper is a square pyramid, whose basal plane is formed by the two pyrazolate nitrogens and the ‘articular’ nitrogens [Cu–N 1.906(3)–2.028(3)A] and the apical site by one of the ‘terminal’ nitrogens [Cu–N 2.496(5)A]. The other terminal nitrogen is free from co-ordination. Cryomagnetic investigations over the temperature range 100–300 K revealed a strong antiferromagnetic spin exchange in both complexes. The exchange integral (J) based on the Heisenberg model, was evaluated as – 214 cm–1 for [Cu2L12][BPh4]2 and –181 cm–1 for [Cu2L22][BPh4]2.

Synthesis, X-ray structure, and nuclear magnetic resonance (1H and 13C) studies of ruthenium(II) complexes containing pyrazolyl ligands

Abstract: The synthesis and n.m.r. spectra (1H and 13C) are reported for 24 p-cymeneruthenium complexes belonging to one of the following families: [Ru(MeC6H4Pri-p)(acac)X](3)–(9), [Ru(MeC6H4Pri-p)(acac)L]BF4(10)–(17), [Ru(MeC6H4Pri-p)ClL2]BF4(19)–(22), and [Ru(MeC6H4Pri-p)L3][BF4]2(23), [Ru(MeC6H4Pri-p)XL2]BF4(24), and [Ru(MeC6H4Pri-p)X2L](25), where X = Br, I, N3, pz, mpz, dmpz, or idz, and L = pyridine, PPh3, CNBut, P(OMe)3, Hpz (pyrazole), Hmpz (3-methylpyrazole), Hdmpz (3,5-dimethylpyrazole), and Hidz (indazole) for complexes (3)–(17), and only azoles (pyrazoles and indazole) for the remaining ones. Crystals of [Ru(MeC6H4Pri-p)(pz)(Hpz)2]BF4 are monoclinic, space group P21/c, with a= 9.882 6(2), b= 13.966 3(3), c= 31.690 2(15)A, β= 94.650(3)°, and Z= 8. The structure was determined by X-ray diffraction and refined to R= 0.045 (R′= 0.036). There are two crystallographic units, each having an intramolecular hydrogen bond between a pyrazole and a pyrazolate ring, and another between the other pyrazole ligand and the BF4 anion. The n.m.r. data (δ and J) of the azole complexes were carefully determined and are thoroughly discussed.

Chemistry of Pyrazoles Condensed to Heteroaromatic Five- and Six-Membered Rings

Abstract: Publisher Summary This chapter discusses the chemistry of pyrazoles condensed to heteroaromatic five- and six-membered ring structures, and the synthesis of pyrazoloazines and its related compound. The synthesis of pyrazoles condensed to five-membered rings is analyzed along with the synthetic routes to ring systems. There exist three systems where pyrazoles are condensed to five-membered rings with one heteroatom. For pyrrolopyrazoles, a fourth isomerer is also possible. When the pyrazole ring is fused to a heterocyclic system in which the heteroatom is tetravalent, several isomeric structures can be drawn. The chemistry of pyrazoles condensed to six-membered rings can best be understood by assuming that the system consists of a five-membered π-excessive heterocyclic ring that is fused to a six-membered π-deficient ring. Thus, electrophilic reagents are expected to attack either the pyrazole nitrogens or carbons. On the other hand, nucleophilic reagents are expected to attack the six-membered ring. Pyrazoles condensed to a five-membered ring with one heteroatom have a π-deficient pyrazole and an electron-rich, five-membered ring.

Electron spin resonance and pulse radiolysis studies on the reaction of hydroxyl radical and sulfate(1-) radical with five-membered heterocyclic compounds in aqueous solution

Abstract: The reactions of several five-membered oxygen and nitrogen heterocyclics with OH • and SO 4 •− radicals have been investigated in aqueous solution using in-situ radiolysis and photolysis ESR, and optical and conductometric pulse radiolysis techniques for detection. OH . reacts with (the saturated) oxazolidone, imidazolidinone, hydantoin, and oxazoline derivatives by hydrogen abstraction, preferentially from the carbon adjacent to the nitrogen atom. With (the unsaturated) oxazoles and isoxazoles, OH • reacts by addition to the carbon at the 5-position of the ring to produce allylic radicals. In basic and acidic solutions of oxazole a ring opening process follows the OH • addition. SO 4 •− reacts with oxazoles and isoxazoles by addition to C5 yielding SO 4 − adducts, whereas with imidazole, pyrazole, and pyrrole derivatives, SO 4 •− gives rise to neutral, conjugated radicals with the unpaired electron delocalized over the entire ring, which are derived from the parent compounds by one-electron oxidation followed by deprotonation

3,5-Diphenyl-1H-pyrazole derivatives. V--1-Acetyl-4-hydroxy-3,5-diphenyl-2-pyrazoline esters, 4-hydroxy-3,5-diphenyl-1H-pyrazole esters and N-substituted 4-(3-amino-2-hydroxy-1-propoxy)-1-methyl-3,5-diphenyl-1H-pyrazoles with antiarrhythmic, sedative and platelet antiaggregating activities.

Abstract: The synthesis of 1-acetyl-4-hydroxy-3,5-diphenyl-2-pyrazoline esters 3, 4-hydroxy-3,5-diphenyl-1H-pyrazole esters 5 and N-substituted 4-(3-amino-2-hydroxy-1-propoxy)-1-methyl-3,5-diphenyl-1H-pyrazoles 7, starting from 4-hydroxy-3,5-diphenyl-2-pyrazoline is described. Some of compounds 3, 5 and 7 showed a considerable antiarrhythmic and sedative activity in rats and mice, respectively, as well as a remarkable in vitro platelet antiaggregating activity. Moreover, the above compounds usually exhibited moderate antihypertensive, local anesthetic, analgesic and antiinflammatory activities in rats and mice.

Pyrazole derivatives, their production and use

Abstract: Novel pyrazole derivatives of the formula (I): wherein R is an alkyl group and D is an alkoxy group, a hydroxyl group, a halogen atom or an amino group which may be substituted, and salts thereof show strong antagonistic actions to angiotensin II, thus being useful as therapeutics for cardiovascular diseases.

Unusual behaviour of the thioether function of the ligand 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo) towards transition-metal salts. X-Ray structures of a green and a red modification of [Cu(bddo)Cl2]

Abstract: Co-ordination compounds of the new ligand 1,8-bis(3,5-dimethyl-1 -pyrazolyl)-3,6-dithiaoctane (bddo) with MCl2(M = Fe, Mn, Ni, Co, Zn, Cu, or Cd), MBr2(M = Mn, Co, Ni, or Zn), Cu(BF4)2, and CuX (X = BF4, NCS, Cl, Br, or I) are described. The general formula for the divalent metal is [M(bddo)X2] and for copper(I), [Cu2(bddo)X2]. With CuCl2 two modifications were obtained. The green modification of [Cu(bddo)Cl2] crystallises in space group P21/n with a= 9.019(2), b= 28.671(5), c= 8.431(2)A, β= 113.65(2)°, R= 0.055, and R′= 0.066 for 1 578 unique reflections [I > 2σ(I)]. The compound consists of Cu(bddo)Cl2 units. The copper atom is co-ordinated by two pyrazole nitrogens and two chloride atoms, in trans positions, in a distorted square-planar geometry. The red modification of [Cu(bddo)Cl2] crystallises in space group Pbcn with a= 9.397(4), b= 15.093(4), c= 15.142(4)A, Z= 4, R= 0.069, and R′= 0.089 for 864 unique reflections [I > σ(I)]. This compound consists of CuCl2 units linked together by ligand molecules, thus forming chains with distinct C2 symmetry perpendicular to the chain axis. The copper atom is co-ordinated in a distorted-tetrahedral geometry by two pyrazole nitrogens and two chloride atoms in cis positions. The sulphur atoms do not participate in the co-ordination, although molecular-mechanics calculations show that the ligand bddo is not sterically hindered to form tetradentate mononuclear chelates, i.e. with a MN2S2 chromophore. The structures of the other divalent metal halides were established as being very similar to that of the red modification. For [Cu(bddo)(BF4)2] semi-co-ordination of one or both tetrafluoroborates is indicated by the i.r. spectrum. Solid-state 13C n.m.r. spectra of the copper(I) compounds indicate that the S atoms show significant shifts, suggesting co-ordination. In the thiocyanate and iodide compounds both thioether sulphurs co-ordinate in an identical manner, whereas in the chloride and bromide compounds they co-ordinate in a different manner.

Structural investigation of pyrazole derivatives as corrosion inhibitors for delta steel in acid chloride solutions

Abstract: The effect of type and position of the substituted group of pyrazole derivatives for corrosion inhibition of Delta steel in acid chloride solutions has been investigated. It was found that increase of inhibitor concentration decreased both the corrosion rate,Rcorr, and the corrosion current,icorr, and shifted the corrosion potential,Ecorr, to more positive values, i.e. the predominant action was as an anodic inhibitor. The results showed that the adsorption isotherm is S-shaped. The inhibition efficiency of the different substituted pyrazole derivatives follows the order: methyl

Pyrazole‐Organoboranes, VI. Monomeric and Dimeric 9‐Pyrazolyl‐9‐borabicyclo[3.3.1]nonanes

Abstract: Bis(9H-9-borabicyclo[3.3.1]nonane) (9H-9-BBN)2 reacts with pyrazole (Pz) and its 4-bromo, 3-methyl, 3-phenyl, 3,5-dimethyl, 3-methyl-5-phenyl, 3,5-diphenyl, 3,5-di-ert-butyl, 3,5-diadamantyl, 3,5-di-tert-butyl-4-methyl, and 3,5-di-tert-butyl-4-ethyl derivatives [brPz, mPz, pPz, m2Pz, mpPz, p2Pz, (tb)2Pz, (ad)2Pz, (tb)2mPz, and (tb)2mPz, and (tb)2ePz, respectively] to give the 9-pyrazolyl-9-borabicyclo[3.3.1]nonanes with the dimeric structure (1)2–(3)2 (X-ray, NMR, and MS analysis), and 4–11 with monomeric structures (X-ray, NMR, MS).

Pyrazole chemistry. Part 4. Directed lithiation of 4-bromo-1-phenyl-sulphonylpyrazole: a convenient approach to vicinally disubstituted pyrazoles

Abstract: 4-Bromo-1 -phenylsulphonylpyrazole (10), obtained from 4-bromopyrazole (5) and benzenesulphonyl chloride, can be metallated regioselectively by phenyl-lithium to give the 5-lithio derivative (15) which upon quenching with appropriate electrophiles leads to the 4-bromo-1 -phenylsulphonyl-5-substituted pyrazoles (16)–(23), (25), and (26). Compounds (22), (23), and (25) were found to undergo isomerisation to afford the thermodynamically more stable 4-bromo-1 -phenylsulphonyl-3-substituted pyrazoles (11), (24), and (13) under the reaction conditions applied. The phenylsulphonyl protecting group then can be removed readily under alkaline conditions to yield the corresponding 4-, bromo-3(5)-substituted 1H-pyrazoles (6), (9), (28), (29), and (30).

Reactions with cyanothioacetamide derivatives: Synthesis of several new pyridine and annelated pyridine derivatives

Abstract: Several new pyridine, pyridinethione, pyrazole[3,4-b]-pyridine, pyrido [1,2-a]-1,3-thiazine and pyrido[1,2-a]pyridine thione derivatives have be synthesised via the reactions of 2-methyl-3-ethoxycarbonyl-4-phenyl-5-cyano-1,4,5,6-tetrahydro-pyridine-6-one 2 with different reagents. The structures of the newly synthesised derivatives were established on the basis of elemental analyses and spectal data studies.

Electrogenerated chemiluminescence. 52. Binuclear iridium(I) complexes

Abstract: The electrochemistry and electrogenerated chemiluminescence of [Ir(COD)(μ-L)] 2 , where COD is 1,5-cyclooctadiene and L is the anion of pyrazole and substituted derivatives 3-methylpyrazole and 3,5-dimethylpyrazole were studied in tetrahydrofuran 0.3 M tetra-n-butylammonium hexafluorophosphate