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Showing papers on "Pyrazole published in 1974"


Journal ArticleDOI
TL;DR: The effects of substitution, lanthanide-shift reagents, solvent changes, and tautomerism were investigated in this article, where it was concluded that chemical shifts are of limited value to ascertain the positions of tautomers.
Abstract: The effects of substitution, lanthanide-shift reagents, solvent changes, and tautomerism were investigated on the ^(13)C chemical shifts of pyrrole, pyrazole, imidazole, s- and v-triazole, and tetrazole. It was concluded that ^(13)C chemical shifts are of limited value to ascertain the positions of tautomeric equilibrium for rapidly interconverting azole tautomers.

174 citations


Journal ArticleDOI
TL;DR: In this article, the deuterated and 15 N species of pyrazole were compared to crystal structures derived by X-ray and neutron diffraction showing the N-H bond in the crystal to be prolonged, but no significant differences seem to develop when bringing the molecule from its isolated state into the crystal with its strong hydrogen bonds.

71 citations


Journal ArticleDOI
TL;DR: In this article, the metal-catalyzed reaction of 1,1′-carbonyldipyrazoles with aldehydes or ketones to give 1, 1′-alkylidenedipydrugs and carbon dioxide, the latter being derived from the amide carbonyl group as shown by labeling experiments, is sensitive to electronic and to steric substituent effects.
Abstract: The metal-catalyzed reaction of 1,1′-carbonyldipyrazoles with aldehydes or ketones to give 1,1′-alkylidenedipyrazoles and carbon dioxide, the latter being derived from the amide carbonyl group as shown by labeling experiments, is sensitive to electronic and to steric substituent effects. Under comparable reaction conditions, 1,1′-carbonyldiimidazole, N-acetylpyrazole, and 1-pyrazole-N,N-diethylcarbonamide do not react with acetone while pyrazole-1-carbo(N′-phenylhydrazide) yields an anilino isocyanate dimer. These results are interpreted in terms of a mechanism that involves coordination of the metal ion at the 2,2′-nitrogen atoms of the pyrazole rings and heterolytic cleavage of an amide bond, followed by formation of a carbamate intermediate, decarboxylation, and metal ion exchange. Unsymmetrically substituted 1,1′-carbonyldipyrazoles were found to equilibrate thermally with their respective symmetrical analogs by an intermolecular exchange mechanism.

59 citations


Journal ArticleDOI
TL;DR: The effect of increasing the size of this side chain was studied and the inhbitory power was found to increase by a factor of two for each methyl group added in a normal side chain.

52 citations


Patent
12 Apr 1974
TL;DR: In this paper, 5-(2-Aminophenyl)pyrazole-3-carboxylic acids, useful as intermediates in the preparation of compounds useful as complement inhibitors, are prepared by reacting a 2-nitroacetophenone with a dialkyl oxalate in the presence of a strong base and in an inert solvent.
Abstract: 5-(2-Aminophenyl)pyrazole-3-carboxylic acids, useful as intermediates in the preparation of compounds useful as complement inhibitors, are prepared by reacting a 2-nitroacetophenone with a dialkyl oxalate in the presence of a strong base and in an inert solvent to give the corresponding alkyl 2-nitrobenzoylpyruvate, condensing the alkyl 2-nitrobenzoylpyruvate with hydrazine in an inert solvent to give an alkyl 5-(2-nitrophenyl)-pyrazole-3-carboxylate, reducing the nitro group catalytically to give the alkyl 5-(2-aminophenyl)pyrazole-3-carboxylate, and, if desired, hydrolyzing the ester to the free acid.

44 citations


Journal ArticleDOI
TL;DR: The utilization of [(1 R )1- 3 H]ethanol is slower than that of unlabeled ethanol, both in the absence and presence of 5 m m pyrazole, indicating isotope discrimination against tritium in both the alcohol dehydrogenase and non-alcohol dehydrogenases pathways.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of solvent and structure on the stability to light of a series of 1,3-diphenyl-2-pyrazolines has been studied.
Abstract: The effect of solvent and structure on the stability to light of a series of 1,3-diphenyl-2-pyrazolines has been studied. The major photochemical reaction observed is dehydrogenation to the corresponding 1,3-diphenylpyrazole unless the 5-position is disubstituted when, as in the case of 1,3,5,5-tetraphenyl-2- pyrazoline, photo-oxidation, with either retention or destruction of the heterocyclic ring, occurs. Evidence is presented that singlet oxygen may be involved in the photodehydrogenation of 1,3- diphenyl-2-pyrazoline. The observation that the presence of bulky groups in both the 4- and 5-positions improved both the fluorescence efficiency and the stability to light of the 1,3-diphenyl-2-pyrazoline molecule may have significance for the design of pyrazoline whitening agents. Dehydrogenation of the same series of pyrazolines with chloranil has been studied in order to determine the effect of substituents on the yield of pyrazole.

31 citations


Journal ArticleDOI
TL;DR: The following N-substituted azoles have been prepared: diphenylphosphine derivatives of pyrazole (1a), 3,5,dimethylpyrazole(1b), 3(5)-methylpyrazoles (isomers 2a and 2b), pyrrole (7), imidazol...
Abstract: The following N-substituted azoles have been prepared: (a) diphenylphosphine derivatives of pyrazole (1a), 3,5,-dimethylpyrazole (1b), 3(5)-methylpyrazole (isomers 2a and 2b), pyrrole (7), imidazol...

29 citations



Journal ArticleDOI
TL;DR: Pyrazole, a potent alcohol dehydrogenase inhibitor, given to mice in a single dose of 300 mg/kg increased the LD50 of orally administered ethylene glycol from 12 ml/ kg to 22 ml/kg, lending significant indirect support to the idea that a portion of the toxicity of ethylene Glycol is due to metabolism of the parent compound to more toxic products via alcohol dehydrogensase.

21 citations


Journal ArticleDOI
TL;DR: Rhodium complexes containing poly(pyrazolyl)borate ligands are described, and the fluxional nature of some of them considered in this article, where they are considered in terms of the number of poly(poly(poly)borates) in the complex.


Journal ArticleDOI
TL;DR: It is suggested that the use of pyrazole to assess ethanol metabolism and its sequelae in vivo may have limitations, and the data mandate caution in advocating the therapeutic use ofpyrazole or its derivatives in man.

Journal ArticleDOI
TL;DR: The previously unestablished structure of 2:1 adducts isolated from the reaction of Δ 1-azirines with s-tetrazines is now shown to be identical with the aziridine derivatives resulting from thermally promoted addition of pyrazoles to Δ 1 -azirine as mentioned in this paper.
Abstract: The previously unestablished structure of purported 2:1 adducts isolated from the reaction of Δ1-azirines with s-tetrazines is now shown to be identical with the aziridine derivatives resulting from thermally promoted addition of pyrazoles to Δ1-azirines.

Journal ArticleDOI
TL;DR: It is shown that pyrazole, a drug also used as an alcohol dehydrogenase inhibitor, is eliminated from the liver in a simple exponential process with a half-life of 3.45 hr, which agrees with its reported effects on ethanol metabolism in vivo.

Journal ArticleDOI
TL;DR: In this paper, it was shown that substituents in the pyrazole nucleus could sufficiently stabilize the tricyclic tetrazolo form over the bicyclic azido form.

Journal ArticleDOI
TL;DR: A series of volatile tricyclic derivatives, [ N2C3H3·MR2]2 (where M = Al or Ga; R = H, D, Me, Et, or Cl) has been synthesised by reacting pyrazole with the appropriate aluminium or gallium precursor as discussed by the authors.
Abstract: A series of volatile, tricyclic derivatives, [ N2C3H3·MR2]2(where M = Al or Ga; R = H, D, Me, Et, or Cl) has been synthesised by reacting pyrazole with the appropriate aluminium or gallium precursor. The resulting dimeric compounds have been characterised by elemental analyses, molecular weight determinations, and by 1H n.m.r. and mass spectroscopic measurements. In all cases a boat conformation for the six-membered ring of four nitrogen and two metal atoms is consistent with the experimental results.

Journal ArticleDOI
TL;DR: The structure of the title compound has been determined by single-crystal X-ray diffraction as mentioned in this paper, which was solved by Patterson and Fourier methods and refined by least-squares using 825 observed three-dimensional photographic data to R 0·073.
Abstract: The structure of the title compound has been determined by single-crystal X-ray diffraction. Crystals are rhombohedral with Z= 3 in a unit cell (based on hexagonal axes) of dimensions: a= 13·896(3), c= 31·986(6)A, γ= 120°, space group R. The structure was solved by Patterson and Fourier methods and refined by least-squares using 825 observed three-dimensional photographic data to R 0·073. The Y3+ ion is co-ordinated to six antipyrine molecules through the carbonyl oxygen and the molecular symmetry is , S6. The angle between the normals to the phenyl ring and the pyrazole ring is 58°.

Journal ArticleDOI
TL;DR: The crystal structure of the tautomeric title compound, C10H10N2, has been determined by direct methods from X-ray diffractometer data, and refined by least squares to R 0·060 (1614 reflections) as discussed by the authors.
Abstract: The crystal structure of the tautomeric title compound, C10H10N2, has been determined by direct methods from X-ray diffractometer data, and refined by least squares to R 0·060 (1614 reflections). Crystals are monoclinic, space group C2/c, a= 19·841(6), b= 12·000(2), c= 15·079(4)A, β= 92·58(2)°, Z= 16 (two independent molecules in the asymmetric unit).The geometry of the molecule is as expected; interaction between the pyrazole substituents in each case imparts a twist (21·35 and 18·21°) about the bond between the phenyl and pyrazole rings. The molecules are clustered in groups of four about the two-fold axes of the cell with the pyrazole nitrogen atoms directed toward, or close to, that axis. It has not been possible to locate the NH hydrogen atoms, which are presumed to exist as a loose association within each molecular grouping.

Journal ArticleDOI
Abstract: Acid-catalysed deuteriodeprotonation rates are recorded for isoxazole, isothiazole, and some methyl derivatives. The rates are extrapolated to give rate constants at 100° and pH 0 which are compared with those for other heteroaromatic ring systems to provide quantitative estimates of relative reactivity. Quantitative effects of methyl groups provide evidence for the relative degree of bond-fixation, and indicate that the aromaticity increases in the series isoxazole, pyrazole, isothiazole.

Journal ArticleDOI
TL;DR: In this paper, the NH+3 proton resonances of dodecylammonium propionate (DAP) in benzene, deuterochloroform or dichloromethane were analyzed.
Abstract: Addition of dimethyl sulphoxide (DMSO), imidazole, methanol, pyrazole, 2-pyridone, and tetra-butylammonium perchlorate, in the concentration range of 0.02 to 0.10 mol dm–3, to 0.50 mol dm–3 dodecylammonium propionate (DAP) in benzene, deuterochloroform or dichloromethane results in large shifts of the NH+3 proton resonances of DAP. Less pronounced shifts occur also for the protons immediately adjacent to the functional head groups of DAP (i.e. CH2NH+3 and CH2CO–2) while protons further removed are unaffected. Plots of the observed shift of the NH+3 of DAP against solubilizate concentration are linear and the shifts decrease in the order pyrazole ≳2-pyridone ≳imidazole > tetrabutylammonium perchlorate > DMSO > methanol in benzene, pyrazole∼2-pyridone∼imidazol > methanol in CDCl3, and pyrazole∼imidazole > methanol in CH2Cl2. The data are interpreted in terms of the interactions among the solubilizate, the solvent, and the surfactant. Solubilization sites as well as specific interactions in the reversed micellar pseudo-phase are discussed.


Journal ArticleDOI
TL;DR: 2,3-Dihydro-1-H-imidazo[1,2-b] pyrazole (IMPY) has been shown to be a useful agent for synchronizing monolayer and suspension cultures of HeLa for cell cycle studies.

Journal ArticleDOI
TL;DR: In this paper, derivatives of 1H-[1]Benzothieno[3,2−c]pyrazole were synthesized by a new method: 1.3-dipolar cycloaddition of substituted benzo[b]thiophene-1.1-dioxides with C-methyl-N-phenyl and C,N-diaryl-nitrilimines.
Abstract: Derivatives of 1H-[1]Benzothieno[3,2−c]pyrazole were synthesized by a new method: 1.3-dipolar cycloaddition of substituted benzo[b]thiophene-1.1-dioxides with C-methyl-N-phenyl and C,N-diaryl-nitrilimines, resp., gave the corresponding title compounds. The structure was proved by conversion to known compounds.

Journal ArticleDOI
TL;DR: In this article, the selectivity of these reactions is discussed with respect to the correlation previously noted between the rate of carbon-halogen bond fragmentation and the free-electron density distribution in the first formed radical-anion.
Abstract: Selective monodehalogenation of some dihalogeno-aromatic compounds has been achieved by controlled potential electrochemical reduction in dimethylformamide. 5-(4-Chlorophenyl)-3-(4-chlorostyryl)-1-phenyl-Δ2-pyrazoline and 3-(4-chlorophenyl)-5-(4-chlorostyryl)pyrazole were dehalogenated at the styryl 4-position, and the corresponding bromo-derivatives behaved in a similar manner. The selectivity of these reactions is discussed with respect to the correlation previously noted between the rate of carbon–halogen bond fragmentation and the free-electron density distribution in the first formed radical-anion. Only 1,5-diphenyl-3-styrylpyrazole could be isolated from reduction of 5-(4-chlorophenyl)-3-(4-chlorostyryl)-1-phenylpyrazole or the corresponding dibromoderivative. Reduction in the presence of 1% deuterium oxide resulted in no deuterium being incorporated into the product, in accord with the mechanism previously proposed for the reaction.

Journal ArticleDOI
TL;DR: In this article, vanadium(II) chloride with pyrazole and imidazole of the type VCl 2(pyrazole)4 and VCl2 (imidazoles)6 were prepared.

Journal ArticleDOI
TL;DR: In this article, the infrared and Raman spectra of organometallic compounds with a pyrazole ring, such as: where R3M = Me3Si (I), Et3Ge (II, III), n-Bu3Sn (IV) were examined.

Journal ArticleDOI
TL;DR: Using appropriate precursors, the two unnatural alkaloids 4(5)-[ N -isocaproylaminomethyl]imidazole and 3-aminoethylpyrazole were produced by Dolichothele sphaerica and represents an aberrant alkaloid formed by the introduction of a precursor of different heterocyclic entity.

Journal ArticleDOI
TL;DR: A number of new complexes between MSO4 (M = Mn, Co, Zn or Cd) and pyrazole (pz), 3,5-dimethylpyrazoles (DMP) and 3-methylpyrazole(3MePz) are reported in this article.

Patent
22 Aug 1974
TL;DR: In this article, a process for the preparation of 3,5-disubstituted pyrazoles is described, which involves: A. The reaction of a methyl ketone, such as acetophenone or an appropriate derivative thereof, with an appropriate aldehyde such as benzaldehyde in the presence of base to form a 1,3-dissubstitutive α,β-unsaturated ketone such as chalcone or a substituted chalecone, B. The acidification of the acidified reaction mixture with hydrazine, followed by treatment
Abstract: There is provided a process for the preparation of 3,5-disubstituted pyrazoles which involves: A. the reaction of a methyl ketone, such as acetophenone or an appropriate derivative thereof, with an appropriate aldehyde, such as benzaldehyde in the presence of base to form a 1,3-disubstituted α,β-unsaturated ketone, such as chalcone or a substituted chalcone, B. the acidification of said α,β-unsaturated ketone, followed by treatment of the acidified reaction mixture with hydrazine to form a disubstituted pyrazoline, and C. the catalytic dehydrogenation of said pyrazoline to yield the desired 3,5-disubstituted pyrazole.