Showing papers on "Pyrazole published in 1982"
TL;DR: In this paper, the relative amounts of isomeric mixtures obtained with asymmetric azoles or with equimolar mixtures of azoles are compared with literature results on monoalkylation of azole.
183 citations
TL;DR: In this article, open-chain and cyclic sym-1,3-diones with N,N-dimethylformamide dimethyl acetal gave, generally in high yield, a series of sym-2-dimethylaminomethylene-1.3-Diones which reacted with phenylhydrazine and methylhydrazines to afford, generally, in satisfactory yield, 1,5-disubstituted 4-acylpyrazoles.
85 citations
TL;DR: Pyrazole derivatives with long alkyl chains bound in the 4 position are outstanding inhibitors, and this property is related to the topography of the hydrophobic substrate cleft.
Abstract: Pyrazole is a strong inhibitor of liver alcohol dehydrogenase in combination with oxidized coenzyme NAD+. We have studied three different complexes of the inhibitor with the enzyme by using crystallographic methods: (1) the binary complex with pyrazole to 3.2-A resolution, (2) the ternary ternary complex with NAD+-4-iodopyrazole to 2.9-A resolution. Crystals of the binary complex are isomorphous to the apoenzyme, and pyrazole binds to the active-site zinc atom in a way analogous to imidazole. Crystals of the two ternary complexes are isomorphous with the ternary alcohol dehydrogenase-NADH-dimethyl sulfoxide complex. One of the nitrogen atoms of the pyrazole ring is directly bound to the active-site zinc atom with a Zn-N bond distance of 2.1A. The other nitrogen atom is 2 A from the C4 atom of the nicotinamide ring of the coenzyme. The iodine atom in 4-iodopyrazole is located in the hydrophobic substrate cleft. The effect of substitutions on the pyrazole ring are discussed in relation to the structure of the active site and substrate pocket. Pyrazole derivatives with long alkyl chains bound in the 4 position are outstanding inhibitors, and this property is related to the topography of the hydrophobic substrate cleft. The conformation of the oxidized coenzyme in the ternary complexes is essentially the same as that of the reduced coenzyme NADH in the NADH-dimethyl sulfoxide complex.
79 citations
TL;DR: In this paper, the authors describe the reaction between U(C5Me5) 2cl2 and pyrazole (C3H4N2), or sodium pyrazolate 3 H 3 N 2 ), in THF.
Abstract: The title compounds have been prepared by.the reaction between U(C5Me5) 2cl2 and pyrazole (C3H4N2), or sodium pyrazolate 3 H 3 N 2 ), in THF. The new compounds are characterized by their infrared, pmr, visible near-IR, and mass spectra; and by single crystal X-ray diffraction (monochromatic MoK~ radiation). The molecular structure of U(C 5 Me 5 ) 2 cl2(C3H4N2) consists of discrete mononuclear units at positions of ~ (c 2 v) 4+ 5 symmetry. The U ion is coordinated by two n -pentamethylcyclopentadienide rings, two chloride ions, and one nitrogen atom from the neutral pyrazole ring, for a total coordination number of nine. Redbrown crystals from toluene conform to space group Cmcm with a= 13.697(4), 0 b = 11.496(2), c = 15.555(2) A, and four molecules per unit cell. For the 924 independent reflections with F2 > 3C1(F2), the final weighted and unweighted R factors are 3.48 and 2.45%, respec:tively. The 0 average U-C bond distance is 2.74(2) A, the U-N bond distance is 0 0 2.607(8) A, and the U-Cl distance is 2.696(2) A. This compound exhibits Curie-Weiss behavior with C = 1.46, 6 = 43.3 K, and ~eff (from the slope of 1/X vs T) = 3.24 ~B· The molecular structure of U(C 5 Me 5 ) 2 Cl(C 3 H 3 N 2 ) · f d · u4+ i di d b 5 h 1 1 cons1sts o 1screte ons coor nate y two n -pentamet y eye opentadienide rings, one chloride ion, and both nitrogen atoms from the pyrazolate anion, for a total coordination number of nine. Red-brown crystals from toluene conform to space group P2 1 /n with a= 8.737(1), 0 b = 18.068(1), c = 15.229(1) A, S = 92.38(1) 0 , and four molecules per unit cell. For the 2566 independent reflections with F2 > 3cr(F 2 ), the final weighted and unweighted R factors are 4.50 and 3.27%, 0 respectively. The average U-C bond disance is 2.73(3) A, the U-N . '
66 citations
TL;DR: In this paper, it was shown that N-substituted pyrazoles and imidazoles are better sigma donors toward MeHg(II) than pyridines.
39 citations
TL;DR: Low concentrations of pyrazole and 4-methylpyrazole should be used in studies on pathways of alcohol metabolism, and caution should be made in interpreting the actions of these compounds when used at high concentrations.
39 citations
TL;DR: The most active compound was 8-bromo-4-(diethylamino)-7-phenylpyrazolo[ 1,3-a]-1,3,5-triazine, which was 185 times more potent than theophylline as an inhibitor of PDE isolated from rabbit lung.
Abstract: A series of various pyrazolo[1,5-a]-1,3,5-triazines have been prepared and studied as inhibitors of cAMP phosphodiesterase isolated from bovine brain, bovine heart, and rabbit lung. A number of compounds were found to be superior to theophylline. 2-Ethyl-7-phenylpyrazolo[1,5-a]-1,3,5-triazine (35) was found to be 97 times more potent than theophylline as an inhibitor of bovine brain PDE. 8-Bromo-2,4-dimethyl-7-phenylpyrazolo[1,5-a]-1,3,5-triazine (52) showed alpha lung = 40 compared to alpha heart = 3.0. Thus, various substituents could increase or decrease the inhibition relative to the type and source of tissue from which the PDE was isolated. The most active compound was 8-bromo-4-(diethylamino)-7-phenylpyrazolo[1,3-a]-1,3,5-triazine (25), which was 185 times more potent than theophylline as an inhibitor of PDE isolated from rabbit lung. The stepwise synthesis via ring-closure procedures of requisite pyrazole intermediates, followed by electrophilic substitution in the pyrazole ring and/or nucleophilic substitution in the 1,3,5-triazine moiety, resulted in the various pyrazolo[1,5-a]1,3,5-triazines listed in Tables I and II. Structure-activity relationships are reviewed.
35 citations
TL;DR: Pyrazole, a potent inhibitor of alcohol dehydrogenase, was found to be a potent inducer of the activity of low Km dimethylnitrosamine demethylase (DMN-d) and pyrazole administration reduced arylhydrocarbon hydroxylase (AHH) activity.
33 citations
TL;DR: The chlorophosphazenes (NPCl2)3-6 and the phenylchlorophosphaspazenes gem-N3P3Ph4Cl2 and gem-n3p3Ph2Cl4 react with pyrazole, 3-methylpyrazole and 3,5-dimethyl pyrazoles to give (NPpz2) 3-6, [NP(Mepz)2]3]3...
Abstract: The chlorophosphazenes (NPCl2)3–6 and the phenylchlorophosphazenes gem-N3P3Ph4Cl2 and gem-N3P3Ph2Cl4 react with pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole to give (NPpz2)3–6, [NP(Mepz)2]3...
33 citations
29 citations
Patent•
01 Nov 1982TL;DR: Aryl pyrazole carboxylic acids and derivatives thereof, are xanthine oxidase inhibitors in vivo as discussed by the authors, and derivatives of such acids are used as xanthines.
Abstract: Aryl pyrazole carboxylic acids and derivatives thereof, are xanthine oxidase inhibitors in vivo.
TL;DR: In this paper, the presence of coenzyme and/or pyrazole or trifluoroethanol in the catalytic site of liver alcohol dehydrogenase was investigated.
TL;DR: The cyclopalladation occurs mainly at position 2 of the thiophene ring with a significant amount of the reaction at position 4 (ratio 3 : 1), contrary to lithiation which is reported to occur exclusively at position 1.
TL;DR: New pyrazolato derivatives of platinum(II) are isolated, (LL)Pt(pz)2, A, by reaction of PtCl2 with pyrazole and potassium hydroxide in methanol as discussed by the authors.
TL;DR: Biosynthetic studies implicate 1,3-diaminopropane as a precursor of the pyrazole moiety of β-pyrazol-1-yl- l -alanine as discussed by the authors.
TL;DR: In this paper, a convenient synthetic procedure is described for the synthesis of heteronuclear bimetallic complexes involving platinum and one other Group VIII metal with a single bridging pyrazolide group.
TL;DR: Diazotised pyrazolone (1) coupled with 3-chloropentane-2,4-dione and with ethyl 2-chloro-3-oxobutanoate to yield the pyrazolo[4,3-c]pyrazole derivatives (9a and b).
Abstract: Diazotised 4-amino-1,5-dimethyl-2-phenylpyrazol-3(2H)-one (1) coupled with active methylene nitriles to yield the corresponding cyanohydrazones (3a–c) and (11). Compounds (3a–c) afforded the 4-(3-aminopyrazol-4-ylidenehydrazino)-1,5-dimethyl-2-phenylpyrazol-3(2H)-ones (5a–c) on treatment with hydrazine hydrate, and cyclised to give the pyrazolo[4,3-c]pyridazines (7a–c) on treatment with ethanolic hydrochloric acid. The hydrazone (11) cyclised to give the pyridazin-6-one derivative (12) when boiled under reflux in ethanol. Diazotised pyrazolone (1) coupled with 3-chloropentane-2,4-dione and with ethyl 2-chloro-3-oxobutanoate to yield the pyrazolo[4,3-c]pyrazole derivatives (9a and b).
TL;DR: In this article, it was shown that 1-substituted-4-oxo-1,4-dihydro-6H-furo[3, 4-c] pyrazoles can be obtained from the carbonyl of the acetyl side chain towards hydrazines and not 2,4,5,6-tetrahydropyrazoles.
TL;DR: In this article, a cyclic transition state involving a B 2 N 3 ring system is suggested for this process in which the corresponding 2-dimethylamino-1,3,2-diazaboracyclopentane and B -tetraalkylpyrazaboles are the final products.
TL;DR: In this paper, low energy, low intensity shake-up satellites are observed in various energy regions of the XPS spectra of imidazole, pyrazole, thiazole, isothiazole and isooxazole.
TL;DR: In this article, MeHgL]N03 [L = 1-(2-pyridyl)pyrazole or di(1-pyrazolyl)methane] have L present as bidentate ligands to give irregular three coordination for Hg in the CHgN2Moieties.
Abstract: The complexes [MeHgL]N03[L = 1-(2-pyridyl)pyrazole or di(1-pyrazolyl)methane] have L present as bidentate ligands to give irregular three coordination for Hg in the CHgN2
moieties. The 1-(2-pyridyl)pyrazole complex has C(1)-Hg-N(1) 168(2)° and Hg-N(1) 2·21(3) A [N(1) is the pyrazole
donor atom], Hg-N(1')(pyridine ring) 2·61(5) A, and nitrate oxygen atoms 2·97(3), 3·07(3), and 3·14(3) Afrom Hg. The di(l-pyrazolyl)methane cation complex has
C(1)-Hg-N(1) 179(1), Hg-N(1) 2·16(1), Hg-N(1') 2·96(2) A, and nitrate oxygen atoms 2·88(2)and 2·90(2) A from Hg. In both structures the cations and anions are grouped to form [MeHgL]NO3 dimeric units via Hg...O interactions.
TL;DR: In this article, the structure of the furanones was established from their ir, 1H nmr and mass spectral data, and their reaction with hydrazine hydrate gave pyrazole derivatives.
TL;DR: Analogues of apomorphine (1) having the catechol moiety replaced by pyrrole (10, 18), pyrazole (12), isoxazole (13, 14), thiazole (16) and thiadiazole(20) ring systems have been synthesized from the key intermediate ketone 6 as mentioned in this paper.
Abstract: Analogues of apomorphine (1) having the catechol moiety replaced by pyrrole (10, 18), pyrazole (12), isoxazole (13, 14), thiazole (16) and thiadiazole (20) ring systems have been synthesized from the key intermediate ketone 6.
Patent•
21 May 1982
TL;DR: In this paper, N-arylbenzamide derivatives of formula (I) wherein Z is oxygen or sulfur, R 1, R 2, R 3 are hydrogen or a substituent, R 4 is an heteroaryl group linked to the nitrogen atom by a carbon atom, selected from possibly substituted isoxazole, isothiazole, pyrazole, imidazole and thiadiazole.
Abstract: N-arylbenzamide derivatives of formula (I) wherein Z is oxygen or sulfur, R1, R2, R3 are hydrogen or a substituent, R4 is an heteroaryl group linked to the nitrogen atom by a carbon atom, selected from possibly substituted isoxazole, isothiazole, pyrazole, imidazole, thiadiazole, oxadiazole or pyridazine. These compounds can be used as herbicides.
TL;DR: In this paper, the synthesis of Condensed Heterocycles from 5-Thioxo-3-pyrazoline-4-carboxylates is described. But it is not shown how to obtain 1, 3-Dithietanes.
Abstract: Syntheses with 1, 3-Dithietanes. XIII. Syntheses of Condensed Heterocycles from 5-Thioxo-3-pyrazoline-4-carboxylates
3-Amino-2-aroyl-5-thioxo-3-pyrazoline-4-carboxylates 1d–f react with bromoacetal-dehydediethylacetale, phenacyl bromides, ethyl bromopyruvate, ethyl α-chloro-acetate or chloro-acetylacetone to give ethyl dihydropyrazolo[5,1-b]thiazolecarboxylates 2, 4, 5 or 7. The derivatives of ethyl tetrahydropyrazolo [5,1-b]thiazolecarboxylates 8 or 9 are obtained by reaction of 1d–f with ethyl β-anilino-α-chloro-crotonate and oxalylchloride, respectively. The ethyl methylthiopyrazoline-carboxylate 10d and an excess of hydrazine hydrate afford pyrazolo[3,4-c]pyrazole 11. Compounds 10 react with phenyl isocyanate to give pyrazolo[3,4-d][1,3]oxazin-6-ones 13. The dithietanes 12 and cinnamohydrazide yield pyrazolo[1,2-a]pyrazolecarboxylates 15.
TL;DR: In this paper, a highly convergent entry to chiral heteroaromatic prostacyclin analogues is outlined, and a chiral Hetero-ARAM algorithm is presented.
TL;DR: In this article, a novel rearrangement was observed during the cyclization of N-(2-aminobenzoyl)-N-methylhydrazones of β-dicarbonyl compounds, leading to pyrazole derivatives 2, 4, and 5 depending on substituents and the reaction media.
TL;DR: In this paper, the pyridine with dimethyl acethylenedicarboxylate gives the pyrimidone (10), the pyrazole (6), and the 1 : 2-adduct (7).
Abstract: Reaction of 1,2,4-triazolo[4,3-a] pyridine (1) with dimethyl acethylenedicarboxylate gives the pyrimidone (10), the pyrazole (6), and the 1 : 2-adduct (7); reaction mechanisms, which include a [1,5] CN shift from nitrogen to carbon, are proposed, and two earlier structures for products of this reaction are corrected.