Showing papers on "Pyrazole published in 1981"
TL;DR: In this article, condensation of o-phenylenediamines with carboxylic acids and reaction of bifunctional alkyl halides with bifunctionsal nucleophiles are described.
303 citations
99 citations
TL;DR: Results further substantiate the idea that the P-450-containing monooxygenase is responsible for the metabolism of dimethylnitrosamine in both the control and pyrazole induced microsomes.
76 citations
TL;DR: In this article, the spectra of pyrazole and imidazole were obtained using the magic angle spinning technique; both compounds show three separate signals corresponding to Cs structures (no proton exchange).
Abstract: 13 C N.m.r. spectra of solid samples of pyrazole and imidazole were obtained using the ‘magic angle’ spinning technique; both compounds show three separate signals corresponding to Cs structures (no proton exchange).
35 citations
TL;DR: Binuclear pyrazolato-bridged complexes were obtained in alkaline solution from (OC) 4 as discussed by the authors, I or II, and they were shown to be stable with respect to temperature.
35 citations
TL;DR: In this paper, Fischer and Kollmar have been extended to the MNDO SCF-MO method and used in an effort to ascertain the main factors which determine the greater basicity of imidazole and oxazole relative to pyrazole and isoxazole, respectively.
34 citations
TL;DR: None of the compounds showed significant inhibition of the rat passive cutaneous anaphylaxis (PCA) with the exception of the already known 5-aminoindazole (2).
Abstract: The synthesis and study of the oral antiallergic activity of a series of monopyrazole derivatives (2-14) considered as analogues of active bispyrazole 1 are described. None of the compounds showed significant inhibition of the rat passive cutaneous anaphylaxis (PCA), with the exception of the already known 5-aminoindazole (2). The activity of this compound, is however, lower than that of compound 1.
33 citations
TL;DR: Experimental dipole moments, molar Kerr constants and molar Cotton-Mouton constants at 298 K and 633 nm are reported for pyrrole, pyrazole, imidazole and their N-methyl derivatives as solutes in dioxan as mentioned in this paper.
Abstract: Experimental dipole moments, molar Kerr constants and molar Cotton-Mouton constants at 298 K and 633 nm are reported for pyrrole, pyrazole, imidazole and their N-methyl derivatives as solutes in dioxan. Analysis of the Kerr-effect data yields the effective polarizability anisotropies which are used to evaluate the molecular magnetic anisotropies from the Cotton-Mouton constants. The magnetic criterion of aromaticity is applied by estimating for each molecule the non-local contribution to the out-of-plane component of the magnetizability and the magnetic anisotropy. Electron delocalization in these molecules is significantly less than that exhibited by benzene: pyrrole and N-methylpyrrole, c. 70%; pyrazole and N-methylpyrazole, c. 65%; imidazole and N-methyl-imidazole, c. 60%. Approximately one-third of the observed magnetic anisotropy arises from localized contributions.
31 citations
TL;DR: The newly synthesized pyrano [2, 3-c] pyrazoles showed analgesic activity in mice when tested by two methods.
Abstract: Syntheses of pyrano [2, 3-c] pyrazoles by means of the reaction of 3-ethoxycarbonyl-5-hydroxy-1-methyl (or phenyl) pyrazole (Ia, b) and acetylenecarboxylates or ethyl acetoacetate were examined. The reactions of Ia, b with acetylenecarboxylates gave 3-ethoxycarbonyl-4-substituted-1-methyl (or phenyl) pyrano [2, 3-c] pyrazol-6 (1H)-ones (IIa-c) in 5.9-23.9% yields. The Pechmann-Duisberg reaction of Ia-c with ethyl acetoacetate gave 3-ethoxycarbonyl-4-methyl-1-substitutedpyrano [2, 3-c] pyrazol-6 (1H)-ones (VIIa-c) in 33.1-46.2% yields. Similar reactions of 5-hydroxy-3-methylcarbamoyl-1-phenyl (or m-chlorophenyl) pyrazoles (IXa, b) with ethyl acetoacetate gave 4-methyl-3-methylcarbamoyl-1-phenyl (or m-chlorophenyl) pyrano [2, 3-c] pyrazol-6 (1H)-ones (Xa, b) in 17.4-30% yields. The newly synthesized pyrano [2, 3-c] pyrazoles (Xa, Xb, XII) showed analgesic activity in mice when tested by two methods.
31 citations
Patent•
15 Sep 1981TL;DR: In this paper, N-arylbenzamide derivatives of formula (I) are defined as follows: Z is oxygen or sulfur, R 1,R 2, R 3 are hydrogen or a substituent, R 4 is an hetero-aryl 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, 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, thiadiazole, oxadiazole or pyridazine. These compounds can be used as herbicides.
31 citations
TL;DR: It is concluded that pyrazole undergoes a drastic pKa perturbation on binding to the catalytic zinc ion in the enzyme .
Abstract: 1. Kinetic and equilibrium data have been determined at different pH between 4 and 10 for binding of the inhibitor pyrazole to liver alcohol dehydrogenase and to the binary complexes formed between enzyme and NADH or NAD+. 2. Pyrazole binding to free enzyme requires the protonated form of an ionizing group with a pKa of 9.2, agreeing with the pKa value reported for the water molecule bound at the catalytic zinc ion of the enzyme subunit. The rate of association of the inhibitor to the enzyme . NAD+ complex exhibits a similar pKa-7.6-dependence attributable to ionization of zinc-bound water in the latter binary complex. These observations lend support to the idea that pyrazole combines to the catalytic zinc ion on complex formation with the enzyme, zinc-bound water most likely being displaced by the inhibitor. 3. The rate of dissociation of the inhibitor from the ternary enzyme . NAD+ . pyrazole complex is proportional to the hydrogen ion concentration over the examined pH range (4-8). This effect of pH, which is proposed to reflect ionization of the enzyme-bound inhibitor with a pKa value below 4 (indirectly estimated to 2.4), accounts for the exceptional stability of the ternary complex at neutral and alkaline pH. It is concluded that pyrazole, by analogy to water and alcohol ligands, undergoes a drastic pKa perturbation on binding to the catalytic zinc ion in the enzyme . NAD+ complex.
TL;DR: Ni(II) complexes of 5(3)-methylpyrazole-3(5)-carbohydrazide (MPCH) and its deprotonated anion (MPC) have been isolated and characterised in the solid state.
TL;DR: The crystal and molecular structures of the trans-nitrito compounds [Ni(py)4(ONO)2],2py, [Niγmpy,(ono)2] and [Ni[Ni(prz)4 (ONO2) 2] are reported in this article.
Abstract: The crystal and molecular structures of the compounds [Ni(py)4(ONO)2],2py, [Ni(γmpy),(ONO)2] and [Ni(prz)4(ONO)2] are reported. All three are trans nitrito complexes, the pyridine (py) compound containing two pyridine molecules of solvation. The aromatic rings in the first two complexes adopt 'paddle wheel' conformations with pitch angles varying between 40 and 70o. The nitrite ions are positioned so as to minimize repulsive interactions with the amines, and it seems likely that these groups bond through oxygen rather than nitrogen because this allows a lesser degree of interligand steric interference. The amine rings in [Ni(prz)4(ONO)2] are orthogonal to the plane containing the nickel and coordinated pyrazole nitrogen atoms; the nitrito groups are disordered between two inequivalent positions, each of which involves hydrogen bonding with the pyrazole NH groups. The nitrite infrared frequencies are similar to those observed for other nickel(II) nitrito complexes except that the antisymmetric NO stretching mode of one of the groups in the pyrazole complex is much lower in energy than expected, being in the range normally associated with a nitrogen-bonded or chelated nitrite group. It is suggested that this deviation may be caused by the hydrogen bonding in the complex. The electronic spectra of the compounds yield 10Dq values of 9100 and 8500 cm-1 for the nitrite ligands in [Ni(py)4(ONO)2] and Ni(prz)4(ONO)2], respectively, placing the nitrito group towards the weaker end of the spectro-chemical series.
Patent•
19 Mar 1981
TL;DR: In this paper, a pyrazole compound is added to a photographic sensitive silver halide material, and a coupler is stably bonded to the photographically useful substance, the substance is released at a desired speed under certain processing conditions, and stable preservability is provided.
Abstract: PURPOSE: To release a photographically useful substance from a photographic sensitive silver halide material at a desired speed under specified processing condtions and to enhance the shelf stability of the material by adding a specified pyrazole compound to the material. CONSTITUTION: To a photographic sensitive silver halide material is added a pyrazole compound represented by formulaI[where A is a group capable of being eliminated under photographic processing conditions; X is O, S or a group represented by formula II (where R 5 is H, alkyl, aryl, acyl or sulfone, and it may form a condensed ring together with R 1 ); R 1 is H, alkyl, aryl, acyl, sulfone or the like; R 2 is H, alkyl, aryl, alkoxy, amino, cyano or the like; each of R 3 and R 4 is H, alkyl or aryl; and PUG is a photographically useful substance bonding to C substituted at the 4-position of the pyrazole ring through a hetero atom], e.g. the compound of formula III or IV. A protective group or a coupler is stably bonded to the photographically useful substance, the substance is released at a desired speed under certain processing conditions, and stable preservability is provided. COPYRIGHT: (C)1982,JPO&Japio
Abstract: Ligand displacement by a pyrazole on Me2SAuCl afforded LnAUAuCl (n = 1 or 2, and L = 3,5-Me2pzH, 3(5)-Me-5(3)-PhpzH; n = 1, and L = pyrazole or 3,5-Me2-4-(p-tolylazo)pyrazole), while Ph3PAuCl, silv...
TL;DR: Severity of handling-induced convulsions was reduced in mice in comparison to the scores on an initial test administered 4 days earlier and daily injections of pyrazole prevented the reduction of convulsion in handled mice and exacerbated Convulsions in mice tested for the first time after injection.
Patent•
29 Jul 1981
TL;DR: A process for dyeing and printing cellulose-containing textile material, where the dye used is a compound of the general formula I ##STR1## where K is the radical of a coupling component of the pyridone, pyrazole or indole series, is described in this paper.
Abstract: A process for dyeing and printing cellulose-containing textile material, wherein the dye used is a compound of the general formula I ##STR1## where K is the radical of a coupling component of the pyridone, pyrazole or indole series, one of the radicals X, Y and Z is a carboxylic acid ester group of a total of 2 to 19 carbon atoms, a carboxamide group of a total of 1 to 19 carbon atoms, an unsubstituted or substituted sulfonic acid phenyl ester group or a sulfonamide group of a total of 6 to 18 carbon atoms, and the remaining substituents X, Y and Z are hydrogen, methyl, chlorine, bromine or nitro.
TL;DR: In this article, two pairs of isomeric compounds were isolated from the Cu(II)NCO−-pyrazole (pz) system and the IR spectra showed that the first pair represents the cyanato complexes Cu(NCO)2(pz), while the second includes the compounds Cu(pZ)2, containing 1-carbamoylpyrazolate anions as chelating ligands.
TL;DR: In this article, free-radical decomposition of diazonium salts catalyzed by titanous or titanous and ferrous salts in the presence of β-substituted α,β-unsaturated carbonyl compounds leads to 1,4-diaryl pyrazole derivatives.
TL;DR: In this article, the β-linked pyrazole gluconucleosides 6b, 12b, 13b, and 14b were obtained regio-and diastereoselectively from 2,3,4,6-tetra-O-benzyl-D-glucose hydrazone (5b) and acetylacetone, (ethoxymethylene)malondinitrile, and (aminomethylene)cyanoacetamide, respectively, in a onepot reaction after two ring closures.
TL;DR: In this paper, the preparation of C-N coupled tripyrazolyl VII, by two consecutive cine substitution reactions starting from 1,4-dinitropyrazole and using pyrazole as a nucleophile, is described.
TL;DR: In this paper, the reaction of 4-aminomethylene-Δ2-pyrazolin-5-ones with metal acetates new chelate complexes with a ligand-metal ratio of 2:1 are formed.
Abstract: In the reaction of 4-aminomethylene-Δ2-pyrazolin-5-ones with metal acetates new chelate complexes with a ligand-metal ratio of 2:1 are formed. For structural investigations15N-labeled compounds and azomethines of the pyrazole type are also prepared. The15N-,13C-, and1H-chemical shifts have been measured in CDCl3. Chemical shifts as well as coupling constantsnJ (13C−15N)n=1, 2;2
J (HC=15N);2
J (=CH−15N) are discussed with regard to the structure of metal complexes and azomethines. It has been shown that complex formation causes a considerable change of the π-electron structure within the merocyanin part.
TL;DR: In this article, new monomeric N -borylated pyrazole and imidazole derivatives have been synthesized and some of their characteristic features have been explored.
TL;DR: A dihydro derivative of a new ring system, pyrazolo[1′,2′-a]pyrido[2,1-c][l,2,4]triazine was also obtained as mentioned in this paper.
TL;DR: 3-(2,3:4,5,5-Di-O-isopropylidene-D-gulo-pentahydroxypentyl)pyrazole (13) was prepared in four steps (45% overall yield) from D-gulonolactone as discussed by the authors.
Abstract: 3-(2,3:4,5-Di-O-isopropylidene-D-gulo-pentahydroxypentyl)pyrazole (13) was prepared in four steps (45% overall yield) from D-gulonolactone (9) Treatment with 1-fluoro-2,4-dinitrobenzene and triethylamine followed by reaction with methanesulphonyl chloride in pyridine afforded 1-(2,4-dinitrophenyl)-3-(1-O-methylsulphonyl-2,3:4,5-di-O-isopropylidene-D-gulo-pentahydroxypentyl)pyrazole (15) which, on treatment with boron trichloride and subsequent methanolysis, followed by exposure to methanolic ammonia, yielded 3-(α-D-xylofuranosyl)pyrazole (5) Oxidation of the pyrazole (13) and subsequent hydride reduction afforded, stereoselectively, 3-(2,3:4,5-di-O-isopropylidene-D-ido-pentahydroxypentyl)pyrazole(18); treatment of this in the same manner as the pyrazole (13) yielded 3-(β-D-xylofuranosyl)pyrazole (7)The reactions of sodium benzoate in dimethylformamide with 1-methylsulphonyl-3-(1-O-methylsulphonyl-2,3:4,5-di-O-isopropylidene-D-gulo-pentahydroxypentyl)pyrazole (24) and with its D-ido-isomer (27) appear to involve a common fulvene-type intermediate (30)
TL;DR: The 13C incorporation data indicate that carbons 1, 2, 3, and 4, but not 5, of glutamate serve as the four-carbon donor for the carboxamide carbon, C-5,C-4, and C-3, respectively, of the pyrazole ring of pyrazofurin.
Abstract: Pyrazofurin is one of four naturally occurring C-nucleoside antibiotics; it is elaborated by Streptomyces candidus. The biosynthesis of the pyrazole ring of pyrazofurin has been studied by using 13C- and 14C-labeled acetate. Carbon-13 incorporation into pyrazofurin was observed by proton-decoupled 13C Fourier transform NMR spectroscopy. The incorporation of 14C from [1-14C]acetate was 0.7%. The enrichment of carbons 3, 4, and 5 of pyrazofurin from [2-13C]acetate by S. candidus confirms earlier findings that acetate is converted to glutamate by the combined action of the Krebs cycle and malic enzyme [Elstner, E. F., Suhadolnik, R. J., & Allerhand, A. (1973) J. Biol. Chem. 248, 5385]. Malic enzyme will give rise to [1,2-13C]acetate from [2-13C]acetate. The [1,2-13C]acetate is then converted to glutamate labeled with 13C in carbons 2--5. The 13C incorporation data indicate that carbons 1, 2, 3, and 4, but not 5, of glutamate serve as the four-carbon donor for the carboxamide carbon, C-5, C-4, and C-3, respectively, of the pyrazole ring of pyrazofurin.
TL;DR: The reaction of 3-bromo-4,5-dihydro-5-hydroperoxy with tertiary amines and sulfides produced amine oxides and sulfoxides in high yield with k 2's for amines as discussed by the authors.
TL;DR: The synthesis of some [1]benzopyrano[3,4b]pyrazine, -[3 4b]imidazole, - [4 3c]-imidaxine, and -[4 4b]-pyrazole analogues of cannabinoids is reported as discussed by the authors.