Showing papers on "Pyrazole published in 1992"

New ultraviolet stabilizers: 3- and 5-(2'-hydroxyphenyl)pyrazoles

Abstract: A new class of ultraviolet stabilizers, the C-(2'-hydroxyphenyl)pyrazoles, is described. The combined use of X-ray crystallography [3(5)-(2'-hydroxyphenyl)pyrazole (5), 1-methyl-3-(2'hydroxyphenyl)pyrazole (7), and 1-methyl-5-(2'-hydroxyphenyl)pyrazole (8)], NMR ( 1 H and 13 C), and UV spectroscopies allows the determination of the major tautomers, the coplanarity of both rings if present, and the existence of hydrogen bonds. Compounds 5 and 7, in which there is an intramolecular hydrogen bond (IMHB), do not fluoresce in cyclohexane. Solvent and temperature experiments prove that for these compounds in cyclohexane proton transfer took place in the excited singlet state but not in the tripler state (phosphorescence) and that the latter one is of higher than the former

Asymmetrische Katalysen, 77[1] Neue optisch aktive Pyrazolderivate für die enantioselektive Katalyse

Abstract: Asymmetric Catalysis, 77[1]. – New Optically Active Pyrazole Derivatives for Enantioselective Catalysis Starting from the amines 3–6 and the dipyrazolopyrazinedione 2, the optically active (pyrazolylmethyl)amines 11–14 have been synthesized. Furthermore, the preparation of the (+)-camphor-derived optically active pyrazole 17 is described. Pyrazoles 11–13 and 17 are introduced as chiral building blocks into the 2-(1-pyrazolyl)pyridines 30–33. The optically active compounds 23–25 are formed from 2-[3(5)-pyrazolyl]pyridine and 2,6-bis[3(5-)pyrazolyl]pyridine, respectively, and (+)-3-(bromomethyl)pinane. The pyrazole derivatives 27–29 contain (+)-(1-phenylethyl)hydrazine as the optically active component.

Pyrazole-related nucleosides. Synthesis and antiviral/antitumor activity of some substituted pyrazole and pyrazolo[4,3-d]-1,2,3-triazin-4-one nucleosides

Abstract: Several pyrazole and pyrazolo[4,3-d]-1,2,3-triazin-4-one ribonucleosides were prepared and tested for antiviral/antitumor activities. Appropriate heterocyclic bases were prepared by standard methodologies. Glycosylation of pyrazoles 6a-e,g,i and of pyrazolo[4,3-d]-1,2,3-triazin-4-ones 12f-1 mediated by silylation with hexamethyldisilazane, with 1-beta-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose, gave in good yields the corresponding glycosides 7a-e,g, 8g,i, 13f,h,k, and 14f, but could not be applied to compounds 12g,i,j,l. To overcome this occurrence, a different strategy involving the preparation, diazotization, and in situ cyclization of opportune pyrazole glycosides 9 and 10 was required. Moreover derivatives having the general formula 5 were considered not only as synthetic intermediates in the synthesis of 3 but also as carbon bioisosteres of ribavirin 4. All compounds were evaluated in vitro for cytostatic and antiviral activity. The pyrazolo[4,3-d]-1,2,3-triazin-4-one nucleosides that resulted were substantially devoid of any activity; only 15h,k showed a moderate cytostatic activity against T-cells. However, pyrazole nucleosides 9b,c,e were potent and selective cytotoxic agents against T-lymphocytes, whereas 9e showed a selective, although not very potent, activity against coxsackie B1.

Hair dye containing aminopyrazole derivatives as well as pyrazole derivatives

Abstract: The composition for oxidative dyeing of hair contains at least one coupler and 0.010 to 3.0 percent by weight of at least one developer selected from the group consisting of aminopyrazole derivatives of the formula (I): ##STR1## wherein R is selected from the group consisting of hydrogen and alkyl groups having one to four carbon atoms; n=2 or 3; and physiologically tolerated, water-soluble salts thereof. The developer and coupler substances are present in the composition in a total amount of from 0.1 to 5.0 percent. New pyrazole derivative compounds are also part of the invention.

Pyrazole carboxanilide fungicides

Abstract: Novel N-[2-(cyclic alkyl)phenyl]pyrazole-4-carboxamides useful as fungicides, methods of using said compounds, and fungicidal compositions containing them.

Mesogenic behaviour in some pyrazole and isoxazole derivatives

Abstract: Several aromatic β-diketones with a different number of alkyloxy groups in the aromatic rings and their derived pyrazoles, isoxazoles and thallium (I) complexes have been synthesized. The potential mesomorphic properties of these compounds have been investigated by optical microscopy, DSC and X-ray diffraction. The pyrazoles and isoxazoles with one chain in each aromatic ring are mesogenic, showing smectic A and smectic C mesophases, whereas the pyrazoles and isoxazoles with two chains per ring and the β-diketones and thallium complexes are not. The mesogenic potentiality is shown to be related to the molecular linearity and to the number of alkyloxy groups. To the best of our knowledge, this is the first time liquid crystal properties have been described for pyrazole and isoxazole derivatives.

Effect of pyrazole, cobalt and phenobarbital on mouse liver cytochrome P-450 2a-4/5 (Cyp2a-4/5) expression.

Abstract: Pyrazole, cobalt and phenobarbital increase the activity of coumarin 7-hydroxylase (COH) in mouse liver. To study the mechanism of this increase, we measured the expression of the cytochrome P-450 2a-4/5 (Cyp2a-4/5) complex, which mediates testosterone 15 alpha-hydroxylase and COH activities, as a function of dose and time after the treatment of C57BL/6 (B6) and DBA/2 (D2) male mice with the inducers. COH activity and Cyp2a-4/5 steady-state mRNA levels were increased in both strains in response to the inducers. No marked effect occurred with testosterone 15 alpha-hydroxylase or activities associated with Cyp1a-1 or Cyp2e-1. A 2-7-fold increase in response to the inducers was seen in the amount of P-450Coh (cytochrome P-450 isoenzyme catalysing coumarin 7-hydroxylation) protein in Western immunoblots. PCR amplification of a 1 kb region in Cyp2a-4/5-mRNA-derived cDNA, followed by cutting at the diagnostic PstI site, showed that most of the steady-state mRNA consisted of Cyp2a-5, which is also the form most affected by pyrazole. Nuclear run-off analysis revealed no increase in the transcription rate of Cyp2a-4/5 after pyrazole or cobalt treatment, whereas a 2-3-fold increase occurred after phenobarbital pretreatment in B6 mice. Together with previous reports [Aida & Negishi (1991) Biochemistry 30, 8041-8045], the current data suggest that both pyrazole and cobalt increase COH catalytic activity by affecting Cyp2a-5 by post-transcriptional mechanisms in mice.

Pyrazole carboxanilide fungicides and use

Abstract: Novel N-[2-(cyclic alkyl)phenyl]pyrazole-4-carboxamides useful as fungicides, methods of using said compounds, and fungicidal compositions containing them.

Condensed pyrazole derivatives with interleukin-1 and tumour necrosis factor inhibitory activity

Abstract: 1. A compound of the formula : wherein R¹ is aryl which may have suitable substituent(s) or heterocyclic group which may have suitable substituent(s), R² is aryl which may have suitable substituent(s) or heterocyclic group which may have suitable substituent(s), and Y is a bivalent radical selected from (in which ---- means single bond or double bond), each of which may have suitable substituent(s), and pharmaceutically acceptable salts thereof, processes for their preparation and pharmaceutical compositions comprising them.

Eight-co-ordination in manganese(II) and iron(II) complexes with a pyrazole-functionalised tetraazamacrocycle

Abstract: The potentially octadentate ligand 1,4,7,10-tetrakis(pyrazol-1-ylmethyl)-1,4,7,10-tetraazacyclododecane (L) gives with manganese(II) the complex [MnL][PF6]2·(CH3)2CO and with iron(II) species of formula [FeLxL'1–x][PF6]2·solvent where the ligand L' originates from L by substitution of an ethoxy group for a pyrazolyl group in one of the pendant arms of the macrocycle. The crystal structure of [MnL][PF6]2·(CH3)2CO has been determined by X-ray diffraction: orthorhombic, space group Pcab, with a= 15.801(6), b= 17.973(4), c= 26.793(3)A and Z= 8. The manganese(II) atom is co-ordinated by the eight nitrogen atoms of the L ligand. X-Ray analyses on the isomorphous crystals of the iron(II) species have shown that these contain both eight- and seven-co-ordinate iron(II) in complex cations respectively formed by the L and L' ligands.

Facile synthetic methods for 3- and 5-trifluoromethyl-4-trifluoroacetyl-pyrazoles and their conversion into pyrazole-4-carboxylic acids

Abstract: 3- And 5-trifluoromethyl-4-trifluoroacetylpyrazoles (4 and 5) were easily synthesized in excellent yields by reaction of β,β-bis(trifluoroacetyl) vinyl ethers 1, sulfides 2, and -amines 3 with hydrazines. Hydrolysis of these compounds (4 and 5) with aqueous potassium hydroxide gave the corresponding pyrazole-4-carboxylic acids (6 and 7) in high yields

Structure-activity relationships associated with 3,4,5-triphenyl-1H-pyrazole-1-nonanoic acid, a nonprostanoid prostacyclin mimetic.

Abstract: A series of phenylated pyrazoloalkanoic acid derivatives were synthesized and evaluated as inhibitors of ADP-induced human platelet aggregation. 3,4,5-Triphenyl-1H-pyrazole-1-nonanoic acid (8d), with an IC50 of 0.4 microM, was the most potent inhibitor identified in this study. Biochemical studies determined that 8d increased intraplatelet cAMP accumulation and stimulated platelet membrane-bound adenylate cyclase in a concentration-dependent fashion. Displacement of [3H]iloprost by 8d from platelet membranes indicated that the platelet prostacyclin (PGI2) receptor is the locus of biological action. Structure-activity studies demonstrated that the minimum structural requirements for binding to the platelet PGI2 receptor and inhibition of ADP-induced platelet aggregation within this series are a vicinally diphenylated pyrazole substituted with an omega-alkanoic acid side chain eight or nine atoms long. Potency depended upon both side-chain length and its topological relationship with the two phenyl rings.

Reaction of pyrazole addition to quinones

Abstract: The reactions of pyrazole, 4-nitropyrazole, 3,5-dimethylpyrazole, and 4-chloro-3,5-dimethylpyrazole with 1,4-benzoquinone in dioxane have been analyzed. Mono- and 2,3-bis-adducts were obtained and only in the case of pyrazole was a 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene formed. Further oxidation of the mono- and bis-adducts with 2,3-dichloro-5,6-dicyano-1,4-henzoquinone (DDQ) afforded the quinones, which in turn added 1 mol of azole (pyrazole and imidazole) to yield tetrapyrazolylquinols

Quantum mechanical calculations of amino pyrazole derivatives as corrosion inhibitors for zinc, copper and α-brass in acid chloride solution

Abstract: Quantum mechanical calculations have been applied to a series of pyrazole derivatives used as corrosion inhibitors for zinc, copper and α-brass in order to assess quantum chemistry as a means of evaluating effectiveness of corrosion inhibitors. The corresponding structures have been optimized and the energies and coefficients of their molecular orbitals (HOMO and LUMO) have been computed using the semi-empirical method, MNDO. The theoretical results are then compared with experimental data.

Condensed heterotricycles: synthesis of pyrazolo[3,4-c]qumoline derivatives

Abstract: Pyrazol[3,4-c]quinoline 4a is obtained from 4-(2-riitrophenyl)pyrazole-3-carboxylate (3a) by reduction followed by thermal cyclization. 4a undergoes aminoalkylation uniquely at N(3) to form 4b-d, as shown by I3 C NMR. Pyrazoles 3a and 3c are methylated at N(2) to 6a and 6b respectively which are re-ductively cyclized to pyrazoloquinolones 7a and 7b. The later are transformed into amino derivatives 8b-d and 8g,h via chloro compounds 8a and 8f. The.amino alkoxypyrazoloquinoline (8e) is obtained from 8a or the lactam 7a. Cyclic hydroxamic acids 7c and 7d are prepared from the nitropyrazoles 6a and 6b by using NaBH 4 and Pd - C. A second synthesis of die pyrazolo[3,4-c]quinoline ring system consists of heating mercaptoacid (8) with methyl or phenyl hydrazine when 10a or 10b is obtained. Attempts to convert the pyrazole carboxylate 13a into an isomeric pyrazoloisoquinoline system 12 via the isocyan-ate 13d resulted only in the formation of bis-urea 14.

A manganese(III) complex of 3,5-bis((salicylideneamino)methyl)pyrazole: Synthesis, structure, and properties

Abstract: 3,5-Bis((salicylideneamino)methyl)pyrazole forms a manganese(III) complex of the formula Mn 4 (L) 2 (CH 3 O) 4 (CH 3 -OH) 8 (ClO 4 ) 2 that crystallizes in the triclinic crystal system, space group P1.

Studies of formal [1,5]-sigmatropic thermal rearrangements of dimethyl 3-alkyl-3-methyl-3H-pyrazole-4,5-dicarboxylates and dimethyl 4-alkyl-5-methyl-4H-pyrazole-3,4-dicarboxylates

Abstract: Studies of the thermal rearrangements of 3H-pyrazoles, 10a-e, in benzene/toluene, chloroform, and methanol solvents are described. The mechanism for rearrangement appears to be two-step, involving discrete ion-pair intermediates. Large rate enhancements for these rearrangements in methanol and canion trapping by methanol are consistent with the proposed mechanism. Observed rate constants for the rearrangements of 3H-pyrazoles 10c, 10d, and 10e in benzene-d 6 were determined. Insight into the sense of rearrangement by an ion-pair mechanism is also provided by analysis of the 1 H NMR spectra of the product mixtures

The uses of 4-phenyl-3-thiosemicarbazide in heterocyclic synthesis: novel synthesis of thiazole, pyrazole and 1,3,4-thiadiazine derivatives

Abstract: 4-Phenyl-3-thiosemicarbazide derivatives 1a-c react with phenacylbromide, 3-bromoacetylcoumarin and monochloroacetic acid to afford thiazole derivatives 3a-c, 8a-c and 12a-c respectively. Reaction of 1a with ethyl acetoacetate afford the condensated product 17. Reaction of 3a-c and 8a-c with aromatic diazonium salts afford the 5-arylazothiazole derivatives 5a-f and 9a-f respectively. Most of the synthesized products show high fungicidal and bactericidal activities.

Pyrazole, an alcohol dehydrogenase inhibitor, has dual effects on N-methyl-D-aspartate receptors of hippocampal pyramidal cells: agonist and noncompetitive antagonist.

Abstract: Electrophysiological and biochemical studies demonstrated that pyrazole, an inhibitor of alcohol dehydrogenase and a proposed therapeutic agent for treatment of alcoholic intoxication, activated and blocked the N-methyl-D-aspartate (NMDA) receptor and did not interact significantly with the end-plate nicotinic acetylcholine receptor (AChR). Pyrazole, at concentrations as low as 0.5 microM, applied to outside-out patches excised from the membrane of cultured rat hippocampal neurons, elicited single-channel currents of 48 pS which were blocked by DL-2-amino-5-phosphorovaleric acid, a competitive antagonist of NMDA. In addition, binding studies showed that pyrazole displaced 1-(cis-2-carboxypiperidine-4-yl)methyl-1-phosphoric acid from the agonist recognition site of the NMDA receptor in a concentration-dependent manner and enhanced the binding of (+)-5-methyl-10,11-dihydro-5H- dibenzo[a,d]cyclohepten-5,10-imine to this complex. These data indicate that pyrazole is an agonist at NMDA receptors. However, at higher concentrations, open and burst times as well as the frequency of single-channel currents activated by pyrazole were reduced significantly, a finding which suggests that this compound is also an open channel blocker. In agreement with these results, it was shown biochemically that pyrazole was able to stimulate influx of Ca++ into rat brain microsomes via NMDA receptors and on the other hand to block the influx of Ca++ induced by NMDA. Pyrazole was unable to affect the neuromuscular transmission of frog sartorius muscle-sciatic nerve preparations. Additionally, pyrazole did not interact either with the agonist recognition site or with noncompetitive sites of the AChR. However, this drug had a very weak agonist-like action on the AChR of the Torpedo electric organ, most likely via binding sites different from those described previously for acetylcholine. Therefore, the therapeutic efficacy of pyrazole may be related at least in part to its effects on the NMDA receptor. Furthermore, this compound, because of the small size and rigidity of its molecular structure, becomes a promising drug for the study of the NMDA receptor. Indeed its use may allow a better understanding of the physiological and pathological processes involving this receptor.

Synthesis and thermotropic properties of new mesogenic pyrazole and isoxazole derivatives

Abstract: The synthesis of new mesogenic alkyloxy pyrazole and isoxazole derivatives is reported. The mesogenic properties of these compounds were investigated by differential scanning calorimetry, polarizing microscopy and X-ray diffraction. Almost all compounds show preferred orientation in a magnetic field of about 1·5 T. Pyrazole derivatives show higher transition temperatures than the corresponding isoxazole derivatives. Small differences (1–3 A) between the molecular lengths (as determined from models and the smectic layer thickness indicated by X-rays) are explained in terms of interdigitation or skewing of the alkyloxy chains.

Synthesis and Mesomorphic Properties of the 3,5-Bis-Alkoxyphenyl-Pyrazoles and-Isoxazoles

Abstract: The synthesis and measurement of physical properties using DSC, X-ray and optical methods are described for the 3,5-bis-(p-n-alkoxyphenyl)-pyrazole and 3,5-bis-(p-n-alkoxyphenyl)-isoxazole series with the carbon number of the n-alkylgroup from three to eight. The pyrazole series with longer n-alkylgroups (n = 6, 7, and 8) show the smectic A (SmA) as well as smectic C (SmC) phases. The corresponding isoxazole compounds show nematic (N) and also SmA phases. The compounds with shorter n-alkylgroups (n = 3, 4 and 5) show either nematic or SmA phases for both series respectively.

3,4,N-Trisubstituted-4,5-dihydro-1H-pyrazole-1-carboxamides and their use as insecticides

Abstract: 3,4,N-triaryl-4,5-dihydro-1H-pyrazole-1-carboxamide compounds having an aryl moiety in the 4-position that is an optionally substituted pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, or quinolinyl moiety and aryl moieties in the 3-position and the N-position that are optionally substituted phenyl, pyridinyl, pyrimidinyl, pyridazinyl, pyrazinyl, or quinolinyl moieties, such as N-(4-chlorophenyl)-4,5- -dihydro-3-(4-fluorophenyl)-4-(5-trifluoromethyl-2- -pyridinyl)-1H-pyrazole-1-carboxamide, were prepared and found to possess insecticidal utility. 1,2-Diarylethanone compounds were converted to 1,2-diaryl-2-propen-1-one compounds by treatment with bis(dimethylamino)methane, the 1,2-diaryl-2-propen-1-one compounds were converted to 3,4-diaryl-4,5-dihydro-1H-pyrazole compounds by treatment with hydrazine, and the 3,4-diaryl-4,5-dihydro-1H-pyrazole compounds were converted to the insecticidal subject compounds by treatment with an aryl isocyanate.