Showing papers on "Pyrazole published in 1995"

The geometry of pyrazole: A test for ab initio calculations

Abstract: Ab initio calculations on the structure of pyrazole have been carried out at different levels of accuracy. At the Hartree‐Fock (HF) level, the performance of several basis sets, namely 3‐21G, 6‐31G, 6‐31G**, and 6–311G** was investigated. The influence of electron correlation effects also was studied by carrying out geometry optimizations at the MP2, MP4, and QCISD levels. The performance of a density functional method also was evaluated. We have also investigated the possible influence of the frozen core approximation on the final optimized geometry. Three different statistical analyses were considered in determining which geometry is closest to the experimental microwave geometry—namely Paul Curtin's diagrams, cluster analysis, and multidimensional scaling. From these analyses, we conclude that there is no asymptotic approach to the experimental geometry by increasing the quality of the theoretical model, although, as expected, the more reliable structures are those obtained at the MP2, MP4, and QCISD levels, as well as those obtained by the B3LYP density functional method. We have also found that the values of the rotational constants are a tight criterion to define the quality of a molecular geometry. © 1995 by John Wiley & Sons, Inc.

1-Benzyl-3-(substituted aryl)-condensed pyrazole derivatives as inhibitors of platelet aggregation

Abstract: 1-Benzyl-3-(substituted aryl) condensed pyrazoles of the general formula (A): wherein R₁ represents H, C₁₋₃ alkyl, halogen, or -OR, in which R represents H or C₁₋₃ alkyl; represents wherein R₂ represents -COOR, -CH₂OR, H, C₁₋₃ alkyl, or halogen, in which R is as defined above; represents wherein R₃ represents H, C₁₋₃ alkyl, halogen, or -OR, in which R is as defined above; and pharmaceutically acceptable salts thereof, have utility as pharmaceuticals, in particular as inhibitors of platelet aggregation.

Highly Substituted Tris(pyrazolyl)methane Ligands and Some Zinc Complexes Thereof

Abstract: Tris(pyrazolyl)methane ligands in which two or three of the pyrazole carbon atoms bear organic substituents (L1-L7) were synthesized from chloroform and the corresponding pyrazole under phase transfer conditions. Their behavior towards zinc salts was found to span the range from no reaction at all to hydrolytic destruction. One hydrolysis product isolated and structurally characterized was the perchlorate complex [(HPz5)3Zn-OClO3]ClO4 (1), other ones were the 2:1 complexes (HPz3)2ZnBr2 (2) and (HPz6)2Zn(NO3)2 (3, HPzn = substituted pyrazole). Zinc perchlorate and tris(trimethylpy-razolyl)methane (L2) formed the octahedral binary complex [L22Zn](ClO4)2 (4) as evidenced by a structure determination. Zinc halides produced the 1:1 complexes L1 · ZnBr2 (5), L4 · ZnCl2 (6), and L4 · ZnBr2 (7), which according to the structure determinations of 6 and 7 contain tetrahedral ZnN2Hal2 units with only bidentate tris(pyrazolyl)methane ligands. In contrast, the zinc nitrate complex L4 · Zn(NO3)2 (8) was found to have an octahedral structure with mono- and bidentate nitrate and tridentate L4. The bromide complex 7 was converted by silver perchlorate hydrate into the labile compound [L4 · ZnBr]ClO4 (9) and then into the unstable product [L4 · Zn-OH2](ClO4)2 (10), both presumed to contain zinc in a tetrahedral ZnN3Br or ZnN3O environment, respectively. The ease of hydrolytic self-destruction prevented the exploitation of the reactivity of 9 and 10 in analogy to that of the corresponding tris(pyrazolyl)borate zinc complexes.

A novel type of retinoic acid receptor antagonist: synthesis and structure-activity relationships of heterocyclic ring-containing benzoic acid derivatives.

Abstract: A new series of heterocyclic ring-containing benzoic acids was prepared, and the binding affinity and antagonism of its members against all-trans-retinoic acid were evaluated by in vitro assay systems using human promyelocytic leukemia (HL-60) cells. Structure-activity relationships indicated that both an N-substituted pyrrole or pyrazole (1-position) and a hydrophobic region, with these linked by a ring system, were indispensable for effective antagonism. Among the compounds evaluated, optimal antagonism was exhibited by 4-[4,5,7,8,9,10-hexahydro-7,7,10,-10-tetramethyl-1-(3- pyridylmethyl)anthra[1,2-b]pyrrol-3-yl]benzoic acid (31), 4-[4,5,7,8,9,10-hexahydro-7,7,10,10-tetramethyl-1-(3-pyridylmethyl)-5- thiaanthral[1,2-b]pyrrol-3-yl]benzoic acid (40), and 4-[4,5,7,8,9,10-hexahydro-7,7,10,10-tetramethyl-1-(3- pyridylmethyl)anthra[2,1-d]pyrazol-3-yl]benzoic acid (55), all of which possess a 3-pyridylmethyl group at the five-membered ring nitrogen atom.

Co-ordinative versatility of 3,5-bis(2-pyridyl)pyrazole in silver and copper compounds

Abstract: Two silver(I) and one copper(II) complex with 3,5-bis(2-pyridyl)pyrazole (Hbpypz) have been synthesized and their molecular structures determined by X-ray crystallography. In the dinuclear complex [Ag2(Hbpypz)4][CIO4]2·2Me2CO there are two crystallographically independent monomeric units linked by intramolecular hydrogen bonds. In each unit Hbpypz only uses two of its four nitrogen atoms, acting as a typical bidentate chelate ligand. In the polymeric complex {[Ag(Hbpypz)]CIO4}∞ each silver(I) ion is co-ordinated to three nitrogen atoms of two different Hbpypz molecules and each ligand in turn bridges two spearate Ag atoms forming an infinite-chain structure of macrocations with non-interacting CIO4– anions. The tetranuclear complex [Cu4(bpypz)4(CIO4)4]·2H2O consists of two weakly associated dimeric units coupled via intramolecular stacking between the pyridine and pyrazole rings with an average spacing of 3.50 A, which gives rise to charge-transfer absorption bands in the near-UV region. The temperature dependence of the ESR spectrum and magnetic susceptibility indicates the presence of an antiferromagnetic interaction in the system. While Hbpypz is strictly planar in the copper(II) complex, a non-coplanar conformation is observed in both silver(I) complexes, indicative of the unique co-ordinative versatility of the pyrazole derivative.

Synergistic termiticidal composition of pyrethroid and n-phenyl-pyrazole

Abstract: A termite control composition for soil treatment containing 3-cyano-1-(substituted phenyl) pyrazole derivative and a pyrethroid compound as effective ingredients, and a method of controlling pests such as termites using said composition. The termite control composition is improved for soil treatment as well as for the ability to prevent termites from passing through the pesticidally treated layer.

Structure-activity study on antiinflammatory pyrazole carboxylic acid hydrazide analogs using molecular connectivity indices.

Abstract: The relationship between molecular connectivity indices and the antiinflammatory activity of a series of pyrazole carboxylic acid hydrazide analogs has been investigated. The values of molecular connectivity index, valence molecular connectivity index, and a modified index, termed as atomic molecular connectivity index for 76 compounds, were computed and active ranges were identified. Each compound was assigned an activity which was subsequently compared with the reported activity against lipoxygenase enzyme. Predictions with a degree of accuracy above 80% were observed using the valence molecular connectivity index.

Metal-ion binding affinity of azole-modified oxirane and thiirane resins

Abstract: The azole ligands pyrazole, imidazole, 1,2,4-triazole and tetrazole have been immobilized onto poly(glycidyl methacrylate) p(GMA-O) and onto its sulfur analogue p(GMA-S), which contains a thiirane ring instead of an oxirane ring. The ligands were introduced using ring-opening reactions of the pendant oxirane or thiirane groups with the azoles, resulting in formation of the chelating ion-exchange resins PYROH, IMOH, TRIOH, TETOH, PYRSH, IMSH, TRISH and TETSH. The resins have been characterized by solid-state 13C cross-polarization and magic-angle spinning NMR, FT-IR spectroscopy and elemental analysis. Batch extraction capacities were determined for the chloride salts of Cu2+, Ni2+, Co2+, Zn2+ and Cd2+ in buffered solutions in the pH range 0.9–6.0. Both modified oxirane and thiirane resins are very selective for Cu2+ in the presence of other divalent heavy metal ions. The maximum uptake capacities for Cu2+ for the oxirane resins under non-competitive conditions are 0.28 mmol/g for TRIOH, 0.39 mmol/g for IMOH and 1.14 mmol/g for PYROH. The resin TETOH is an exception, and does not show any detectable uptake of M2+ at all. The maximum uptake capacities for Cu2+ for the thiirane resins under non-competitive conditions are 0.87 mmol/g for TETSH, 0.96 mmol/g for TRISH, 0.58 mmol/g for IMSH and 0.98 mmol/g for PYRSH. The 4 thiirane resins also sorb noticeable amounts of Cd2+ and Zn2+ especially the resin PYRSH. The maximum uptakes of Cd2+ and Zn2+ for PYRSH are 0.65 and 0.74 mmol/g respectively. The complexation of Cd2+ and Zn2+ by the thiirane is ascribed to the presence of thiol groups. The resins PYROH and PYRSH have the highest uptake capacity for Cu2+ of all the resins tested. The M2+-uptake sorption behavior of all the 8 resins show very steep pH-dependent curves, i.e. virtually no M2+-uptake below pH 2.5 and, depending on the particular metal ion, maximum uptake at pH 5.5. The thiirane resins are stable in the presence of dilute mineral acid, as was shown by regeneration experiments performed with 1.0 M H2SO4.

µ-Pyrazolato-µ-carboxylato- and di(µ-pyrazolato)dimanganese(II) complexes: synthesis, characterization and catalase-like function

Abstract: 3,5-Bis[N,N-di(2-pyridylmethyl)aminomethyl]pyrazole (HL1) and 3,5-bis[N,N-bis(2-diethylaminoethyl)aminomethyl]pyrazole (HL2) formed µ-pyrazolato-µ-carboxylato-dimanganese(II) complexes [Mn2L(O2CR)][BPh4]2(L = L1, R = Ph; 1; L = L2, R = Me 2) and 3,5-bis[N-(2-pyridylmethyl)aminomethyl]pyrazole (HL3) gave a di(µ-pyrazolato)-dimanganese(II) complex [Mn2L32][BPh4]23. The ditoluene adduct of 3 crystallizes in the triclinic space group P with a= 14.452(3), b= 15.573(5), c= 10.988(4)A, α= 108.78(3), β= 93.31(2) and γ= 115.10(2)°. X-Ray diffraction analysis revealed a di(µ-pyrazolato)-dimanganese(II) core with Mn ⋯ Mn separation 4.181(2)A. All the complexes showed catalytic activity towards disproportionation of H2O2 in dimethylformamide at 0 °C. The initial rate of dioxygen evolution in the presence of 1 is first order in both the complex concentration and that of H2O2; v=k[Mn2][H2O2], k= 1.45 dm3 mol–1 s–1. Together with the observation of a ligand-to-metal charge-transfer band characteristic of MnIVO in the catalysis by 2, a mechanistic scheme involving a cycle from {MnIII(OH)}2 to {MnIV(O)}2 is inferred. In the disproportionation by 3 the initial rate of evolution is first order in complex concentration and second order in that of H2O2; v=k[Mn2][H2O2]2, k= 29 dm6 mol–2 s–1).

Chiral Heterocyclic Ligands. VIII. Syntheses and Complexes of New Chelating Ligands Derived From Camphor

Abstract: The syntheses of 23 new chelating ligands are described. Most of these ligands are derived from the chiral pyrazole (1) which has been linked to a variety of heterocycles , namely pyridine, pyrimidine, pyridazine, isoxazole , benzimidazole, thiophen and furan. In certain cases the parent achiral analogues have also been prepared. Preliminary studies of the coordination chemistry of these ligands with selected transition metals have been carried out. The X-ray crystal structures of palladium complexes of isoxazole- and thiophen-containing ligands have also been determined.

Tricyclic pyrazole derivatives

Abstract: Issued in Week 9616 First Major Country Equivalent to NO9503162A minoalkyl-substd tricyclic pyrazoles of formula (I) and their salts are new: R -R = H, OH, halo, lower alkyl, or lower alkoxy; R = H or lower alkyl; R = H, lower alkyl or lower alkoxy; X = (CR R )n or CH=CH; R , R = H or lower alkyl; n = 1 or 2

Pyrazole derivatives as herbicides

Abstract: Compounds of formula (I) in which the substituents W, R100, R101 and R102 are as defined in claim 1, and the pyrazole N-oxides, salts, complexes and stereoisomer of the compounds of formula (I) have good pre- and post-emergence selective herbicidal properties. The preparation of theses compounds and their use as herbicidal active compounds are described.

An efficient synthesis of 1-aminophosphonic acids and esters bearing heterocyclic moiety

Abstract: New α-aminophosphonic esters and acids derived from furan, thiophene and pyrazole were prepared in high yield, in the reactions of benzylamine, benzhydrylaraine or benzyl carbamate with heterocyclic aldehydes and diethyl or diphenyl phosphonates. The protecting groups at amine (benzyl or benzhydryl) were removed by hydrogenolysis or hydrolysis, respectively. The N-benzyloxycarbonyl (Z-group) was removed by treatment with 45% HBr in acetic acid.

Deuterated Derivatives of 3,5-Dimethyl-1-(4-nitrophenyl)pyrazole for Nonlinear Optical Materials

Abstract: A weak absorption of laser light by a nonlinear optical crystal causes a noticeable temperature rise in the crystal. Such absorption may undesirably shift the reflactive indices (some optical characteristics) of the crystal. 3,5-dimethyl-1-(4-nitrophenyl)pyrazole [DMNP], an excellent nonlinear optical material, was deuterated in order to suppress its absorption in the 1 μm wavelength region. Three deuterated deriatives were synthesized; their crystal structures were identical with that of DMNP. The deuteration of the pyrazole part including the two methyl moieties proved to be more effective than deuteration of the phenyl part (benzene ring) with regard to a reduction of the IR absorption. A good correlation was confirmed between the temperature elevation under laser irradiation and IR absorption.

Synthesis of novel chiral diazole ligands for enantioselective addition of diethylzinc to benzaldehyde

Abstract: A variety of chiral pyrazole and imidazole derivatived ligands have been prepared under high pressure conditions and their catalytic efficiency in the enantioselective addition of diethylzinc to benzaldehyde has been examined.