Showing papers on "Pyrazoline published in 1992"

Detection of IgE antibodies specific for 1-phenyl-2,3-dimethyl-3-pyrazoline-5-one by RAST: a serological diagnostic method for sensitivity to pyrazoline drugs.

Abstract: Certain adverse reactions to pyrazoline drugs resemble IgE-mediated hypersensitivity. However, convincing evidence of antigen-antibody interactions is not fully demonstrated. In this study, IgE antibodies specific for 1-phenyl-2,3-dimethyl-3-pyrazoline-5-one have been found in 17 out of 19 serum samples from individuals sensitive to pyrazoline drugs with 4-aminoantipyrine discs by Radio Allergo Sorbent Test (RAST). In contrast, we have not found any positive results from 10 normal donors without sensitivity to pyrazoline drugs after ingestion of metamizol 500 mg/day for 14 days. Therefore, our results provide further evidence in favor of an IgE-dependent mechanism in patients suffering from sensitivity to pyrazoline drugs. The determination of specific IgE antibodies could be used as a serodiagnostics method.

Rotational relaxation of pyrazoline compounds in solution

Abstract: The photophysical behaviour of pyrazoline derivatives was studied in this work. The fluorescence quantum yields of these compounds were measured in various media with identical polarity but different viscosity. In accordance with microviscosity theory, a linear relationship was observed between the product of the non-radiative decay rate constant and solvent viscosity and η x . It is suggested that the process of non-radiative decay occurs via rotation of the phenyl group which is connected to the N-1 position in the diphenyl pyrazoline molecule.

Stereoselective decomposition of pyrazolines containing trifluoromethyl groups

Abstract: The reaction of (Z)- and (E)-6,6,6-trifluoro-4-trifluoromethyl-4-hexen-3-ones (1) with diazomethane afforded the corresponding cis- and trans-pyrazolines (2), respectively. Photochemical and thermal decompositions of the r-3, t-4-bis(trifluoromethyl)pyrazoline gave selectively r-1, t-2-bis(trifluoromethyl)-1-propionylcyclopropane (3) and 3,4-bis(trifluoromethyl)-2-ethyl-4,5-dihydrofuran (4). On the other hand, those transformations of the r-3,c-4-isomer of the pyrazoline gave a mixture of the r-1,c-2-isomer of 3, 4, and 4,5-bis(trifluoromethyl)-5-hexen-3-one (5).

Synthesis and Characterization of Some Hovel Pehta-Coordihated Mixed-Ligakd Derivatives of Zinc(II)-bis(Acetylacetone) and-bis(Acetoacetanilide) Chelates with 2/3-Pyrazoline-5-One Derivatives

Abstract: A series of novel penta-coordinated mixed-ligand complexes of zinc(II) with the general formula, [zn(acac) 2 (L)](where acacH = acetylacetone and L = 3-methyl-l-phenyl-2-pyrazoline-5-one, 3-methyl-...

Electron‐impact induced fragmentation of spiro‐1‐pyrazolines

Abstract: The positive-ion electron impact mass spectra of twelve spiro-1-pyrazolines have been recorded as 70 eV electron energy and the dat analyzed to elucidate their fragmentation pathways. None of these compounds gave abundant molecular ions (M+) due to the instability of the pyrazoline ring. The first step in the decomposition of M+ ions is the elimination of a nitrogen molecule followed by a rearrangement resulting in the formation of the cation radical [M–28]+, the decomposition of which is discussed in detail. The proposed fragmentation pathways and their mechanisms are supported by high-resolution data, linked-scan measurements at constant B/E and collision-induced dissociation-mass-analyzed ion kinetic energy spectra.

Substituted aminosulfonamide and herbicide

Abstract: PURPOSE:To provide a substituted aminosulfonamide derivative or an agricultur ally suitable salt thereof having a strong herbicidal force against many weeds and high safety for wheat, soybeans, etc., and useful as a herbicide. CONSTITUTION:A compound of formula I [Q is a group of formula II, III or IV (R1 is H, 1-6C alkyl, 3-7C cycloalkyl, etc.; R2 is 1-6C alkyl, 2-6C alkenyl, 2-6C alkinyl, etc.,); X is O, S; G is a group of formula V (a, b, c, d are H, 1-6C alkyl, 2-6C alkenyl, etc.)]. The compound of formula I is produced e.g. by dissolving a substituted aminosulfonyliso(thio)cyanate derivative in a sufficiently dry inert solvent such as dioxane or acetonitrile and subsequently adding a pyrazoline derivative of formula VII to the solution with stirring. When the reaction is difficult to proceed, a fine amount of triethylamine, etc., is preferably added to the mixture.

Stereoselective Synthesis of Pyrazoline Derivatives by 1,3‐Dipolar Cycloaddition of Diazoalkanes to α,β‐Unsaturated Carbonyl Derivatives of Sugars.

Abstract: New pyrazoline acyclonucleosides have been prepared by 1,3-dipolar cycloaddition reactions of diazoalkanes to derivatives of d-galacto-oct-2-enonate and d-galacto-non-3-enulose. The reactions were highly regio- and stereo-selective, and single isomers were obtained in good yields. A tautomeric equilibrium between the 1- and 2-pyrazoline structures was observed for some of the isomers in solution.

Stereoselective Decomposition of Pyrazolines Containing Trifluoromethyl Groups.

Abstract: The reaction of (Z)- and (E)-6,6,6-trifluoro-4-trifluoromethyl-4-hexen-3-ones (1) with diazomethane afforded the corresponding cis- and trans-pyrazolines (2), respectively. Photochemical and thermal decompositions of the r-3, t-4-bis(trifluoromethyl)pyrazoline gave selectively r-1, t-2-bis(trifluoromethyl)-1-propionylcyclopropane (3) and 3,4-bis(trifluoromethyl)-2-ethyl-4,5-dihydrofuran (4). On the other hand, those transformations of the r-3,c-4-isomer of the pyrazoline gave a mixture of the r-1,c-2-isomer of 3, 4, and 4,5-bis(trifluoromethyl)-5-hexen-3-one (5).