Formation of dihydropyrazoles by fragmentation of a strained bishydrazone

Aluminium chloride induced cleavage of the tetracyclic bishydrazone (1) gives a tricyclic pyrazole characterised as the bisamide (5). Similarly lithium aluminium hydride reduces the bishydrazone (1) with cleavage of a strained ring to give a dihydropyrazole characterised as the bisamide (10).     

Glyoxal bishydrazones through facile ring cleavage of hydrazinopyrazine by hydrazines

The reaction of chloropyrazine and hydrazine was reinvestigated and was shown to produce hydrazinopyrazine and glyoxal bishydrazone. The latter was obtained also when hydrazine hydrochloride was allowed to react with Hydrazinopyrazine. The fusion of hydrazinopyrazine at 160° produced glyoxal his(pyrazinythydrazone). The interconversions of glyoxal bishydrazone with Hydrazinopyrazine were studied. Mechanisms to explain the various transformations are discussed.     

Crystal Structure and Magnetic Properties of Copper(II) and Nickel(II) Binuclear Complexes with Bisacylhydrazones Based on 2,6‐Diformyl‐4‐methylphenol

The series of binuclear Cu(II) and Ni(II) complexes with an asymmetrical exchange fragment based on 2,6‐diformyl‐4‐methylphenol bishydrazone has been synthesized for the first time. The compositions and structures of both ligands and its complexes have been established with the data of IR, ¹H NMR, and extended X‐ray absorption fine structure (EXAFS) spectroscopical studies as well as magnetic measurements. The structure of [Ni₂L₃(μ‐Pz)] · 2CH₃OH (L = triply deprotonated form of bishydrazone, Pz = pyrazol) was confirmed by X‐ray crystallographic analysis. In this complex, the coordination environment of two nickel ions is quite different, one nickel atom is square‐planar and the other is distorted octahedral coordinated. The values of exchange parameter calculated in terms of HDVV theory have been compared with the features of an asymmetrical exchange fragment's electronic and geometrical structure.     

Magnetochemistry of Homo- and Heterobinuclear Complexes with Bis(hydrazones) of 2,6-Diformyl-4-R-Phenols

Data on the magnetochemical properties of binuclear copper(II) complexes with different bishydrazone ligands prepared from 2,6-diformylphenol are surveyed. An attempt to systematize the investigation results by elucidating the magnetostructural dependences that relate the strength of exchange interaction to the structure of the binuclear complex is made. Experimental and theoretical data are presented demonstrating the dependence of the exchange interaction strength on both the geometry of the exchange fragment and the nearest environment and the nature of the nonbridging donor atoms coordinated directly by the metal.     

Synthesis of side-chain functionalised ligands for the generation of quartet receptor arrays via self-assembly of [2×2] grid complexes

The decoration of bishydrazone compounds of types 2 and 3 by attachment of various side chains, in particular of biological nature, yields a set of functionalised ligands. Their self-assembly with zinc(II) and cobalt(II) ions into [2×2] grids provides an approach towards nanosized metallosupramolecular architectures presenting quartet receptor arrays of interest for the development of nanosized biochips.     

Synthesis, Characterization, Electrochemical Properties and Antibacterial Activity of Some Transiton Metal Complexes with [(2-hydroxy-1-naphthaldehyde)-3-isatin]-bishydrazone

A bishydrazone was prepared by reacting isatin monohydrazone with 2-hydroxy-1-naphthaldehyde and a series of metal complexes with this new ligand were synthesised by reaction with Mn^II, Fe^II, Co^II, Ni^II, Cu^II and Zn^II salts. The complexes were characterised on the basis of elemental analysis, molar conductance, magnetic susceptibility data, u.v.–visible, i.r., e.s.r. and n.m.r. spectral studies, wherever possible and applicable. Analytical data reveal that the nickel(II), copper(II) and zinc(II) complexes possess 1:1 metal–ligand ratios and that manganese(II), iron(II) and cobalt (II) complexes exhibit 1:2 ratios. Infrared spectral data suggest that the bishydrazone behaves as a monobasic tridentate ligand with ONO donor sequence towards the metal ions. X-ray diffraction study of the copper(II) complex indicated an orthorhombic crystal lattice. The e.p.r. spectral data show that the metal–ligand bond has considerable covalent character. The electrochemical behaviour of the copper(II) complex was investigated by cyclic voltammetry (CV). Antibacterial tests of the ligand and the metal complexes were also carried out and it has been observed that the complexes are more potent bactericides than the ligand.     

Mechanism of Inhibition of Advanced Glycosylation by Aminoguanidine in Vitro

Abstract

A triazine and a bishydrazone were isolated from a solution of aminoguanidine incubated with an Amadori product (1-deoxy-1-propylamino-D-fructose) under physiological conditions. The new products were characterized by NMR and mass spectrometric analysis. The mechanism of the inhibition was proposed to involve the reactive intermediate 1, 4-dideoxy-1-(propylamino)-D-glycero-2, 3-hexodiulose (i.e., 1-propylamino-1, 4-dideoxyosone). The existence of this intermediate was supported by acetylation and characterization of the product. Formation of a proposed triazine and bis(amidinohydrazone) after the incubation of 1-propylamino-1, 4-dideoxyosone with aminoguanidine also supported the proposed mechanism.     

Studies on enaminonitriles: A new synthesis of 1,3‐substituted pyrazole‐4‐carbonitrile

3‐Diethylaminoacrylonitrile ( 1 ) reacts with hydrazonyl halides ( 2a‐d ) to yield 1,3‐disubstituted pyrazole‐4‐carbonitriles 5a‐d. The acetyl 1‐p‐chlorophenylpyrazole‐4‐carbonitrile ( 5a ) condensed with hydrazine hydrate to yield the bishydrazone 10 and with dimethylformamide dimethylacetal to yield 1‐aryl‐3‐(3‐dimethylamino)acryloyl pyrazole‐4‐carbonitrile ( 11 ). This enamine reacts with hydrazine hydrate to yield the pyrazolylpyrazole ( 12 ) and with naphthoquinone to yield the 3‐naphthofuranoyl pyrazole 13. The pyra‐zolyl pyridine derivative 14 was obtained upon treatment of 11 with acetylacetone in the presence of ammonium acetate. Compound 11 was coupled with p‐chlorobenzene diazonium chloride to yield the hydrazone 16 that was coupled further with p‐chlorobenzenediazonium chloride to yield the formazane 18.     

Synthesis and Antimicrobial Activity of Novel Heterocycles Utilizing 3‐(1,4‐Dioxo‐3,4‐dihydrophthalazin‐2(1H)‐yl)‐3‐oxopropanenitrile as Precursors

The reaction of 3‐(1,4‐dioxo‐3,4‐dihydrophthalazin‐2(1H)‐yl)‐3‐oxopropanenitrile 1 and salicyladehyde furnished coumarin derivatives 4 and 5 . Coupling reaction of 1 with aryl diazonium chlorides and benzene‐1,4‐bis (diazonium) chloride gave the corresponding hydrazones 6a , b and bishydrazone 9 , respectively. Hydrazones 6 underwent intramolecular cyclization upon treating with hydrazine hydrate to give 3‐aminopyrazoles 7 . Pyranyl phthalazine 13 was prepared from the reaction of 1 with ethyl 2‐cyano‐3‐ethoxyacrylate 10 . Enaminonitrile 14 was reacted with hydrazine hydrate/phenylhydrazine and hydroxylamine to afford the corresponding pyrazoles 16 and oxime 17 . The antimicrobial evaluation revealed pyrazole derivatives 7a , b and 16a , b displayed a broad spectrum activity against most strains. 3‐Aminopyrazole derivative 7b showed potent antibacterial activity against all tested microorganisms.     

Polyfluorinated hydrazones in organic synthesis

Oxidation ofN,N-unsubstituted 1,1,1,5,5,5-hexafluoro-4-trifIuoromethylpentane-2,3-dione bishydrazone with sulfuryl chloride or bromine in CCl₄ gives 1-amino-5-trifluoromethyl-4-(1,1,1,3,3,3-hexafluoroisopropyl)-1,2,3-triazole in high yield. Its structure has been confirmed by X-ray structural analysis.For Part 1 see Ref. 1.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No.12, pp. 2465–2467, December, 1995.The work was supported by the Russian Foundation for Basic Research (Project Nos. 94-03-08548 and 94-03-08338) and the International Science Foundation (Grants NDL 000 and NDL 300).     

Retracted: Acid‐Catalyzed Aquation of Ni(II)‐Hydrazone Complexes: Kinetics and Solvent Effect

Complexes of the type [Ni(L)(H₂O)]Cl₂·nH₂O, where L = 2‐pyridyl‐3‐isatinbishydrazone ligands, have been synthesized and characterized on the bases of elemental analysis, molar conductance, IR, electronic spectra, and thermal analysis (TGA and DTA). Acid‐catalyzed aquation of the Ni(II) isatin‐bishydrazone complexes was followed spectrophotometrically in various water–methanol and water–acetone mixtures at temperature 298 K. Kinetic behavior of the acid aquation is a linear rate law, indicating that the acid‐catalyzed aquation of these complexes in water–methanol and water–acetone mixtures follows a rate law with k_obs = k₂[H⁺]. The effect of the mole fraction of the ganic solvent, i.e., methanol and acetone, on the acid aquation has been analyzed; the decrease in the rate constant values with increasing of the methanol or acetone ratios is attributable to the effect of the co‐organic solvent on the initial states of the acid aquation by the destabilization of the H⁺ ion.     

Polyfluorinated hydrazones in organic synthesis

The oxidation of 1,1,1,5,5,5-hexafluoro-4-trifluoromethylpentane-2,3-dione bishydrazone (1) with SeO₂, HgO, and Hg(OAc)₂ was studied. The use of selenium dioxide leads to 1,1,1,5,5,5-hexafluoro-4-trifluoromethylpent-2-ene (2) and C₁₂H₄F₁₈Se₂. 1,1,1,5,5,5-Hexafluoro-4-trifluoromethylpent-2-yne (4) and C₆H₂F₉HgC₆H₂F₉ were obtained by the oxidation of bishydrazone1 with mercuric oxide. The oxidation of compound1 with mercuric acetate in diglyme affords 1,1,1,5,5,5-hexafluoro-4-trifluoromethylpenta-2,3-diene (6). Alkyne4 is isomerized to allene6 at 130 °C. For Part 3, see Ref. 1 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 677–680, April, 1998.     

Structural Study and Biological Evaluation of Some Novel 1,2,4-Triazole,Thiazole, and Bisthiazole Derivatives Bearing a Sulfonamide Moiety

The starting material 1,2,4-triazole derivative ( 3 ) was used to synthesize some novel condensed triazoles. Thus, treatment of compound ( 3 ) with phenyl isocyanate in refluxing pyridine furnished the novel [1,2,4]triazolo[4,3-b][1,2,4]triazole derivative ( 5 ). Also, cyclization of compound ( 3 ) with phenyl isothiocyanate afforded the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivative ( 7 ). Hydrazone derivative ( 9d ) was allowed to react with some halogenated reagents such as chloroacetone, ethyl chloroacetate, and chloroacetonitrile to furnish thiazole derivatives ( 12 ), ( 13 ), and ( 15 ), respectively. In a similar manner, bishydrazone ( 17 ) was used to prepare the novel bisthiazoles ( 18 ) and ( 19 ). Some of the synthesized compounds were evaluated for their antibacterial activity.     

Die Einheitlichkeit des 2,4-Dinitrophenylosazons des Glyoxals

Zusammenfassung Aus Glyoxal wurden mit salzsaurer 2,4-Dinitrophenylhydrazinlösung Hydrazone dargestellt. Als Ausgangssubstanz kamen das Mono- und Polyglyoxal sowie die Hydrogensulfitverbindung des Glyoxals und dessen Tetraäthylacetal zur Anwendung. Bei Einhaltung einer genügend langen Fällungsdauer erhielt man als Reaktionsprodukt in allen Fällen dieselbe Verbindung, das Osazon des Monoglyoxals, das bei der Reduktion mit Zinn und Salzsäure in 1,2-Diaminoäthan überging. Bei zu kurzer Fällungsdauer wurde als Reaktionsprodukt — unabhängig von der zugegebenen Reagensmenge — ein Gemisch der Mono- und Bishydrazone des Monoglyoxals erhalten. Die Komponenten wurden sowohl papierals auch dünnschichtchromatographisch getrennt. Bei Behandlung mit alkalischem Äthanol wurde das Monohydrazon orange und das Bishydrazon, das Osazon, blau gefärbt. Die von uns früher geäußerte Auffassung^18,19, daß sich das Osazon des Glyoxals mit alkalischem Äthanol blau färbt, erwies sich somit als stichhaltig.

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Summary Hydrazones of glyoxal were prepared from mono- and polyglyoxal, from the bisulfite derivative of glyoxal and the tetraethyl acetal with 2,4-dinitrophenylhydrazine in hydrochloric acid solution. When sufficient time was used for precipitation the same compound, monoglyoxal osazone, was obtained in all cases. Reduction of the monoglyoxal osazone with tin and hydrochloric acid gave diaminoethane. If the precipitation time was too short, a mixture of the mono- and bishydrazones of monoglyoxal was obtained-independently of the amount of reagent added. The components were separated by paper and thin-layer chromatography. The monohydrazone gave an orange colour with alkaline ethanol, while the bishydrazone, osazone, gave a blue one. Thus our previous opinion^18,19 that the osazone of glyoxal gives a blue colour with alkaline ethanol has been confirmed.

     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.