Showing papers on "Hydrazone published in 1991"

Heterocycles from Nitrile Imines. Part IV. Chiral 4,5-Dihydro-1,2,4-triazin-6-ones

Abstract: The reaction of nitrile imines (II) with α-amino esters (III) proceeds with no detectable racemization and constitutes a convenient synthetic route to 4,5-dihydro-1,2,4-triazin-6-ones (IV). Permanganate oxidation of the heterocycles (IV) affords the corresponding 1,2,4-triazin-6-ones (V). The reaction of (II) with β-amino esters gives the respective acyclic amidrazone adducts (VI)

Hole drift mobility and chemical structure of charge‐transporting hydrazone compounds

Abstract: The hole drift mobility of several hydrazone compounds dispersed in a polymer binder was correlated with their chemical structure. The mobility of hydrazone compounds having the same basic skeleton, i.e., aminophenylhydrazone, varied over about two orders of magnitude by systematic change of the substituents on the N atoms. The variety of the hole mobility was discussed on the basis of the concept of polyfunctionality and intramolecular mobility. From molecular orbital calculations, the importance of the positive charge distribution on a molecule in the cation radical state was emphasized for the molecular design of high‐mobility charge‐transporting compounds.

Reduction of C X to CH 2 by Wolff–Kishner and Other Hydrazone Methods

Abstract: Since its introduction early in this century,1,2 the deoxygenation of aldehydes and ketones to methyl or methylene derivatives, respectively, via base treatment of hydrazone intermediates (equation 1) has proven to be one of the most convenient and synthetically useful processes available for this important type of transformation. The reaction is termed the Wolff–Kishner reduction in recognition of the two original independent discoverers.1,2 However, the initial recipes introduced proved tedious and unreliable with many structural, especially hindered, examples. This led to substantial efforts devoted over the years to developing more convenient and successful experimental procedures, resulting in a number of improved and more reliable modifications which are most often utilized at present. More recently, modified procedures have been provided which utilize hydride reductions of p–toluenesulfonylhydrazone (to– sylhydrazone) derivatives and subsequent decomposition to release the hydrocarbon products under much milder and less basic conditions than those normally required for Wolff–Kishner reductions (equation 2).

Construction of a new versatile hydrazonic ligand and its chemical and structural behaviour towards metal ions

Abstract: The synthesis of a new hydrazonic ligand, 2,6-diacetylpyridine bis[2-(semicarbazono) propionylhydrazone](H4L), is reported together with the synthesis, X-ray structure analysis and the IR spectroscopic characterisation of the complexes [{Ni2(H2L)(OH2)Cl}2Cl2]·2dmf·5H2O 1(dmf = dimethylformamide), [Co(H4L)(OH2)2][NO3]2·2H2O 2 and [Zn(H3L′)(OH2)2][ClO4]2·1.5H2O 3[H3L′= 2,6-diacetylpyridine semicarbazone 2-(semicarbazono) propionylhydrazone]. The interest of these structures pertains mainly to the cations. In 1 a tetranuclear complex is present with two nonequivalent nickel atoms, both of which exhibit distorted-octahedral co-ordination, and with the hydrazone acting as enneadentate donor. The structures of 2 and 3 consist of monomeric units in which the metal atom has a pentagonal-bipyramidal environment with two axial H2O molecules and the hydrazone ligand forming the basal plane.

Regio-, Diastereo-, and Enantioselective synthesis of vic-diols via α-silyl ketones according to the SAMP/RAMP hydrazone method

Abstract: α-Silylated ketones 5 or 10 of high enantiomeric purity (ee ≥ 90%) are easily available by silylation or silylation/alkylation of ketones 1 or 6, resp., according to the SAMP/RAMP hydrazone method. Reduction of 5 or 10 with L-selectride™, followed by oxidative cleavage of the C–Si bond, leads to vic-diols 11–13 with high diastereoselectivity (de ≥ 90%) and without racemization. The stereoselectivity of the reduction depends on the structure of the α-silyl ketones 5 or 10, the reducing reagents, and the solvents used.

Synthesis of N,N‐Disubstituted Lactone Hydrazones via (Sulfonylimino)‐ethers

Abstract: The dihydropyran 3 reacts with sulfonyl azides to give the known (sulfonylimino)-ethers ( = lactone sul-fonylimines) 4 and 18. Reaction of 4 with NH2NH2 · H2O leads to the aminoiriazole-dibulanol 5, characterized as its tetraacetate 8, and not, as previously claimed, to 6 or 7. Similarly, the dihydrofuran-derived (tosylimino)-ether 10 yields 11 The structure of 5 was established by X-ray analysis, and a mechanism for its formation is proposed. Reaction of 4 with NH2NMe2 afforded the lactone hydrazone 16 and the hydrazidine 17. Catalysis by imidazole suppressed the formation of 17similarly, the [(trifluoromethyl)sulfonyl]imine 18 yielded 16, and, by reaction with NH2N(Me)Ph or 4-amino-4H-1,2,4-triazole, the lactone hydrazone 19 and the adduct 20, respectively. The 1,4-lactone hydrazone 21 was obtained from 10 or from 22. The structure of 20 was established by X-ray analysis. Treatment of 16 with BuLi followed by BnBr yielded the α-alkylated lactone hydrazone 23.

Hydrazone derivatives, processes for production thereof, and uses thereof

Abstract: The present invention relates to a hydrazone derivative represented by the general formula (I) shown below: ##STR1## wherein the substituents are as defined in the specification, processes for preparing the derivative, and uses of the derivative as an insecticide. The hydrazone derivative has a marked insecticidal effect on insect pests, especially against LEPIDOPTERA and COLEOPTERA.

Halogen – Kohlenstoff – Schwefel-Verbindungen: Synthese und Reaktionsverhalten von 4,5-Bis(trifluormethyl)-1,3-dithiol-Derivaten

Abstract: Halogen – Carbon – Sulfur Compounds: Synthesis and Modes of Reactions of 4.5-Bis(trifluoromethyl)-1,3-dithiole Derivatives The chemistry of the bis(trifluoromethyl)-1,3-dithiole system is thoroughly investigated starting from the 2-thione 6. By its oxidation the sulfine 2 and the ketone 7 are obtained. Further oxidation of 2 leads to the spiro compound 3. By chlorination of 6 the 2-sulfenyl chloride 5 is obtained, which can be desulfurized by PCl3 to the 2,2-dichloro compound 10. The best method for the preparation of the latter is the reaction of 6 with PCl5. Hydrolysis of 10 yields again the ketone 7. By reaction of 1,2-ethanedithiol with 10 the spiro compound 11 is obtained, the reaction of which with hexafluoro-2-butyne also affords 3. 10 reacts with primary amines to the 2-imines 9a and 9b, whereas 5 under similar conditions reacts via the thione S-imides 4a and 4b to 9a (with sulfur extrusion) or in a rearrangement reaction to the 1,2,4-trithiine 1. The preparation of the tosyl hydrazone 12 does not open an access to the diazo compound 16, neither does the reaction of 10 with hydrazine, which yields the ketazine 14. The homogeneous reaction of disilylhydrazine and 10 produced the tetrazene 17, which is a dimer of 16 and decomposes at its high melting point to the ketazine 14.

Diastereo- and enantioselective synthesis of α,α'-disubstituted, C2-symmetric ketones using the SAMP-/RAMP-hydrazone method

Abstract: Starting from simple, symmetric ketones such as, 3-pentanone, 1,3-diphenyl-2-propanone and 2,2-dimethyl-1,3-dioxan-5-one, α,α'-bisalkylation of the corresponding SAMP-hydrazones (S)-2 and (S)-8 [(S)-1-(alkylideneamino)-2-(methoxymethyl)pyrrolidines and (S)-1-(2,2-dimethyl-1,3-dioxan-5-ylideneamino)-2-(methoxymethyl)pyrrolidines, respectively], followed by oxidative cleavage with ozone affords chiral, C 2 -symmetric ketones 5 and (S,S)-11 of high diastereo- and enantiomeric purity (de, ee>98%)

Synthesis of some new heterocyclic compounds containing thieno[2,3-b]quinoline moiety

Abstract: 2-Cyano-3-amino-4-aryl-5, 6, 7, 8-tetrahydro-thieno[2,3-b]quinoline (1) reacted with carbon disulfide to give compound 2. Alkylation of 2 with different reagents gave the corresponding thioethers 3–7. Diazotisation of 1 furnished chloro derivative 8 which reacted with thiourea to give mercaptotriazine 9. Methylation of 9 yielded 10. On treatment of 8 with hydrazone hydrate, the expected hydrazinocompound 11 was obtained. Reaction of 11 with aromatic aldehydes, acetylacetone, acetic acid, acetic anhydride, carbon disulfide and nitrous acid gave compounds 12–17, respectively. The structures of all synthesized compounds were confirmed by elemental and spectral analysis.

Determination of Manganese by Flow Injection Analysis Based on Its Catalytic Effect on the Oxidative Coupling Reaction of 3-Methyl-2-benzothiazolinone Hydrazone with N, N-Dimethylaniline

Abstract: A catalytic-photometric method with a continuous-flow system was developed for the determination of nanogram amounts of manganese. The method is based on its catalytic effect on the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N, N-dimethylaniline to form a blue-violet compound (λmax=590nm) in the presence of hydrogen peroxide. In this reaction, 1, 10-phenanthroline and citrate acted as activators for the catalytic action of manganese(II). Manganese(II) at the 2-30ng ml-1 level can be determined at a rate of 10 samples h-1. The methodcan be applied to the determination of manganese in biological materials.

Voltammetric Studies on Some Arylhydrazones of α-Cyano Ketones and α-Cyano Esters

Abstract: The redox characteristics of the title compounds are extensively studied using DC-, cyclic voltammetry, coulometry, and controlled potential electrolysis in benzonitrile at platinum electrodes. These compounds are oxidized in one-electron transfer process followed by deprotonation which leads to dimerization. The reduction process differs according to the nature of the compound and the electron-withdrawing power of the substituent in the α-position. They can be reduced in a single two electron or two one electron waves leading in both cases to saturation of the hydrazonic moiety.