3893-33-2

Evidence is presented that the conversion of azibenzil, PhC(N2)COPh, into benzil azine induced by catalytic quantities of carbanions or of NaBH4 in Me2SO or MeCN involves a novel hydride-ion transfer chain mechanism.

Abstract: Ring opening of 3-[(diarylmethylidene)hydrazinylidene]-5-tert-butylfuran-2(3H)-ones by the action of alcohols afforded previously unknownalkyl 2-[2-(diarylmethylidene)hydrazinyl]-5,5-dimethyl-4-oxohex-2-enoates whichwere found to exist in soluti

Electrode kinetic studies on the reduction of azibenzil PhCOC(N2)Ph in MeCN solution indicate that the reaction follows an ECEh mechanism, the chemical step most propably involving unimolecular loss of N2 from the diazoalkane anion radical with formation of the related carbene anion radical.

A series of 10 hydrazones were synthesized by condensation of the selected hydrazine and the appropriate aldehyde. After the characterization and electrochemical analysis of each compound, amoebicidal activity was evaluated in vitro against the HM1:IMSS s

A series of benzil monohydrazones (1a, 1d) and corresponding dibenzil azines (2a-2d) featuring different p-aryl substituents have been synthesized and studied in regard of their crystal structures. Configurational and conformational properties as well as non-covalent interaction and packing behaviour of the molecules connected with the different substitution are discussed. The dibenzil azine 2a was found as a polymorph with reference to a known crystal structure.

The claims that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine can be prepared by the thermal condensation of two moles of benzil monohydrazone or of an equimolar mixture of benzil and benzil dihydrazone have been thoroughly reinvestigated. When such thermolyses were conducted in moist air, neither the claimed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine nor the precedented isomeric tetraazapentalene derivative was detected. The following products were unambiguously formed from the heating of molten benzil monohydrazone (%): benzil (10), benzaldehyde (10), benzamide (22), benzyl phenyl ketone (19), benzil bis(ketazine) (11), 3,4,5,6-tetraphenylpyridazine (9), benzil benzaldehyde azine (10), and, after column chromatography, 2,4,5-triphenylimidazole (2). This last component had a melting point and the fluorescent properties in UV light attributed by the original investigator to the mistakenly presumed 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine. Thus, the original claims for the synthesis of such a novel tetraazocine ring or even for the synthesis of the precedented isomeric zwitterionic tetraazapentalene have now been repudiated. The formation of 2,4,5-triphenylimidazole as a side reaction in the thermolysis of benzil monohydrazone can readily be rationalized as arising from benzil, benzaldehyde, and a source of ammonia, namely, benzamide, in the long-known Radziszewski reaction. Corroborating evidence was provided by data from the thermolysis of benzil dihydrazone. In addition, the origin of other side products is explained in terms of other possible condensations. Finally, preliminary experiments on using irreversible dehydrating agents such as titanium(IV) isopropoxide with benzil monohydrazone indicate that 3,4,7,8-tetraphenyl-1,2,5,6-tetraazocine is formed at room temperature as a transitory intermediate, which eliminates dinitrogen to produce 3,4,5,6-tetraphenylpyridazine. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

In an extremely fast method the reaction of hydrazine sulfate with a number of aldehydes and ketones, is accelerated by microwave irradiation under solvent free conditions in the presence of CH2CO2Na/CaCl2 to afford high yields of relevant azines.

An efficient Cu(acac)2-catalyzed oxidation of ketohydrazones afforded the corresponding α-diazeketones or ketazines in high yields depending on the reaction conditions. However, the reaction of benzophenone hydrazone gave benzophenone azine without affording diphenyldiazomethane. The formation of azines is explained by intermediacy of carbenoid generated by the Cu(acac)2-catalyzed decomposition of diazo compounds.

The thermal cyclization of monodisubstituted hydrazones (1) affords the corresponding N-substituted-4,5-diphenylimidazoles in good to excellent yields; possible mechanisms for this unusual cyclization are presented.

The reactions of azibenzil (I) with 3-aryliminobornan-2-ones (IIa-d) and 3-arylimino-1-methylindol-2-ones (IIe,f) afford 1-aryl-3,3-diphenyl-2-oxospiro (IIIa-d) and 1-aryl-1'-methyl-3,3-diphenyl-2-oxospiro (IIIe,f), respectively, in good yields together with 1,1',4,4'-tetraphenyl-2,2'-azinodiethanone.The spiroazetidinones are stable towards reagents like potassium hydroxide, conc. hydrochloric acid, sodium borohydride and lithium aluminum hydride.

The reaction of 2-diazo-1,2-diphenylethanone (1) with 2-imino-1,2-diphenylethanones 2a-e gave new N-substituted 3,3,4-triphenyl-4-benzoylazetidin-2-ones 3a-e, together with 1,1',2,2'-tetraphenyl-2,2'-azinodiethanone (4).Similar reaction of 1 with 2-iminoa

Bis(acetylacetonato)copper(II) catalysed thermal decomposition of 2-diazo-1,2-diphenylethanone (1) gives cis-1,2,3,4-tetraphenylbut-2-ene-1,4-dione (3) and N,N'-bis(2-oxo-1,2-diphenylethylidene)azine (4), characterised by analytical and spectral (UV, IR a

The reactions of 2-diazo-1,2-diphenylethanone with Schiff's bases Ar-CH=N-R gave new substituted 2-azetidinones together with 1,1',4,4'-tetraphenyl-2,2'-azinodiethanone. 2-Diazo-1,2-diphenylethanone reacts with N-benzhydrylidene-N'-phenylurea to give 1-(phenylcarbamoyl)-3,3,4,4-tetraphenyl-2-azetidinone.

Reaction of benzilmonohydrazone (1) with S4N4 gives the azine (6) and not the 2-H-imidazole (2); this invalidates the claim that (2) is not the intermediate in the formation of N-benzoyltriphenylimidazole from benzil and ammonia.S4N4 converts diphenylketene into thiobenzophenone.

Azibenzil (I) reacts with benzaldehyde N-benzhydrylimine (II) to give 1-benzhydryl-3,3,4-triphenylazetidin-2-one (III), characterised by analyses and spectral (IR, PMR and mass) data.III is stable towards conc. hydrochloric acid, aq. alkali (NaOH or KOH),

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