Hydrazones dihydrazones

Reactions of c -[Ru(bpy)2Cl2] with ligands (86) or (87) (X = CH2) in EtOH(aq) lead to [Ru(bpy)2(86)] + and [Ru(bpy)2(87, X = CH2)] respectively. When X = 0 in ligand (87), the product is the pyridine carboxylate complex [Ru(bpy)2(pyC02)], the structure of which is confirmed by X-ray crystallography. Complexes of the type [Ru(bpy)2L] " in which L represents a series of mono- and dihydrazones have been prepared and characterized by spectroscopic methods (including variable temperature H NMR) and a structure determination for L = biacetyl di(phenylhydrazone). When L is 2-acetylpyridine hydrazone or 2-acetylpyridine phenylhydrazone, [Ru(bpy)2L] + shows an emission, but none is observed for the dihydrazone complexes. The pyrazoline complex [Ru(bpy)2L] (L = 5-(4-nitrophenyl)-l-phenyl-3-(2-pyridyl)-2-pyrazoline) can be isolated in two diastereoisomeric forms. At 298 K, these exhibit similar MLCT absorptions, but at 77 K, their emission maxima and lifetimes are significantly different. ... 

From what was plarmed as a straightforward displacement of the chloride atom in 36 with hydrazine followed by a condensation with 2-tetralone and Fischer indolization to produce 39, dihydrazone 38 was isolated as an intermediate, resulting fi om dihydrazine 37 <99JHC441>. Subsequent Fischer indole cyclization and aminolysis of 38 produced 39 a mono-hydrazone intermediate (as opposed to 38) was ruled out by the authors on the basis of H NMR. 

Condensation of a monocarbonyl compound with a dihydrazone initially yields a macrocycle with a tetraaza six-membered chelate ring, e.g. (21 Scheme 8) or (23 Scheme 9), but this can isomerize to give a triaza five-membered chelate ring, as for (27 Scheme 10), where cyclization is by a reaction subsequent to the hydrazone/carbonyl condensation,21 or for the isomeric pair of compounds (25) and (26) of Scheme 9. Compounds with triaza (28) and tetraaza (22) seven-membered chelate rings have also been prepared.22 Tetradentate and pentadentate aza macrocycles are formed by condensations of 2,6-diacetylpyridine with hydrazine (29) or with dihydrazines (30).21... 

A large number of derivatives of the triazolo[l,2-6]triazoles (178) have been prepared either by self-condensation of aroyl- or acyl-hydrazones (177 -> 178) or by condensation of dihydrazones with dicarbonyl derivatives (179 -> 178) (57CB2411,63CB1827,67GEP1245386, 71GEP1620103). 

Mercuric oxide, HgO (yellow modification or the less reactive red modification), resembles silver oxide in its oxidizing properties. This reagent transforms phenols and hydroquinones into quinones [383, 384] and is used especially for the conversion of hydrazones into diazo compounds [355, 386, 387, 388, 389, 390, 391, 392]. Dihydrazones of a-diketones furnish acetylenes [393, 394, 395, 396], A -Aminopiperidines are dehydrogenated to tetrazenes [397] or converted into hydrocarbons [395]. 

Ketone derivatives whose oxidations have wide applications in synthesis are hydrazones and vicinal dihydrazones. Hydrazones are transformed into diazo compounds, and vicinal dihydrazones are converted into acetylenes. By far the most widely used oxidant is yellow mercuric oxide... 

Oxidation of bis-hydrazones of aliphatic polyfluorinated a-dicarbonyl compounds with S02C12 or bromine forms isomeric 1-amino-1,2,3-triazoles, one of which was identified by X-ray analysis (96JFC(79)45) (Scheme 86). Oxidation of polyfluoroalkyl-substituted glyoxal dihydrazones gives only one isomer. 

Hydrazone See Ethanedial dihydrazone in The Combined Chemical Dictionary. Semicarbazone Mp 273°. 

Bargamov and Bargamova reported on new polyflnorinated l-amino-1,2,3-triazoles 60 which were obtained by oxidation of the bis-hydrazones of aliphatic polyfluorinated a-dicarbonyl componnds with snlfnryl chloride, bromine, or selenium dioxide in an aprotic solvent [64, 65]. In a later article these anthors described an oxidation of a dihydrazone of l,l,l,5,5,5-hexafluoro-4-triflnoro-methylpentane-2,3-dione in the presence of the H2SO4 - P2O5 mixtnre (molar ratio 3 1) to 4-(l,l,l,3,3,3-hexaflnoroisopropyl)-5-triflnoromethyl-2/f-l,2,3-tri-azole 61 (no yield was given) [66]. 

Hydrazones stemming from aldehydes are easily converted into nitriles. For example, when treated with alkylating agents hydrazones form hydrazonium salts [232], which upon ehmination give nitriles as the formally oxidized products. Alternatively, hydrazones can be oxidized directly, and for this reaction oxidants such as peracids [233], oxone [234] and dioxirane [235] were found to be effective. Finally, catalytic systems based on combinations of hydrogen peroxide with metal catalysts [236] or selenium compounds [237] have been developed for this process. Other reactions along these lines include oxidations of monohydrazones giving diazo compounds [238] or nitrilimines [239] and conversions of vicinal dihydrazones into alkynes [240]. 

Diazomalonates have been prepared from dialkyl mesoxylates via the Silver(I) Ojcidc-catalyzed decomposition of the intermediate hydrazones. Monohydrazones of 1,2-diketones yield ketenes after mercury(II) oxide oxidation followed by heating. Dihydrazones of the same compounds give alkynes under similar conditions. ... 

Monoxime, 2-benzothiazolylhydrazone see 2,3-Butanedione (2-benzothiazolyl)hydrazone, B-00588 Dioxime see Dimethylglyoxime, D-00862 Dihydrazone [3457-52-1]. 2,3-Butanedione dihvdrazone, 9CI C4H10N4 M 114.150... 

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