Diastereo‐Divergent Synthesis of Saturated Azaheterocycles Enabled by tBuOK‐Mediated Hydroamination of Alkenyl Hydrazones

Diastereo‐divergent synthesis of saturated azaheterocycles has been achieved by tBuOK‐mediated hydroamination of alkenyl hydrazones. DFT calculations suggested that the cation–π interactions between a potassium cation and aryl substituents on hydrazones give rise to 2,5‐cis selectivity in pyrrolidines, which were synthesized by the reaction of γ,δ‐unsaturated N‐benzyl hydrazones. By contrast, 2,5‐trans selectivity was observed when an isopropyl group was used as the substituent on hydrazones. An unusual 2,6‐trans selectivity in piperidine formation was also realized using the present strategy.     

Cyclization of 2,6-dialkoxy acetophenone hydrazones in the presence of polyphosphoric acid (PPA)

Cyclization of a series of 2,6-dialkoxy acetophenone hydrazones gave 3-methyl-4-alkoxyindazoles with elimination of the 2- or 6-alkoxy group in the presence of PPA. The reaction mechanism was discussed.     

Adamantane and its derivatives. 1. Hydrazones and pyrazolones of adamantane

The dihydrazones, bis(diphenylhydrazones), and bis (2,4-dinitrophenylhydrazones) of adamantanone-2-carboxylic acid, dimethyl adamantane-2,6-dione-1,5-dicarboxylate, and tetramethyl adamantane-2,6-dione-1,3,5,7-tetracarboxylate and the pyrazolones of the corresponding acids were synthesized. It is shown that the methyl esters of adamantane-2,6-dione-1,5-dicarboxylic and -1,3,5,7-tetracarboxylic acids and their hydrazones cannot be converted to adamantane-1,5-dicarboxylic and -1,3,5,7-tetracarboxylic acids under the conditions of the Huang-Minlon and Locke reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 528–531, April, 1982.     

Effects of Electronic and Steric Factors on the Magnetic Properties of Novel Homo- and Heterobinuclear Transition-Metal Complexes with Asymmetric 2,6-Diformyl-4-R-Phenol Bis(Hydrazones)

A series of novel homo- and heterobinuclear copper(II), manganese(II), and VO²⁺ complexes with asymmetric 2,6-diformyl-4-R-phenol bis(hydrazones) are synthesized. The values of exchange parameters of these compounds are determined. The comparison of experimental results with the quantum-chemical calculations of the model fragments of binuclear metal chelates allows one to elucidate the main electronic and geometric factors determining the character of changes in the magnetic properties in systematic series of transition-metal complexes with bis(hydrazones).     

A convenient synthesis of 2-amino-6-methoxy-1-methyl (and 1,4-dimethyl)carbazole derivatives and their 6-aza analogues

2,6-Diaminotoluene ( 3a ) and 2,6-diamino-p-xylene ( 3c ) led to 2-methyl (and 2,5-dimethyl)-3-acetylamino-phenylhydrazines 5a,b. Fischer indolization of their hydrazones 6a,b and 7a,b derived from 4-methoxycy-clohexanone and 4-piperidone, and subsequent aromatization of intermediate tetrahydrocarbazole derivatives 8a,b and 9a,b allowed us to work out a convenient route to the title compounds.     

Synthesis,spectroscopic studies,and crystal structure of 2,6-diacetylpyridinediphenylhydrazone perchlorate and its complexing ability toward the lanthanides

2,6-diacetylpyridinediphenylhydrazone perchlorate was prepared and characterized by spectroscopic (IR, ESI–MS, UV–Vis, ¹H NMR) and analytical data and its crystal structure was determined by single X-ray analysis. The lanthanum(III), praseodymium(III), and neodymium(III) perchlorate complexes of 2,6-diacetylpyridinediphenylhydrazone were prepared in a direct reaction of the ligand with appropriate metal perchlorates. The spectroscopic and analytical data indicate 1:2 metal to ligand stoichiometry. In all the complexes the hydrazones act as monodeprotonated terdentate NNN donor chelators. The same lanthanum(III) complex was also obtained in a one-step condensation reaction between 2,6-diacetylpyridine and phenylhydrazine in the presence of lanthanum(III) perchlorate.     

吲唑类化合物合成新方法的研究（Ⅰ）

本文研究了2,6-二烷氧基苯乙酮腙在多聚磷酸(PPA)存在下受热脱去一分子醇环化生成3-甲基-4-烷氧基吲唑的合成反应.并研究了水杨醛、邻甲氧基苯甲醛、2,4-二羟基苯甲醛以及邻羟基苯乙酮、2-羟基-3,5-二甲基苯乙酮腙在PPA存在下的受热反应过程.     

Spectroscopic identification of some derivatives of 3,4-diamino-4H-1,2,4-triazole and 3-Hydrazino-4H-1,2,4-triazole

Spectroscopic methods (ir, ¹H- and ¹³C-nmr, ms and uv) have been used for the structural elucidation and identification of different isomeric 1,2,4-triazole derivatives, obtained by cyclisation reactions from appropriate diaminoguanidines. The four compounds 3,4-diamino-4H-1,2,4-triazole, 3-hydrazino-4H-1,2,4-triazole, 3-amino-4-(2,6-dichlorobenzylideneamino)-4H-1,2,4-triazole and 3-(2,6-dichlorobenzylidenehydrazino)-4H-1,2,4-triazole, were chosen as representative structures to illustrate the general spectroscopic properties for 3,4-diamino- and 3-hydrazino-substituted 4H-1,2,4-triazoles and the corresponding hydrazones, with different substituents in the 5-position of the triazole ring (alkyl-, aralkyl-, mercapto-, hydroxy- and amino-groups). Nmr and uv spectroscopy were found to be the best methods for confirmation of the different series of hydrazones, while ir and nmr were found to be suitable for the structural elucidation of compounds in the series of 3,4-diamino- and 3-hydrazino-4H-1,2,4-triazoles, respectively.     

Thermal Analysis in Structural Characterization of Hydrazone Ligands and Their Complexes

Results of our research on synthesis and characterization of complexes with acylhydrazone derivatives are described in this review paper. Structural characterization of newly synthesized complexes by thermal analysis (TG, DTA, DSC) is particularly emphasized in this paper. Thermal analysis enabled us to study not only structural changes of substances during thermal treatment, but also the mode of coordination and degree of deprotonation of acylhydrazones, as well as geometry of the coordination sphere of complexes, the structure of which had not been determined by X-ray analysis. Topics in this paper are as follows: complexes of dioxomolybdenum(VI) with tridentate hydrazones, usnic acid derivatives and their Cu(II) complexes, as well as transition metal complexes with 2,6-diacetylpyridine bis(hydrazones). This revised version was published online in July 2006 with corrections to the Cover Date.     

SYNTHESIS,REACTIONS AND SPECTRAL PROPERTIES OF 3-CHLORO-2,6DIARYL-4H-THIOPYRAN-4-ONES. SYNTHESIS OF SOME NEW 3-CHLORO-SPIROTHIOPYRAN DERIVATIVES

3-Chloro-2-phenyl-6-p-tolyl and 3-chloro-2,6-di-p-tolyl-4H-thiopyran-4-ones have been synthesized in moderate yieldes from the reaction of 3-chloro-tetrahydrothiopyran-4-ones with phosphorus pentachloride. Their thiones, oximes, and hydrazones have been also prepared. Treatment of thiones with malononitrile gave the corresponding 3-chloro-4-thiopyrylidenemalononitriles which gave 3-chloro-spirothiopyran derivatives of pyrazole, isoxazole, 1,3-thiazines when treated with hydrazine hydrate, hydroxylamine hydrochloride, thiourea and thiosemicarbazide, respectively. While treatment of 3-chloro-thiopyrylidene-malononitriles with acetylacetone gave the corresponding 3-chloro-spirothiopyran derivatives of pyran.     

Azines and azoles: CXXV. New regioselective synthesis of 1-amino-6-methyluracils

Readily accessible 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione reacts with substituted hydrazines and carboxylic acid hydrazides under mild conditions to give the corresponding hydrazones. Under severe conditions (heating in boiling dimethylformamide) the reaction is accompanied by extrusion of COS with formation of substituted 1-amino-6-methyluracils. Reactions of 5-acetyl-4-hydroxy-3,6-dihydro-2H-1,3-thiazine-2,6-dione with monosubstituted alkyl-and arylhydrazines take different pathways, depending on the conditions. Heating of equimolar mixtures of the reactants in ethanol or propan-1-ol leads to the formation of 2-substituted 5-methyl-3-oxo-2,3-dihydro-1H-pyrazole-4-carboxamides rather than 1-amino-6-methyluracil derivatives.     

Synthesis and properties of ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-3-carboxylates

Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3-carboxylates reacted with phenylhydrazine to give the corresponding hydrazones, ethyl 1-aryl-5-methyl-4-[1-(phenylhydrazinylidene)ethyl]-1H-pyrazole-3-carboxylates, which were converted to ethyl 1′-aryl-4-formyl-5′-methyl-1-phenyl-1H,1′H-3,4′-bipyrazole-3′-carboxylates by treatment with the Vilsmeier–Haack reagent. No indole derivatives were formed from the same hydrazones under the Fischer reaction conditions, but cyclization to 2-aryl-3,4-dimethyl-6-phenyl-2,6-dihydro-7H-pyrazolo[3,4-d]pyridazin-7-ones was observed.     

Synthesis of Bicyclic N‐Methylpyrazoline and Pyrazole Derivatives from α,β‐Unsaturated Ketones and N,N‐Dimethylhydrazine: An Illustration of Reductive Cyclization

The reaction of N,N‐dimethylhydrazine with α,β‐unsaturated keto precursors such as 2‐benzylidenecyclohexanone, 2,6‐bis(benzylidene)cyclohexanone, and 3,5‐bis(benzylidene)‐1‐methyl‐4‐piperidone hydrochloride provided bicyclic N‐methylpyrazoles instead of hydrazones or any Michael addition products. The crystal structure of a representative pyrazole is reported. The proposed mechanism for the formation of the bicyclic N‐methylpyrazole 1 is outlined.     

Synthesis and Characterizations of Some New Diacylhydrazones

Acylhydrazine and hydrazine are highly reactive chemicals that have a wide spectrum of uses such as in the chemical and pharmaceutical industries and as a fuel and propellant in aircraft, rockets and satellites. And they can react with microelement in the organism, so they were reported to possess different biological and pharmacological activities, such as antiphthistic, antitumour and so on. But, acylhydrazine and hydrazine have free group of NH2, so they usually have some toxicity to the organism. Hydrazones were investigated in view of the possibility of their being less toxic than the parent hydrazides, because of the blocking of the free NH2 group. In order to reduce the toxicity to the organism, people have been interested in the hydrazones compounds in recent years. In this work, 2,6-dimethylpyridine-3,5-diacylhydrazones were synthesized.     

A simple procedure for synthesis of 3H-quinazolin-4-one hydrazones under mild conditions

Condensation of 6-bromo- and 6,8-dibromo-2-hydrazino-3-phenyl-3H-quinazolin-4-ones with d-sugars in the presence of a catalytic quantity of glacial acetic acid gave the corresponding hydrazones in good yields. Acetylation of hydrazones with acetic anhydride in anhydrous pyridine gave the corresponding acetyl hydrazones in high yields. Also, other hydrazones were synthesized from condensation of 2-hydrazino-3H-quinazolin-4-ones with aromatic aldehydes in the presence of a catalytic quantity of piperidine.     

Hole-transporting hydrazones

This tutorial review covers recent contributions in the area of hole-transporting hydrazones, which are widely used in optoelectronic devices. It is addressed to students and researchers interested in the synthesis and properties of organic electroactive materials. The thermal, charge transport and other properties of electroactive hydrazones are compared and the relationships between the molecular structures and properties are emphasized. The first part discusses the low-molar-mass hydrazones and presents examples of their synthetic routes and chemical structures. In the second part, polymeric arylaldehyde hydrazones containing hydrazone moieties as the side substituents and in the main-chain are described.     

Configurational and constitutional information storage: multiple dynamics in systems based on pyridyl and acyl hydrazones

The C=N group of hydrazones can undergo E/Z isomerization both photochemically and thermally, allowing the generation of a closed process that can be tuned by either of these two physical stimuli. On the other hand, hydrazine-exchange reactions enable a constitutional change in a given hydrazone. The two classes of processes: 1) configurational (physically stimulated) and 2) constitutional (chemically stimulated) give access to short-term and long-term information storage, respectively. Such transformations are reported herein for two hydrazones (bis-pyridyl hydrazone and 2-pyridinecarboxaldehyde phenylhydrazone) that undergo a closed, chemically or physically driven process, and, in addition, can be locked or unlocked at will by metal-ion coordination or removal. These features also extend to acyl hydrazones derived from 2-pyridinecarboxaldehyde. Similarly to the terpydine-like hydrazones, such acyl hydrazones can undergo both constitutional and configurational changes, as well as metal-ion coordination. All these types of hydrazones represent dynamic systems capable of acting as multiple state molecular devices, in which the presence of coordination sites furthermore allows the metal ion-controlled locking and unlocking of the interconversion of the different states.     

Synthesis of pyrazoles via electrophilic cyclization

Electrophilic cyclizations of α,β-alkynic hydrazones by molecular iodine were investigated for the synthesis of 4-iodopyrazoles. α,β-Alkynic hydrazones were readily prepared by the reactions of hydrazines with propargyl aldehydes and ketones. When treated with molecular iodine in the presence of sodium bicarbonate, α,β-alkynic hydrazones underwent electrophilic cyclization to afford 4-iodopyrazoles in good to high yields. Iodocyclization was general for a wide range of α,β-alkynic hydrazones and tolerated the presence of aliphatic, aromatic, heteroaromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.     

Protolytic properties of 8-quinolylhydrazones of substituted salicylaldehydes and physicochemical properties of their copper(II) complexes

Acid-base properties of hydrazones derived from 8-hydrazinoquinoline and substituted salicylaldehydes were studied. Under the experimental conditions, only the first step of ionization of the hydrazones is realized. The ionization constants were calculated quantum-chemically. Copper(II) complexes of these hydrazones, (HL)Cu(X)(CH₃OH)_n, were isolated (HL^? is the monodeprotonated form of hydrazones, and X^? is the acid residue). According to the data of elemental analysis, IR spectroscopy, conductometry, and magnetochemistry, the majority of the complexes have a binuclear structure. The copper(II) ions in the dimeric complex show antiferromagnetic exchange coupling. The ionization constants of the hydrazones and the exchange parameters strongly depend on the substituent in the salicylaldehyde moiety.