Reactions of trialkylborines with hydrazine and phenylhydrazine

Summary With hydrazine and phenylhydrazine trialkylborines form complex compounds which decompose when heated with formation, respectively, of 1,2-bisdialkylborinohydrazines and 1-dialkylborino-2-phenylhydrazines.     

Ring contraction of a 5-acetylpyrimidine into pyrazoles by the action of substituted hydrazines in acidic medium

We have found previously that two 5-acetyl-4-methylpyrimidines could be transformed by aminoguanidine hydrochloride into 4-acetyl-1-amidino-3-methylpyrazolyl amidinohydrazone dihydrochloride. This reaction beside the fact that it led to a molecule closely related to the antitumor drug M.G.B.G. pointed out to a new possibility of ring contraction of pyrimidines into pyrazoles. We attempted therefore to study the possibility of extending this transformation to other substituted hydrazines and to define more accurately the conditions of this reaction as well as to prepare new potential anticancer drugs.     

Reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine

Polyfluorinated di-and triarylpyrazolines were synthesized by the reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine, respectively. Reactions of benzyl-idenepolyfluoroacetophenones with phenylhydrazine resulted in the mixtures of isomeric 1,5-diphenyl-3-polyfluoroaryl-and 1,3-diphenyl-5-polyfluoroarylpyrazolines. Fluorescence properties of the synthesized triarylpyrazolines were studied.     

Reactions of adamantyl-substituted keto esters with hydrazine and phenylhydrazine

Reactions of adamantyl-substituted keto and diketo carboxylic acid esters with hydrazine and phenylhydrazine were studied. Ethyl 3-(1-adamantyl)-2-(1-adamantylcarbonyl)-3-oxopropanoate reacted with hydrazine to give ethyl 3,5-di(1-adamantyl)-1H-pyrazole-4-carboxylate. Reactions of ethyl 2-(1-adamantylcarbonyl)-3-oxobutanoate and ethyl 4-(1-adamantyl)-3-oxo-2-(1-oxoethyl)butanoate with hydrazine and phenylhydrazine followed a complicated pattern and led to the formation of mixtures of the corresponding hydrazides and pyrazolones.     

Ring transformation of 3-halo-4-methoxycoumarins into pyrazoles with hydrazines

3-Chloro- and 3-bromo-4-methoxycoumarins 1a,b were readily transformed into 4-halo-5-(2-hydroxyphenyl)-3-oxo-2,3-dihydropyrazoles 2a,b with hydrazines. In the reaction of 1a,b with excess hydrazine and phenylhydrazine in boiling ethanol, unexpected 4-hydrazono-3-(2-hydroxyphenyl)-2-pyrazolin-5-ones 3 , 5 were obtained. The structure of 3 was determined by X-ray diffraction analysis.     

Mass spectra of 5-styryl and 5-acylpyrazoles

High-resolution, electron-impact, mass-spectrometric measurements have been made on three types of pyrazoles. Type 1 comprised ethyl 5-styrylpyrazole-3-carboxylates having in the α-position of the styryl group either a hydrogen atom, a methyl, or a phenyl group. Type II were 1,3,5-trisubstituted pyrazoles having phenyl (or p-substituted phenyl) groups in position 1, amide or carboxylate groups in position 3, and styryl (or α-substituted styryl) groups in position 5. Type III differed from type II in possessing a readily cleaved acyl or aroyl group instead of the styryl group. The compounds containing styryl groups gave significant ions corresponding to the formation of polycyclic heteroaromatic rings, in addition to various other fragments derived from such rings. Intensities and accurate mass-measurements are given for all ions having intensities exceeding 5% of the base peak.     

Pyrimidines-19: Ring transformation of 5-nitrouracil into nitroresorcinols

The first intermolecular right transformation of a uracil derivative into the benzene system is reported. Treatment of 1,3-dimethyl-5-nitrouracil (1) with acetone in NaOMe/MeOH afforded 6-acetonyl-5,6-dihydro-1,3-dimethyl-5-nitrouracil (6) which was converted into 4-nitroresorcinol (5) upon treatment with NaOEt/EtOH at reflux. Reaction of1 with butanone gave two major products, 3-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)butanone (7) and the 1-(uracil-6-yl)butanone isomer (8). Prolonged treatment of7 with NaOEt/EtOH afforded 4-methyl-6-nitro-resorcinol (9) whereas8 was converted into 2-methyl-4-nitro-resorcinol (10). Treatment of1 with diethyl acetonedicar?ylate in NaOEt/EtOH afforded diethyl-2-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)-acetonedicar?ylate (2). Prolonged treatment of2 with NaOEt/EtOH at reflux afforded (5,6-dihydro-1,3-dimethyl-6-nitrouracil-6-yl)-acetate (3). Apparently,2 underwent a retroClaisen reaction to give3. Reaction of1 with ethyl acetoacetate in NaOEt/EtOH gave adduct isomers4 which underwent transformation reaction to give eventually 6-nitroresorcinol (5).     

Kinetics and mechanism of oxidation of phenylhydrazine and P-bromophenylhydrazine by hexacyanoferrate(III) in acidic medium

Kietics of oxidation of phenylhydrazine and p-bromophenylhydrazine by hexacyanoferrate(III) in acidic medium have been studied. The reactions follow similar kinetics, being first order with respect to both hydrazine and exacyanoferrate(III) and inverse first order with respect to the hydrogen ion. Addition of hexacyanoferrate(II) has no retarding effect on the rate of oxidation. The effects of varying ionic strength, dielectric constant, and temperature on the reaction rates have been investigated. A plausible mechanism has been proposed to account for the experimental results. Benzene and bromobenzene have been identified as the oxidation products.     

Synthesis of trifluoromethyl-substituted pyrazoles and 1,2,4-triazines by ring transformation of mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates with phenylhydrazine

Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates 1 were easily prepared by the cyclodehydration reaction of N-acyl-N-alkyl-alpha-amino acids with trifluoroacetic anhydride. Due to the presence of the trifluoromethyl ketone and the mesoionic five-membered oxazole, there are three reaction sites to be attacked by the nucleophiles at C-2, C-5 and the trifluoroacetyl group in 1. Based on this model, three modes of regioselective attack by phenylhydrazine were found to provide three different products, i.e., 6-trifluoromethyl-1,2,4-triazines 3, 3-trifluoromethyl-5-pyrazolones 5 and 5-trifluoromethyl-3-hydroxypyrazoles 4, in good yields, respectively, depending on the nature of the solvent and reaction temperature. These three types of different reactions may be explained by the polarity of the reaction solvent and the mesoionic oxazole-ketene tautomerism.     

Oxidation of 2-amino-4-methylphenol in acidic medium

The oxidation of 2-amino-4-methylphenol 1 , by ferricyanide, in acetic acid yields benzoquinonimine 2 , phenoxazinonimine 3 and 4 , triphenodioxazines 5 and phenoxazinone 6 . The reaction mechanism seems to start with an electrophilic substitution of the quinonimine, from 1 , on the electron rich 1 , rather than with a nucleophilic attack of 1 on the arising quinonimine.     

Photochemically induced reactions of selected ketones with 4-cyanopyridine in neutral and acidic medium

The presence of the 4-cyanopyridine, in neutral or acidic medium, interferes with the normal behavior of the biradicals obtained by direct excitation of selected ketones, and results in formation of pyridinic derivatives.     

弱酸性介质中Ga-ZSM-5型分子筛的合成与鉴定

本文报道在弱酸性介质中, NH4F存在下, Ga-ZSM-5型分子筛的合成, 这种新的合成途径, 克服了在碱性介质中合成的缺点, 用多种手段研究了Ga-ZSM-5型分子筛结构与性能的关系, 为Ga对ZSM-5沸石骨架的同晶取代提供了充分的证据.     

The paper chromatographic separation of ammonium chloride,hydrazine, hydroxylamine,phenylhydrazine and phenylhydroxylamine

The paper chromatographie separation of ammonium chloride, hydrazine, hydroxylamme, phenylhydrazine and phenylhydroxylamine is accomplished using the solvent system; 50 parts by volume diethyl ether, 30 parts methyl alcohol, 15 parts water and 4 parts concentrated bydrochloric acid. A double-spot phenomenon is described which depends upon the distance of the starting line from the solvent level.     

Stereoselective electrochemical transformation of 4-substituted cyclohexanones into cis-5-substituted 2,2-dimethoxycyclohexanols

Electrolysis of 4-substituted cyclohexanones in methanol in the presence of sodium halides as mediators in an undivided cell results in the stereoselective formation of cis-5-substituted 2,2-dimethoxycyclohexanols in 70—80% yields.     

Ring transformation of 4-amino-1H-1,5-benzodiazepine-3-carbonitrile and ethyl 4-amino-1H-1,5-benzodiazepine-3-carboxylate into benzimidazole derivatives with amines

The ring contraction of 4-ammo-1H-1,5-benzodiazepine-3-carbonitrile hydrochloride 1 and ethyl 4-amino-1H-1,5-benzodiazepine-3-carboxylate hydrochloride 2 with aromatic primary amines into benzimidazole derivatives 3 and 4 was readily accomplished by heating in methanol. Benzodiazepine 1 also reacted with methylamine and ethylamine at about 40° to give ring-opened amine adducts 7 which were recyclized to 1 with hydrochloric acid.     

Oxygen reduction reaction on polycrystalline gold. Pathways of hydrogen peroxide transformation in the acidic medium

The mechanism of oxygen electroreduction on polycrystalline gold is studied in the acidic medium. Hydrogen peroxide is the main reaction product. However, two potential regions can be singled out in which the oxygen electroreduction reaction proceeds by different pathways. The first region is the potential interval close to the steady-state potential. Here, the oxygen electroreduction virtually completely produces peroxide. The second interval is the potential range of considerable cathodic polarization values. In this case, peroxide can be reduced to water. The low energy of hydrogen peroxide adsorption on gold determines the considerable overpotential of peroxide reduction. It is shown that on the gold electrode surface, the catalytic decomposition of peroxide occurs. The use of the method of electrochemical impedance spectroscopy allows the peculiarities of the oxygen reaction associated with hydrogen peroxide transformations to be revealed. In the acidic medium, the reactions of consecutive reduction of oxygen through the intermediate formation of hydrogen peroxide and the catalytic decomposition of the intermediate product are shown to proceed simultaneously. The ratio of rate constants of electrochemical stages depends on the potential. The chemical decomposition is observed both near the steady-state potential and in the cathodic region where considerable electrochemical reduction of peroxide occurs.