Electrocarboxylation of Carbon Tetrachloride in Dimethylformamide with Use of a Soluble Zinc Anode

Regularities of electrochemical carboxylation of carbon tetrachloride in conditions of galvanostatic diaphragmless electrolysis with a soluble zinc anode are studied. It is established that the generation of the CCl ₃ ^? anion at the cathode is accompanied by the discharge of salts of Zn²⁺, with the deposition of Zn⁰ at the surface. The interaction between and CCl ₃ ^? and CO₂ in experimental conditions leads to the formation of zinc trichloromethylacetate, which proves to be very unstable in the dimethylformamide environment and undergoes fragmentation with the CO₂ evolution. It is found that this process competes with currentless reduction of trichloromethylacetate under the action of Zn⁰ deposited on the cathode surface. As a result, corresponding dichloromethylacetate with a small yield of ≤5.5% forms as the sole product of electrolysis.     

Double bond isomerization of 5-vinylbicyclo[2.2.1]hept-2-ene to 5-ethylidenebicyclo[2.2.1]hept-2-ene over alkaline earth oxides

All the alkaline earth oxides exhibit activities for double, bond isomerization of 5-vinylbicyclo[2.2.1]hept-2-ene (VBH) to 5-ethylidenebicyclo[2.2.1]hept-2-ene (EBH) at a reaction temperature of 273 K. The order of the activity on the basis of unit weight of catalyst was CaO>MgO>SrO>BaO when compared under optimum pretreatment conditions. The E/Z ratio in the products is determined by the reaction temperature regardless of the type of catalyst; the ratios were 82/18 and 88/12 for the reaction temperatures of 323 and 273 K, respectively.     

Reaction of perfluoro-2-methylpent-2-ene with ethylenediamine and hexamethylenediamine

Reaction of perfluoro-2-methylpent-2-ene with ethylenediamine and hexamethylenediamine results in 9-fluoro-5,9-bis(pentafluoroethyl)-6,8,8-tris(trifluoromethyl)-1,4-diazabicyclo[5.2.0]nona-4,6-diene, whose structure was confirmed by X-ray analysis, and 11-pentafluoroethyl-10-trifluoromethyl-1,8-diazabicyclo[7.2.0]undeca-8,10-diene, respectively. The reaction pathways are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1578–1582, August, 1999.     

超临界二氧化碳介质中端炔C—H键与CO_2的羧化反应研究

建立了一个不使用有机溶剂的端炔C—H键羧化新体系:在Ag(I)/DBU(1,8-二氮杂二环十一碳-7-烯)催化体系中,通过超临界二氧化碳与端基炔的羧化反应,以较高产率得到了相应丙炔酸产物.在反应体系中,超临界二氧化碳既是反应物又是反应溶剂;助剂DBU起到了碱、亲核体和共催化剂的作用,并能够明显加快反应速率.筛选出的催化体系具有良好的催化反应活性和底物适应能力,能够实现液态、固态端基炔与超临界二氧化碳的直接羧化反应,为制备功能化丙炔酸类化合物提供了一个环境友好、简单、经济的合成路线.     

Reaction of perfluoro-2-methylpent-2-ene with azoles

Perfluoro-2-methylpent-2-ene reacts with pyrazole, imidazole, 1,2,4-triazole, and benzotriazole to give products of the replacement of the vinylic fluorine atom. In the case of imidazole, the product of allylic fluorine substitution, 1,3-bisimidazolylperfluoro-2-methylpent-2-ene, is also formed. The structures of the products were confirmed by spectral data. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 835–837, April, 1997.     

Synthesis and electrical conductivity of poly(1,4-phenylenevinylene-co-2-nitro-1,4-phenylenevinylene)

A series of PPV copolymers containing 2-nitro-1,4-phenylenevinylene (NO₂-PV) units were prepared via the water-soluble precursor route. They were obtained in film form and were doped with I₂ and FeCl₃. Doping increased the electrical conductivities to maximum values of about 3×10^?2 and 3×10^?1 s cm^?1, respectively, for the two dopants. Conductivity depended strongly on the composition of the copolymers; it reached a maximum value at ca. 1–2 mol % of NO₂-PV units in the copolymers and then dropped rapidly with further increase in NO₂-PV content. Electronic effects of the substituent and morphological changes induced by copolymerization appear to interplay intricately, resulting in the occurrence of a maximum conducting composition. © 1993 John Wiley & Sons, Inc.     

Iridium-catalyzed asymmetric hydrogenation of 2-substituted 1,4-benzodioxines

An Ir-catalyzed asymmetric hydrogenation of 2-substituted 1,4-benzodioxines was developed for the preparation of chiral 1,4-benzodioxanes, which are present in numerous biologically active compounds and natural products. Our tropos biphenyl phosphine-oxazoline ligand is essential for obtaining good ee. A broad range of substrates were tolerable to the reaction conditions and gave the corresponding hydrogenation products in excellent yields and with moderate to good enantioselectivities using the Ir-complex of our tropos phosphine-oxazoline ligand.     

A new synthesis of 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethylene-1,4-benzodioxin-2(3H)-one derivatives

The 1,4-benzodioxin-2-carboxylic esters or carboxamides react with nucleophilic amines to give access to 3-hydroxy-2,3-dihydro-1,4-benzodioxin-2-carboxamides and 3-aminomethyn-1,4-benzodioxin-2(3H)-one precursors of potential therapeutical compounds. The basic environment (K₂CO₃ or amine) facilitates the process.     

Electrolytic Fixation of CO2 by Electrocarboxylation of RX on Nanocrystalline TiO2-Pt Cathode

Electrolytic fixation of CO2 was investigated by electrocarboxylation of organic halides (RX), and four esters Ⅰ,Ⅱ Ⅲ, Ⅳ) were obtained in moderate yields. Electrochemical reduction esterifications of RX in the presence of CO2 were carried out on nanocry‘stalline TiO2-Pt electrode. The electrochemical behavior of RX in the presence of CO2 was investigated by the technique of cyclic voltammetry, and the probable reaction mechanism w,as proposed.     

Novel synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and benzo[b][1,4]thiazin-2-one O-(tert-butyl) oximes in the presence of K2CO3/SiO2

A simple and efficient method was developed for the synthesis of 1,4-thiazin-2-one O-(tert-butyl) oximes and benzo[b][1,4]thiazin-2-one O-(tert-butyl) oximes from N-tert-butoxy acyl imidoyl bromides and 2-aminothiols in the presence of K₂CO₃/SiO₂. Twenty five novel compounds were readily synthesized in excellent yields using this procedure. The products possessed Z-stereochemistry with regard to the CN double bond. The reaction proceeded with initial substitution of bromine in the N-tert-butoxy acyl imidoyl bromides by mercapto groups in the presence of K₂CO₃/SiO₂, and subsequent intramolecular Schiff base formation.     

Preparation of cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective semi-hydrogenation of perfluoro-2-butyne

Cis-1,1,1,4,4,4-hexafluorobut-2-ene has a zero ozone depletion potential (ODP), low global warming potential (GWP) and non-flammable properties, so it is believed to be a potential foam expansion agent. For the synthetic process of cis-1,1,1,4,4,4-hexafluorobut-2-ene, the process catalysts are the key factors for its yield and cost. In this paper, the catalysts of palladium attached to porous aluminum fluoride, to active carbon, to Al₂O₃, and the blends of palladium and bismuth to AlF₃ used to prepare cis-1,1,1,4,4,4-hexafluorobut-2-ene by cis-selective semi-hydrogenation of perfluoro-2-butyne were investigated. The performance of above-mentioned catalysts was compared in reaction process. The experimental results indicate that the additive of bismuth to palladium catalyst is useful for improving the activity and selectivity compared to Pd/C and Pd/Al₂O₃. The role of bismuth in the synthetic process is discussed based on the experimental results and theory analysis.     

氮杂炔正离子与环烯反应的机理及取代基效应

用DFT方法研究了氮杂炔正离子[R-C≡N-CH3] 与二环[2,2,1]-2-庚烯的反应机理。所有几何构型用B3LYP/6-31G**基组进行优化,过渡态通过振动分析和内聚反应坐标进行了确认。并在相同基组上研究了当R为不同取代基时的反应变化规律。结果表明该反应为环加成反应,有两条反应途径,产物主要通过能量较低的过渡态TSa生成。当取代基为支链烷烃基团时,反应位垒较大;取代基为直链烷烃基团和苯环时,反应较易进行。     

Rearrangement of 2-amino-1-aryl-1,4-dihydropyridines

Heating of 2-amino-1-aryl-1,4-dihydropyridines in acidic aqueous media gives 2-arylamino-1,4-dihydropyridines. The reaction formally involves the migration of the aryl substituent from the endo-to exocyclic N atom. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1259–1260, July, 2006.     

Use of [hydroxy(tosyloxy)iodo]benzene in a novel and facile synthesis of 1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones

The reaction of acetophenones 1 with [hydroxy(tosyloxy)iodo]benzene followed by treatment of the resulting α-tosyloxyacetophenones 2 thus formed with anilines 3 in the presence of sodium carbonate in ethanol provides a novel one-pot synthesis of 1,4-diaryl-2-(arylamino)but-2-ene-1,4-diones 4.     

Three-component synthesis of 2-imino-1,4-benzoxazines

A series of 2-imino-1,4-benzoxazines (8a-e) were prepared by the one-pot, three-component, condensation of salicylaldehyde (4), various ortho-aminophenols (5), and 2,6-dimethylphenylisonitrile (6). The structures of four of the crystalline benzoxazine derivatives (8b-e) were unambiguously established by X-ray analysis.     

Synthesis of methylvinylpolyfluoroalkoxysilanes by photoinitiated radical reaction of dialkoxy(methyl)vinylsilanes with perfluoro-4-methylpent-2-ene

A new method was elaborated for the synthesis of vinylsilanes with polyfluoroalkoxy substituents at the silicon atom using the photoinitiated radical reaction of dialkoxy(methyl)vinylsilanes with perfluoro-4-metliylpent-2-ene in the presence of di-tert-butyl peroxide at room temperature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2976–2978, December, 1996,     

Synthesis and efficiency of photolysis of methylated 2-dialkylamino- and 2-piperidino-1,4-naphthoquinones

2-Dialkylamino- and 2-piperidino-1,4-naphthoquinones with a methyl group in position 3 or 5(8) of the naphthoquinone were synthesized by reacting dimethyl- and diethylamines and piperidine with 2- and 5-methyl-1,4-naphthoquinones. The quantum yields of photoconversion of the synthesized compounds in benzene were determined. A 1.2- to 6.5-fold increase of the quantum yield over that of 2-dimethylamino-1,4-naphthoquinone was established. A comparison of the quantum yields with the calculated charges on the reaction centers in the excited (T ₁) state showed that there is not a linear relationship between them.Institute of Organic Chemistry, Russian Academy of Sciences, Siberian Branch, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 707–714, March, 1992.     

Systematic HPLC Study of a New Series of 4-Methyl-1,4-dihydropyridines with Antitrombotic Activity

Abstract

A systematic study of a new series of 4-methyl-1,4-dihydropyridine derivatives by HPLC by both photodiode array and electrochemical detectors is reported.

The optimum mobile phase was acetonitrile 0.05 M phosphate buffer pH 3 (55/45, v/v) at a flow-rate of 1.5 mL/min.

Compounds I–VIII were determined with UV detection at 250 nm and by electrochemical detection at + 1200 mV.

Retention times varied between 3.0 and 14.0 minutes in the optimal experimental conditions.

Good linear relationships between the peak areas and concentration were found, with limits of quantification ranging between 1 x 10^?8 M and 1 x 10^?6 M. Repeatability studies showed average variation coefficients lower than 1% for a photodiode array detector. No significant differences between the detectors in sensitivity and selectivity were found.

Also, we used different degradation trials to test the selectivity of the methods. Results of these experiments revealed that the developed methods exhibited a good selectivity.