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The electrotransport properties and the structure of polyaniline-modified sulfocationic membranes MK-40 and MF-4SK are studied in solutions of sulfuric acid and sulfates of nickel and chromium. The modification by polyaniline is performed in elelectrodialyzer. The decrease in conductivity and diffusion permeability of membranes after their modification with polyaniline is assessed in electrolyte solutions of different nature. The key effect of the counter-ion charge on the conductivity of original and modified membranes is confirmed. The unusual effect of the decrease in the MF-4SK/PANI membrane conductivity with an increase in the concentration of solutions containing multiply-charged cations is observed. The information acquired by porosimetry on the effect of multiply-charged ions on the structure of homogeneous and heterogeneous membranes is supplemented by calculations of the transport and structure parameters using the microheterogeneous model of ion-exchange membrane. Based on the analysis of parameters of current–voltage curves in solutions of nickel sulfate and sulfuric acid, the prospects of using the modified membranes in the electrodialysis of solutions containing sulfuric acid and multiply-charged ions are assessed. [ABSTRACT FROM AUTHOR]

A new chiral 10,11-didehydro analog of epothilone D with isosteric substitution in the C15–C3 fragment of natural epothilones has been synthesized. [ABSTRACT FROM AUTHOR]

The limiting diffusion current density in electromembrane systems is theoretically estimated by using refined Pears equation and different model approaches for the calculating of the counter-ion transport number in the membrane and its diffusion permeability differential coefficient. To this purpose, experimental data on specific conductivity, diffusion and electroosmotic permeability, as well as the apparent transport numbers of counter-ions in perfluorinated sulfocationite MF-4SK membranes with different specific water content over wide range of sodium chloride solution concentrations are used. Special features of different approaches and models used in the evaluating of the membrane parameters necessary for calculating the electrodiffusion characteristics and the limiting diffusion current are analyzed. The possibility of adequate theoretical estimation of the limiting diffusion current for ion-exchange membranes modified by organic and inorganic dopants is shown. This allows predicting the effectiveness of membranes in electromembrane processes basing on relatively simple measurements of the transport characteristics of the modified ion-exchange membranes. [ABSTRACT FROM AUTHOR]

1,3-Cyclopentadienes, fulvenes and their derivatives regio- and stereoselectively react with the in situ generated dichloroketene to form the corresponding bicycles of the [3.2.0]heptane topology. The latter are transformed into block synthons with a higher synthetic potential, including chiral ones. A number of examples are used to demonstrate the possibility of their use in the targeted synthesis of bioactive cyclopentanoids. [ABSTRACT FROM AUTHOR]

Demineralization of a solution containing aniline and sulfuric acid was studied at different voltages on the electrodialyzer with heterogeneous anion-exchange membranes MA-41 and perfluorinated homogeneous cation-exchange membranes MF-4SK. The main mass transfer characteristics of the process were evaluated. The limiting current density was evaluated for the cation- and anion-exchange membrane. The limiting current density on the anion-exchange membrane was reached much earlier than on the cation-exchange membrane. Electrodialysis was found to be most effective at voltages of up to 6 V in a pair chamber. [ABSTRACT FROM AUTHOR]

Acylation of cloprostenol with acetic anhydride in pyridine, followed by treatment of the exhaustive acetylation product with water, gave 9,11,15-triacetoxy derivative whose reaction with 1,1′-carbonyldiimidazole afforded the corresponding imidazolide. The subsequent condensation with 2-aminoethanol and removal of acetate protecting group lead to the formation of N-(2-hydroxyethyl) cloprostenol amide. Analogous N-ethyl amide was synthesized by reaction of cloprostenol methyl ester with aqueous ethylamine. [ABSTRACT FROM AUTHOR]

The review covers the literature on the total synthesis of cross-conjugated cyclopentenone prostaglandins (PGs), published from 2000 until present. In view of the specific features differentiating cyclopentenone PGs from prostaglandins of other types, special attention in the review is focused on the biochemistry and physiological functions of the most important representatives of cyclopentenone PGs. Data on analogs of cyclopentenone PGs are presented, and certain aspects of structure-activity correlations and potential practical applications of these compounds are discussed. [ABSTRACT FROM AUTHOR]

The synthesis of acyclic precursors to epothilone D analogs has been explored. Optimal conditions have been found for enolization of (1R)-1-(1,3-dithiolan-2-yl)-1-(methoxymethoxy)-2,2-dimethylpentan-3-one and its aldol condensation with C6‒C21 and C6‒C9 aldehydes. [ABSTRACT FROM AUTHOR]

The condensation of ethyl 7-(2-oxo-5-formulcyclopentyl)heptanoate by Wittig reaction with the ylide prepared from [(2 E)-3-methylhept-2-en-1-yl]triphenylphosphonium bromide afforded ethyl (±)-(13,15-dideoxy)-16-methyl-9-oxoprosta-13( E,Z),15( E)-dienoate as a mixture of two isomers, 2:1. [ABSTRACT FROM AUTHOR]