Electrochemical Hydrogenation of Acetophenone and Methyl-4-isobutylacetophenone in a Two-phase Water–Organic System Containing β-Cyclodextrin

The possibility of the formation of inclusion complexes based on methyl-4-isobutylphenyl ketone, -cyclodextrin (-CD), and o-hydroxy propylated -cyclodextrin in an aqueous phosphate buffer is demonstrated by methods of NMR spectroscopy and cyclic voltammetry. Preparative electroreduction of acetophenone and methyl-4-isobutylphenyl ketone is performed on a lead electrode in aqueous phosphate and acetate buffers in the absence and presence of -CD and the composition of products of electrochemical reactions is ascertained. It is shown that the products of reduction of ketones are corresponding alcohols and pinacones. The possibility of asymmetric electrochemical hydrogenation of ketones in the presence of -CD, which yields relevant chiral alcohols, is shown.     

A rapid catalytic asymmetric synthesis of 1,3,4-trisubstituted pyrrolidines

The asymmetric synthesis of 1,3,4-trisubstituted pyrrolidines was accomplished in two steps from readily available starting materials. A 1,3-dipolar cycloaddition of an azomethine ylide to a propiolate ester followed by a Rh-catalyzed asymmetric 1,4-arylation of the resulting pyrroline with an arylboronic acid provided the desired 1,3,4-trisubstituted pyrrolidine products in good to excellent enantioselectivities.     

Effect of substituent in para-substituted anilines on the isomerization rate of 5-vinylbicyclo[2,2,1]hept-2-ene catalyzed by anilinepentacarbonyliron complexes

The isomerization kinetics of 5-vinylbicyclo [2,2,1]-hept-1ene to 5-enthylidenbicyclo [2,2,1] hept-2-ene in the presence of iron pentacarbonyl and parasubstituted anilines has been investigated. The kinetic data correlate with -constants of the substitutes according to Jaffe.

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5- [2,2,1]-2- 5- [2,2,1] -2- - . - .

     

Conformational and phase transitions in lysozyme-thermosensitive polyelectrolyte complexes

The interaction of a small globular protein, lysozyme, with a thermosensitive N-isopropylacrylamide-sodium styrene sulfonate copolymer at pH 4.6 was studied by high-sensitivity differential scanning calorimetry. It was shown that, under these conditions, the copolymer and the protein are involved in formation of polyelectrolyte complexes. It was demonstrated that complexation affects the conformational state of lysozyme. One heat capacity peak attributed to protein denaturation or two well-resolved peaks related to denaturation of free and bound proteins were observed in the DSC curves depending on the mixture composition. For both forms of lysozyme, denaturation parameters (temperature and enthalpy) were determined as a function of mixture composition. For mixtures with low lysozyme contents, the above parameters of bound protein denaturation were independent of the mixture composition. At higher protein contents, these parameters increased with a rise in the protein content. The binding isotherm for the protein with the copolymer was obtained from calorimetric data at 64 ± 1°C. An analysis of the isotherm suggests that the native protein is bound to 24 equivalent binding sites of the polymer matrix. It was established that there are nearly 10 charged units of the copolymer per protein molecule in the native conformation. Lysozyme in the unfolded conformation additionally interacts with hydrophobic groups of the copolymer.     

Anodic Processes Involving Trifluoromethyl Cobaloxime and Nucleophiles

Anodic oxidation of trifluoromethyl cobaloxime (CF₃)Co(DH)₂Py in the presence of such nucleophiles as pyridine or NO^– ₃ and C₆F₁₃COO^– anions is studied. A controlled-potential electrolysis and ¹⁹F NMR spectroscopy show the anodic reaction products to contain compounds with the bond >N–CF₃. A mechanism for the reaction between a labile Co(+4) complex and pyridine is offered. At potentials more positive than that of the Co(+3) Co(+4) oxidation, secondary products of electrochemical reaction form and are revealed by a cathodic reduction peak.