Reactions of diazoalkanes with unsaturated compounds 15. Catalytic reactions of unsaturated carbonyl compounds and their derivatives with diazomethane

The present study concerned with the influence of the nature of the acetal fragment in unsaturated compounds on the reactivity of the C=C bond in cyclopropanation reactions with diazomethane catalyzed by copper and palladium compounds. The acetal substituents at the α- or γ-position with respect to the C=C bond were found to exert an activating effect on the yields of cyclopropanation products compared to the starting unsaturated carbonyl compounds, which give 1,3-dipolar cycloaddition adducts with CH₂N₂ as by-products. Cyclopropanation of the double bonds appeared to be most efficiently catalyzed by Pd(acac)₂. Dedicated to Corresponding Member of the Russian Academy of Sciences E. P. Serebryakov on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 979–983, April, 2005.     

Isolation and investigation of the ethylene-producing enzyme of cotton

The activity of the ethylene-producing enzyme (EPE) in a homogenate of cotton leaves and in fractions obtained via differential centrifugation and fractional precipitation is studied. A model system is developed for testing EPE. The effect of known activators and inhibitors of ethylene biosynthesis on the EPE activity is studied. Chromatographic methods are used to prepare the highly purified enzyme from the water-soluble fraction of cotton proteins and to identify it as ACC-oxidase. The enzyme has MM ∼38 kDa and converts aminocyclopropanecarboxylic acid (ACC) into ethylene. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 654–657, September–October, 1999.     

Electrochemical control of association and deposition of tetraviologen calix[4]resorcin

The association and deposition of tetraviologen calix[4]resorcin MVCA-C ₅ ⁸⁺ can be controlled using the electrochemical reduction-reoxidation cycle of viologen units. The monomeric MVCA-C ₅ ⁸⁺ was converted into the highly molecular (MVCA-C ₅ ^4+· ) _n associate (π-polymer) by reducing it to the MVCA-C ₅ ^4+· tetra(radical cation) and completely returns to the starting monomeric state by reverse oxidation. The reduction to the neutral state MVCA-C ₅ ⁰ allowed calixresorcin to pass from solution to precipitate and the reverse oxidation led to its returning in solution.     

Controlling the Size and Morphology of Supramolecular Assemblies of Viologen–Resorcin[4]arene Cavitands

A novel class of self‐assembling nanoparticles is formed with viologen–resorcin[4]arene cavitands; the association model is strongly controlled by their hydrophobicity. Interestingly, the cavitand assemblies are designed through click chemistry to form self‐assembled noncovalently connected aggregates through counterion displacement. The iodide and benzoate ions are utilized as strongly polarizable counterions to induce cavitand self‐assembly. The counterion‐mediated decrease in hydrophilicity of the viologen–resorcin[4]arenes is the underlying trigger to induce particle formation. These particles can be used as nanocontainers and find their applications in delivery systems.     

Molecular structure of 5-[(triphenyl-phosphoranylidene)hydrazono]-exo-3-azatricyclo[5.2.1.02.6]decane-4-one

The molecular structure of 5-[(triphenylphosphoranylidene)hydrazono]-exo-3-azatricyclo[5.2.1.0^2.6]decane-4-one is determined. The C₂₇H₂₆N₃OP compound crystallizes in the space group P?1: a = 9.2163(9) Å, b = 11.1102(11) Å, c = 11.9397(12) Å, α = 74.284(2)°, β = 78.532(2)°, γ = 72.004(2)°.     

Synthesis and properties of cyclopropane derivatives of polybutadienes

Polymer products containing methoxycarbonyl-substituted cyclopropane groups in macromolecules with degrees of functionalization up to 40% have been obtained through the interaction of polybutadiene with methyl diazoacetate in an organic solvent in the presence of an organometallic catalyst. The comparative catalyst activity in the reaction of cyclopropanation of polybutadiene has been estimated. The incorporation of methoxycarbonyl-substituted cyclopropane groups into polydiene units results in substantial changes in the polymer properties: solution viscosity, melt flow, glass-transition temperature, and thermal stability.     

Hyperbolic smoothing function method for minimax problems

In this article, an approach for solving finite minimax problems is proposed. This approach is based on the use of hyperbolic smoothing functions. In order to apply the hyperbolic smoothing we reformulate the objective function in the minimax problem and study the relationship between the original minimax and reformulated problems. We also study main properties of the hyperbolic smoothing function. Based on these results an algorithm for solving the finite minimax problem is proposed and this algorithm is implemented in general algebraic modelling system. We present preliminary results of numerical experiments with well-known nonsmooth optimization test problems. We also compare the proposed algorithm with the algorithm that uses the exponential smoothing function as well as with the algorithm based on nonlinear programming reformulation of the finite minimax problem.     

Effect of cotton-seed biocidal peptides and gossypol on resistance to biotic factors

Peptide fractions were isolated from seeds of eight cotton varieties differing in resistance to fungal pathogens and cotton bollworm. Their ability to inhibit the growth of V. dahliae fungal conidiae and α-amylase from various sources was studied. A correlation was found between the fungicidal activity of the peptides and the resistance of the cotton varieties to the pathogens. α-Amylase of cotton bollworm was inhibited less by the isolated peptides than α-amylase of other insects that are not cotton pests. It was shown for the first time that gossypol inhibits α-amylase of insects. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 186-188, March-April, 2009.