Cu-deposits on Mg metal surfaces promote electron transfer reactions

The enhancement of the electron transfer processes in the Grignard reagent formation-type ring silylation and the defluorination–silylation of perfluoroalkyl benzenes by Cu(0)-deposited Mg metal were confirmed. Microscopic analysis and substituent effects implied a different reduction process in the presence of Cu-deposited Mg metal than in the presence of bare Mg metal.     

High-speed deposition of RE123 film with large current capacity by hot-wall type PLD system

We have studied a hot-wall heating system to produce GdBa₂Cu₃O_y (GdBCO) films with large critical currents (I_c) at a high production rate by a pulsed-laser-deposition (PLD) method. GdBCO films fabricated at a production rate of 30 m/h under the optimized conditions, especially a distance of 95 mm between the target and the substrate (T–S), exhibited high critical current densities (J_c) of about 3 MA/cm² and I_c over 300 A at a thickness of 1–2 μm. Furthermore, long GdBCO tapes prepared by repeated depositions at each tape-passing speed of 80 m/h showed uniform I_c distribution along the longitudinal direction, because the hot-wall system enabled to stabilize temperature within a few degrees at 800 °C. A 170 m long tape with I_c over 600 A was successfully fabricated at a production rate of 16 m/h using a laser power of 360 W.     

QSAR and mode of action studies of insecticidal ecdysone agonists†

A series of our SAR and QSAR studies of synthetic moulting hormone agonists, dibenzoylhydrazines (DBH), exhibiting insecticidal/larvicidal activity are reviewed in this article. We prepared a number of analogues where various substituents are introduced into the two benzene rings of DBH and measured their biological activity using various biological systems. Larvicidal activity was against larvae of the rice stem borer Chilo suppressalis and the moulting hormone activity was in terms of the stimulation of N-acetylglucosamine incorporation in a cultured integument system of the same insect species. Binding affinity to the ecdysone receptor was assayed with intact Sf-9 cell lines in which the ADME processes are negligible as well as using receptor proteins obtained by in vitro translation of the responsible cDNA cloned from cell-free preparation of integumentary tissue of C. suppressalis. Variations in the biological activity indices were either correlated between two types of activity or correlated using physicochemical molecular and substituent parameters in terms of the classical QSAR. Comparisons among correlations and with recently revealed X-ray crystallographic findings clearly indicate the physicochemical meaning of parameters significant in the correlation equations to help understanding molecular mechanism of the moulting hormonal action.     

Synthesis of Unsaturated Nitriles from Trisubstituted Olefins Via Ene-Type Chlorination

Unsaturated nitriles have been synthesized from trisubstituted olefins via ene-type chlorination and regioselective substitution with cyanide ion followed by double bond migration.     

A highly selective cobalt-catalyzed carbonylative cyclization of internal alkynes with carbon monoxide and organic thiols

Despite the fact that many transition-metal-catalyzed reactions of organosulfur compounds with internal alkynes are ineffective, cobalt carbonyl (Co₂(CO)₈) is an excellent catalyst for carbonylative cyclization of internal alkynes with carbon monoxide. When Co₂(CO)₈-catalyzed reactions of internal alkynes with organic thiols are conducted in acetonitrile under 4 MPa pressure of carbon monoxide, thiolative lactonization of internal alkynes successfully takes place with incorporation of two molecules of CO. This carbonylation provides a useful tool to prepare the corresponding α,β-unsaturated γ-thio-γ-lactones (butenolide derivatives) in good yields. In the cases of unsymmetrical alkynes, such as 2-octyne and 6-methyl-2-heptyne, the thiolative lactonization proceeds with moderate regioselectivity to give the butenolide derivatives on which the carbonyl group preferentially bonds to the less hindered acetylenic carbon. Mechanistic pathways about the present thiolative lactonization are also discussed.     

Yeasts and Lactic Acid Bacteria Mixed-Specie Biofilm Formation is a Promising Cell Immobilization Technology for Ethanol Fermentation

We previously found that some Saccharomyces cerevisiae and Lactobacillus plantarum remarkably formed mixed-specie biofilm in a static co-culture and deduced that this biofilm had potential as immobilized cells. We investigated the application of mixed-specie biofilm formed by S. cerevisiae BY4741 and L. plantarum HM23 for ethanol fermentation in repeated batch cultures. This mixed-specie biofilm was far abundantly formed and far resistant to washing compared with S. cerevisiae single biofilm. Adopting mixed-specie biofilm formed on cellulose beads as immobilized cells, we could produce enough ethanol from 10 or 20 % glucose during ten times repeated batch cultures for a duration of 10 days. Cell numbers of S. cerevisiae and L. plantarum during this period were stable. In mixed-specie biofilm system, though ethanol production was slightly lower compared to S. cerevisiae single-culture system due to by-production of lactate, pH was stably maintained under pH 4 without artificial control suggesting high resistance to contamination. Inoculated model contaminants, Escherichia coli and Bacillus subtilis, were excluded from the system in a short time. From the above results, it was indicated that the mixed-specie biofilm of S. cerevisiae and L. plantarum was a promising immobilized cell for ethanol fermentation for its ethanol productivity and robustness due to high resistance to contamination.     

Photocycloaddition reaction of methyl 2- and 3-chromonecarboxylates with various alkenes

The irradiation of methyl 2- and 3-chromonecarboxylate in the presence of various alkenes afforded cyclobutane type adducts, whose structures were established by X-ray structural analysis. Methyl 2-chromonecarboxylate showed higher photochemical reactivity than methyl 3-chromonecarboxylate, in which endo adducts were yielded as major products.     

Ni‐Catalyzed [4+3+2] Cycloaddition of Ethyl Cyclopropylideneacetate and Dienynes: Scope and Mechanistic Insights

A detailed study of the Ni‐catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine‐membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes.