Application of high pressure induced by water-freezing to the direct catalytic asymmetric three-component List-Barbas-Mannich reaction

High pressure induced by water-freezing has been successfully applied to the direct catalytic asymmetric-three component List-Barbas-Mannich reaction, in which higher yield and better enantioselectivity can be realized than those from the reaction at room temperature under 0.1 MPa.     

Long-lived charge-separated state leading to DNA damage through hole transfer

The hole transfer causes the long-lived charge-separated state in DNA during the photosensitized one-electron oxidation of DNA. The combination of the transient absorption measurement and DNA damage quantification by HPLC clearly demonstrated that the yield of the DNA damage correlates well with the lifetime of the charge-separated state.     

Practical synthesis of a 1beta-methylcarbapenem, J-111,225, using 4-mercapto-2-[4-(N-methylaminomethyl)phenyl]pyrrolidine as a precursor

An effective and practical procedure for the synthesis of J-111,225 (1), a new 1beta-methylcarbapenem, was developed using 4-mercapto-2-14-(N-methylaminomethyl)phenyl]pyrrolidine (2a) as a precursor. The coupling reaction of 2a with p-nitrobenzyl (PNB)-protected 1beta-methylcarbapenem enolphosphate 3a and successive removal of PNB group afforded J-111,225 (1) in significantly increased yield compared to the ordinary procedure using a C-2 side-chain thiol with amino-protective groups.     

Hydrobromic acid-dimethyl sulfoxide reagent for dealkylation of 5,10-dialkyl-5,10-dihydrophenazines: Synthesis of 10-alkyl-2(10H)-phenazinones

By the reaction of 5,10-dialkyl-substituted 5,10-dihydrophenazine with hydrobromic acid in dimethyl sulfoxide at 90–110°, 10-alkyl-2(10H)-phenazinone was obtained as a major product. Brominated dihydrophenazine was isolated in the case of 1,6-dichloro-5,10-dimethyl-5,10-dihydrophenazine.     

Fixed point properties for semigroup of nonexpansive mappings on Fréchet spaces

In this paper, we shall establish a fixed point property on Fréchet spaces for left reversible semitopological semigroups generalizing some classical results.     

Laccase‐catalyzed polymerization of lignocatechol and affinity on proteins of resulting polymers

For the synthesis of a new biologically functional polymer from a natural resource by an environment‐friendly method, the laccase‐catalyzed polymerization of a lignin‐based macromonomer, lignocatechol, was carried out for the first time in ethanol–phosphate buffer solvent system to give crosslinked polymers in good yields. Lignocatechol was prepared by the phase separation system of lignin and catechol in aqueous sulfuric acid. The copolymerization was also performed with urushiol to afford the corresponding copolymers in high yields. The polymerization mechanism was estimated by the IR and pyrolysis GC‐MS measurements, suggesting that the polymerization proceeded mainly at the catechol ring through a quinone radical intermediate. The thermal properties were measured by the DSC, TG, and TMA analyses, indicating that the polymers had high thermal stabilities because of the crosslinked structures. In addition, it was found that the resulting polymers had the affinity of bovine serum albumin (BSA) and glucoamylase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 824–832, 2009     

Synthesis of proton conductive inorganic–organic hybrid membranes through copolymerization of dimethylethoxyvinylsilane with vinylphosphonic acid

Proton conductive inorganic–organic hybrid membranes were synthesized from dimethylethoxyvinylsilane (DMEVS), vinylphosphonic acid (VPA) and 3-glycidoxypropyltrimethoxysilane (GPTMS) through copolymerization followed by sol–gel process. The ratio of phosphorus to silicon in the copolymer almost corresponded to the charged molar ratio of VPA to DMEVS when the ratio of VPA to DMEVS was below 1/2. Self-standing, homogeneous, highly transparent membranes were synthesized from DMEVS–VPA copolymer and GPTMS via sol–gel condensation. Differential thermal analysis-thermogravimetry analyses indicated that these membranes were thermally stable up to 200 °C. The results of Fourier transform infrared and ¹³C NMR revealed that phosphonic acid groups of VPA were chemically bound to organosiloxane network. The copolymerization and condensation of (DMEVS–VPA)/GPTMS were confirmed by ³¹P and ²⁹Si NMR spectra. The proton conductivity of the hybrid membranes increased with phosphonic acid content. The membrane of (DMEVS–VPA)/GPTMS showed a remarkable conductivity of 6.3 × 10⁻² S cm⁻¹ at 130 °C and 100% relative humidity.