Preparation, Characterization and Nonlinear Optical Properties of One-Dimensional Tetranuclear Platinum Complex/Alumina Composite Films

The preparation of transparent films consisting of one-dimensional tetranuclear platinum complex and an alumina gel was attempted. Characterization of the composite films obtained was performed by UV-Vis-NIR spectroscopy. From the redox behavior of the complex in films, it was confirmed that the complex maintains the tetranuclear structure in the alumina gel, when the content of the complex is low. However, it seems to turn into another complex with a longer platinum chain, as the content of complex in the gel increases. The third-order nonlinear susceptibility (³) values of composite films was estimated from the third harmonic generation (THG) Maker-fringe measurements of this preliminary study.     

Chemo- and regioselective direct hydroxylation of arenes with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate

Peroxide in, phenol out: The catalyst [γ-PW(10)O(38)V(2)(μ-OH)(2)](3-) showed high activity in the hydroxylation of various aromatic compounds with aqueous H(2)O(2). The system was regioselective, producing para-phenols from monosubstituted benzene derivatives. Furthermore, alkylarenes with reactive side-chain C?sp?3-H bonds could be chemoselectively hydroxylated without significant formation of side-chain oxygenated products.     

Low pressure Pd-catalyzed carbonylation in an ionic liquid using a multiphase microflow system

A low pressure microflow system was developed for palladium-catalyzed multiphase carbonylation reactions in an ionic liquid. The microflow system resulted in superior selectivity and higher yields in carbonylative Sonogashira coupling and amidation reactions of aryl iodides compared to the conventional batch system.     

Catalytic oxidation of hydrocarbons with hydrogen peroxide by vanadium-based polyoxometalates

Vanadium compounds have attracted much attention because they have widely been used for homogeneous, heterogeneous, industrial, and biological oxidation processes with alkyl hydroperoxides, H₂O₂, and O₂. The present review summarizes recent developments for homogeneous and heterogeneous liquid-phase oxidation of hydrocarbons with H₂O₂ catalyzed by vanadium complexes and vanadium-based polyoxometalates including our recent studies on selective oxidation of hydrocarbons with H₂O₂ catalyzed by divanadium-substituted polyoxotungstates, [γ-SiW₁₀O₃₆V₂(μ-OH)₂]^4? (I) and [γ-PW₁₀O₃₆V₂(μ-OH)₂]^3? (II).     

One-step synthesis of oxazolinoazetidinones from penicillin sulfoxides: potential intermediates for 1-oxacephem synthesis

Reaction of penicillin sulfoxides with a tervalent phosphorous compound in the presence of a catalytic amount of squaric acid gave oxazolinoazetidinones, potential intermediates for synthesis of 1-oxacephems, in good yields.2β-Chloromethyl- and 6α-methoxypenicillin sulfoxides also undergo this reaction. The reaction contrasts with the well-known Cooper reaction which usually gives thiazolinoazetidinones.     

A novel class of platelet activating factor (PAF) antagonists. II. Modification of the 2-position of the glycerol backbone of PAF-sulfonamide isosteres.

In a continuing effort to obtain more potent platelet activating factor (PAF) antagonists, we tried to synthesize a series of PAF-sulfonamide isosteres in which the substituent at the 2-position was modified to an acetoxy equivalent other than the methoxy group. These modifications produced highly active PAF antagonists. Compound 3-[2-(5-methyl-2H-tetrazol-2-yl)-3-(octadecylcarbamoyloxy) propylaminosulfonyl]propylquinolinium iodide (52) showed the most potent activity in the in vitro inhibitory effect on PAF-induced platelet aggregation in rabbit platelet-rich plasma (IC50 = 125 nM) and also in the in vivo protective effect on PAF-induced lethality in mice, with prolonged duration of action. Optically active enantiomers of this compound were synthesized and the (S)-(-)-isomer (IC50 = 87 nM) was found to be three times more potent that the (R)-(+)-isomer (IC50 = 289 nM), clearly exemplifying the enantioselectivity in the PAF-antagonist action of this novel compound.