Palladium-catalyzed direct coupling reaction of propargylic alcohols with arylboronic acids

The direct coupling of propargylic alcohols with arylboronic acids has been achieved using palladium catalyst. Various propargylic alcohols and arylboronic acids can be coupled to afford the corresponding allenic and propargylic arenes, which are selectively produced depending on the substituent on the propargylic alcohol, respectively.     

Structure-activity relationship (SAR) studies on oxazolidinone antibacterial agents. 1. Conversion of 5-substituent on oxazolidinone

A structure-activity relationship (SAR) study on 5-substituted oxazolidinones as an antibacterial agent is described. The oxazolidinones, of which 5-acetylaminomethyl moiety was converted into other functions, were prepared and evaluated for antibacterial activity. Elongation of the methylene chain (8) and conversion of the acetamido moiety into guanidino moiety (12) decreased the antibacterial activity. The replacement of carbonyl oxygen (=O) by thiocarbonyl sulfur (=S) enhanced in vitro antibacterial activity. Especially, compound 16, which had the 5-thiourea group, showed 4-8 stronger in vitro activity than linezolid. Our SAR study revealed that the antibacterial activity was greatly affected by the conversion of 5-substituent.     

Woodfordin C, a macro-ring hydrolyzable tannin dimer with antitumor activity, and accompanying dimers from Woodfordia fruticosa flowers

Three new dimeric hydrolyzable tannins, woodfordins A, B and C, along with seven known hydrolyzable tannins, including oenothein B, a dimer exhibiting marked host-mediated antitumor activity, were isolated from an Indonesian crude drug, Sidowayah [dried flowers of Woodfordia fruticosa (L.) Kurz (Lythraceae)]. The structures of the new tannins were elucidated based on chemical and spectral evidence. Woodfordin C, having a macro-ring structure, was also found to exhibit a significant antitumor activity.     

Polymerization of vinyl chloride and copolymerization with propylene by a ternary catalyst system

Polymerization of vinyl chloride by the ternary catalyst system of VOCl₃–AIR_nCl_3–n complexing agent was investigated. It was suggested that the formation of a polar complex (or charge-transfer complex) between AlR_nCl_3–n and the complexing agent participated in the polymerization of vinyl chloride. In the copolymerization of vinyl chloride with propylene with the present catalyst system, it was more difficult to incorporate the propylene unit in the copolymer than with a typical radical catalyst.     

A mediator-type biosensor as a new approach to biochemical oxygen demand estimation

A novel biosensor for the determination of biochemical oxygen demand (BOD) was developed using potassium hexacyanoferrate(III) [HCF(III)] as a mediator. The sensor element consists of a three-electrode system, with both working and counter electrodes compactly integrated as a disposable using etching and electroplating processes. Pseudomonas fluorescens biovar V (isolated from a wastewater treatment plant) was immobilized on the surface of the working electrode using poly(vinyl alcohol)-quaternized stilbazol (PVA-SbQ) photopolymer gel. Synthetic wastewater described by the Organization for Economic Cooperation and Development (OECD) was used as a standard solution instead of glucose-glutamic acid synthetic wastewater. The conditions of amperometric measurement were optimized at +600 mV (vs. Ag/AgCl) operating potential, namely 40 mM HCF(III) in a 0.1 M phosphate buffer (pH 7.0) at 20 degrees C. The sensor response was linear from 15 up to 200 mg O l-1 BOD. The response time was 15 min at 200 mg O l-1 BOD. To demonstrate the wide metabolic range of activity of the sensor, the sensor response to 14 substances in four categories of organic compounds was investigated. Further, it was shown that the response of this BOD sensor was not influenced in samples with low concentrations of dissolved oxygen under the measuring conditions used. For real wastewaters, the BOD values were determined using the sensor and compared favorably with those determined by the conventional BOD5 method.     

Ferrocene-containing polymers. I. Radiation-induced polymerization of ferrocenylmethyl methacrylate

γ-Ray-induced polymerizations of ferrocenylmethyl methacrylate (FMMA) in crystalline and amorphous states were investigated with kinetical and ESR methods. In the crystalline state the polymerization of FMMA proceeded slowly and gave low-molecular-weight polymers, whereas in the amorphous state it proceeded rapidly and gave polymers of much higher molecular weight. Molecular weight distributions of these polymers were binodal. The temperature dependence and the dose-rate dependence of the polymerization rates were different between the two states. Wide-line nuclear magnetic resonance (NMR) spectra of the amorphous monomer suggested that the polymerization proceeded in a supercooled state. Electron spin resonance (ESR) spectra of γ-irradiated FMMA and 1,1′-ferrocenyl-di(methyl methacrylate) showed that ferrocene radicals and methacrylic radicals were formed simultaneously at low temperature; with increasing temperature the former radicals disappeared, whereas the latter changed into growing chain radicals. The yields of radicals were relatively low; this means that ferrocene groups in the monomers behave as a radiation energy absorber.