A highly efficient method for introduction of butenolide moieties to various electrophiles

Lithiated 5-(trimethylsilyl)furfuryl phenyl sulfides or the corresponding diphenylthioacetal can be used efficiently for introduction of butenolide moieties to various types of electrophilic reagents through their addition or substitution reactions followed by oxidation of the silylfuran moieties.     

Selective adsorption of thiophene and 1-benzothiophene on metal-ion-exchanged zeolites in organic medium

Adsorption of the organic sulfur compounds thiophene (TP) and 1-benzothiophene (1-BTP) in an organic model solution of hydrodesulfurizated gasoline (heptane with 1 wt% toluene and 0.156 mM (5 ppmw as sulfur) TP or 1-BTP) was studied by a batch method at 80 degrees C using metal-ion-exchanged Y-zeolites. Although NaY-zeolite or its acid-treated material rarely adsorbed the organic sulfur compounds, NaY-zeolites exchanged with Ag+, Cu2+, and Ce3+ ions and NH(4)Y-zeolites exchanged with Ce3+ ions showed markedly high adsorptive capacities for TP and 1-BTP. The sulfur uptake increased in the order CuY-zeolite(Na)相似文献   

Development of a simple system for dehydrocondensation using solid-phase adsorption of a water-soluble dehydrocondensing reagent (DMT-MM)

It has been indicated that hydrophilic solid powder to which aqueous solution of a novel dehydrocondensing reagent DMT-MM is adsorbed becomes a simple solid-phase dehydrocondensing reagent of low cost. Reaction in a liquid--liquid biphasic system on the surface of a solid phase with a large area was accelerated by suspending this powder in a dichloromethane solution of a carboxylic acid and an amine to be condensed. The reaction was rapid with a high yield despite the heterogeneity of the system. Like general solid-phase reagents, a hydrophobic carboxamide alone could be isolated at a relatively high purity only by filtration of the resulting suspension of reaction mixture.     

Synthesis of polysulfone-sulfides by polyadditions of dithiols to divinyl sulfones

Polyadditions of 1,6-hexanedithiol and 1,10-decanedithiol to divinyl sulfone (DVS) in hexamethylphosphoramide in the presence of triethylamine or potassium fluoride afforded polysulfone-sulfides (IIIa and IIIb) with inherent viscosities as high as 0.8 dl/g. Polymerizations of other dithiols with DVS and distyryl sulfone (DSS) were also carried out, however, only low-molecular-weight polymers were obtained. A series of polymers derived from DVS were highly crystalline and soluble in hot dimethylacetamide and hot m-cresol, whereas a polymer from DSS was quite amorphous and showed excellent solubility in a wide range of solvents. Polymers IIIa and IIIb had melting temperature below 150°C.     

Medicinal flowers. XII.(1)) New spirostane-type steroid saponins with antidiabetogenic activity from Borassus flabellifer

The methanolic extract from the male flowers of Borassus flabellifer was found to inhibit the increase of serum glucose levels in sucrose-loaded rats at a dose of 250 mg/kg, p.o. From the methanolic extract, six new spirostane-type steroid saponins, borassosides A-F (1-6), were isolated together with 23 known constituents. The structures of borassosides (1-6) were elucidated on the basis of chemical and physicochemical evidences. In addition, the principal steroid saponin, dioscin (13), inhibited the increase of serum glucose levels in sucrose-loaded rats at a dose of 50 mg/kg, p.o.     

Detection of non-cross-linking interaction between DNA-modified gold nanoparticles and a DNA-modified flat gold surface using surface plasmon resonance imaging on a microchip

Gold nanoparticles (GNPs) with fully matched DNA duplexes on their surfaces aggregate together without molecular cross-linking at high salt concentrations. The mechanism of this non-cross-linking (NCL) interaction has been elusive. In this paper, NCL interaction between duplex-modified GNPs and a duplex-modified flat gold surface is presented for the first time. This new experimental platform has enabled us to study the NCL interaction between duplexes with different sequences. We immobilized 15-base single-stranded (ss) DNA onto the surfaces of GNPs with a diameter of 40nm and onto a flat gold substrate. The GNPs were hybridized with 15-base ssDNA at a low salt concentration. A microfluidic device was used for simultaneous delivery of the following three components onto the gold substrate: the duplex-modified GNPs, 15-base ssDNA to be hybridized onto the substrate, and NaCl at a high concentration. Adsorption of the GNPs onto the substrate was monitored using surface plasmon resonance imaging. When the GNPs and the substrate had an identical sequence, the adsorption behavior was analogous to the aggregation behavior of GNPs in test tubes. Furthermore, we investigated 12 cases in which the GNPs and the substrate had completely different sequences, and obtained results suggesting that the NCL attraction force primarily depends on the terminal base pairs of the duplexes. This means that the main mechanism of the NCL interaction is likely to be inter-duplex base stacking rather than formation of Holliday junctions.