Synthesis and Characterization of p—[Perfluoro—1—（2—fluorosulfonylethoxy）]ethylated Polystyrene

A new fluorinated polystyrene bearing a p-sulbstiuted perfluoro[1-(2-fluorosulfonylethoxy)]ethyl group was synthesized via one-electron oxidation of polystyrene by perfluoro[2-(2-fluorosulfonylethoxy)]propionyl peroxide at different peroxide to polystyrene molar ratios.The yield of perfluoroalkylation decreases with the increase of the reactant molar ratio.The modified polymer has been characterized by various techniques:the ring pefluoro[1-(2-fluorosulfonylethoxy)]ethylation has been proved by FT-IR and ^19FNMR;the X-ray photoelectron spectra(XPS) show the maximum binding energy of F18,O18,C18(two kinds of carbon atoms,namely C-H and C-F)and S2p,respectively; desulfonylation of the fluorinated polystyrene appearing at 217℃ has been found by its thermogravimetric analysis (TGA).The determinations of contact angle,refractive index and glass transition temperature of the modified polymer have disclosed that when the contact angle increases with the increase of the molar ratio,the refractive index and glass transition temperature decrease.The polydispersity values indicate that the degradation of the polymer chains did not occur during the reaction.     

Amperometric determination of 6-mercaptopurine on functionalized multi-wall carbon nanotubes modified electrode by liquid chromatography coupled with microdialysis and its application to pharmacokinetics in rabbit

In this paper, multi-wall carbon nanotubes fuctionalized with carboxylic groups modified electrode (MWNT-COOH CME) was fabricated. This chemically modified electrode (CME) can be used as the working electrode in the liquid chromatography for the determination of 6-mercaptopurine (6-MP). The results indicate that the CME exhibits efficiently electrocatalytic oxidation for 6-MP with relatively high sensitivity, stability and long-life. The peak currents of 6-MP are linear to its concentrations ranging from 4.0×10⁻⁷ to 1.0×10⁻⁴ mol l⁻¹ with the calculated detection limit (S/N=3) of 2.0×10⁻⁷ mol l⁻¹. Coupled with microdialysis, the method has been successfully applied to the pharmacokinetic study of 6-MP in rabbit blood. This method provides a fast, sensible and simple technique for the pharmacokinetic study of 6-MP in vivo.     

A facile synthesis of (6S,1′S)-(+)-hernandulcin and (6S,1′R)-(+)-epihernandulcin

A facile total synthesis of (+)-hernandulcin (1) was accomplished from (−)-isopulegol in 6 steps with 15% overall yield. Epoxidation of (−)-isopulegol with m-chloroperbenzoic acid followed by opening of the epoxide 3a with prenyl Grignard afforded the tertiary alcohol 4a with correct C-6 and C-1′ stereochemistry as a major product. Oxidation of the secondary alcohol in compound 4a to the ketone 5a was accomplished in high yield by using TPAP and N-methylmorpholine N-oxide. Conversion of the ketone 5a to α,β-unsaturated ketone via organoselenium intermediate gave (+)-hernandulcin (1). This method was also successfully applied to the synthesis of (+)-epihernandulcin (2).     

STRUCTURE OF CRYSTALLINE DOMAINS IN SEMICRYSTALLINE BLOCK COPOLYMER THIN FILMS

Thin film morphology of a symmetric semicrystalline oxyethylene/oxybutylene diblock copolymer （E76B38） on silicon was investigated by tapping mode atomic force microscopy （AFM）. It is found that the nascent thin film is composed of multiple polymer layers having mixed thicknesses of L ≈ L0 and L ≈ L0/2 （L0 is the long period of the block copolymer in bulk） besides the first layer near the substrate. This shows that the crystalline domain in the block copolymer consists of double poly（oxyethylene） layers. Annealing leads to disappearance of the polymer layers with thickness L ≈L0/2, indicating that such polymer layers are metastable.     

Structure and electrical properties of Pb(Zr<Subscript>0.25</Subscript>Ti<Subscript>0.75</Subscript>)O<Subscript>3</Subscript> thin films on LaNiO<Subscript>3</Subscript>—Coated thermally oxidized Si substrates

Pb(Zr_0.25Ti_0.75)O₃ (PZT25) thin films were prepared on LaNiO₃-coated thermally oxidized silicon substrates by chemical solution deposition method, where LaNiO₃ electrodes were also prepared by a chemical solution deposition technique. The dielectric constant and dielectric loss of the PZT25 thin films were 570 and 0.057, respectively. The remanent polarization and coercive field were 20.11 μC/cm² and 60.7 kV/cm, respectively. The PZT25 thin films on LaNiO₃-coated thermally oxidized silicon substrates showed improved fatigue characteristics compared with their counterparts on plantium-coated silicon substrates.     

Intermolecular and intramolecular Diels-Alder cycloadditions of 3-ylidenepiperazine-2,5-diones and 5-acyloxy-2(1h)-pyrazinones

The 3-ylidenepiperazine-2,5-diones 16 and 39 and 5-acyloxy-2(1H)-pyrazinones 17 can serve as starting materials for the Diels-Alder reactions of alkenes and alkynes to the piperazine ring, under acidic conditions or in the presence of acetyl chloride, to afford tricyclic piperazine-2,5-diones 19, 20, 23-25, 27, 44, and 45. Intramolecular cycloadditions occur if 3-ylidenepiperazine-2,5-diones 30 and 32 are used as the starting materials. This procedure is a convenient path to bridged bicyclo[2.2.2]diazaoctane ring systems such as 31 and 33, the former being found in biologically active secondary mold metabolites, such as VM55599 (1) or brevianamide A (5), which have been isolated from various fungi. The synthesis of the indole compound 31 provided evidence for the proposed biochemical pathway with a Diels-Alder reaction as key step. Quantum chemical calculations have revealed that piperazinones with a cationic azadiene moiety are the most reactive species in Diels-Alder cycloadditions.     

Synthesis of an optically active intermediate for A-ring of 19-nor- 1α,25-dihydroxyvitamin D3

An optically active intermediate 5 for A-ring of 19-nor-1a,25-dihydroxyvitamin D3 2 has been synthesized in five steps, starting from readily available, inexpensive D( )-xylose 6 with good yield.     

Furostanol saponins with inhibitory action against COX-2 production from Tupistra chinensis rhizomes

Two furostanol saponins were obtained from the n-butanol fraction of methanol extract from Tupistra chinensis rhizomes,a folk medicine of Shennongjia Forest District of Hubei Province.Their structures were determined as (25S)-26-O-(β-D-glucopyranosyl)- furost-1β,3β,22α,26-tetrol-3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glucopyranoside (1) and (25R)- 26-O-(β-D-glucopyranosyl)-furost-1β,3β22α,26-tetrol 3-O-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→2)-β-D-glu- copyranoside (2),on basis of chemical and spectroscopic evidences.1 and 2 displayed marked inhibitory action towards COX-2 production in macrophages of the rat abdomen induced by LPS at 20μg/mL.     

Solid-phase synthesis of 4-biaryl-piperidine-4-carboxamides

A novel solid-phase synthesis of 4-biaryl-piperidine-4-carboxamides has been developed using FDMP resin with a carboxamide as the anchor point. With this approach, three points of diversity were incorporated into a GPCR-directed scaffold. Final products were obtained in good purity and yield.     

CHEMOTHERAPEUTIC POLYMERS Ⅻ. SYNTHESIS AND ANTITUMOR ACTIVITY OF POLYAMIDES CONTAINING 5-FLUOROURACILS AS PENDANT GROUP

Six polyamides with pendant 5-fluorouracil group were synthesized by the polycondensation ofdi-p-nitrophenyl N-(5-fluorouracil-1-acetyl)glutamate with a series of polymethylene diamines.All of the new polyamides obtained are soluble in water. Their chemical structures were confirmedby ~1H NMR, UV and IR spectra as well as elemental analyses. The antitumor activity of some ofthese polyamides were tested against Ehrlich Ascites Carcinoma in mice, III_a showed an inhibitionrate of 43%.