Palladium-catalyzed aminoallylation of activated olefins with allylic halides and phthalimide

The three-component aminoallylation reaction of the activated olefins 2 with the phthalimide 1a and allyl chloride proceeded very smoothly in the presence of Pd(2)dba(3).CHCl(3) (5 mol %)/P(4-FC(6)H(4))(3) (40 mol %) and Cs(2)CO(3) (3 equiv against 2) in dichloromethane at room temperature to give the corresponding aminoallylated products, N-pent-4-enylphthalimides 3, in 58-99% yields. The reaction of oxazolidinone 1b also proceeded very smoothly to give N-(2,2-dicyano-1-phenylpent-4-enyl)oxazolidinone in a quantitative yield; however, the Tsuji-Trost-type allylation products 4 were obtained in the case of dibenzylamine, N-tosylaniline, and pyrrolidin-2-one. Further, 2 underwent cycloaddition with N-tosylvinylaziridine 9a in the presence of Pd(2)dba(3).CHCl(3) (5 mol %)/P(4-FC(6)H(4))(3) (40 mol %) in THF at room temperature, giving the corresponding pyrrolidines 11 in 69-99% yields.     

Synthesis of 4-fluorinated UDP-MurNAc pentapeptide as an inhibitor of bacterial growth

4-Fluorinated UDP-MurNAc pentapeptide, 2, has been synthesized. In our previous study, UDP-MurNAc pentapeptide analogue 1 was found to be incorporated into the bacterial cell wall through biosynthesis. Compound 2 showed growth-inhibition activity against Gram-positive bacteria when it was added to growth media at 0.01 mg/mL. [structure--see text]     

Ceric-ion-initiated grafting of methyl methacrylate onto (1 → 5)-α-D-ribofuranan and (1 → 5)-α-D-xylofuranan

We report herein studies of grafting of MMA onto (1 → 5)-α-D -ribofuranan and (1 → 5)-α-D -xylofuranan by ceric ion initiation both in water and in dimethyl sulfoxide (DMSO). In aqueous medium, the graft polymer having high grafting (%) can be obtained easily without adding any nitric acid. The degradation of polysaccharide by the acidic ceric ion solution is not serious; 73–82% of its original molecular weight remained after the polymerization. In DMSO, graft polymers having lower grafting (%) and lower molecular weight of grafts were obtained.     

Synthesis of polyamides by the polyaddition of bisimidazoline with dicarboxylic acids

N,N′-Dipropionylethylenediamine was synthesized by the ring-opening addition reaction of 2-ethyl-2-imidazoline with propionic acid at 220°C. By applying this reaction to polymerization, polyamides were synthesized by the ring-opening polyaddition reaction at 220°C. of 1,4-bis(imidazoline-2-yl)butane with adipic acid, succinic acid, sebacic acid, and terephthalic acid. The reaction product of 1,4-bis(imidazoline-2-yl)butane with adipic acid, which was proposed to be nylon 26, was compared with an authentic sample of nylon 26 and shown to possess a very similar infrared spectrum and melting point.     

Characterization of chemiluminescence from singlet oxygen under laminar flow conditions in a micro-channel and its quenching with beverages

Singlet oxygen was generated by reaction of sodium hypochlorite and hydrogen peroxide in a micro-channel. The two reagent solutions were delivered into the micro-channel by a syringe pump, providing a laminar flow liquid-liquid interface. The chemiluminescence from the singlet oxygen was emitted in the collapse of the interface due to molecular diffusion under laminar flow conditions. The chemiluminescence intensity was observed continuously and stably for each combination of reagents fed into the micro-channel; while, in the normal batch-type reactor the chemiluminescence peaks from singlet oxygen were observed within ca. 5 s. The features of the chemiluminescence emitted under laminar flow conditions were examined by changing the concentrations of sodium hypochlorite and hydrogen peroxide; the concentrations of 2.5 mM sodium hypochlorite and 7.5 mM hydrogen peroxide provided highest chemiluminescence intensities without bubble formation. Also, the effects of beverages, such as green tea, coffee, white wine, red wine, and sake (rice wine), on the chemiluminescence intensity as well as the concentrations of sodium hypochlorite and hydrogen peroxide were examined. The chemiluminescence intensities observed with addition of the beverages to the reagents decreased in the following orders; green tea > coffee > red wine > rice wine > white wine (being added to sodium hypochlorite); coffee > white wine > green tea > red wine > rice wine (being added to hydrogen peroxide). It was found that coffee decreased the chemiluminescence intensity (ca. 33% chemiluminescence decrease) without altering the concentrations of sodium hypochlorite or hydrogen peroxide. The cause of the decrease in chemiluminescence with coffee is discussed.     

Isomerization of aldehyde-2,4-dinitrophenylhydrazone derivatives and validation of high-performance liquid chromatographic analysis

The most widely used method for qualitative and quantitative analysis of carbonyl compounds is the 2,4-dinitrophenylhydrazine method through the formation of 2,4-dinitrophenylhydrazone derivatives. However, this method may cause an analytical error because 2,4-dinitrophenylhydrazones have both E- and Z-stereoisomers. Purified aldehyde-2,4-dinitrophenylhydrazone demonstrated only the E-isomer. However under UV irradiation and the addition of acid, both E- and Z-isomers were seen. The spectral patterns of Z-isomers were different from those of E-isomers and the absorption maximum wavelengths were shifted towards shorter wavelengths by 5-8 nm. An equilibrium Z/E isomer ratio was observed in 0.02-0.2% (v/v) phosphoric acid solutions. In the case of acetaldehyde- and propanal-2,4-dinitrophenylhydrazones, the equilibrium Z/E isomer ratios were 0.32 and 0.14, respectively. However, when irradiated with ultraviolet light at 364 nm, the isomer ratios were increased beyond this constant ratio and reached 0.55 and 0.33, respectively. Zero-order rates for decreases of aldehyde derivatives were observed under UV irradiation (364 nm), however the decreases of concentration were not observed in phosphoric acid solutions. The best method for the determination of aldehyde-2,4-dinitrophenylhydrazones by HPLC is to add phosphoric acid to both the sample and the standard solution, to form a 0.02-1% acid solution.     

Stability of crown ether complexes: a mo theoretical study

Calculation using CNDO/2 method have been performed for the crown ethers and their cation complexes. The photoelectron spectra of 18-crown-6 and 12-crown-4 are well described by the present MO calculations. The orbital interactions between the crown ligand and the cation indicate the importance of the charge transfer interaction for the complex formation. The destabilization energy due to the ring-shrinking (~ 0.5 eV) is very small compared with the complexation energy (5–8 eV). The stability of the complex was reasonably explained by the considering the hydrated species of the cation and the complex, indicating the important role of the solvation effect in the selectivity of the crown ether to the cation.