One-pot synthesis of 3-fluoro-4-(trifluoromethyl)quinolines from pentafluoropropen-2-ol and their molecular modification

Pentafluoropropen-2-ol (PFP) was prepared by the reaction of hexafluoroacetone (HFA) with Mg/TMSCl. The one-pot tandem sequential reactions of PFP via Mannich addition with aldimines followed by Friedel-Crafts cyclization and aromatization afforded the title quinolines. A variety of corresponding 3-substituted quinolines were derived from the title quinoline by nucleophilic substitution of 3-fluorine with nucleophiles. A defluorinative transformation of the 4-trifluoromethyl group of the title quinoline with hydrazine afforded pyrazoloquinoline.     

Photocontrol of spatial orientation and DNA cleavage activity of copper(II)-bound dipeptides linked by an azobenzene derivative

Copper(II) ion-bound CysGly dipeptides linked by an azobenzene derivative were photoisomerized between the trans and cis forms. The two copper(II) ion centers were positioned close to each other in the cis form, whereas they were far away from each other in the trans form. The copper complex in the cis form exhibited DNA cleavage activity, whereas the activity in the trans form was negligible. The DNA cleavage activity of the cis form is attributed to the cooperation of the closely located copper(II) centers. The present results show the photocontrol of the cooperation of metal ions for DNA cleavage.     

Method validation by interlaboratory studies of improved hydrophilic oxygen radical absorbance capacity methods for the determination of antioxidant capacities of antioxidant solutions and food extracts

Hydrophilic oxygen radical absorbance capacity (H-ORAC) is a method for evaluating antioxidant capacities of solutions of hydrophilic compounds. In this study, we improved the original method for H-ORAC determination, and evaluated the precision of the two improved methods (methods A and B) by interlaboratory studies using 5 antioxidant solutions and 5 food extracts as test samples. An interlaboratory study of method A, in accordance with the harmonized protocol, demonstrated satisfactory performance (intermediate precision relative standard deviations (RSD(int)) ranging from 4.6 to 18.8%; the reproducibility relative standard deviations (RSD(R)) ranging from 7.0 to 21.1%, and the HorRat values ranging from 0.40 to 1.93). However, methodological problems remained, and a further improved method, method B, was thus developed. An interlaboratory study of method B by 5 participating laboratories showed better intermediate precision and reproducibility (RSD(int) and RSD(R) ranging from 1.8 to 9.4%, and from 4.4 to 13.8%, respectively), and all HorRat values for the test samples were less than 1.3, suggesting good performance for the H-ORAC measurement.     

Influence of Amines on Formation and Texture of Uniform Hematite Particles

The structure and properties of hematite particles obtained by hydrolysis of ferric chloride solution doped with various kinds of amines were examined by TEM, XRD, TG-DTA, N₂and H₂O adsorption, and zeta potential measurements. The shape of precipitates was concentration dependent; they changed from large spheres (diameter: ca. 820 nm) to cubes (edge length: ca. 400 nm) via double-spheres (long axis length: ca. 600 nm) with increasing monoamine concentrations. This effect was enhanced by increasing their pK_avalues. Much pronounced effects of di- and triamines on the particle formation were observed; cubic and double-spherical particles were obtained at a much lower concentration of di- and triamines and small spherical (diameter: ca. 100 nm) and diamond-like (long axis length: ca. 100 nm) particles were further produced at higher concentration. It was suggested that the acceleration of the rate of phase transformation from β-FeOOH to hematite induced by amines plays an important role for producing fairly uniform hematite particles with different shape and size. The hematite particles produced with amines contained small amounts of OH⁻ions in the lattice but were confirmed to be nearly single crystal.     

Chemical synthesis of 23 kDa glycoprotein by repetitive segment condensation: a synthesis of MUC2 basal motif carrying multiple O-GalNAc moieties

Peptide thioester corresponding to a MUC2 tandem repeat unit, which retains seven GalNAc moieties, was prepared by the Fmoc method followed by the low TfOH treatment to remove benzyl groups at the carbohydrate portions. The glycosylated peptide thioester was then consecutively joined by the activation of a thioester group by silver ions to obtain a MUC2 tandem repeat model composed of 141 amino acids with 42 GalNAc moieties.     

Preparation of Lead-Calcium Hydroxyapatite Solid Solutions by a Wet Method Using Acetamide

Lead-calcium hydroxyapatite solid solutions with different Pb/(Pb+Ca) molar ratios (X_Pb) were prepared by a wet method using acetamide (AA). The crystal phase and structure of the products depended on the aging period (t_a), Pb/(Pb+Ca) molar ratio ([X_Pb]), and AA concentration ([AA]) of the starting solution. At [AA]=1.6 mol dm⁻³ and t_a=6 days, the large needle-like PbCaHap particles were formed from solutions at [X_Pb]=0-0.6 and 0.9-1. Under the other AA concentrations and aging periods, pure PbCaHap particles could be obtained in a narrower region of [X_Pb]; e.g., PbCaHap was formed from solutions at [AA]=0.8 mol dm⁻³, t_a=6 days, and [X_Pb]= 0-0.1, 0.4-0.5, and 0.9-1.     

Three new sesquiterpenes from the black heartwood of Cryptomeria japonica

Three new sesquiterpenes, (4S)-2,6,10-bisaboratrien-4-ol-1-one (1), 1,8-epoxy-1(6),2,4,7,10-bisaborapenta-en-4-ol (2), and 1-methoxy-4-cadinene (3) have been isolated from the black heartwood of Cryptomeria japonica. Compounds 1 and 2 were designated sugikurojinols A and B, respectively, and the structures of compounds 1-3 were established by extensive NMR experiments. Compounds 1 and 2 were also examined for antibacterial activity against Staphylococcus aureus and Escherichia coli, and for termiticidal activity against Coptotermes formosanus SHIRAKI.     

A major urinary protein of the domestic cat regulates the production of felinine, a putative pheromone precursor

Domestic cats spray urine with species-specific odor for territorial marking. Felinine (2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid), a putative pheromone precursor, is excreted in cat urine. Here, we report that cauxin, a carboxylesterase excreted as a major urinary component, regulates felinine production. In vitro enzyme assays indicated that cauxin hydrolyzed the felinine precursor 3-methylbutanol-cysteinylglycine to felinine and glycine. Cauxin and felinine were excreted age dependently after 3 months of age. The age-dependent increases in cauxin and felinine excretion were significantly correlated. In mature cats, cauxin and felinine levels were sex-dependently correlated and were higher in males than in females. In headspace gas of cat urine, 3-mercapto-3-methyl-1-butanol, 3-mercapto-3-methylbutyl formate, 3-methyl-3-methylthio-1-butanol, and 3-methyl-3-(2-methyldisulfanyl)-1-butanol were identified as candidates for felinine derivatives. These findings demonstrate that cauxin-dependent felinine production is a cat-specific metabolic pathway, and they provide information for the biosynthetic mechanisms of species-specific molecules in mammals.     

Abietane diterpenoids from the barks of Cryptomeria japonica

From the bark of Cryptomeria japonica were isolated sugikurojins I (1) and J (2), and an abietane derivative (3) was obtained for the first time as a natural product. These structures were elucidated primarily through extensive NMR experiments. Sugikurojin I (1) has a unique skeleton incorporating an abietane diterpene and a 1,10-secocadinane sesquiterpene. Sugikurojin J (2) is a peroxyester of hydroxyabietane diterpene and isopimarane acid diterpene. Compound 3 was p-quinone acid, which occurred by cleavage between C-7 and C-8 of sugiol; it was deduced to [4'-isopropyl-1(S),3,3-trimethyl-3',6'-dioxo-bicyclohexyl-1',4'-dien-2(R)-yl]-acetic acid. Also obtained in this investigation were three known diterpenes (4-6).