Formal Alder-ene reaction of a bicyclo[1.1.0]butane in the synthesis of the tricyclic quaternary ammonium core of daphniglaucins

A tricyclic substructure of the tetracyclic nitrogen core of the daphniglaucins was formed by an oxidative activation of the allyl side chain of a bicyclo[1.1.0]butylmethylamine, a spontaneous intramolecular formal Alder-ene reaction, and a selective cyclization of a triol intermediate.     

Syntheses of linear ethoxysiloxanes by the oxidative condensation of triethoxysilane

Linear ethoxysiloxanes were synthesized by the oxidative condensation of hydrosilane. Triethoxysilane was subjected to oxidation to form triethoxysilanol, and pentaethoxydisiloxane was formed by the condensation reaction of triethoxysilane with triethoxysilanol. Pentaethoxydisiloxane was also subjected to oxidative condensation to form a mixture of nona- and decaethoxytetrasiloxanes. In contrast, pentaethoxydisiloxane, heptaethoxytrisiloxane, and nonaethoxytetrasiloxanes were subjected to the reaction with ethanol in the presence of zinc to isolate hexaethoxydisiloxane, octaethoxytrisiloxane, and decaethoxytetrasiloxane, respectively.     

Theoretical and electrochemical studies on organometallic symmetrical schiff base complexes of Zn(II), Cu(II), Ni(II) and Co(II)

The electronic communication between two redox centres through a Schiff base complex has been investigated in a series of ethylenediimine-bis(1-ferrocenyl-1,3-butanedionate) complexes of Zn(II) 1, Cu(II) 2, Ni(II) 3 and Co(II) 4. Cyclic voltammetry experiments of 1 and 2 exhibit a unique two-electron reversible oxidation wave, whereas in the case of 3 and 4 two and three one-electron oxidation processes are, respectively, observed. These results suggest some electronic interaction between the iron atoms of the ferrocenyl groups. DFT calculations carried out on model complexes show that for all the studied compounds the removal of the first two electrons corresponds to the oxidation processes of the iron centres in the weakly coupled ferrocenyl termini. The electronic communication between the two iron centres increases on going from 1 to 4. Finally, a re-indexation of the bands observed in the UV-Visible spectra has been carried out using TDDFT calculations.     

Boron 1s photoelectron spectrum of 11BF3: vibrational structure and linewidth

The boron 1s photoelectron spectrum of (11)BF(3) has been measured at a photon energy of 400 eV and a resolution of about 55 meV. The pronounced vibrational structure seen in the spectrum has been analyzed to give the harmonic and anharmonic vibrational frequencies of the symmetric stretching mode, 128.1 and 0.15 meV, as well as the change in equilibrium BF bond length upon ionization, -5.83 pm. A similar change in bond length has been observed for PF(3) and SiF(4), but a much smaller change for CF(4). Theoretical calculations for BF(3) that include the effects of electron correlation give results that are in reasonable accord with the experimental values. The Lorentzian (lifetime) width of the boron 1s core hole in BF(3) is found to be 72 meV, comparable to the value of 77 meV that has been reported for CF(4).     

Decomposition behaviors of various crystalline celluloses as treated by semi-flow hot-compressed water

Various types of crystalline cellulose consisting of group I (cell I, III_I, IV_I) and group II (cell II, III_II, IV_II) prepared from cotton linter were adjusted for their degree of polymerization (DP) as starting materials. These celluloses were then treated by semi-flow hot-compressed water (HCW) at 230–270 °C/10 MPa/2–15 min to study their decomposition behaviors. The treatments performed resulted in residues of celluloses and water-soluble (WS) portions. Consequently, the crystallinity of the residues was found to remain the same, but the DP was reduced as the temperature increased. Additionally, X-ray diffractometry and Fourier transform-infrared analyses demonstrated that crystallographic changes occurred for residues of cell III_I, IV_I and III_II. Despite these changes, the overall results of the residues showed that group I has higher resistance to decomposing than group II. As for the WS portions, the yields of the hydrolyzed and degraded products were higher in group II than group I, indicating that group II is less resistant to decomposition by HCW treatment. Results for both the residues and WS portions are in agreement with each other, showing that the degree of difficulty of decomposition was higher in group I than group II. Therefore, the decomposition behaviors of the celluloses are due to differences in the crystalline forms.     

Projection of Si 1s photoexcited orbitals into resonant Auger electron spectra in KLL decays of Si(CH3)4 and SiF4

Spectator resonant KL(23)L(23) Auger electron spectra have been measured in the Si 1s photoexcitation region of Si(CH(3))(4) using monochromatized undulator radiation combined with a hemispherical electron spectrometer. The broad peak with high intensity in a total ion yield spectrum, coming mainly from excitation of a 1s electron into the 6t(2) vacant orbital, induces a spectator Auger decay in which the excited electron remains in its excited orbital. The component on the higher energy side of this peak through 1s excitation into a Rydberg orbital produces resonant Auger decays in which the excited Rydberg electron moves into a slightly higher Rydberg orbital, or is partly shaken up to a significantly higher Rydberg orbital. These findings of Si(CH(3))(4) indicate a clear contrast to those for SiF(4), in which the 1s excitation into a Rydberg orbital induces a shake-down phenomenon as well as a shake-up one. The results of these molecules exhibit a clear splitting effect among excited orbitals which are smeared out by overlapping due to lifetime widths and due to densely populated levels in the 1s electron excitation spectrum. This is consistent with the calculation on photoexcitation within the framework of density functional theory.     

Über die Phosphidierung des Nickels durch Phosphortrichlorid

On the Phosphidation of Nickel by Phosphorus Trichloride The phosphidation of nickel sheets by phosphorus trichloride vapor of 30 and 50 Torr has been studied kinetically by gravimetric means in the temperature range of 400–650°C in hydrogen atmosphere. The phosphidation proceeded generally according to the parabolic rate law. The parabolic rate constant increased with an increase of temperature, and its temperature dependence yielded the activation energies of about 33 and 47 kcal/mole for 400–550 and 550–650°C, respectively. X-ray and electron microprobe analyses showed that surfaces of the specimens phosphidized are made up of mixtures of Ni₂P and Ni₆P₅, and that at the phosphide/metal interface the compound Ni₂P is formed. The experiments using argon as carrier gas resulted in the formation of both the phosphides and the chlorides, and this fact could be explained in terms of thermodynamics.     

Medicinal foodstuffs. XXXI. Structures of new aromatic constituents and inhibitors of degranulation in RBL-2H3 cells from a Japanese folk medicine,the stem bark of Acer nikoense

Four new aromatic constituents, rhododendroketoside, (-)-sakuraresinoside, acernikol, and nikoenoside, were isolated from a Japanese folk medicine, the stem bark of Acer nikoense MAXIM. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. The principle cyclic diarylheptanoids were found to show inhibitory effects on the release of beta-hexosaminidase in RBL-2H3 cells.     

Synthesis of novel 1,4-, 3,4-, and 4,5-dihydropyrimidines: First successful POCl3 chlorination and regioselective alkoxycarbonylation

Chlorination of 5,6-dihydropyrimidine-4-(3H)-one derivatives (1) with POCl₃ gave 1,4(3,4)-dihydropyrimidines (3), whose alkoxycarbonylation (ClCOOREt₃N or NaH) afforded regioselectively novel compounds (4). A new Pummerer rearrangement of compound (1, X= ---S(O)CH₃) with ₃, gave compound (5h).     

Effect of Alkynyl Group on Reactivity in Photoaffinity Labeling with 2-Thienyl-Substituted α-Ketoamide

Minimalist photo-reactive probes, which consist of a photo-reactive group and a tag for detection of target proteins, are useful tools in chemical biology. Although several diazirine-based and aryl azide-based minimalist probes are available, no keto-based minimalist probe has yet been reported. Here we describe minimalist probes based on a 2-thienyl-substituted α-ketoamide bearing an alkyne group on the thiophene ring. The 3-alkyne probe showed the highest photo-affinity labeling efficiency.