Diastereoselective Aldol Reaction with an Acetate Enolate: 2,6-Bis(2-isopropylphenyl)-3,5-dimethylphenol as an Extremely Effective Chiral Auxiliary

A C ₂ -symmetrical phenol was used as a chiral auxiliary in the asymmetric aldol reaction of chiral acetates with various aldehydes [Eq. (a)]. The reaction proceeds readily under mild conditions to provide aldol adducts with high enantioselectivity. LDA=lithium diisopropylamide.     

AtTrxh3, a Thioredoxin,Is Identified as an Abscisic AcidBinding Protein in Arabidopsis thaliana

Abscisic acid (ABA, 1) is a plant hormone that regulates various plant physiological processes such as seed developing and stress responses. The ABA signaling system has been elucidated; binding of ABA with PYL proteins triggers ABA signaling. We have previously reported a new method to isolate a protein targeted with a bioactive small molecule using a biotin linker with alkyne and amino groups, a protein cross-linker, and a bioactive small molecule with an azido group (azido probe). This method was used to identify the unknown ABA binding protein of Arabidopsis thaliana. As a result, AtTrxh3, a thioredoxin, was isolated as an ABA binding protein. Our developed method can be applied to the identification of binding proteins of bioactive compounds.     

Observation of traveling thermoacoustic shock waves (L)

Shock waves were explored in the thermoacoustic spontaneous gas oscillations occurring in a gas column with a steep temperature gradient. The results show that a periodic shock occurs in the traveling wave mode in a looped tube but not in the standing wave mode in a resonator. Measurements of the harmonic components of the acoustic intensity reveal a clear difference between them. The temperature gradient acts as an acoustic energy source for the harmonic components of the shock wave in the traveling wave mode but as an acoustic energy sink of the second harmonic in the standing wave mode.     

Conversion of disilanes to functional monosilanes: XII. The palladium(0)-catalyzed dechlorinative silylation of benzylic chlorides with methylchlorodisilanes. A facile route to benzylmethylchlorosilanes

This paper describes the facile dechlorinative silylation of benzylic chlorides of types XC₆H₄CH₂Cl (X = H, Me and Cl) and ClCH₂C₆H₄CH₂Cl (o-, m- and p-isomers) with methylchlorodisilanes ClMe₂SiSiMe₂Cl, ClMe₂SiSiMeCl₂ and Cl₂MeSiSiMeCl₂ in the presence of Pd(PPh₃)₄ to give the corresponding benzylmethylchlorosilanes in good to high yields.     

The extraction of thorium from nitric acid solutions by long-chain aliphatic amines

The partition of thorium between nitric acid solutions and solutions of long-chain aliphatic amines in benzene is described. The organic phase was examined by infrared spectroscopy. Tertiary amines are more efficient extractants for thorium than are secondary amines; the efficiency is enhanced when the alkyl chain is branched and is strongly influenced by the organic solvent used as diluent.     

Novel phenolic glycoside dimer and trimer from the whole herb of Pyrola rotundifolia

From the water-soluble constituents of the whole herb of Pyrola rotundifolia (Pyrolaceae), one novel phenolic glycoside dimer, pyrolaside A (1), and one novel phenolic glycoside trimer, pyrolaside B (2), together with two known phenolic glycosides homoarbutin (3) and isohomoarbutin (4), were isolated. The structures were elucidated by spectroscopic analysis and confirmed with chemical degradation. In vitro tests for antimicrobial activity showed pyrolaside B (2) to possess significant activity against two Gram-positive organisms, Staphylococcus aureus and Micrococcus luteus.     

Analysis of the π-electronic structure of infinitely large networks. I. Some remarks on the characteristic polynomial and density of states of large polycyclic aromatic hydrocarbons

General expressions of the characteristic polynomials of various series of cyclic and linear polymers of polycyclic aromatic hydrocarbons are presented, i.e., polyacene, zigzag-polyacene, 1,4-dimethylbenzene polymer, polyperylene, etc. The densities of states of cyclic and linear polymers with the same repetitive units are shown. In some cases the allowed region of the energy levels of these polymers is found not to be the same. Several related problems are discussed.     

The extraction of divalent cobalt,copper, zinc,and cadmium from hydrochloric acid solutions by tri-n-octyl phosphine oxide

The partitions of divalent cobalt, copper, zinc and cadmium between hydrochloric acid solutions and solutions of tri-n-octyl phosphine oxide (TOPO) in benzene or kerosene have been investigated under different conditions. Further the absorption spectra of both the aqueous and organic phases have been examined, and the infra-red spectra of the organic phases have been studied. As a result, it is found that the order of the extraction efficiency of TOPO for divalent metals is Zn > Cd > Cu > Co at low aqueous acidity; Zn > Cd > Co > Cu at higher acidity. The mechanism of extraction is discussed on the basis of the results obtained.     

Effects of aging and oxidation on positronium formation in polyethylenes

Positron annihilation lifetimes (PAL) have been measured for polythylenes (PEs) under differenr conditions of heat treatment. It is shown that the intensity, I₃, of the long-lived component of positronium (Ps) shows hystereses between the heating and cooling processes due to aging effect. It is also shown that about half of Ps observed at low temperatures below the glass transition is inhibited after the sample is heat-treated above the melting point in the atmosphere containing oxygen. It is suggested that carbonyl groups (C=0) formed by thermal oxidation can inhibit Ps formation through trapping the precursors of Ps, e⁺ and/or e^-.     

The thermal decomposition of zirconium oxyhydroxide

The thermal decomposition of zirconium oxyhydroxides prepared by the mixture of aqueous zirconium oxychloride solutions and aqueous solutions of sodium hydroxide or ammonium hydroxide under various conditions has been examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectrophotometry. As a result, it is seen that the thermal decomposition of zirconium oxyhydroxide, in which the composition is ZrO_2-x(OH)_2xyH₂O where x2 and 1y<2, proceeds according to the following process: