Practical Enantioselective Arylation and Heteroarylation of Aldehydes with In Situ Prepared Organotitanium Reagents Catalyzed by 3‐Aryl‐H8‐BINOL‐Derived Titanium Complexes

A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl‐ and heteroaryllithium reagents with ClTi(OiPr)₃, is described. Titanium complexes derived from DPP‐H₈‐BINOL ( 3 d ; DPP=3,5‐diphenylphenyl) and DTBP‐H₈‐BINOL ( 3 e ; DTBP=3,5‐di‐tert‐butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl‐, aryl heteroaryl‐, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2–2 mol %). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2‐thienylmethanols can be synthesized enantioselectively by using commercially available 2‐thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol % catalyst loading, demonstrating its preparative utility.     

Conformational Analysis of Four Stereoisomeric Methyl 3-Acetoxy-2-Butyl-1-Cyclohexanecarboxylates and Their Derivatives in Solution

The conformational analysis of six-membered ring compounds such as mono- and disubstituted cyclohexane is a well-documented subject, and hence prediction of the most stable conformation of a given compound can be in general achieved with reasonable accuracy either by use of thermodynamic data or by spectroscopic methods.¹⁾ When considering polysubstituted cyclohexane, the configurational and the conformationay possibilities become large. The conformational aspects of 1,2,3-trisubstituted cyclohexanes would be complex depending on the nature of substituents because so many parameters are involved.¹⁾     

In vitro analysis of radioprotective effect of monoterpenes

Monoterpenes are naturally occurring hydrocarbons composed of two units of isoprenes. They exhibit antioxidant activity to scavenge reactive oxygen species, such as hydroxyl radicals. We investigated the potential of monoterpenes such as thymol, linalool, and menthol to act as radioprotectants. The proliferation of EL4 cells, a mouse lymphoma cell line, treated with linalool at a concentration of 500 μM or more was not affected by X-ray irradiation. Plasmid-nicking assay performed using formamidopyrimidine-DNA glycosylase showed that linalool prevented single strand breaks and oxidized purines on pUC19 plasmid DNA. These findings indicate that linalool has the ability to scavenge reactive oxygen species and is a potential radioprotector.     

Radiation Phenomena of Plasma Waves Part 3. Radiation from Finite Sources

Radiation phenomena of plasma waves has been reviewed in three parts, fundamental radiation theory, radiation from point sources, and radiation from finite sources. It is the author's impression that the theoretical prediction of the resonance cone by Kuehl (Phys. Fluids 5, 1095 [1962]) initiated much of the theoretical work. The experimental observation of the resonance cone by Fisher and Gould (Phys. Fluids 14, 857 [1971]) is an epoch-making work in the field of radiation problems from point sources. Although finite sources had been used for excitation of many plasma waves, the experimental confirmation of the radiation patterns from finite sources by Shen et al. (Rad. Sci. 5, 611 [1970]) has initiated much later work. Since thier investigations, radiation phenomena of plasma waves have been investigated and been made clear by many authors, as shown in this review paper Parts 1 - 3. The essential radiation phenomena from point sources have been clarified experimentally except for an observation of electromagnetic ion waves radiated from point sources. Radiation phenomena from finite sources will be investigated further because there are various sources required for various goals, e.g., for heating of plasma infusion devices, etc. These investigations will progress into nonlinear phenomena, instabilities, and inhomogenuous effects in plasmas. It is a great pleasure for the author of this review paper if he could give some insight or any help for further developments in plasma sciences.     

Effects of pre-treatment on the nitrogen isotope composition of Japanese black pine (Pinus thunbergii) tree-rings as affected by high N input

Temporal changes in the acquisition of nitrogen (N) are recorded in tree-rings together with unique N isotopic values. Some debate continues regarding the importance of wood pre-treatment in isotope analysis and, thus, this study focuses on the removal of labile components to determine the intrinsic nature of N in tree-rings. The total concentration and stable isotopic value of N in annual tree-rings were determined for two cores from Japanese black pine (Pinus thunbergii) from areas colonized by black cormorant (Phalacrocorax carbo). One core sample was also collected from a control site, without cormorants. Sharp increases in tree-ring δ(15)N values associated with migration of the cormorant population indicate positive incorporation of N from soils, whereas a less pronounced trend was observed for ring samples for periods without or substantially less migration, and for those obtained from the control site. All labile N components were removed by repeated extraction with toluene/ethanol (1:1) solution. Radial translocation of labile N is limited in tree-rings from Japanese black pine, providing intrinsic records on N acquisition. The difference in N isotopic values (up to 7.0‰) following pre-treatment was statistically significant for trees affected by the avian colony, whereas the pre-treatment of the control samples did not influence N values. The implication is that in agreement with previous studies pre-treatment is not necessary when trees are exposed to natural N concentrations in the soil but the removal of enriched δ(15)N labile components is necessary when woody plants are exposed to unusually high inputs of N into soils. However, the temporal trend in tree-ring δ(15)N series of the avian N affected trees did not change. Thus, if the priority is not the value but the trend then pre-treatment is not necessary.     

Fabrication of Sn-doped zinc phosphate glass using a platinum crucible

The authors investigate the structural change of a ZnO–P₂O₅ sintered matrix for the preparation of SnO-doped zinc phosphate (SZP) glass using a platinum crucible. Heat treatment of zinc oxide and ammonium phosphate at 800 °C causes the formation of a Zn₂P₂O₇-like species, which is effective in preventing damage to the platinum crucible. Although the thermal property of the glass was affected by added Al₂O₃, Al₂O₃ hardly affects the quantum efficiency of the SZP glass phosphor. This process is important for the fabrication of contamination-free phosphate glass using ammonium phosphate as a starting material.