Carbon-fluorine reductive elimination from a high-valent palladium fluoride

We have observed two high-valent arylpalladiumfluoride complexes that afford carbon-fluorine bond formation upon thermolysis.     

Reaction of p‐toluenesulfonyl isocyanate with polymers having amide moieties and hydrolysis of the obtained polymers

The chemical modification of polymers having amide moieties was carried out with p‐toluenesulfonyl isocyanate. The resulting polymers revealed high hydrolytic character. For example, poly(acrylamide) was refluxed with an excess amount of p‐toluenesulfonyl isocyanate in THF for 50 h to obtain a structurally modified polymer in 76% yield, whose sulfonylurea functionality was 100%. The resulting polymer was subjected to hydrolysis in a 1 M NaOH solution at 50 °C to convert 90% of the sulfonylurea in the side chain to the carboxylic acid moieties. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3440–3449, 2000     

Spin‐Orbit Coupling in All‐Electron Mixed Basis Approach

In the evaluation of the spin‐orbit coupling (SOC), the use of the L · S formula is invalid in the interatomic region where the effective potential is not spherically symmetric. This problem occurs in the LCAO, LMTO, and APW methods, while the plane‐wave pseudopotential and PAW methods cannot treat the spin‐orbit splitting (SOS) of core orbitals. To avoid these problems, the all‐electron mixed basis approach is adopted, which uses both plane waves (PWs) and atomic orbitals (AOs) as a basis set. The general form S · ?V × p can be used for PWs, while the standard form L · S can be used for AOs, which are well localized inside the non‐overlapping atomic sphere in the spherical potential region and composed of the numerical radial function on a logarithmic radial mesh and analytic cubic harmonics. The explicit formula of the AO–AO, PW–AO, and PW–PW matrix elements of the SOC for spin‐polarized systems is presented. In particular, the AO–AO matrices are explicitly derived for p, d, and f orbitals. The method is applied to the SOS of core and valence levels in X‐ray photoelectron spectra. The results are in excellent agreement with the available experimental data, which suggests the validity of the present method.     

Iridium‐Catalyzed Intramolecular Methoxy C−H Addition to Carbon–Carbon Triple Bonds: Direct Synthesis of 3‐Substituted Benzofurans from o‐Methoxyphenylalkynes

Catalytic hydroalkylation of an alkyne with methyl ether was accomplished. Intramolecular addition of the C?H bond of a methoxy group in 1‐methoxy‐2‐(arylethynyl)benzenes across a carbon–carbon triple bond took place efficiently either in toluene at 110 °C or in p‐xylene at 135 °C in the presence of an iridium catalyst. The initial 5‐exo cyclization products underwent double‐bond migration during the reaction to give 3‐(arylmethyl)benzofurans in high yields.     

Aggregation feature of fluorine-substituted benzene rings and intermolecular C-H.F interaction: crystal structure analyses of mono- and trifluoro-L-phenylalanines

X-Ray crystal structures of four different fluorine-substituted phenylalanines (two mono- and two tri-substitutions) were analyzed to investigate the effect of fluorine atom on the association pattern of benzene rings. Although respective structures showed similar molecular packing in such a way that the layers of hydrophobic benzene rings and hydrophilic amino/carboxyl groups were alternately running along a crystallographic axis, the association patterns of benzene rings were different depending on the substitution position and number of fluorine atoms. The general features could be that the partially displaced face-to-face interactions are increased with increase in the number of fluorine atoms, whereas the edge-to-face interactions are decreased. The C-H bond next to a fluorine-substituted carbon atom could serve as a donor of an intermolecular C-H.F hydrogen bond.     

Synthesis of γ-amino alcohols from aldehydes, enamines, and trichlorosilane using Lewis base catalysts

The reaction of aldehydes, enamines, and trichlorosilane in the presence of a Lewis base catalyst, particularly N-methylpyrrolidinone and DMF, affords γ-amino alcohols with a high diastereoselectivity. The method consists of C-C bond formation between an aldehyde and an enamine, and a subsequent intramolecular reduction of the resulting iminium ion intermediate. In most cases, one diastereomer is exclusively generated, and we propose a transition state model for the intramolecular reduction of the iminium ion intermediate. Enamines, prepared beforehand from the corresponding ketone and amine, can be used in the reaction without purification. Furthermore, enantioselective catalysis using a chiral Lewis base catalyst is possible, although the enantioselectivity is modest. The current tandem method offers the first, concise synthetic method of γ-amino alcohols from aldehydes and enamines.     

Application of Hamiltonian of ray motion to room acoustics

Based on a standard Hamiltonian of acoustic ray, it is shown that a ray motion in a finite region can be treated as a particle motion inside a potential well. The boundary reflections of ray can be described by introducing a so-called confining potential to confine a ray motion in a closed domain. It is shown that the square well potential model for the ray motion can reproduce the reverberation time in a two-dimensional room with irregular walls which is consistent with the Norris-Eyring law. It is also shown that the sound reverberation relates the ray chaos of the billiards in polygons with smooth convex walls.     

Development of beam-pointing stabilizer on a 10-TW Ti:Al2O3 laser system JLITE-X for laser-excited ion accelerator research

We developed a beam-pointing stabilizer for a 10-TW Ti:sapphire laser system to study laser-induced ion acceleration. We confirmed the improvement in the laser beam pointing stability by using a 10-TW laser system (we call it JLITE-X) at JAERI-APRC. The original long-term pointing stability on a 10-TW laser system is ～70 μrad without beam stabilizing. By using a beam-pointing stabilizer, the laser beam stability was improved within 10 μrad. If f/1 focusing optics and a target which is tilted 45° to the target normal is used, the fluctuation of the laser intensity at the focus will be improved from 80% without stabilizing to <0.4% with it.     

Imino ene-type reaction of enamines with N-sulfonylimines and application to diastereoselective synthesis of N-sulfonyl-1,3-diamines

Enamines react rapidly with N-sulfonylimines to afford imino ene-type adducts. The reaction proceeds even at −78 °C in the presence of acetic acid and shows high diastereoselectivity. Acid hydrolysis of imino ene-type products affords β-amino ketones, and reduction with NaBH₃CN furnishes N-sulfonyl-1,3-diamines with high diastereoselectivities. The stereochemistry of these transformations is considered based on transition state models.