Tin-free radical addition of acyloxymethyl to imines

Acyloxymethyl radicals were generated from the corresponding iodomethyl esters and successfully underwent addition to the CN bond of N-Ts, N-PMP, and N-Dpp imines by the action of dimethylzinc or triethylborane. Ethyl acetate, toluene, and benzene as well as dichloromethane were suitable solvents. The utility of acyloxymethyl radicals as a hydroxymethyl anion equivalent was highlighted by the facile hydrolysis of the acyloxy moiety of the adducts to give the corresponding amino alcohol derivatives in good to high yield.     

Equilibrium conditions for clathrate hydrates formed from methane and aqueous propanol solutions

Equilibrium conditions for clathrate hydrates formed from methane and different concentrations of 1-propanol or 2-propanol aqueous solutions were experimentally determined at temperatures of 274.0–287.1 K and pressures up to 11.0 MPa. Each propanol has an inhibiting and/or promoting effect on hydrate formation depending on the propanol concentration. A structural transition from a structure I to a different hydrate structure occurred at concentrations between 3 and 5 mass% for 1-propanol and between 2 and 3 mass% for 2-propanol.     

Quantification of local oxygen defects around Yttrium ions for yttria-doped ceria–zirconia ternary system

Local coordination structure around Yttrium ions in CeO₂–Y₂O₃ binary and [(CeO₂)_x(ZrO₂)_1?x]_0.8(YO_1.5)_0.2 (x = 0.0 ~ 1.0) ternary system has been investigated by ⁸⁹Y MAS-NMR. NMR spectra are found to be consisted of multiple peaks that can be assigned to 6-, 7- and 8-oxygen coordinated Yttrium ions. Compositional dependence of the spectrum was observed and compared with the previous results for ZrO₂–Y₂O₃ binary system. The present investigation suggested the degree of localization of the oxygen vacancy around the cation is in the order of Zr⁴⁺ > Y³⁺ > Ce⁴⁺. The degree of the oxygen vacancy preference for each cation was quantitatively determined for CeO₂–ZrO₂–Y₂O₃ ternary system the first time.     

Bis(μ‐6‐hydroxy­picolinato)‐μ‐oxo‐bis­[di­pyridine­manganese(III)] monohydrate

The title compound, [Mn₂(μ‐O)(C₆H₃NO₃)₂(C₅H₅N)₄]·H₂O, was isolated from the reaction of 2,6‐pyridine­di­carboxylic acid with [Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄] in pyridine. The dimanganese complex has twofold symmetry; the Mn^III atoms are bridged by one oxo and two amidate ligands and show compressed octahedral Jahn–Teller distortion. The molecular packing comprises a three‐dimensional structure constructed by means of extensive intermolecular interactions, including three kinds of hydrogen bonds and π–π interactions.     

On the existence of Burgers vortices for high Reynolds numbers

Axisymmetric or non-axisymmetric Burgers vortices have been studied numerically as a model of concentrated vorticity fields. Recently it has been rigorously proved that non-axisymmetric Burgers vortices exist for all values of the vortex Reynolds number if an asymmetry parameter is sufficiently small. On the other hand, several numerical results indicate that Burgers vortices have simpler structures as the vortex Reynolds number is increasing, even when the asymmetry parameter is not sufficiently small. In this paper we give a rigorous explanation for this numerical observation and extend the existence and stability results of Burgers vortices for high vortex Reynolds numbers.     

Mg-promoted reductive coupling of aromatic carbonyl compounds with trimethylsilyl chloride and bis(chlorodimethylsilyl) compounds

Mg-promoted reductive coupling of aromatic carbonyl compounds (1) with chlorosilanes, such as trimethylsilyl chloride (TMSCl:2), 1,2-bis(chlorodimethylsilyl)ethane (3) and 1,5-dichlorohexamethyltrisiloxane (4), in N,N-dimethylformamide (DMF) at room temperature brought about selective and facile reductive formation of both of carbon-silicon and oxygen-silicon bonds to give the corresponding α-trimethylsilylalkyl trimethylsilyl ethers (5) and cyclic siloxanes (6), (7) in moderate to good yields, respectively. The present facile and selective coupling may be initiated through electron transfer from Mg metal to aromatic carbonyl compounds (1).     

Palladium-catalyzed asymmetric 6-endo cyclization of dienamides with substituent-driven activation

Chiral 2-piperidinone compounds with various C-6 substituents were successfully synthesized via a Pd-catalyzed asymmetric 6-endo cyclization of dienamides, which were evidently activated by both N-p-toluenesulfonyl and C-3 ester substituents.     

Generation and characterization of electrons from a gas target irradiated by high-peak-power lasers

We present the results of electron generation experiments conducted at the Advanced Photon Research Center, Japan Atomic Energy Research Institute, using 23-fs relativistically intense 20-TW tightly focused laser pulses with underdense plasma. We observed electron energies up to 40 MeV characterized by a two-temperature Maxwell distribution. With the help of particle-in-cell simulations, we found that these are due to different plasma wave-breaking processes. A charge of 5 nC/shot was obtained at a small solid angle, which corresponds to high peak current generation.     

Mg-promoted mixed pinacol coupling

Mg-promoted reduction of a mixture of aromatic ketones (or imines) and aliphatic carbonyl compounds in N,N-dimethylformamide (DMF) brought about unique mixed pinacol type of cross coupling to give unsymmetrical vicinal diols (or amino alcohols) or α-hydroxyketones in good to moderate yields. The reaction may be initiated by electron transfer from magnesium metal to an aromatic carbonyl compound possessing a less negative reduction potential. The difference of reduction potential between aromatic ketones (or imines) and aliphatic carbonyl compounds was found to be one of the important key factors in this selective cross coupling.