Stereoselective iodocyclopropanation of terminal alkenes with iodoform, chromium(II) chloride, and N,N,N',N'-tetraethylethylenediamine

Chemoselectivity of a reagent for (E)-olefination of aldehydes derived by reduction of iodoform with chromium(II) chloride in THF changes markedly by addition of TEEDA (N,N,N',N'-tetraethylethylenediamine), and trans-iodocyclopropanes are produced stereoselectively from terminal alkenes by treatment with the base-added reagent system. The iodocyclopropanation occurs only at terminal double bonds, and di- and trisubstituted double bonds in the same molecules remained unchanged. Such functional groups as alcohol, ether, silyl ether, ester, tertiary amine, and amide groups are compatible with the reaction conditions.     

Feasibility Study of Introducing Redox Property by Modification of PMBN Polymer for Biofuel Cell Applications

In this study, the feasibility of introducing redox property to an amphiphilic phospholipid polymer (PMBN) was investigated. The active ester group in the side chain of the polymer was used to react with pyrroloquinoline quinine (PQQ). Redox peaks that corresponded to PQQ redox potentials were observed after the modification. Glucose oxidase was immobilized to the modified polymer. Electrochemical oxidation of glucose was carried out with the polymer electrode. The oxidation current increased with elevating glucose concentration indicating electron transfer established between the electrode and enzyme. It suggests that by modification, PMBN is possible to use for enzyme electrode for bioelectronics.     

Atomic Level Characterization Based on Focus Modulation Electron Microscopy

Defocus image modulation processing and three-dimensional Fourier filtering methods are compared from the viewpoint of application to high-resolution phase transmission electron microscopy. Both methods can successfully correct the spherical aberration in TEM by image processing using through-focus images resulting in resolution improvement from the Scherzer resolution limit to the information limit. Comparing the processed images demonstrates that the potential to determine localized atomic structures between the two methods is at the same level when the sample thickness is thin. However, the achieved signal-to-noise ratio is better in images processed by the three-dimensional Fourier filtering method because the filtering process in Fourier space effectively reduces quantum noises involved in the original images. Spherical aberration-free phase observation by the latter method clearly shows the existence of individual gadolinium atoms in C₈₂ molecules encapsulated in single wall carbon nanotubes. It is demonstrated that the three-dimensional Fourier filtering method works effectively for atomic level characterization even when a sample consisting of light atoms is observed under the condition of a low electron dose.     

Rhodium(I)-catalyzed carboxylation of aryl- and alkenylboronic esters with CO2

When the esters of arylboronic acids with 2,2-dimethylpropan-1,3-diol were treated with a catalytic amount of [Rh(OH)(cod)]2 in the presence of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60 degrees C under carbon dioxide atmosphere, the benzoic acid derivatives were obtained in good yields. Reactions of alkenylboronic esters also proceeded under similar conditions to give alpha,beta-unsaturated carboxylic acids. As these boronic esters are now easily available through coupling or direct borylation reactions, this method would be a useful method for the preparation of various functionalized aryl- and alkenyl-carboxylic acids.     

Rhenium-catalyzed allylation of C-H bonds of benzoic and acrylic acids

We have succeeded in the allylation of aromatic and olefinic C-H bonds of benzoic and acrylic acids using a rhenium catalyst, Re(2)(CO)(10). In this reaction, isomerization of the introduced allyl group to the 1-propenyl group did not occur.     

Key techniques to control porous microsphere morphology in S/O/W emulsion system

A solid-in-oil-in-water (S/O/W) emulsion system has been developed to prepare porous polymeric microspheres. The obtained microspheres showed unique core–shell structure with a dense core and a surface porous layer. The emulsion system has two processes. In the first process, S/O/W₁ viscous emulsion is prepared by dropping of S/O phase in the first water phase (W₁). In the second process, the S/O/W₁ emulsion is poured to another water phase (W₂) as S/O/W₁/W₂ emulsion. During the process, S/O/W₁ droplet becomes microsphere after organic medium completely diffusion. Emulsion techniques have various effective combinations such as additive and process conditions to design microsphere morphology. With regards to the proposed S/O/W system, addition of the solid phase in the system is a key factor to form the porous structure. When the medium diffusion starts, the solid makes W₁ phase kept inside the S/O/W₁ droplet. The remained W₁ phase changes surface porous layer after purification. Affinity between the solid and oil phase should be adjusted as well. In this study, an optimization of the emulsion system was attempted considering solubility parameter and polarity. Additionally, it is found that process conditions could help to design microsphere morphology such as pore size and porous layer thickness.     

Pt nanoworms: creation of a bumpy surface on one-dimensional (1D) Pt nanowires with the assistance of surfactants embedded in mesochannels

A new type of platinum nanowire with a bumpy surface "Pt nanoworm" is electrochemically synthesized in mesochannels of mesoporous silica films with the assistance of a nonionic surfactant (C(16)EO(8)).     

Silyl Ligand Mediated Reversible β‐Hydrogen Elimination and Hydrometalation at Palladium

The mechanism and origin of the facile β‐hydrogen elimination and hydrometalation of a palladium complex bearing a phenylene‐bridged PSiP pincer ligand are clarified. Experimental and theoretical studies demonstrate a new mechanism for β‐hydrogen elimination and hydrometalation mediated by a silyl ligand at palladium, which enables direct interconversion between an ethylpalladium(II) complex and an η²‐(Si‐H)palladium(0) complex without formation of a square‐planar palladium(II) hydride intermediate. The flexibility of the PSiP pincer ligand enables it to act as an efficient scaffold to deliver the hydrogen atom as a hydride ligand.     

Effect of alkoxy terminal chain length on mesomorphism of 1,6-disubstituted pyrene-based hexacatenar liquid crystals: columnar phase control

Synthesis and mesophase-transition behaviors of six 1,6-disubstituted pyrene-based hexacatenar liquid crystals 1_n (n=8–18) are reported here. They were synthesized by the Sonogashira coupling between 1,6-diethynylpyrene and 2-bromothiophene bearing a trialkoxybenzoyl group. The phase-transition behavior was studied by differential scanning calorimetry and polarized optical microscopy; a few mesophase progressions, I–Col/I–X–Col and Col–Sm, were observed, where X was an optically isotropic but unidentified phase. The structures of Col_r, Col_h, and Sm phases were analyzed by the X-ray crystallography, and the effect of the terminal alkoxy chain length on the mesomorphism was evaluated.     

Synthesis of Cp-Re complexes via olefinic C-H activation and successive formation of cyclopentadienes

Treatment of an alpha,beta-unsaturated ketimine with an alpha,beta-unsaturated carbonyl compound in the presence of a rhenium complex, Re2(CO)10, gave a cyclopentadienyl-rhenium complex. This reaction proceeds via rhenium-catalyzed C-H bond activation of an olefinic C-H bond, insertion of an alpha,beta-unsaturated carbonyl compound into a Re-C bond of the alkenylrhenium intermediate, intramolecular nucleophilic cyclization, reductive elimination, elimination of aniline to give a cyclopentadiene derivative, followed by the formation of a cyclopentadienyl-rhenium complex from the cyclopentadiene derivative and the rhenium complex.