Chemoselective Hydrogenation of Functionalized Nitroarenes and Imines by Using Carbon Nanofiber‐Supported Iridium Nanoparticles

The reaction of three types of carbon nanofibers (CNFs; platelet: CNF‐P, tubular: CNF‐T, herringbone: CNF‐H) with Ir₄(CO)₁₂ in mesitylene at 165 °C provided the corresponding CNF‐supported iridium nanoparticles, Ir/CNFs (Ir content=2.3–2.6 wt. %). Transmission electron microscopy (TEM) studies of these Ir/CNF samples revealed that size‐controlled Ir nanoparticles (average particle size of 1.1–1.5 nm) existed on the CNFs. Among the three Ir/CNF samples, Ir/CNF‐T showed an excellent catalytic activity and chemoselectivity towards hydrogenation of functionalized nitroarenes and imines; the corresponding aniline derivatives were obtained with high turnover numbers at ambient temperature under 10 atm of H₂, and the catalyst is reusable. Ir/CNF‐T was also effective for the reductive N‐alkylation of anilines with carbonyl compounds.     

Homoaldol condensation of aromatic ketones in fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid oligomeric gel network cores

Aromatic ketones such as 4′‐methoxyacetophenone (MAP), acetophenone (AP), 4‐acetylbiphenyl (ABP), and 2‐acetyl‐6‐methoxynapthalene (AMN) interacted with fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid oligomer [R_F‐(AMPS)_n‐R_F] at 80°C for 3 h to give the corresponding fluorinated oligomer/aromatic ketones composites. In these composites, the R_F‐(AMPS)_n‐R_F/MAP and /AP composites were found to give the homoaldol condensation products of MAP and AP, respectively. In contrast, the corresponding non‐fluorinated AMPS oligomer/MAP and sulfuric acid/MAP composites could not give the homoaldol product at all under similar conditions. This suggests that the R_F‐(AMPS)_n‐R_F oligomer could provide the suitable fluorinated oligomeric gel newtwok cores to interact with MAP or AP as a guest molecule, and the homoaldol condensation of encapsulated MAP and AP should proceed smoothly in the fluorinated oligomeric gel network cores. The R_F‐(AMPS)_n‐R_F/ABP and /AMN composites could not give the homoaldol products at all under similar conditions, indicating that the more bulky aromotic ketones than MAP or AP are not likely to be encapasulated as guest molecules into the fluorinated AMPS oligomeric gel netwok cores. Copyright © 2013 John Wiley & Sons, Ltd.     

Functional renormalization group beyond the static approximation and its application to the two-dimensional Hubbard model

While the functional renormalization group is a powerful theoretical method, the static approximation has been usually adopted in which the Matsubara frequency dependence of vertex functions is ignored. We propose a formalism beyond the static approximation with an efficient parameterization in the Matsubara frequency space for the vertex functions to incorporate the self-energy.     

2-Fluoro-3-phenyl-allyltrimethylsilane: A new fluorinated reagent for Hosomi-Sakurai reaction

2-Fluoro-3-phenyl-allyltrimethylsilane, prepared from β-fluorinated allylic acetate via a π-allylpalladium intermediate, reacted with various aldehydes and acetals in the presence of TiCl₄ to afford the corresponding homoallyl alcohols and homoallyl ethers, respectively, in good to moderate yields.     

Genetically-increased taste cell population with Gα-gustducin-coupled sweet receptors is associated with increase of gurmarin-sensitive taste nerve fibers in mice

Background  

The peptide gurmarin is a selective sweet response inhibitor for rodents. In mice, gurmarin sensitivity differs among strains with gurmarin-sensitive C57BL and gurmarin-poorly-sensitive BALB strains. In C57BL mice, sweet-responsive fibers of the chorda tympani (CT) nerve can be divided into two distinct populations, gurmarin-sensitive (GS) and gurmarin-insensitive (GI) types, suggesting the existence of two distinct reception pathways for sweet taste responses. By using the dpa congenic strain (dpa CG) whose genetic background is identical to BALB except that the gene(s) controlling gurmarin sensitivity are derived from C57BL, we previously found that genetically-elevated gurmarin sensitivity in dpa CG mice, confirmed by using behavioral response and whole CT nerve response analyses, was linked to a greater taste cell population co-expressing sweet taste receptors and a Gα protein, Gα-gustducin. However, the formation of neural pathways from the increased taste cell population to nerve fibers has not yet been examined.     

Synthesis of macrocyclic bis(phenylbenzoxazole) derivatives via tandem claisen rearrangement and their fluorescence behavior

Novel macrocyclic bis(phenylbenzoxazole) derivatives were easily synthesized from macrocyclic isobutenyl bis(amide‐ether)s by tandem Claisen rearrangement and subsequent intramolecular cyclization of the amide‐phenol intermediates. The position of substitution of the oligoethylene glycol moiety on the phenylamido groups of the macrocycles did not have a large effect on the yields of the bis(benzoxazole)s for the meta and para derivatives. The fluorescence quantum yields of most of the macrocyclic bis(benzoxa‐zole)s were lower than those of the corresponding nonmacrocyclic bis(benzoxazole) model compounds. The quantum yields of the para‐substituted macrocyclic bis(benzoxazole)s were clearly lower than those of the model compounds and decreased with increasing length of the oligoethylene chain.     

Aluminum thickness dependence of resistance change in spin tunneling junctions Co/Al-oxide/Co

The oxidation states of Al-oxide layer and the leakage current density in coercive differential spin tunneling junctions Co/Al-oxide/Co have been investigated in order to clear the mechanism of the increasing resistance change. X-ray photoelectron spectroscopy analysis shows that the resistance change increases with decreasing unoxidized Al, which can be qualitatively explained by using first-principle band calculation based on linear-muffin-tin-orbital atomic-sphere-approximation method. The resistance change decreases with increasing leakage current density, which originates from Schottky effect. Reduction of unoxidized Al and leakage current density originating from Schottky effect is required to obtain the large resistance change in spin tunneling junctions.     

Adsorption behavior of phospholipid vesicles at oil/water interfaces

By measuring the change in interfacial tension after adding phospholipid vesicles to an aqueous solution of electrolyte, we studied the adsorption behavior of phospholipid vesicles at oil/water interfaces. The effects of concentration of three kinds of electrolyte (NaCl, MgCl₂, LaCl₃) and of the mixing ratio of two kinds of phospholipids (phosphatidylcholine and phosphatidylserine), on the adsorption behavior at an oil/water interface were examined. The results were interpreted using the DLVO theory.     

Note on the Paper “The Norm Convergence¶ of the Trotter–Kato Product Formula with Error Bound” by Ichinose and Tamura

The norm convergence of the Trotter–Kato product formula is established with ultimate optimal error bound for the selfadjoint semigroup generated by the operator sum of two selfadjoint operators. A generalization is also given to the operator sum of several selfadjoint operators. Received: 5 October 2000 / Accepted: 12 March 2001