π‑AllylPdCl-Based Initiating Systems for Polymerization of Alkyl Diazoacetates: Initiation and Termination Mechanism Based on Analysis of Polymer Chain End Structures

Polymerization of ethyl and benzyl diazoacetates (EDA and BDA) initiated with π-allylPdCl-based systems [π-allylPdCl/NaBPh₄, π-allylPdCl/NaBAr^F₄ (Ar^F = 3,5-{CF₃}₂C₆H₃), and π-allylPdCl] is described. Initiation efficiencies of the π-allylPdCl-based systems are much higher than those of the previously reported (NHC)­Pd/borate (NHC = <i>N</i>-heterocyclic carbene) systems, and the new systems are capable of polymerizing the alkyl diazoacetates at low temperatures (0 ∼ −20 °C), where the (NHC)­Pd/borate systems cannot initiate the polymerization. MALDI–TOF–MS analyses of the polymers obtained from EDA provide information for the chain-end structures of the polymers, based on which initiation and termination mechanisms are proposed. Interestingly, EDA polymerization by the π-allylPdCl-based systems in the presence of alcohols (EtOH, nPrOH, and nBuOH) or water was found to afford RO- or HO-initiated polymers as major products, as confirmed by MALDI–TOF–MS analyses

Differing susceptibility to autophagic degradation of two LC3-binding proteins: SQSTM1/p62 and TBC1D25/OATL1

<p>MAP1LC3/LC3 (a mammalian ortholog family of yeast Atg8) is a ubiquitin-like protein that is essential for autophagosome formation. LC3 is conjugated to phosphatidylethanolamine on phagophores and ends up distributed both inside and outside the autophagosome membrane. One of the well-known functions of LC3 is as a binding partner for receptor proteins, which target polyubiquitinated organelles and proteins to the phagophore through direct interaction with LC3 in selective autophagy, and their LC3-binding ability is essential for degradation of the polyubiquitinated substances. Although a number of LC3-binding proteins have been identified, it is unknown whether they are substrates of autophagy or how their interaction with LC3 is regulated. We previously showed that one LC3-binding protein, TBC1D25/OATL1, plays an inhibitory role in the maturation step of autophagosomes and that this function depends on its binding to LC3. Interestingly, TBC1D25 seems not to be a substrate of autophagy, despite being present on the phagophore. In this study we investigated the molecular basis for the escape of TBC1D25 from autophagic degradation by performing a chimeric analysis between TBC1D25 and SQSTM1/p62 (sequestosome 1), and the results showed that mutant TBC1D25 with an intact LC3-binding site can become an autophagic substrate when TBC1D25 is forcibly oligomerized. In addition, an ultrastructural analysis showed that TBC1D25 is mainly localized outside autophagosomes, whereas an oligomerized TBC1D25 mutant rather uniformly resides both inside and outside the autophagosomes. Our findings indicate that oligomerization is a key factor in the degradation of LC3-binding proteins and suggest that lack of oligomerization ability of TBC1D25 results in its asymmetric localization at the outer autophagosome membrane.</p

Asymmetric Synthesis and Catalytic Activity of 3‑Methyl-β-proline in Enantioselective <i>anti</i>-Mannich-type Reactions

Enantiomerically pure 3-methyl-β-proline was synthesized using an asymmetric phase-transfer-catalyzed alkylation of a cyanopropanoate to establish the all-carbon stereogenic center. The catalytic activity of 3-methyl-β-proline in the Mannich-type reaction between a glyoxylate imine and ketones/aldehydes was subsequently investigated. The catalyst was designed and found to be more soluble in nonpolar organic solvents relative to the unsubstituted β-proline catalyst, and as a result allowed for added flexibility during optimization efforts. This work culminated in the development of a highly <i>anti</i>-diastereo- and enantioselective process employing low catalyst loading

In Situ Electrochemical Raman Spectroscopy of Air-Oxidized Semiconducting Single-Walled Carbon Nanotube Bundles in Aqueous Sulfuric Acid Solution

In this study, we oxidized approximately 90% semiconducting, highly crystalline single-walled carbon nanotube (hc-SWCNT) bundles in the atmosphere at 450 °C for 30 min to obtain SWCNTs modified with oxygen-containing functional groups and investigated not only the influence of air oxidation on the electrochemical doping of the air-oxidized SWCNT (AO-SWCNT) bundles in aqueous sulfuric acid solution using in situ Raman spectroscopy, but also the relationship between the in situ electrochemical Raman data and the properties of electric double-layered supercapacitors (EDLSCs). By oxidizing the hc-SWCNTs in air, AO-SWCNTs with a small diameter distribution could be prepared. When a negative charge was applied to the AO-SWCNTs used as a working electrode in a three-electrode electrochemical cell for in situ Raman spectroscopy, a large downshift of the G⁺ line of the AO-SWCNTs was observed compared to that before air oxidation. On increasing the ratio of small-diameter nanotubes/total nanotubes, the Raman data obtained in situ revealed that the effect of the weakening of the C–C bond was stronger than that of the renormalization of the phonon energy. In contrast, in the case of applying a positive charge to the AO-SWCNTs, the magnitude of the upshift of the G⁺ line for the AO-SWCNTs was slightly larger than that for the hc-SWCNTs. The influent electric charges per unit mass and the specific capacitances of the AO-SWCNT electrodes for the maximum magnitude of the shift of the G⁺ line (10.7 cm^–1) were 60.1 C/g and 50.1 F/g, respectively, which are larger than those of hc-SWCNT electrodes. In situ Raman spectroscopy is a useful method to simultaneously assess the increase or decrease in the diameter distribution of small nanotubes and the specific capacitances of electric double-layered supercapacitors of chemically functionalized SWCNTs by the magnitude of the shift of the G⁺ line compared to unfunctionalized SWCNTs

Enantioselective α‑Benzoyloxylation of Malonic Diesters by Phase-Transfer Catalysis

A highly enantioselective α-benzoyloxylation of malonic diester has been achieved by phase-transfer catalysis. The reaction of α-monosubstituted <i>tert</i>-butyl methyl malonate with benzoyl peroxide in the presence of aqueous KOH and <i>N</i>-(9-anthracenyl­methyl)­cinchoninium chloride afforded the corresponding α,α-disubstituted products in generally excellent chemical yields (up to 99% yield) with high enantioselectivities (up to 96% ee). In addition, the utility of this methodology was exhibited by the synthesis of a mineralocorticoid receptor antagonist

Structural and Electrochemical Characterization of Ethylenediaminated Single-Walled Carbon Nanotubes Prepared from Fluorinated SWCNTs

We prepared ethylenediaminated single-walled carbon nanotubes (SWCNTs) from fluorinated SWCNTs by substituting fluorine groups with ethylenediamine groups. The ethylenediaminated SWCNTs were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman scattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area measurement by nitrogen adsorption, contact angle measurement, zeta potential analysis, and thermogravimetry. In addition, the properties of 30 wt % sulfuric acid aqueous electrolyte-based electric double-layer supercapacitors (EDLSCs) with free-standing ethylenediaminated SWCNT electrodes were investigated. The degree of ethylenediamine functionalization was 0.603 mmol/g and 1.46 μmol/m², and the specific surface area was ∼413.3 m²/g. From HRTEM observation, isolated nanotubes disentangled from the bundled SWCNTs were present in many observed areas, and the structures retained a nanotube skeleton. The properties of the EDLSCs with the ethylenediaminated SWCNT electrodes included an average specific capacitance of 94 F/g at a low scan rate of 10 mV/s and an energy density of 2.6 Wh/kg at a power density of 0.24 kW/kg. The EDLSCs exhibited an average specific capacitance of 67 F/g at a high scan rate of 1000 mV/s and an energy density of 1.3 Wh/kg at a power density of 24 kW/kg, values that were superior to those of carboxylated SWCNT electrodes