Intermolecular [2+2+1] Carbonylative Cycloaddition of Aldehydes with Alkynes,and Subsequent Oxidation to γ‐Hydroxybutenolides by a Supported Ruthenium Catalyst

Intermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ‐hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria‐supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ‐hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity.     

Copper‐Mediated C6‐Selective Dehydrogenative Heteroarylation of 2‐Pyridones with 1,3‐Azoles

A copper‐mediated C6‐selective dehydrogenative heteroarylation of 2‐pyridones with 1,3‐azoles has been developed. The reaction proceeded smoothly by twofold C? H cleavage even in the absence of noble‐metal catalysts. The observed site selectivity was directed by a pyridyl substituent on the nitrogen atom of the pyridone ring. This directing group was readily removed after the coupling event, thus leading to 2‐pyridone derivatives with a free N? H group. Moreover, in some cases, catalytic turnover of the Cu salt was also possible with the ideal terminal oxidant: molecular oxygen in air.     

Selective Aerobic Oxidation of Primary Alcohols to Aldehydes over Nb2O5 Photocatalyst with Visible Light

Primary alcohols are selectively converted into aldehydes by using a Nb₂O₅ photocatalyst under visible‐light irradiation. A strong interaction between the alcohol and Nb₂O₅ generates a donor level within the forbidden band of Nb₂O₅, which provides a visible‐light‐harvesting ability. Over oxidation of aldehydes into carboxylic acids does not proceed under visible‐light irradiation.     

Exploring transition state structures for intramolecular pathways by the artificial force induced reaction method

Finding all required transition state (TS) structures is an important but hard task in theoretical study of complex reaction mechanisms. In the present article, an efficient automated TS search method, artificial force induced reaction (AFIR), was extended to intramolecular reactions. The AFIR method has been developed for intermolecular associative pathways between two or more reactants. Although it has also been applied to intramolecular reactions by dividing molecules manually into fragments, the fragmentation scheme was not automated. In this work, we propose an automated fragmentation scheme. Using this fragmentation scheme and the AFIR method, a fully automated search algorithm for intramolecular pathways is introduced. This version for intramolecular reactions is called single‐component AFIR (SC‐AFIR), to distinguish it from multicomponent AFIR for intermolecular reactions. SC‐AFIR was tested with two reactions, the Claisen rearrangement and the first step of cobalt‐catalyzed hydroformylation, and successfully located all important pathways reported in the literature. © 2013 Wiley Periodicals, Inc.     

Electrochemical decomposition of layer-by-layer thin films composed of TEMPO-modified poly(acrylic acid) and poly(ethyleneimine)

The decomposition of layer-by-layer (LbL) thin films composed of 2,2,6,6-tetramethylpiperidine-1-oxyl free radical-appended poly(acrylic acid) (TEMPO-PAA) and poly(ethylenimine) (PEI) was studied by using a quartz crystal microbalance (QCM) and cyclic voltammetry. The electrode potential of the (PEI/TEMPO-PAA)₄/PEI film-coated Au resonator was scanned from +0.2 to +0.8 V vs Ag/AgCl. The CV showed that the oxidation peak current decreased as the number of scans increased. The change in the resonance frequency of the QCM increased after electrolysis, indicating that the film was decomposed by electrolysis. The positive charges originating from the oxoammonium ions probably destabilized the (PEI/TEMPO-PAA)₄/PEI film. Furthermore, the release of 5,10,15,20-tetraphenyl-21H,23H-porphine tetrasulfonic acid (TPPS) from TPPS-loaded (PEI/TEMPO-PAA)₄/PEI-coated ITO electrodes was investigated. TPPS was released at electrode potentials greater than +0.6 V by the decomposition of the film. The results suggest that TEMPO-PAA/PEI LbL films are suitable for electrochemically controlled drug delivery systems.     

Recognition of gram-negative and gram-positive bacteria with a functionalized conducting polymer film

In this work, we successfully developed bacterial templates on the surface of an overoxidized polypyrrole film using both gram-negative and gram-positive bacteria in which bacterial surface chemical structures are precisely transferred at a molecular level. The sensor film identified target bacteria within minutes through a unique combination with dielectrophoresis. The bacterial cavities had high selectivity for distinguishing specific target bacteria in bacterial mixtures containing gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Bacillus subtilis and Staphylococcus aureus) bacteria. This rapid and specific recognition system will enable not only bacterial sensing but also analysis of various biological species.