Vicinal C-functionalization of alkenes. Pd/light-induced multicomponent coupling reactions leading to functionalized esters and lactones

Under photoirradiation conditions using a xenon light, and in the presence of PdCl(2)(PPh(3))(2) as a catalyst, four-component coupling reactions comprising of α-substituted iodoalkanes, alkenes, carbon monoxide, and alcohols proceeded smoothly to give functionalized esters in good yields. When alkenyl alcohols were used as acceptor alkenes, three-component coupling reactions accompanied by intramolecular esterification proceeded to give lactones in good yields. The present reaction system represents the vicinal C-functionalization of alkenes.     

The importance of temperature and viscosity effects for surfactant adsorption measurements made using the electrochemical quartz crystal microbalance

The measurement of adsorbed surfactant is important to fields such as corrosion inhibition, metal cleaning, and separation technologies. The electrochemical quartz crystal microbalance (EQCM) is an important tool that can be used to measure adsorbed surfactant. However, such measurements are subject to significant temperature and viscosity effects that must be appropriately considered. This paper discusses the effect of temperature and viscosity on EQCM measurements in solution environments and the ability of the EQCM to measure surfactant adsorption.     

Catalyzing methanolysis of alkyl halides in the interior of an amphiphilic molecular basket

A molecular basket with four cholate units assembled on a cone-shaped calix[4]arene assumed reversed micelle-like conformation in 5% methanol/carbon tetrachloride. The inwardly facing hydroxyl groups on the cholates concentrated the polar solvent from the mostly nonpolar mixture. Methanolysis of alkyl halides benefited from the concentrated pocket of methanol if the substrate was capable of entering the basket. Substrates that were too large or too hydrophobic to fit within the basket showed no rate acceleration.     

Gold-catalyzed intramolecular hydroalkoxylation/cyclization of conjugated dienyl alcohols

Catalytic intramolecular additions of hydroxyl groups to tethered conjugated dienes are described. The reactions proceed smoothly at 60 °C in the presence of 5 mol % of (PPh₃)AuCl/AgOTf as a catalyst. A broad range of structurally diverse conjugated dienes produce substituted tetrahydrofurans and tetrahydropyrans in good yields. This reaction represents an atom-economic route to construct five- and six-membered cyclic ethers.     

Nido‐Carboranes: Donors for Thermally Activated Delayed Fluorescence

An approach to the design of nido‐carborane‐based luminescent compounds that can exhibit thermally activated delayed fluorescence (TADF) is proposed. 7,8‐Dicarba‐nido‐undecaboranes (nido‐carboranes) having various 8‐R groups (R=H, Me, i‐Pr, Ph) are appended to the meta or para position of the phenyl ring of the dimesitylphenylborane (PhBMes₂) acceptor, forming donor–acceptor compounds (nido‐ m1 – m4 and nido‐ p1 – p4 ). The bulky 8‐R group and meta substitution of the nido‐carborane are essential to attain a highly twisted arrangement between the donor and acceptor moieties, leading to a very small energy splitting between the singlet and triplet excited states (ΔE_ST <0.05 eV for nido‐ m2 , ‐ m3 , and ‐ p3 ). These compounds exhibit efficient TADF with microsecond‐range lifetimes. In particular, nido‐ m2 and ‐ m3 display aggregation‐induced emission (AIE) with TADF properties.     

Conformational analysis of N-aryl-N-(2-azulenyl)acetamides

Aromatic amides bearing 2-azulenyl group on the amide nitrogen were synthesized and their structures were investigated. The π-electron density of the N-aryl group was found to influence the cis-trans conformational preferences of these compounds in solution. X-ray crystallography revealed that the plane of the 2-azulenyl ring has a strong tendency to lie coplanar with the amide plane when the azulene group is located on the same side as the amide oxygen atom.     

Sieving properties of end group‐halogenated Pluronic polymer matrix in DNA separation under nondenaturing CE analysis

CE‐SSCP analysis is a well‐established DNA separation method that is based on variations in mobility caused by sequence‐induced differences in the conformation of single‐stranded DNA. The resolution of CE‐SSCP analysis was improved by using a Pluronic polymer matrix, and it has been successfully applied in various genetic analyses. Because the Pluronic polymer forms a micellar cubic structure in the capillary, it provides a stable internal structure for high‐resolution CE‐SSCP analysis. We hypothesized that formation of micellar cubic structure is influenced by the end hydroxyl group of the Pluronic polymer, which affords structural stability through hydrogen bonding. To test this hypothesis, the hydroxyl group was halogenated to eliminate the hydrogen bonding without disturbing the polarity of polymer matrix. CE‐SSCP resolution of two DNA fragments with a single base difference was significantly worse in the halogenated polymer matrices due to band broadening. The viscoelastic properties of control (which has hydroxyl group), chlorinated, and brominated F108 solution upon heating were also investigated by rheological experiments, and we found that gelation was significantly associated with resolution. In this series of experiments, the effect of the hydroxyl group in Pluronic polymer matrix on separation resolution of CE‐SSCP analysis was demonstrated.     

Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels

Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acoustic wave in various internal channel structures ((a) sudden expansion and contraction channels, (b) bifurcating channels, (c) gradual contraction wall channels and (d) a cylinder). Fairly good agreement between the experimental results and numerical simulation is observed.     

Nonparallelism between reaction rate and dienophile-catalyst affinity in catalytic enantioselective Diels-Alder reactions

[reaction: see text] The above reaction is much faster with Y = CF(3)CH(2)O than with Y = CH(3)O. However, the methyl ester is a strong inhibitor of the Diels-Alder reaction of the trifluoroethyl ester, since it has a higher affinity for the catalyst 1.     

Self-consistent generation of superthermal electrons by beam-plasma interaction

It has been known since the early days of plasma physics research that superthermal electrons are generated during beam-plasma laboratory experiments. Superthermal electrons (the kappa distribution) are also ubiquitously observed in space. To explain such a feature, various particle acceleration mechanisms have been proposed. However, self-consistent acceleration of electrons in the context of plasma kinetic theory has not been demonstrated to date. This Letter reports such a demonstration. It is shown that the collisionality, defined via the "plasma parameter" g=1/n(lambda(D)(3), plays a pivotal role. It is found that a small but moderately finite value of is necessary for the superthermal tail to be generated, implying that purely collisionless (g=0) Vlasov theory cannot produce a superthermal population.