Enantioselective synthesis of aurisides A and B, cytotoxic macrolide glycosides of marine origin

The enantioselective synthesis of aurisides A and B, macrolide glycosides of marine origin, was achieved by a convergent approach. The C1-C9 segment 4 was prepared from (R)-pantolactone, and the C10-C17 segment 14 was synthesized from (R)-glycidyl trityl ether. The Nozaki-Hiyama-Kishi reaction between 4 and 14 and subsequent reactions gave seco acid 10, which was converted into the aglycon (3) of aurisides by construction of the 14-membered lactone and bromine-substituted conjugated diene. The glycosylation reaction of the aglycon provided aurisides A and B.     

Zirconium-promoted epoxide rearrangement-alkynylation sequence

Additions of terminal alkynes to electrophiles are important transformations in organic chemistry. Generally, activated terminal alkynes react with epoxides in an S(N)2 fashion to form homopropargylic alcohols. We have developed a new synthetic method to form propargylic alcohols from epoxides and terminal alkynes via 1,2-shifts. This method involves cationic zirconium acetylides as both the activator of epoxides and nucleophiles. Due to the mild conditions to pre-activate alkynes with silver nitrate, this synthetic method is useful for both electron-rich and electron-deficient alkynes with other acid- and base-sensitive functional groups.     

Round-efficient perfectly secure message transmission scheme against general adversary

In the model of Perfectly Secure Message Transmission Schemes (PSMTs), there are n channels between a sender and a receiver, and they share no key. An infinitely powerful adversary A can corrupt   (observe and forge) the messages sent through some subset of n channels. For non-threshold adversaries called Q ², Kumar et al. showed a many round PSMT (Ashwin Kumar et al. On perfectly secure communication over arbitrary networks. PODC 2002, pp. 193–202, 2002). In this paper, we show round efficient PSMTs against Q ²-adevrsaries. We first give a 3-round PSMT which runs in polynomial time in the size of the underlying linear secret sharing scheme. We next present a 2-round PSMT which is inefficient in general. (However, it is efficient for some special case.)     

Catalytic Reductive Cross-Coupling between Aromatic Aldehydes and Arylnitriles

A reductive cross-coupling reaction between aromatic aldehydes and arylnitriles using a copper catalyst and a silylboronate as a reductant is reported. This protocol represents an unprecedented approach to the chemoselective synthesis of α-hydroxy ketones by electrophile–electrophile cross-coupling.     

Novel combination of hydrophilic/hydrophobic surface for large wettability difference and its application to liquid manipulation

This paper reports a novel combination of hydrophilic/hydrophobic materials for the evolution of liquid manipulation. Droplet generation based on a hydrophilic/hydrophobic mechanism is a promising method for highly accurate liquid manipulations. Although several droplet manipulation devices utilizing hydrophilic/hydrophobic patterns have been reported, it has been difficult to split fluid into droplets solely through hydrophilic/hydrophobic patterns in a microchannel. In this study, a material combination for fabricating hydrophilic/hydrophobic patterns was investigated and their wettability difference was enhanced for droplet generation. To improve hydrophilicity, we attempted to increase the surface area of silicon oxide through pulsed plasma chemical vapor deposition (PPCVD). To improve hydrophobicity, the damage to the hydrophobic patterns in the fabrication process was reduced. We successfully enhanced the difference in contact angles from 54.3° to 86.6° by combining the developed hydrophilic material and hydrophobic material. The developed material combination could successfully split fluid into a quantitative droplet of 14.1 nL in a microfluidic chip. Because the developed hydrophilic/hydrophobic combination enables the formation of a droplet with desirable shape in microchannels, the developed hydrophilic/hydrophobic combination is a promising component for lab-on-a-chip applications.     

Synthesis of the enantiomers of 1,7-dioxaspiro[5.5]undecane, 4-hydroxy-1,7-dioxaspirol[5.5]undecane and 3-hydroxy-1,7-dioxaspiroi[5.5]undecane : The components of the olive fruit fly pheromone

All of the enantiomers of the title compounds, the components of the pheromone of the olive fruit fly ($\text{Dacus}$$\text{oleae}$ Gmelin), were synthesized from ($\text{S}$)-malic acid.     

Fiber-Optic Ammonia Sensors Utilizing Rectangular-Cladding Eccentric-Core Fiber

A new fiber-optic ammonia sensor utilizing rectangular-cladding eccentric-core fiber and a sensitive film containing an indicator dye is demonstrated. The sensitive film is a SiO₂-GeO₂ gel film including an indicator dye of bromocresol purple or bromocresol green, which is dip-coated by a sol-gel technique. The attenuation of this sensor changes depending on the concentration of ammonia at the wavelength range of 500–700 nm. This sensor can detect several ppm of gaseous ammonia. Various factors determining the sensitivity to detect the ammonia gas and time response of the sensor are also studied.     

Dehydration process in NaCl solutions under various external electric fields

Ionic motions at solid-liquid interface in supersaturated NaCl solutions have been investigated by molecular dynamics (MD) simulation for understanding crystal growth processes. The density profile in the vicinity of the interfaces between NaCl(100) and the supersaturated NaCl solution was calculated. Diffusion coefficients of water molecules in the solution were estimated as a function of distance from the crystal interface. It turned out that the structure and dynamics of the solution in the interfaces was different from those of bulk solution owing to electric fields depending on the surface charge. Therefore, the electric field was applied to the supersaturated solutions and dehydration phenomenon occurring in the process of the crystal growth was discussed. As the electric field increased, it was observed that the Na⁺ keeping strongly hydration structure broke out by the electric force. In supersaturated concentration, the solution structure is significantly different from that of dilution and has a complicated structure with hydration ions and clusters of NaCl. If the electric fields were applied to the solutions, the breakout of hydration structure was not affected with increasing the supersaturated ratio. This reason is that the cluster structures are destroyed by the electric force. The situation depends on the electric field or crystal surface structure.     

Stability of ubiquinol‐10 (reduced form of coenzyme Q10) in human blood

The ratio of ubiquinol‐10 in total coenzyme Q₁₀ (TQ₁₀) in human plasma has been proposed as a useful biomarker of oxidative stress. Since ubiquinol‐10 is easily oxidized in air, it is necessary to perform suitable processing at medical institutions prior to analysis. To establish stable storage conditions for blood to determine the ubiquinol‐10/TQ₁₀ ratios properly, the effects of temperature conditions on the stability of ubiquinol‐10 were studied. Blood samples were collected from nine male Japanese volunteers. Changes in ubiquinol‐10/TQ₁₀ ratios in blood samples were evaluated under three temperature conditions (room temperature, refrigerated and ice‐cooled). Plasma levels of ubiquinol‐10 and ubiquinone‐10 were determined by an HPLC system with electrochemical detection and the ubiquinol‐10/TQ₁₀ ratios were calculated. We found that the ubiquinol‐10/TQ₁₀ ratio was stable up to 8 or 4 h when blood samples were stored in refrigerator or ice‐cold container, respectively, and its decreases during these periods were <1.0%. We conclude that, in order to evaluate ubiquinol‐10/TQ₁₀ ratios, blood samples should be stored in a refrigerator or an ice‐cold container, and processed for plasma separation within 4 h. Copyright © 2015 John Wiley & Sons, Ltd.