Efficient Synthesis,Structure, and Complexation Studies of Electron‐Donating Thiacalix[n]dithienothiophene

A series of thiacalix[n]dithiothiophenes (n=4–10) was prepared by a facile method and X‐ray analysis was used to determine the molecular structures of square‐ (4‐mer) and pentagonal‐shaped macrocycles (5‐mer). In the cyclic voltammograms, reversible multielectron redox processes, which are due to electronic delocalization, were observed at low oxidation potentials. The cyclic 4‐mer acted as a “Janus‐head” cavitand for two C₆₀ molecules, whereas the 5‐ and 6‐mer formed stable 1:1 complexes with C₆₀ .     

First enantioselective synthesis of salinipostin A,a marine cyclic enol-phosphotriester isolated from Salinispora sp

Salinipostins are cyclic enol-phosphotriesters isolated from a marine-derived Salinispora sp. as antimalarial compounds. Herein, the first enantioselective synthesis of salinipostin A was achieved. Organocatalyst-mediated asymmetric cyclopropanation and regioselective cyclopropane ring opening were the key steps.     

A new method for fabricating water repellent silica films having high heat-resistance using the sol–gel method

There has been a great demand in the field of kitchen appliances to develop transparent water repellent films which have high heat-resistance around 300°C. However, those films have not been obtained by conventional sol–gel methods. In this paper, we propose a new method for fabricating transparent water repellent films with high heat-resistance using the sol–gel method, in which silicon or germanium substrates were coated with a solution including tetraethoxysilane (Si(OC₂H₅)₄) and (2-perfluorooctyl)ethyltrimethoxysilane (CF₃(CF₂)₇C₂H₄Si(OCH₃)₃), followed by ‘ammonia-treatment' and annealed at 300°C. The contact angles of water on the ammonia-treated film maintained its initial value, 110° after the heat treatment at 300°C for 250 h while those on the untreated film decreased to 70°, indicating that the ammonia-treatment improves heat-resistance on the film. The mechanism of ammonia-treatment was inferred from FT-IR results; the ammonia-treatment should accelerate hydrolysis and polymerization of FAS and TEOS molecules, resulting in high density of siloxane bonds between FAS and silica glass. These bonds suppress the evaporation of FAS molecules from the film during the heat treatment at 300°C, thus the film has high heat-resistance.     

Tumor cell detection method using complement-mediated cytolytic reaction and imaging sensor system

A novel tumor-detection system consisting of complementmediated cytolytic reaction and an image processing system was developed for the simple and rapid determination of tumor cells. The present system consists of a CCD image sensor, image memory board, personal computer, and microscope. When monoclonal antibody 3C4, which is specific to the guinea pig hepatoma L-10, was added to cell suspension, only L-10 cytolysis occurred. Cytolysis caused a decrease in brightness of the cells observed by phase-contrast microscopy. The phase contrast image of the cells before cytolysis was converted to a digitalized signal and stored in computer memory. After cytolysis, a brightness threshold above that of lysed cells was subtracted from the digitalized signal and compared to the signal stored before reaction. L-10 cells in mixed cell suspension were determined specifically by the system. Measurement time was only 2 sec and overall time, including reaction time, was approximately 30 min. Since this method does not require a cell washing process, automation of the whole system is possible.     

Total synthesis of gliotoxin,dehydrogliotoxin and hyalodendrin

Two general methods, Method A and Method B in Scheme 19, to synthesize epidithiapiperazinediones, are described. A total synthesis of racemic and optically active gliotoxin (1) and of racemic dehydrogliotoxin (53) was achieved by using Method A, whereas a total synthesis of racemic hyalodendrin (52) was completed by using Method B.     

Direct Enantioselective Three‐Component Synthesis of Optically Active Propargylamines in Water

An enantioselective three‐component reaction of aldehydes, amines, and alkynes in water by using a bis(imidazoline)–Cu^I catalysts having a hydrophobic substituent and sodium dodecyl sulfate as a surfactant was developed. The reaction was applied to a broad range of aldehydes and alkynes to give optically active propargylamines with excellent yields (up to 99 %) and enantiomeric excesses (up to 99 % ee).     

A practical preparation of highly versatile N-acylpyrroles from 2,4,4-trimethoxybutan-1-amine

A novel method for the preparation of N-acylpyrrole is described. The method involves condensation of carboxylic acids with 2,4,4-trimethoxybutan-1-amine, followed by acid-mediated cyclization to form the pyrrole ring. The preparative procedure is highly tolerant of a variety of functional groups.     

Surface adsorption and vesicle formation of dilauroylphosphatidylcholine in room temperature ionic liquids

In this work, we study the adhesion forces between atomic force microscopy (AFM) tips and superficial dentin etched with phosphoric acid. Initially, we quantitatively analyze the effect of acid etching on the surface heterogeneity and the surface roughness, two parameters that play a key role in the adhesion phenomenon. From a statistical study of the force-distance curves, we determine the average adhesion forces on the processed substrates. Our results show that the average adhesion forces, measured in water, increase linearly with the acid exposure time. The highest values of such forces are ascribed to the high density of collagen fibers on the etched surfaces. The individual contribution of exposed collagen fibrils to the adhesion force is highlighted. We also discuss in this paper the influence of the environmental medium (water/air) in the adhesion measurements. We show that the weak forces involved require working in the aqueous medium.