Synthetic Studies on Spirolides A and B: Formation of the Upper Carbon Framework Based on a Lewis Acid Template-Catalyzed Diels–Alder Reaction

The upper fragment of spirolides A and B, which are marine phycotoxins that exhibit strong antagonistic activities on nicotinic acetylcholine receptors, was constructed. The functionalized cyclohexene in spirolides was stereoselectively synthesized from the bicyclic lactone, which could be readily accessed by the Lewis acid template-catalyzed asymmetric Diels–Alder reaction of the pentadienol and methyl acrylate.     

Photoredox‐Catalyzed Alkenylation of Benzylsulfonium Salts

Visible light‐mediated radical alkenylation of benzylsulfonium salts was achieved by means of fac‐Ir(ppy)₃ as a photocatalyst, giving allylbenzenes as products. A variety of functional groups, such as halogen, ester, and cyano, were well tolerated in this transformation. Starting benzylsulfonium salts could be readily prepared from benzyl alcohols by an acid‐mediated substitution, increasing the synthetic utility of this transformation.     

Total synthesis of pleurolactone

The stereoselective total synthesis of pleurolactone has been accomplished in 7 steps. The key synthetic features were the construction of four contiguous stereocenters using an endo-selective Diels-Alder reaction and high diastereoselective dihydroxylation.     

Gas Storage in Single-Walled Carbon Nanotubes

Abstract

X-ray diffraction (XRD) and electrical resistance measurement on single-walled carbon nan-otube (SWNT) samples prepared by the arc-discharge method are reported. The XRD profile of heat-treated sample indicated that air (oxygen, and/or nitrogen and/or water) can be condensed inside the SWNTs. We also found that the electrical resistance of SWNT soot is significantly affected by exposing to the oxygen gas and humid air.     

Statistics of reaction progress variable and mixture fraction gradients of a pulverised coal jet flame using Direct Numerical Simulation data

The statistical behaviour of the variances, covariance and gradients of the reaction progress variable (c), and the mixture fraction (ξ) have been analysed in a pulverised coal jet flame using a three-dimensional carrier phase direct numerical simulation (DNS) dataset. It has been observed that the Favre-probability density functions (PDFs) of c and ξ can be parametrised by the standard β function. Furthermore, the log-normal distribution has been found to accurately represent |?c| and |?ξ|. It is also found that ?c and ?ξ remain aligned throughout the flame brush. Finally the joint PDF of |?c| and |?ξ| has been compared with the product of the PDF of |?c| and PDF of |?ξ| extracted from carrier phase DNS, and it has been found that |?c| and |?ξ| are not statistically independent in the case investigated.The bivariate log-normal distributions with and without correlation have also been considered, and the former is found to be in better agreement with the carrier phase DNS data.     

Decacyclene Radical Anions Showing Strong Low‐energy Intramolecular Absorption and Magnetic Coupling of Spins in a Hexagonal Network

Two salts of the aromatic hydrocarbon decacyclene, {cryptand[2.2.2](Cs⁺)} (decacyclene^.?) ( 1 ) and {Bu₃MeP⁺}(decacyclene^.?) ( 2 ), were obtained. In both salts, decacyclene^.? radical anions formed channels occupied by cations. However, corrugated hexagonal decacyclene^.? layers could be outlined in the crystal structure of 1 with several side‐by‐side C???C approaches. The decacyclene^.? radical anions showed strong distortion in both salts, deviating from the C₃ symmetry owing to the repulsion of closely arranged hydrogen atoms and the Jahn‐Teller effect. Radical anions showed intense unusually low energy absorption in the IR‐range, with maxima at 4800 and 6000 cm^?1. According to the carculations, these bands can originate from the SOMO‐LUMO+1 and SOMO‐LUMO+2 transitions, respectively. Radical anions exhibited a S=1/2 spin state, with an effective magnetic moment of 1.72 μ_B at 300 K. The decacyclene^.? spin antiferromagnetically coupled with a Weiss temperature of ?11 K. Spin ordering was not observed down to 1.9 K owing to spin frustration in the hexagonal decacyclene^.? layers.     

Color adjustment algorithm adapted to the spectral reflectance estimation method

We are developing a daily health monitoring system that uses mobile phones with cameras and analyzes physiological conditions from R, G, and B intensity levels. However, since it is affected by various imaging conditions of the image input, color correction is required for accurate health monitoring. Therefore, we developed and validated a colorcorrection algorithm to derive reliable color information by correcting the spectral reflectance using the Wiener estimation and a color chart.     

Synthesis of Substituted Phenyl Esters of Amino Acids and Polycondensation in Langmuirblodgett Films

Long-alkyl-chain phenyl esters of β-alanine, glycine, and L-valine were prepared, and their monolayer properties were correlated with their molecular structures. These compounds formed stable monolayers on acidic subphases. In particular, the p-hexadecylphenyl esters of β-alanine and glycine were remarkably stable, and their monolayers could be deposited on calcium fluoride plates as Y-type film by Blodgett's technique. The polycondensation of multilayers under an atmosphere saturated with triethylamine was investigated by changes in the IR spectra. It was determined that the polycondensation proceeded by a first-order reaction mechanism in the initial stage and that the rate in multilayers was faster than that in the bulk crystalline powder. These results suggest that the polycondensation is accelerated by a regular arrangement of the monomer in the multilayers, where the active sites are concentrated and located better for the polycondensation. In the case of the polycondensation in multilayers of the glycine ester, two kinds of condensation proceeded to afford poly(glycine) and 2,5-piperazinedione.     

Synthesis of L-Lysine and L-Glutamic Acid Derivatives with Long Alkyl Chains and Polycondensation of Langmuir-Blodgett Films

Two esters of L-lysine and L-glutamic acid containing long alkyl groups were synthesized and their polycondensation in monolayers and multilayers was investigated. The pressure-area isotherms of the ester of L-lysine depend markedly on the time of residence at the air-water interface. The change of FT-IR spectra of the deposited film, which can be lifted as a Z-type film, indicates that polycondensation can occur in the monolayer at 10°C without any treatment. The spectrum of the film cast from chloroform hardly changed with time. These results lead to the conclusion that a regular arrangement of monomer molecules in the monolayer, where the amino and ester carbonyl groups are concentrated, is more suitable for the polycondensation. The ester of L-glutamic acid can also form stable monolayers which can be easily deposited on a hydrophobic plate as a Y-type film by the Blodgett technique. The polycondensation of multilayers under an atmosphere of triethylamine was investigated by IR spectroscopy. It indicates that the condensation in multilayers proceeds via intermolecular and intramolecular reactions, by which poly(L-glutamate) derivatives and 2-pyrrolidone derivatives are formed, respectively. The condensation in the bulk crystalline powder gives exclusively the 2-pyrrolidone derivative by intramolecular reaction. These results suggest that the monomer molecules in the multilayers are favorably aligned for the intermolecular reaction, in contrast to the situation in the bulk crystalline powder.