Modified Yamaguchi Reagent: Convenient and Efficient Esterification

A convenient and efficient esterification method that used a modified Yamaguchi reagent (2,4,6-trichlorobenzoyl chloride–4-dimethylaminopyridine) and avoided use not only of intractable acid chloride but also of acid anhydrides was proposed. The reaction mechanism was described by Fourier transform infrared spectroscopy and supported by a density functional theory calculation.     

Chemoenzymatic synthesis and HPLC analysis of the stereoisomers of miyakosyne A [(4E,24E)-14-methyloctacosa-4,24-diene-1,27-diyne-3,26-diol], a cytotoxic metabolite of a marine sponge Petrosia sp., to determine the absolute configuration of its major component as 3R,14R,26R

Six samples [(3R,14R,26R)-, (3R,14S,26R)-, (3S,14R,26S)-, and (3S,14S,26S)-1, a mixture of (3R,14R,26S)- and (3S,14R,26R)-1, and a mixture of (3R,14S,26S)- and (3S,14S,26R)-1] of miyakosyne A [1, (4E,24E)-14-methyloctacosa-4,24-diene-1,27-diyne-3,26-diol] were synthesized starting from the enantiomers of citronellal (2), employing olefin cross metathesis and R-selective asymmetric acetylation of a stereoisomeric mixture of acetylenic alcohols with vinyl acetate and lipase PS as key reactions. Separation of the eight stereoisomer of 1 by reversed phase HPLC at −56 °C was achieved after their esterification with (1R,2R)-2-(anthracene-2,3-dicarboximido)cyclohexanecarboxylic acid (16), and the natural miyakosyne A was found to be a mixture of 95.7% of (3R,14R,26R)-1 and 4.3% of (3R,14S,26R)-1. This is different from the (3R,14S,26R)-configuration of 1 as tentatively assigned by X-ray analysis.     

Synthesis of 8-halogenated-7-deaza-2′-deoxyguanosine as an 8-oxo-2′-deoxyguanosine analogue and evaluation of its base pairing properties

8-Halogenated-7-deaza-2′-deoxyguanosines (8-halo-7-deaza-dG) were designed to structurally mimic 8-oxo-2′-deoxyguanosine (8-oxo-dG), which is representative of an oxidized nucleoside. It has been shown by NMR that the conformation around the N-glycosidic bond of (8-halo-7-deaza-dG) is preferably syn, similar to 8-oxo-dG. The base pairing properties of 8-halo-7-deaza-dG were studied by measuring the thermal denaturation temperature of the duplexes, showing that their base pair with dC is destabilized compared with natural dG. These results also support their preference for syn conformation. Unlike 8-oxo-dG, 8-halo-7-deaza-dG did not form a stable base pair with dA, most likely due to the lack of N7-H hydrogen bonding with dA. In conclusion, the newly-designed 8-halo-7-deaza-dG analogs resemble 8-oxo-dG in its shape and preference for syn conformation, but they do not form Hoogsteen base pair with the opposing dA.     

Fabrication of Al2O3 Coatings on Metal Substrates by Electrophoretic Deposition by the Addition of Polydimethylsiloxane-Based Organic-Inorganic Hybrid Materials as Binders

Polydimethylsiloxane (PDMS)-based organic-inorganic hybrids have been studied because of their high dielectric strength, heat resistivity, and flexibility. In this study, we fabricated Al₂O₃ coatings on metal substrates with sufficient electrical insulation, heat conductivity, and thermal stability by electrophoretic deposition (EPD) using PDMS-based hybrid binders. The scratch hardness, thermal conductivity, and electrical breakdown strength of the Al₂O₃ coating before and after heat treatment at 300 °C for 500 h were 2.0 N, 3.1 W/mK, and 60 kV/mm, respectively. These results demonstrate the usefulness of EPD using PDMS-based hybrid binders for fabricating flexible heat dissipative substrates used in high-temperature environments.     

MEKC–MS/MS method using a volatile surfactant for the simultaneous determination of 12 synthetic cannabinoids

This study describes a method for the simultaneous determination of 12 synthetic cannabinoids by MEKC–MS/MS using a volatile surfactant (ammonium perfluorooctanoate) as a constituent of the micellar pseudostationary phase. Although most synthetic cannabinoids comigrated by a CZE method, sufficient separation could be achieved by the proposed method. The best separation was made possible by 50 mM ammonium perfluorooctanoate in 20% v/v acetonitrile/water (apparent pH* 9.0) as the BGE, followed by MS detection using a sheath liquid composed of 5 mM ammonium formate in 50% v/v methanol/water mixed hydro‐organic solvent. The standard calibration curve for all analytes showed good linearity (r > 0.99). Satisfactory recoveries, ranging from 89.5 to 101.7%, were obtained. The LODs were 6.5–76.5 μg/g for the target analytes. This method appears to be a useful tool for the identification of synthetic cannabinoids in illegal herbal incense blends.     

A New Method of Synthesizing Phenalen-1-one: Reduction of 3-Hydroxyphenalen-1-one Using NaBH4 and Lanthanoid Chlorides

Phenalen-1-one was obtained in considerable yield by reducing 3-hydroxyphenalen-1-one. Most of known preparation methods are not very practical, either because their yields are very poor or because their processes have many steps. This regioselective 1,2-reduction proceeded by the action of NaBH₄ and various cations of rare-earth elements and metals. The yields of phenalen-1-one were examined as a function of typical lanthanoids, molar ratios of lanthanoid ions to 3-acetoxy-phenalen-1-one, and differing methods of protecting the hydroxyl group. Lanthanum chloride (LaCl₃) gave the greatest yield (45.3%) of phenalen-1-one at molar ratios higher than a third, probably because La³⁺ ion is a hard acid and coordinates easily to a hard solvent such as methanol. Further, it has the largest ionic radius among all lanthanoid ions.     

Synthesis of Calcium Phosphates by Gas-Solid Reaction of CaO-P 2 O 5

Calcium phosphates are useful materials in fertilizer, dentifrice, biomaterials, etc., and have been popularly synthesized by a wet method, a hydrothermal method, a flux method, and a solid-state reaction method. However, there has been no report on synthesis by chemical vapor deposition (CVD) method or gas-phase reaction. In the present study, calcium phosphates were synthesized by gas-solid reaction of CaO solid and P 2 O 5 gas. The CaO/P 2 O 5 ratio of starting materials was changed from 5.06 to 0.64, and the reaction was carried out at 400-1100;C. These calcium phosphates were investigated using X-ray diffractometry (XRD) and scanning electron microscope (SEM). By gas-solid reaction of CaO-P 2 O 5 , g -MET only was synthesized at 400-500;C, g -MET, HA, and g -PYR at 600-700;C, and g -MET, HA, g -PYR, and g -TCP above 800;C. Synthesized calcium phosphates were independent on the CaO/P 2 O 5 ratio of starting materials but dependent on the reaction temperature.     

Development of an ecotoxicity QSAR model for the KAshinhou Tool for Ecotoxicity (KATE) system,March 2009 version

The KAshinhou Tool for Ecotoxicity (KATE) system, including ecotoxicity quantitative structure–activity relationship (QSAR) models, was developed by the Japanese National Institute for Environmental Studies (NIES) using the database of aquatic toxicity results gathered by the Japanese Ministry of the Environment and the US EPA fathead minnow database. In this system chemicals can be entered according to their one-dimensional structures and classified by substructure. The QSAR equations for predicting the toxicity of a chemical compound assume a linear correlation between its log P value and its aquatic toxicity. KATE uses a structural domain called C-judgement, defined by the substructures of specified functional groups in the QSAR models. Internal validation by the leave-one-out method confirms that the QSAR equations, with r ² > 0.7, RMSE ≤ 0.5, and n > 5, give acceptable q ² values. Such external validation indicates that a group of chemicals with an in-domain of KATE C-judgements exhibits a lower root mean square error (RMSE). These findings demonstrate that the KATE system has the potential to enable chemicals to be categorised as potential hazards.     

Polymerization of Olefins by a Ziegler Catalyst Supported on Poly(ethylene-co-Vinyl Alcohol)

The polymerization and catalytic behavior of a Ziegler type catalyst supported on poly(ethylene-co-vinyl alcohol) (EVA) were investigated. The rate of ethylene polymerization by a catalyst prepared from titanium tetrachloride supported on EVA (vinyl alcohol 18 mole %) and triethylaluminum (AlEt₃) is much higher than that of an n-butoxytitanium trichloride (BTT)-AlEt3 catalyst. The polymer-supported catalyst has prolonged high activity during polymerization compared with the BTT-AlEt₃ catalyst. The stabilization of the catalyst seems to depend on its slower reduction by alkylaluminum compounds, due to steric hindrance by bulky polymer ligands. Polypropylene prepared by the polymer supported Ziegler catalyst is essentially atactic, and it differs little from that prepared with a BTT-AlEt₃ catalyst. Vinyl chloride was also polymerized by this catalyst. The catalytic activity was, however, very small.     

Analysis of triacylglycerol hydroperoxides in human lipoproteins by Orbitrap mass spectrometer

Herein, we represent a simple method for the detection and characterization of molecular species of triacylglycerol monohydroperoxides (TGOOH) in biological samples by use of reversed-phase liquid chromatography with a LTQ Orbitrap XL mass spectrometer (LC/LTQ Orbitrap) via an electrospray ionization source. Data were acquired using high-resolution, high-mass accuracy in Fourier-transform mode. Platform performance, related to the identification of TGOOH in human lipoproteins and plasma, was estimated using extracted ion chromatograms with mass tolerance windows of 5 ppm. Native low-density lipoproteins (nLDL) and native high-density lipoproteins (nHDL) from a healthy donor were oxidized by CuSO₄ to generate oxidized LDL (oxLDL) and oxidized HDL (oxHDL). No TGOOH molecular species were detected in the nLDL and nHDL, whereas 11 species of TGOOH molecules were detected in the oxLDL and oxHDL. In positive-ion mode, TGOOH was found as [M + NH₄]⁺. In negative-ion mode, TGOOH was observed as [M + CH₃COO]^–. TGOOH was more easily ionized in positive-ion mode than in negative-ion mode. The LC/LTQ Orbitrap method was applied to human plasma and three molecular species of TGOOH were detected. The limit of detection is 0.1 pmol (S/N?=?10:1) for each synthesized TGOOH.