A Novel Synthesis of Quinazolines by Cyclization of 1‐(2‐Isocyanophenyl)alkylideneamines Generated by the Treatment of 2‐(1‐Azidoalkyl)phenyl Isocyanides with NaH

A new and efficient method for the synthesis of quinazolines has been developed. Thus, N‐[2‐(1‐azidoalkyl)phenyl]formamides 1 are dehydrated with POCl₃ to give the corresponding 2‐(1‐azidoalkyl)phenyl isocyanides 2 , which are then treated with NaH in DMF at 0° to give quinazolines 6 in satisfactory yields via cyclization of 1‐(2‐isocyanophenyl)alkylideneamine intermediates 4 . This methodology can be applied to the synthesis of the 7‐azaanalogs of quinazolines, i.e., pyrido[3,4‐d]pyrimidines 9 .     

One-pot synthesis of 4-substituted 4-alkoxy-1,4-dihydro-3,1-benzoxazine-2-thiones by the reaction of 2-isothiocyanatobenzoates with organolithiums

An efficient one-pot procedure for the preparation of 4-substituted 4-alkoxy-1,4-dihydro-3,1-benzoxazine-2-thiones from 2-isothiocyanatobenzoates has been developed. Thus, 2-isothiocyanatobenzoates were reacted with organolithiums including lithium enolates of acetates and tertiary acetamides in THF at −78 °C to give the desired products in generally good yields.     

Isolation of ethanol from its aqueous solution by liquid phase adsorption and gas phase desorption using molecular sieving carbon

A novel bioethanol separation process was proposed in this study employing molecular sieving carbon (MSC) as an adsorbent, whose pore diameter is close to molecular size of ethanol. In the proposed process, fermentation broth is first introduced to the adsorption bed packed with MSC. In this step, ethanol is selectively adsorbed onto MSC, with highly enriching ethanol in the micropore of MSC. Subsequently, the concentrated ethanol is desorbed from MSC to gaseous phase, resulting in further purification of ethanol owing to a considerable difference in desorption rate between water and ethanol; Because of molecular sieving effect of MSC, the desorption rate of ethanol is much smaller than that of water. To establish this process, adsorption equilibrium and kinetics of ethanol on various MSCs were investigated in aqueous phase as the first step. Also, desorption kinetics of ethanol and water in gaseous phase were investigated. As a result, it was suggested that highly concentrated ethanol could be obtained with high recovery ratio through these simple operations, meaning the proposed process is quite promising.     

Investigation of thermal hazard during the hydrosilylation of 1,6-divinyl(perfluorohexane) with trichlorosilane

In this study, we examined the reaction hazard during the hydrosilylation reaction between trichlorosilane (TCS) and 1,6-divinyl(perfluorohexane) (FDV) in the presence of a butanol solution of chloroplatinic acid (Pt-Cat) as the catalyst. Assuming the three industrial risks of excessive addition of Pt-Cat, contamination by iron rust and mixing with cooling water, we observed the temperature and pressure change of TCS/FDV with an excessive amount of Pt-Cat, TCS/FDV/Pt-Cat with Fe₂O₃ and TCS/FDV/Pt-Cat with distilled water, using an accelerating rate calorimeter (ARC). The temperature and pressure greatly increased, especially in the sample with Fe₂O₃. For instance, in TCS/FDV/Pt-Cat with 1.5 wt.% Fe₂O₃, the heat release rate exceeded 624 K · min^?1 and the pressure rose above 25 MPa during the exothermic reaction.     

Determination of residual fluoroquinolones in honey by liquid chromatography using metal chelate affinity chromatography

A new analytical method for the simultaneous determination of seven fluoroquinolones, namely, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, orbifloxacin, sarafloxacin, and difloxacin, especially in dark-colored honey, has been developed. Fluoroquinolone antibiotics were extracted from samples with MacIlvaine buffer solution (pH 4.0) containing EDTA disodium salt dihydrate. The extracts were treated with both a polymeric cartridge and a metal chelate affinity column preloaded with ferric ion (Fe3+). LC separation with fluorescence detection was performed at 40 degrees C using an Inertsil ODS-4 analytical column (150 x 4.6 mm, 3 microm). The mobile phase was composed of 20 mM/L citrate buffer solution (pH 3.1)-acetonitrile mixture (70 + 30, v/v) containing 1 mM/L sodium dodecyl sulfate. Lomefloxacin was used as an internal standard. The developed method was validated according to the criteria of European Commission Decision 2002/657/EC. Decision limits and detection capabilities were below 2.9 and 4.4 microg/kg, respectively.     

Four eremophil-9-en-8-one derivatives from Cremanthodium stenactinium samples collected in China

Two samples of Cremanthodium stenactinium (Asteraceae) were collected in Sichuan Province, China. From the ethyl acetate extracts of the roots, three new eremophilane-type sesquiterpenoids and one new trinoreremophilane compound were isolated, together with other known eremophilanes. Their structures were determined based on the spectroscopic data. This is the first report of isolation of eremophilane-type compounds from the genus Cremanthodium.     

Low-temperature phase of Li2FeSiO4: crystal structure and a preliminary study of electrochemical behavior

A nearly single-phase of a low-temperature (LT) phase of Li(2)FeSiO(4) is prepared by a hydrothermal method at 150 °C. We report the detailed crystal structure of LT-Li(2)FeSiO(4) (S.G. Pmn2(1)) by applying Rietveld/MEM analysis to the synchrotron XRD pattern. LT-Li(2)FeSiO(4) shows 150 mA h g(-1) as the positive electrode materials of rechargeable batteries.     

Construction of carbocyclic ring of indoles using ruthenium-catalyzed ring-closing olefin metathesis

The selective synthesis of substituted indoles was achieved by the ring-closing olefin metathesis (RCM)/elimination sequence or the RCM/tautomerization sequence of functionalized pyrrole precursors. The RCM/elimination sequence was also applied to double ring closure to yield a substituted carbazole.     

Interplay of olefin metathesis and multiple hydrogen bonding interactions: covalently cross-linked zippers

Hydrogen-bonded zippers bearing terminal alkene groups were treated with Grubbs' catalyst, leading to covalently cross-linked zippers without violating H-bonding sequence specificity. The yield of a cross-linked zipper depended on the stability of its H-bonded precursor, with a weakly associating pair giving reasonable yields only at high concentrations while strongly associating pairs showed nearly quantitative yields. The integration of thermodynamic (H-bonding) and kinetic (irreversible C═C bond formation) processes suggests the possibility of developing many different covalent association units for constructing molecular structures based on a self-assembling way.     

Efficient synthesis of [¹¹C]ramelteon as a positron emission tomography probe for imaging melatonin receptors involved in circadian rhythms

Ramelteon (TAK-375) is a novel melatonin receptor agonist that is used for clinical treatment of insomnia. The present report describes radiolabeling of ramelteon with the short-lived positron-emitter 11C (T(1/2)=20.4 min) by 2 methods. One method was [11C]methylation of an acetoamide precursor and the other was [11C]acylation of the corresponding amine precursor. First, [11C]methylation method showed the low reproducibility together with the production of many kinds of side products from which the [11C-methyl]Ramelteon was separated with chemical purity of <28% and radiochemical purity of >98%. Whereas, the [11C]acylation method showed high efficiency and reproducibility with a good radiochemical yield (22-43%, decay corrected), high chemical and radiochemical purities (>99% each), and high specific activity (43-162 GBq/μmol) (n=5) after HPLC purification. [11C]Ramelteon is a potential positron emission tomography (PET) probe for imaging the melatonin receptor.