Synthesis of pyrazolo[3,4-d]pyrimidine derivatives using ketene dithioacetals

The cyclization of 5-amino-3-methylthiopyrazole-4-carbonitriles or 4-carboxamides 3a-j , which were prepared by the reaction of ketene dithioacetals 1a,b [1a : bis(methylthiomethylenemalononitrile; 1b : bis(methylthio)methylenecyanoacetamide] with hydrazines (hydrazine hydrate, phenylhydrazine, p-chlorophenylhydrazine, p-nitrophenylhydrazine), with formamide or carbon disulfide proceeded to give the corresponding 4-amino- or 4-hydroxy-3-methylthiopyrazolo[3,4-d]pyrimidines 6a-h in good yields. 3-Aminopyrazolo[3,4-d]pyrimidine derivatives 6i-1 were also obtained by the application of the cyclization reaction of 3,5-diaminopyrazoles with formamide.     

Quantitative analysis of protein adsorption on a planar surface by Fourier transform infrared spectroscopy: lysozyme adsorbed on hydrophobic silicon-containing polymer

The adsorption of hen egg white lysozyme onto a solid polytris(trimethylsiloxy)silylstyrene (pTSS) surface from a D(2)O solution at pD 7 containing 100 mM NaCl and 10 mM sodium deuterated phosphate was monitored at 25 degrees C by Fourier transform infrared spectroscopy using the attenuated total reflection (ATR) method. The infrared spectrum attributed to only the adsorbed lysozyme was derived from the observed spectrum, and the amount of adsorbed lysozyme was determined as a function of time and lysozyme concentration. The kinetics of adsorption could be decomposed into two components, one of which was a process with a time constant of larger than 4 h(-1) and the other was a process with one of about 0.1 h(-1). These spectra showed that the lysozyme adsorbed in the faster process had a higher beta-structure content than the dissolved lysozyme. It was also found that the slower adsorption induced some conformational change in the lysozyme adsorbed in the faster process and/or that adsorbed in the slower process. After adsorption for 24 h, the pTSS surface was rinsed out with lysozyme-free solution. The resultant spectra of the surface indicated that the lysozyme adsorbed in the faster process was bound irreversibly on the surface and was changed to a conformer with a higher beta-structure content during the slower process. The experimental procedures and the theoretical applications for such a quantitative analysis in the ATR spectroscopic method are presented in detail.     

Practical synthesis of d-[1-C]mannose, l-[1-C] and l-[6-C]fucose

The chemical synthesis of ¹³C-labeled mannose and fucose is important for the preparation of molecular probes used in the conformational study of the oligosaccharide portions of glycoproteins. A new method for the synthesis of the title [1-¹³C]-labeled compounds via the corresponding olefin compounds, which are in turn derived from d-mannitol or l-arabinose by efficient introduction of ¹³C, by the Wittig reaction using Ph₃P¹³CH₃I and n-BuLi, is described. The introduction of ¹³CH₃I to produce the [1-¹³C]- and [6-¹³C]-labeled compounds was accomplished in 62%, 56%, and 71% yields, respectively. All mannose and fucose protons, from H-1 to H-6, were observed by the HMQC-TOCSY technique using 1:1 mixtures of [1-¹³C]- and [6-¹³C]-labeled compounds.     

Simple analysis of volatile organic compounds (VOCs) in the atmosphere using passive samplers.

A simple analysis of volatile organic compounds (VOCs), such as benzene, toluene, m,p-xylene, and o-xylene, at low levels in the atmosphere was conducted using passive samplers. The methods were applied to analyzing the behavior and origin of VOCs in Kyoto City. The passive samplers were exposed for 7 - 14 days at sampling sites in Kyoto City and for 30 days in the mountains (Mt. Hiei and Mt. Daimonji). Shibata gas-tube samplers packed with activated carbon were used for the determination of VOCs. The absorbed VOCs were extracted into carbon disulfide (CS2) and measured by FID-GC. The determination limits and relative standard deviations for VOCs were 0.3 microg/m3 and 3%, respectively. The samplers were set up at 5 sites in March, 2001 and at 13 stations on Mt. Hiei in November, 2002. The average concentrations of ambient benzene, which were higher than the environmental criterion (3.0 microg/m3), except for those on Mt. Daimonji from March, 2001, to February, 2002, decreased to below 3.0 microg/m3 from March, 2002, to February, 2003. The decrease in ambient benzene may have been due to a decrease in the benzene content in gasoline by the end of 1999, and also by implementation of the Pollutant Release and Transfer Register (PRTR) Act in 2001.     

SmI2-induced reductive cyclization of optically active β-alkoxyvinyl sulfoxides with aldehyde

SmI₂-induced reductive cyclization of optically active (E)- and (Z)-β-alkoxyvinyl sulfoxides with aldehyde was developed for the construction of several stereoisomers of tetrahydropyran derivatives.     

A practical procedure for the synthesis of multifunctional aldehydes through the Fukuyama reduction and elucidation of the reaction site and mechanism

A highly efficient heterogeneous Pd/C catalyst D1 was found to effect the reduction of thiol esters 1 to the corresponding aldehydes 2 with such a low catalyst loading as 0.5-1.0 mol %. The chemical properties of the Pd/C catalysts together with the XRF analysis reveal that the reduction is most likely to proceed on the solid surface of the Pd/C catalyst rather than in the solution phase outside the pores. A reaction mechanism through oxidative addition of Pd to the thiol esters 1 was postulated by detection of the oxidative addition intermediate by React IR analysis. A practical purification of 2 was accomplished by conversion to water-soluble bisulfite adducts 7.     

Measurement and correlation of liquid–liquid equilibria for acetonitrile + n-alkane systems

The reduction of sulfur content in gasoline and diesel fuel is a great environmental concern to reduce the motor vehicle emissions. Oxidative desulfurization using acetonitrile biphasic system has received much attention in recent years. The oxidative desulfurization can be oxidized the unreactive sulfur contents in the hydrodesulfurization and removed effectively. For the oxidative desulfurization process design and development, liquid–liquid equilibria (LLE) for acetonitrile biphasic systems are needed as fundamental information. In our previous work, LLE for acetonitrile + n-octane and + n-decane systems have been reported. In this work, therefore, LLE for acetonitrile + n-hexadecane system was measured. Furthermore, NRTL equation was applied to correlate the LLE for these three acetonitrile + n-alkane systems.     

Structure-affinity relationships of C-terminal cyclic analogue of neuropeptide Y for the Y1-receptor

We previously reported that a cyclic octapeptide amide, c[D-Cys29, Cys-34]NPY Ac-29-36 (YM-42454) showed a high affinity for Y1-receptors in SK-N-MC cells (Ki=0.047,microM) but not for Y2-receptors in the porcine hippocampus membranes (Ki>10microM). To explore the critical residues of this unique cyclic peptide for Y1-binding activity, the structure-affinity relationships were investigated by means of amino acid replacement. The results indicated that the hydrophobic side-chains of Leu30 and Ile31, the guanidinium groups of Arg33 and Arg33, and the C-terminal amide are critical for the binding affinity of YM-42454 to the Y1-receptor. On the other hand, Thr32 in YM-42454 might not be critical for the Y1-binding affinity. 1H-NMR studies for YM-42454 and its derivatives have suggested that the critical residues are involved in the direct interaction with a Y1-receptor rather than in maintaining the bioactive conformation.     

Asymmetric [2 + 1] Cycloaddition Reactions of 1-Seleno-2-silylethene

The reaction of (E)-1-(phenylseleno)-2-(trimethylsilyl)ethene (1) and vinyl ketones 2a-d in the presence of a chiral Lewis acid prepared from TiCl(4), Ti(O(i)Pr)(4), (R)- or (S)-1,1'-binaphthol (BINOL), and MS4A gave enantiomerically enriched cis cyclopropane products 3a-d. The enantiomeric excess and chemical yield varied depending on the ratio of TiCl(4) and Ti(O(i)Pr)(4) to 1. Reproducible results (43-47% ee/33-41% yields) for cis-1-acetyl-2-[(phenylseleno)(trimethylsilyl)methyl]cyclopropane (3a) were obtained using 1.1 equiv of TiCl(4), 0.54-0.65 equiv of Ti(O(i)Pr)(4), and 1.65 equiv of BINOL. The observed enantioselectivity was explained by consideration of the structure of the postulated intermediates, alkoxy titanium-carbonyl complexes, via ab initio MO calculations.     

Characterization of airborne particulates by laser microprobe mass analysis

Summary Laser microprobe mass analysis (LAMMA) was applied to characterize aerosol particles collected and separated from 16m to 0.06m by a low pressure cascade impactor. Positive ion LAMMA spectra showed characteristic molecular peaks such as PbCl⁺, a series of Si₂O⁺–Si₂O₄ ⁺ and NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, and TiO⁺ in 0.06–0.12m, 0.5–1m and 4–8m fraction, respectively. In the negative ion LAMMA spectra, it was observed that the fragment peaks of sulfate ions were deficient above 2m and those of nitrate ions were deficient under 2m. LAMMA allows remarkable insights into the chemical nature of aerosol particles.

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Charakterisierung luftgetragener Teilchen durch Laser-Microprobe-Massenspektrometrie

Zusammenfassung Laser-Microprobe-Spektrometrie (LAMMS) wurde zur Analyse atmosphärischen Aerosols herangezogen, welches im Korngrößenbereich zwischen 16m und 0.06m mit einem Niederdruckkaskadenimpaktor fraktioniert gesammelt wurde. Positive LAMMS-Spektren zeigten charakteristische molekulare Peaks, wie etwa PbCl⁺, eine Serie von Si₂O⁺–Si₂O₄ ⁺ und NaAl₂Si₂O₂ ⁺–NaAl₂Si₂O₅ ⁺, sowie TiO⁺ in der 0,06–0,12-m,- 0,5–1–m- bzw. 4–8-m-Fraktion. In den negativen LAMMS-Spektren konnten über 2m keine Fragmentpeaks für Sulfationen, unter 2m. keine für Nitrationen beobachtet werden. LAMMS ermöglicht eine bemerkenswerte Einsicht in die chemische Natur von Aerosolteilchen.