2,8-二甲基-1,7-二氧杂螺[5,5]十一烷的合成

果蝇 ( Tephritidae)对水果生产有严重的危害 .热带果蝇寿命较长 ,具有很强的迁徙能力和繁殖能力 .因此开展果蝇生物防治和控制措施的相关研究具有重要的意义 [1,2 ] .Baker等 [3]发现性成熟的雌B.dorsalis果蝇 ,性腺分泌物中包含有螺环缩酮化合物 2 ,8-二甲基 - 1 ,7-二氧杂螺 [5 ,5 ]十一烷 ( 1 ) .Bactrocera Latifrons( Hendel)果蝇的雄性腺体分泌物中也存在螺环缩酮 1 [4 ] ,另外在 rove甲虫腹梢分泌物中也分离出 1 [5] ,螺环缩酮不仅作为性信息素组分存在于许多果蝇腺体中 ,而且作为结构单元存在于许多复杂的有强烈生理活性的天然…     

STRUCTURE OF CRYSTALLINE DOMAINS IN SEMICRYSTALLINE BLOCK COPOLYMER THIN FILMS

Thin film morphology of a symmetric semicrystalline oxyethylene/oxybutylene diblock copolymer （E76B38） on silicon was investigated by tapping mode atomic force microscopy （AFM）. It is found that the nascent thin film is composed of multiple polymer layers having mixed thicknesses of L ≈ L0 and L ≈ L0/2 （L0 is the long period of the block copolymer in bulk） besides the first layer near the substrate. This shows that the crystalline domain in the block copolymer consists of double poly（oxyethylene） layers. Annealing leads to disappearance of the polymer layers with thickness L ≈L0/2, indicating that such polymer layers are metastable.     

Unequivocal syntheses of 6-methyl- and 6-phenylisoxanthopterin

Although 6-methyl- ( 1 ) and 6-phenylisoxanthopterin ( 2 ) have previously been synthesized, the requirement of high purity necessary for immunological testing has necessitated our development of the first reported synthesis of these compounds by unequivocal methods. In the process of so doing four new pyrazines, ethyl 3-amino-5-chloro-6-methyl-2-pyrazinecarboxylate ( 11 ), N,N-dimethyl-N'-(6-chloro-3-cyano-5-phenylpyrazin-2-yl)methanimidamide ( 16 ), 2-amino-3-ethoxycarbonyl-5-phenylpyrazine 1-oxide ( 19 ), and ethyl 3-amino-5-chloro-6-phenyl-2-pyrazinecarboxylate ( 20 ) were synthesized. Four new pteridines, 7-methoxy-6-methyl-2,4-pteridinediamine ( 7 ), 7-methoxy-6-phenyl-2,4-pteridinediamine ( 17 ), 2-amino-7-ethoxy-6-methyl-4(3H)-pteridinone ( 12 ), and 2-amino-7-ethoxy-6-phenyl-4(3H)-pteridinone ( 21 ) have also been synthesized enroute to these isoxanthopterins.     

Structure and electrical properties of Pb(Zr<Subscript>0.25</Subscript>Ti<Subscript>0.75</Subscript>)O<Subscript>3</Subscript> thin films on LaNiO<Subscript>3</Subscript>—Coated thermally oxidized Si substrates

Pb(Zr_0.25Ti_0.75)O₃ (PZT25) thin films were prepared on LaNiO₃-coated thermally oxidized silicon substrates by chemical solution deposition method, where LaNiO₃ electrodes were also prepared by a chemical solution deposition technique. The dielectric constant and dielectric loss of the PZT25 thin films were 570 and 0.057, respectively. The remanent polarization and coercive field were 20.11 μC/cm² and 60.7 kV/cm, respectively. The PZT25 thin films on LaNiO₃-coated thermally oxidized silicon substrates showed improved fatigue characteristics compared with their counterparts on plantium-coated silicon substrates.     

The oxidative decarboxylation of polyaminocarboxylic acids

Summary The rates of oxidation of four chelating agents, NTA, EDTA, CDTA, and DTPA with Ce(IV), in sulfuric acid media, were determined spectrophotometrically by a stopped-flow technique. The reductive ability is in the order CDTA > EDTA > DTPA > NTA. The influence of varying the acidity of the medium was studied, and in each case a maximum in the rate constant vs. [H⁺] plot was observed. A possible interpretation of the reactivities and the influence of acidity is advanced.

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Oxydative Decarboxylierung von PolyaminocarbonsäurenII. Vergleichende kinetische Untersuchung der Oxydation von NTA, ÄDTA, CDTA und DTPA mit Ce(IV) in saurer Lösung

Zusammenfassung Die Oxydationsgeschwindigkeiten von 4 Chelaten (NTA, ÄDTA, CDTA und DTPA) mit Ce(IV) in saurer Lösung wurden spektrophotometrisch mit Hilfe der stopped-flow-Technik bestimmt. Die Reduzierfähigkeit nimmt in der Reihenfolge CDTA > ÄDTA > DTPA > NTA ab. Der Einfluß verschiedener Säuregehalte in der Lösung wurde untersucht, und in jedem Fall wurde ein Maximum in der graphischen Darstellung der Geschwindigkeitskonstante gegen [H⁺] beobachtet. Eine mögliche Erklärung des Reaktionsvermögens und des Säureeinflusses wird gegeben.

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Part I: Z. Anal. Chem. 246, 231 (1969).     

Linkage isomerism in 5-exo thiocyanate and isothiocyanate substituted tricarbonyl(η-cyclohexa-1,3-diene)iron and tricarbonyl(η-cyclohepta-1,3-diene)iron

Nucleophilic addition to the tricarbonyl(η-cyclohexadienyl)iron cation and the tricarbonyl(η-cycloheptadienyl)iron cation by the thiocyanate ion forms initially the 5-exo-isothiocyanate (NCS) isomers, C₆H₇NCSFe(CO)₃ and C₇H₉NCSFe(CO)₃, both of which isomerise to the corresponding 5-exo thiocyanate isomers C₆H₇SCNFe(CO)₃ and C₇H₉SCNFe(CO)₃ on exposure to air.     

Stereochemical analysis of isopentenyl diphosphate isomerase type II from Staphylococcus aureus using chemically synthesized (S)- and (R)-[2-2H]isopentenyl diphosphates

[chemical reaction: see text]. To study the catalysis of isopentenyl diphosphate (IPP) isomerase type II from Staphylococcus aureus, which is a flavoprotein catalyzing the interconversion of IPP and dimethylallyl diphosphate, we have chemically synthesized (S)- and (R)-[2-2H]IPP and carried out stereochemical analysis of the reaction. Our results show that the C-2 deprotonation of IPP by this enzyme is pro-R stereospecific, suggesting a similar stereochemical course as the type I enzyme.     

Assessment of phenomenological models for viscosity of liquids based on nonequilibrium atomistic simulations of copper

The shear viscosity of liquid copper is studied using nonequilibrium molecular-dynamics simulations under planar shear flow conditions. We examined variation of viscosity as function of shear rate at a range of pressures (ca. 0 - 40 GPa). We analyzed these results using eight different phenomenological models and find that the observed non-Newtonian behavior is best described by the Powell-Eyring (PE) model: eta(gamma) = (eta(0)-eta(infinity))sinh(-1)(taugamma)(taugamma) + eta(infinity), where gamma is the shear rate. Here eta(0) (the zero-shear-rate viscosity) extracted from the PE fit is in excellent agreement with available experimental data. The relaxation time tau from the PE fit describes the shear response to an applied stress. This provides the framework for interpreting the shear flow phenomena in complex systems, such as liquid metal and amorphous metal alloys.     

Addition of benzylic and allylic organozinc and Grignard reagents to resin-bound imines to provide alpha-branched secondary amines bearing a wide variety of functional groups. Utility in the synthesis of beta-3 adrenergic receptor agonists

Benzylic and allylic organozinc and Grignard reagents have been added to resin-bound imines to provide alpha-branched secondary amines. Many functional groups, including electrophilic groups, were compatible with this methodology. Three modules--a resin-bound primary amine, an aromatic aldehyde, and the organometallic--were independently varied to produce a combinatorial library of alpha-branched secondary amines designed as beta-3 adrenergic receptor agonists.     

Facile syntheses of unsolvated UI3 and tetramethylcyclopentadienyl uranium halides

In the course of comparing the reaction chemistry of (C5Me5)3U, 1, and its slightly less crowded analogue (C5Me4H)3U, 2, new syntheses of UI3, (C5Me4H)3U, (C5Me4H)3UCl, 3, and (C5Me5)3UCl, 4, have been developed. Additionally, (C5Me4H)3UI, 5, and (C5Me4H)2UCl2, 6, have been identified for the first time. A facile synthesis of unsolvated UI3 is reported that proceeds in high yield with inexpensive equipment from iodine and hot uranium turnings. Both UI3 and UI3(THF)4 react with KC5Me4H in toluene to make unsolvated (C5Me4H)3U in higher yield than in previous reports that involve reduction of tetravalent (C5Me4H)3UCl, 3. A more atom-efficient synthesis of complex 3 is also reported that proceeds from reduction of t-BuCl, PhCl, or HgCl2 by 2. Similarly, (C5Me4H)3U reacts with PhI or HgI2 to generate (C5Me4H)3UI. These studies also provided a basis to improve the synthesis of (C5Me5)3UCl from 1 by employing t-BuCl or HgCl2 as the halide source. Like (C5Me5)3UCl, the (C5Me4H)3UCl complex reacts with HgCl2 to form (C5Me4H)2 and (C5Me4H)2UCl2, 6, but unlike (C5Me5)3UX (X = Cl or I), the less substituted (C5Me4H)3UX complexes do not reduce t-BuCl or PhX. The synthesis of 6 from (C5Me4H)MgCl x THF and UCl4 is also included.