Synthesis of novel tryptamine and β-carboline derivatives via palladium-catalyzed reaction of bromotryptamine with organic boronic acids

New tryptamine <b>5, 7</b> and β-carboline derivatives <b>3</b> were preparated by palladium-catalyzed coupling reaction of 5-bromotryptamine <b>1</b> with aryl boronic acids. Dedicated to Professor András Lipták on his 70<sup>th</sup> birthday.     

Regioselectivity of Birch reductive alkylation of biaryls

[reaction: see text] The regioselectivity of the Birch reductive alkylation of polysubstituted biaryls has been investigated. Results indicate that regioselectivity is affected by the electronic nature of substituents on both aromatic rings. The electron-rich 3,5-dimethoxyphenyl moiety is selectively reduced and then alkylated, while phenols and aniline are not dearomatized under these conditions. Biaryls possessing a phenol moiety are alkylated on the second ring, providing that the acidic proton has been removed prior to the Li/NH3 reduction.     

Assessment of the Fe-Sn-Zn phase diagram at 450°C

The Fe-Sn-Zn system is of interest because Sn is one element added to the Zn galvanizing bath to overcome the drawbacks due to the presence of Si in semi-killed steels. This work has been undertaken with the aim to understand the tin effect on the microstructure and the layers growth in batch galvanized coatings on low alloyed steels. Various experimental techniques such as metallography, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX) are used in order to characterize the microstructure and the properties of such coatings elaborated in a zinc bath enriched with tin. Solidification phenomena and layers growth mechanisms during galvanization are explained by means of the ternary phase diagram Fe-Sn-Zn at 450°C. The Calphad method allows to obtain this phase diagram from the three optimized binary phase diagrams Fe-Sn, Fe-Zn and Sn-Zn and some experimental data inside the ternary Fe-Sn-Zn system.     

Synthesis of 2′,3′-dihydrosolanesyl analogues of β-d-arabinofuranosyl-1-monophosphoryldecaprenol with promising antimycobacterial activity

Two new hydrolytically stable analogues of β-d-arabinofuranosyl-1-monophosphoryldecaprenol, the donor substrate for mycobacterial arabinosyltransferase, have been prepared. Biological evaluation of these compounds in vitro against <em>Mycobacterium tuberculosis</em> H<sub>37</sub>Rv strain revealed a promising activity.     

Selected ion flow tube mass spectrometry analyses of stable isotopes in water: Isotopic composition of H3O+ and H3O+(H2O)3 ions in exchange reactions with water vapor

A new method has been developed for the determination of the isotope abundance ratios of deuterium, D, and oxygen-18, 18O, in water vapor (and water) using selected ion flow tube mass spectrometry (SIFT-MS). H3O+ ions are injected into the helium carrier gas where they associate with the H2O and HDO molecules in a sample of water introduced into the carrier gas. The D and 18O contents of the product cluster ions H8DO4+ and H9(18)OO3+ at m/e = 74 and 75, respectively, are determined by reference to the majority cluster ion H9O4+ at m/e = 73. Allowance is made for the contribution of the H8(17)OO3+ ions to the m/z = 74 ions. Absolute isotopic ratios are measured within seconds without the need for precalibration of the SIFT-MS instrument, currently to an accuracy of better than 2%.     

Synthesis,Crystal Structure,and Electrochemical Behaviour of an Azido μ‐bridged Ni2+ Complex

A homo‐dinuclear Ni<sup>II</sup> complex was prepared from 2, 6‐bis(3, 5‐dimethylpyrazolyl)pyridine (Me<sub>4</sub>‐bpp) and azide ions in nonaqueous media. It was characterized by single crystal X‐ray structural analysis, IR spectroscopy, and elemental analysis. In addition, the electrochemical properties of the compound were determined with cyclic voltammetry in DMF. The title compound crystallizes in the P2<sub>1</sub>/n monoclinic space group, with unit cell parameters a = 8.978(1), b = 12.459(1), c = 17.764(1) Å, ß =100.603(3)°, V = 1953.0(3) Å<sup>3</sup>, Z = 2. The Ni<sup>2+</sup> ion has a distorted octahedral environment involving three nitrogen atoms of the Me<sub>4</sub>‐bpp ligand, two nitrogen atoms from the bridged azide group, and one nitrogen atom from the terminal azide group. The Ni···Ni distance is 3.273(5) Å.     

Examining the balance between efficiency and resilience in closed-loop supply chains

Central European Journal of Operations Research - We study a hybrid system where the demand of customers can be satisfied by both manufacturing new products and remanufacturing used products. To...     

Triangulations and moduli spaces of Riemann surfaces with group actions

Summary We study that subset of the moduli space <img src="/content/802746300253420r/229_2007_Article_BF02567818_TeX2GIFIE1.gif" alt=" $$\bar M^g $$ " align="middle" border="0"> of stable genus<i>g</i>,<i>g</i>>1, Riemann surfaces which consists of such stable Riemann surfaces on which a given finite group<i>F</i> acts. We show first that this subset is compact. It turns out that, for general finite groups<i>F</i>, the above subset is not connected. We show, however, that for ℤ<sub>2</sub> actions this subset<i>is</i> connected. Finally, we show that even in the moduli space of<i>smooth</i> genus<i>g</i> Riemann surfaces, the subset of those Riemann surfaces on which ℤ<sub>2</sub> acts<i>is</i> connected. In view of deliberations of Klein ([8]), this was somewhat surprising. These results are based on new coordinates for moduli spaces. These coordinates are obtained by certain<i>regular</i> triangulations of Riemann surfaces. These triangulations play an important role also elsewhere, for instance in approximating eigenfunctions of the Laplace operator numerically. This work has been supported by the European Communities Science Plan Project No SCI<sup>*</sup>-CT91 (TSTS) “Computational Methods in the Theory of Riemann Surfaces and Algebraic Curves,” by Academy of Finland and by the Swiss National Science Foundation Grant 20-34099.92. We thank M. C. Petrus for providing excellent motivation for this work. This article was processed by the author using the LATEX style file<i>cljourl</i> from Springer-Verlag.     

Kneser-type oscillation criteria for self-adjoint two-term differential equations

It is proved that the even-order equation<i>y</i> <sup> <i>(2n)</i> </sup> <i>+p(t)y</i>=0 is (<i>n,n</i>) oscillatory at <img src="/content/P27410776Q7322T3/xxlarge8734.gif" alt="infin" align="MIDDLE" border="0"> if<table width="100%"><tbody><tr><td align="left"> <img src="/content/P27410776Q7322T3/11290_2005_Article_BF02261699_TeX2GIFE1.gif" alt=" $$\mathop {\lim }\limits_{t \to \infty } ( - 1)^n \log t\int_t^\infty {s^{2n - 1} } \left( {p(s) + \frac{{\mu _{2n} }}{{s^{2n} }}} \right) ds< - K_n $$ " align="middle" vspace="20%" border="0">