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Related Derivatives (relate + derivative)
Selected AbstractsChemInform Abstract: Synthesis of New Alkylene-Linked Donepezil-Aminothienoquinoline Hybrid Related Derivatives.CHEMINFORM, Issue 36 2009Yang-Heon Song Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Ruthenium-Catalyzed Cycloisomerization of cis-3-En-1-ynes to Cyclopentadiene and Related Derivatives Through a 1,5-Sigmatropic Hydrogen Shift of Ruthenium,Vinylidene Intermediates.CHEMINFORM, Issue 50 2005Swarup Datta Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Concise Formation of 4-Benzyl Piperidines and Related Derivatives Using a Suzuki Protocol.CHEMINFORM, Issue 34 2001Susan Vice Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] On the Mechanism of the Reductive Metallation of Asymmetrically Substituted Silyl ChloridesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2005Martin Oestreich Abstract An investigation of the stereochemical course of the reductive metallation of silyl chlorides with silicon-centred chirality has revealed two major events which are detrimental to stereoselection during silyl anion formation: (1) chloride-induced racemisation of silyl chlorides and (2) nonstereoselective formal dimerisation during metallation providing the corresponding disilane. In control experiments, the stereochemical course of these processes has been independently verified for the reductive metallation of the enantioenriched cyclic silyl chloride (SiS)- 7a (R = H, er , 88:12). A screening of several related derivatives of (SiS)- 7a led to the sterically encumbered silyl chloride (SiR)- 7c (R = iPr, er , 94:6) which displays some unique features. This structural modification prevents racemisation by lithium chloride (T < ,40 °C) as well as dimerisation (T < ,100 °C) thus allowing for the first generation of an asymmetrically substituted silyl anion (SiS)- 8c (er = 74:26) by reductive metallation of a silyl chloride with silicon-centred chirality. Moreover, the enantiospecificity of the preparation of (SiR)- 7c by chlorination [(SiS)- 9c , (SiR)- 7c] and its reduction with aluminium hydrides [(SiR)- 7c , (SiR)- 9c] have been unambiguously determined by X-ray crystallography as retention (,99%) and inversion (,99%), respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Structure,Efficiency Relations of 1,3,5-Benzenetrisamides as Nucleating Agents and Clarifiers for Isotactic Poly(propylene),MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2010Frank Abraham Abstract This paper presents the synthesis and properties of 1,3,5-benzenetrisamides with a particular focus on structure-efficiency relationships of nucleation and optical property enhancement of isotactic poly(propylene) (i -PP). A family of twenty 1,3,5-benzenetrisamide derivatives was synthesized, in which the direction of the amide linkage between the core and the peripheral substituents, as well as their length (C-3 to C-6) and flexibility were systematically varied. Dissolution- and recrystallization temperatures of the additives in the polymer melt, the crystallization temperature of i -PP, and the optical properties clarity and haze were determined in the additive concentration range from 200 to 2,500,ppm. Within the reported series of compounds, few exhibited very good nucleating and clarification abilities, only one with outstanding characteristics, whereas other, very closely related derivatives were found to be incapable to nucleate or clarify i -PP, although, intriguingly, most are structural isomers. We conclude that it is the particular chemical structure of the additive that determines its crystallization/self-assembly process, and, therewith, the structure of the heterogeneous nuclei, and at a higher hierarchical level the morphology of the poly(propylene) solid state and its final properties; and, hence, that a predictive understanding is still elusive. [source] NMR elucidation of a novel (S)-pentacyclo-undecane bis-(4-phenyloxazoline) ligand and related derivativesMAGNETIC RESONANCE IN CHEMISTRY, Issue 12 2008Grant A. Boyle Abstract The NMR elucidation of a novel ligand (S)-pentacyclo-undecane bis-(4-phenyloxazoline) and related pentacyclo-undecane (PCU) derivatives is reported. Two-dimensional NMR proved to be a powerful technique in overcoming the difficulties associated with the elucidation of these compounds when only one-dimensional NMR data is utilized. A chiral substituent was introduced to both ,arms' of the PCU skeleton to produce derivatives 1,3. These derivatives display C1 symmetry with all thecage atoms being nonequivalent. Owing to overlapping of peaks in the 1H spectra, identification of these diastereomeric protons was very difficult. The 13C spectra gave rise to clear splitting of the nonequivalent carbons. This is unusual compared to similar PCU derivatives with chiral substituents as splitting of all the diastereomeric cage carbons has not yet been reported. Nuclear Overhauser enhancement spectroscopy (NOESY) correlations of derivatives 1,3 confirm the different conformations of the molecule in which the side ,arms' occupy different orientations with respect to cage moiety. Copyright © 2008 John Wiley & Sons, Ltd. [source] Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maizeRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2006Michael Sulyok This paper describes the first validated method for the determination of 39 mycotoxins in wheat and maize using a single extraction step followed by liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS) without the need for any clean-up. The 39 analytes included A- and B-trichothecenes (including deoxynivalenol-3-glucoside), zearalenone and related derivatives, fumonisins, enniatins, ergot alkaloids, ochratoxins, aflatoxins and moniliformin. The large number and the chemical diversity of the analytes required the application of the positive as well as the negative ion ESI mode in two consecutive chromatographic runs of 21,min each. The solvent mixture acetonitrile/water/acetic acid 79,+,20,+,1 (v/v/v) has been determined as the best compromise for the extraction of the analytes from wheat and maize. Raw extracts were diluted 1,+,1 and were injected without any clean-up. Ion-suppression effects due to co-eluting matrix components were negligible in the case of wheat, whereas significant signal suppression for 12 analytes was observed in maize, causing purely proportional systematic errors. Method performance characteristics were determined after spiking blank samples on multiple levels in triplicate. Coefficients of variation of the overall process of <5.1% and <3.0% were obtained for wheat and maize, respectively, from linear calibration data. Limits of detection ranged from 0.03 to 220,µg/kg. Apparent recoveries (including both the recoveries of the extraction step and matrix effects) were within the range of 100,±,10% for approximately half of the analytes. In extreme cases the apparent recoveries dropped to about 20%, but this could be compensated for to a large extent by the application of matrix-matched standards to correct for matrix-induced signal suppression, as only a few analytes such as nivalenol and the fumonisins exhibited incomplete extraction. For deoxynivalenol and zearalenone, the trueness of the method was confirmed through the analysis of certified reference materials. Copyright © 2006 John Wiley & Sons, Ltd. [source] Dithioether ligands containing a 2,6-disubstituted pyridine linker with two thioether-heterocycle armsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Archimede Rotondo The structure of 2,6-bis(2-pyridyltsulfanylmethyl)pyridine (pytmp), (I), C17H15N3S2, presents a twisted conformation, with the three planar moieties almost perpendicular to each other. The structures of two related derivatives, namely 2,6-bis(6-methyl-2-pyridylsulfanylmethyl)pyridine (mpytmp), (II), C19H19N3S2, and 2,6-bis(4-methyl-2-pyrimidylsulfanylmethyl)pyridine (mprtmp) n- pentane hemisolvate, (III), C17H17N5S2·0.5C5H12, present extended planar fragments with just one quasi-perpendicular arylsulfanylmethyl side arm, such that the molecules are folded in an L-shaped conformation. All three conformations appear different from those adopted by similar compounds, demonstrating the great flexibility of such species, although such differences in conformational behaviour might drive specific coordination modes. [source] Remarkably Slow Rotation about a Single Bond between an sp3 -Hybridised Carbon Atom and an Aromatic Ring without ortho SubstituentsCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2009Sarah Murrison Abstract Look, noorthosubstituents! A series of polycycles were prepared by using a three-component Joullié,Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured, and was highly dependent on the substitution. Rotamer half-lives of up to 21,h at 298,K were observed (see figure). Rotamers resulting from this restricted rotation were isolated for the first time. A series of polycycles was prepared by using a three-component Joullié,Ugi reaction. The rate of rotation about the bond between a highly hindered bridgehead and a phenyl ring with no ortho substituents was measured by using, in general, variable-temperature HPLC. The rate of rotation was highly dependent on substitution and rotamer half-lives of up to 21,h at 298,K were observed. Insights into the effect of substitution on the rate of rotation were gleaned through electronic structure calculations on closely related derivatives. Rotamers resulting from restricted rotation about a bond between an sp3 -hybridised carbon atom and a phenyl ring with no ortho substituents were isolated for the first time, and the equilibration of the separated rotamers was followed by using analytical HPLC. It was demonstrated, for the first time, that a highly hindered environment for the sp3 -hybridised atom is sufficient for slow bond rotation about a single bond between sp3 - and sp2 -hybridised carbon atoms. [source] | ||||||||||