Journal articles: 'Β-X elimination'

1

Viola, Luis, and Rita H. de Rossi. "Effect of cyclodextrin on elimination reactions." Canadian Journal of Chemistry 77, no. 5-6 (June 1, 1999): 860–67. http://dx.doi.org/10.1139/v99-085.

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The reaction of 1-bromo-2-X-2-(Y-phenyl) ethane derivatives (1: X = Y = H; 2: X = Ph, Y = H; 3: X = H, Y = 4-Ac; 4: X = H, Y = 3-NO2; 5: X = H, Y = 4-NO2; 6: X = H, Y = 3-Me; 7: X = H, Y = 4-Me) in basic solution was studied, and in most cases, only the elimination product is formed. Only (2-bromo-1-phenylethyl)benzene, 2, yielded significant substitution product, and this yield decreased with the concentration of HO-. Addition of cyclodextrin (β-CD) diminished (about half for 0.02 M cyclodextrin concentration) the reaction rate of all substrates but 4 and 5. In the latter two cases, the rate rises. The observed rate-constant value at 0.5 M NaOH is 6.78 × 10-4 s-1 (at 40°C) and 1.80 × 10-3 s-1 (at 25°C) for 4 and 5, respectively. Under the same reaction conditions but with 0.01 M β-CD, the corresponding rates were 7.70 × 10-4 s-1 and 5.20 × 10-3 s-1. The elimination yield for 2 increased from 64 to 98% when the β-CD changed from zero to 0.02 M at 0.5 M NaHO. Also, there was an increase in the relative elimination products of 20-40% for compounds 6 and 7. The Hammet ρ values were 1.3 and 2.3 for the reaction in pure solvent and in the presence of β-cyclodextrin, indicating an increase in the negative character of the transition state for the reactions in the latter conditions. The results are interpreted in terms of the formation of an inclusion complex whose structure depends on the substrate.Key words: cyclodextrin, elimination reactions, inhibition, catalysis.

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2

Rufanov, Konstantin A., Dominique M. M. Freckmann, Heinz-Jürgen Kroth, Stefan Schutte, and Herbert Schumann. "Studies on the Thermolysis of Ether-Stabilized Lu(CH2SiMe3)3. Molecular Structure of Lu(CH2SiMe3)3(THF)(diglyme)." Zeitschrift für Naturforschung B 60, no. 5 (May 1, 2005): 533–37. http://dx.doi.org/10.1515/znb-2005-0509.

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Lu(CH2SiMe3)3(THF)2 (2) decomposes slowly at room temperature with formation of Me4Si. In order to understand the mechanism of this elimination process, Lu(CH2SiMe3)3([D8]-THF)2 (1), Lu(CH2SiMe3)3(THF)(DME) (3), and Lu(CH2SiMe3)3(THF)(diglyme) (4) were prepared. The results of 1H NMR spectroscopic studies of the decomposition in solution exclude an α- as well as a β -H elimination mechanism and point towards a γ -H elimination. The molecular structure of 4 has been determined by single crystal X-ray diffraction.

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3

Xu, Yuming, Herbert W. Roesky, Frank Schrumpf, and Mathias Noltemeyer. "Substitutionsreaktionen am Niobtetrafluorid-Komplex (η5-C5Me5)NbF4 / Substitution Reactions on the Tetrafluoro Niobium Complex (η5-C5Me5)NbF4." Zeitschrift für Naturforschung B 45, no. 4 (April 1, 1990): 423–26. http://dx.doi.org/10.1515/znb-1990-0403.

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Cp*NbF4 (1) (Cp* = η5-C5Me5) reacts with lithium salts of β-diketones under elimination of LiF to form the chelate complexes (2) and (3). The X-ray crystal structure of 3 was investigated and is compared with the homologous tantalum compound.

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4

Harrington, Laura E., James F. Britten, and Michael J. McGlinchey. "Ferrocenyl-penta-(β-naphthyl)benzene Synthesis, structure, and dynamic behaviour." Canadian Journal of Chemistry 81, no. 11 (November 1, 2003): 1180–86. http://dx.doi.org/10.1139/v03-104.

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3-Ferrocenyl-2,4,5-tri-(β-naphthyl)cyclopentadienone undergoes a DielsAlder reaction with di-(β-naphthyl) acetylene to yield, after elimination of carbon monoxide, ferrocenyl-penta-(β-naphthyl)benzene (4). 1H and 13C variable-temperature NMR studies on 4 reveal the existence of multiple diastereoisomers at low temperature. These data are interpreted in terms of slowed rotation of the naphthyl groups, and are supported by the X-ray crystal structure of 4, which exhibits disorder at three of the naphthyl sites.Key words: sterically crowded molecules, hindered rotations, crystallography, NMR.

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5

Stockland Jr., Robert A., Gordon K. Anderson, Nigam P. Rath, Janet Braddock-Wilking, and J. Christopher Ellegood. "Synthesis of the complexes [PdCIR(cod)] (R = benzyl, ethyl; cod = 1,5-cyclooctadiene). β-Elimination from [PdCIEt(cod)] to give the η1,η2 and η3 isomers of [Pd2(μ-Cl)2(C8H13)2]." Canadian Journal of Chemistry 74, no. 11 (November 1, 1996): 1990–97. http://dx.doi.org/10.1139/v96-226.

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Treatment of [PdCl2(cod)] with tetrabenzyltin gives the benzylpalladium complex [PdCl(CH2Ph)(cod)] (cod = 1,5-cyclooctadiene), 1a, whose structure has been determined by X-ray crystallography. It adopts approximate square-planar geometry, with the double bonds perpendicular to the square plane. The corresponding ethylpalladium derivative 1b has been prepared by a similar method, but it is considerably less stable. It decomposes by (β-elimination to produce ethene and a transient hydride complex, which either undergoes migratory insertion to give [Pd2(μ-Cl)2(η1,η2-C8H13)2], 2a, or dinuclear reductive elimination with a second molecule of 1b to produce ethane, [PdCl2(cod)], free cyclooctadiene, and palladium metal. Complex 2a has also been prepared by reaction of [PdCl2(cod)] with NaBH4. At higher temperatures 2a converts to an equilibrium mixture with its η3-allyl isomer, 2b. Reactions of [PdCl2(cod)] or K2PdCl4 in the presence of cyclooctadiene in aqueous solution to produce 2a or 2b have also been investigated. Key words: palladium, diene complexes, allyl complexes, isomerization, β-elimination.

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6

Steiner, Norbert, Ulrich Nagel, and Wolfgang Beck. "Metallkomplexe mit biologisch wichtigen Liganden, XLVIII [1]. Palladium(II)- und Platin(II)-Komplexe mit α,β-Dehydro- und β-Chlor-α-aminosäurederivaten sowie mit O-Acetyl-L-serin / Metal Complexes with Biologically Important Ligands, XLVIII [1] Palladium(II)- and Platinum(II)-Complexes of α,β-Dehydro- and β-Chloro-α-amino Acid Derivatives and of O-Acetyl-L-serine." Zeitschrift für Naturforschung B 43, no. 11 (November 1, 1988): 1453–60. http://dx.doi.org/10.1515/znb-1988-1110.

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The preparation and spectroscopic data of the complexes cis- and trans- CL2M(NH2C(CO2Et)=C<) , (1) (M - Pd. Pt), trans-Cl2Pd(NH2CH(CH2Cl)CO2CH3)2 (2), trans- Cl2Pd(NH2CH(CH2OAc)CO2)2 (3) and trans-Cl2Pt(Gly-β-Cl-AlaOMe)2 (4) are reported. The structures of l a and 2 have been determined by X-ray structure analysis. Elimination of hydrogen chloride from 4 gives the dehydrodipeptide complex 5.

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7

Tran, Van T., John A. Gurak, Kin S. Yang, and Keary M. Engle. "Activation of diverse carbon–heteroatom and carbon–carbon bonds via palladium(ii)-catalysed β-X elimination." Nature Chemistry 10, no. 11 (August 20, 2018): 1126–33. http://dx.doi.org/10.1038/s41557-018-0110-z.

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8

Cundari, Thomas R., and Christopher D. Taylor. "Olefin Insertion and Subsequent β-X Elimination from a Pentacoordinate Tantalum Complex. A Density Functional Theory Study." Organometallics 22, no. 20 (September 2003): 4047–59. http://dx.doi.org/10.1021/om0303606.

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9

Strazisar, Stephanie A., and Peter T. Wolczanski. "Insertion of H2CCHX (X = F, Cl, Br, OiPr) into (tBu3SiO)3TaH2and β-X-Elimination from (tBu3SiO)3HTaCH2CH2X (X = OR): Relevance to Ziegler−Natta Copolymerizations." Journal of the American Chemical Society 123, no. 20 (May 2001): 4728–40. http://dx.doi.org/10.1021/ja003315n.

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10

Jones, Jane H., Bohumil Štíbr, John D. Kennedy, and Mark Thornton-Pett. "Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]." Collection of Czechoslovak Chemical Communications 58, no. 12 (1993): 2924–35. http://dx.doi.org/10.1135/cccc19932924.

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Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

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11

Giersdorf, Konrad, Ursula Diefenbach, and Udo Engelhardt. "Neuartige Dihydrazido- und Oxyamidoverbindungen der Phosphor- und der Thiophosphorsäure mit Bis(2-chlorethyl)amidosubstituenten / New Dihydrazido and Oxyamido Derivatives of Phosphoric and Thiophosphoric Acid with Bis(2-chloroethyl)amido Substituents." Zeitschrift für Naturforschung B 44, no. 12 (December 1, 1989): 1545–49. http://dx.doi.org/10.1515/znb-1989-1213.

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(Cl—CH2CH2)2N—P(=X)Cl2, X = O, reacts with 1,2-dimethylhydrazine in the presence of triethylamine to give the dihydrazide. Hexahydropyridazine as “cyclic hydrazine” leads to a tetracyclic side product formed by HCl elimination from the reactive 2-chloroethyl groups and active β-NH protons of the hexahydropyridazinyl substituents. The corresponding thio-compound, X = S. yields the monosubstitution product (Cl—CH2CH2)2N—P(=S)(N(CH3)—N(CH3)H)Cl. O-Benzylhydroxyamine hydrochloride substitutes both Cl-atoms at P to ioni (Cl—CH2CH2)2N—P(=S)(NH—O—CH2—C6H5)2. The corresponding phenylesters C6H5O—P(=X)(NH—O–CH2—C6H5)2, X = O, S, are prepared in a similar reaction.

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12

Hřebabecký, Hubert, and Antonín Holý. "Synthesis of 1-(2,3-Dideoxy-4-C-methyl-β-D-glycero-pent-2-enofuranosyl)thymine, 1-(2,3-Dideoxy-4-C-methyl-β-D-glycero-pentofuranosyl)thymine and 1-(4-C-Azidomethyl-2-deoxy-β-D-threo-pentofuranosyl)thymine." Collection of Czechoslovak Chemical Communications 58, no. 7 (1993): 1668–74. http://dx.doi.org/10.1135/cccc19931668.

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Reaction of isopropylidene derivative I with thionyl chloride in hexamethylphosphoric triamide afforded chloro derivative II. Removal of the isopropylidene group in II by treatment with a cation-exchanging resin (H+ form) gave the free chloro nucleoside III. reduction of the chloro derivative II with tributylstannane and subsequent removal of the isopropylidene group yielded deoxy derivative V. This was protected with tert-butyldiphenylsilyl group and converted into the mesylate VII. Elimination of the mesyl group followed by desilylation gave 1-(2,3-dideoxy-4-C-methyl-β-D-glycero-pent-2-enofuranosyl)thymine (IX) which was hydrogenated to afford 1-(2,3-dideoxy-4-C-methyl-β-D-glycero-pentofuranosyl)thymine (X). 1-(1-C-Azidomethyl-2-deoxy-β-D-threo-pentofuranosyl)thymine (XIII) was prepared by mesylation of the isopropylidene derivative I, nucleophilic substitution of the mesyl group with azide and removal of the isopropylidene group.

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13

GRUMMITT, Annaleise R., Peter J. RUTLEDGE, Ian J. CLIFTON, and Jack E. BALDWIN. "Active-site-mediated elimination of hydrogen fluoride from a fluorinated substrate analogue by isopenicillin N synthase." Biochemical Journal 382, no. 2 (August 24, 2004): 659–66. http://dx.doi.org/10.1042/bj20040529.

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Isopenicillin N synthase (IPNS) is a non-haem iron oxidase that catalyses the formation of bicyclic isopenicillin N from δ-(L-α-aminoadipoyl)-L-cysteinyl-D-valine (ACV). In this study we report a novel activity for the iron of the IPNS active site, which behaves as a Lewis acid to catalyse the elimination of HF from the fluorinated substrate analogue, δ-(L-α-aminoadipoyl)-L-cysteinyl-D-β-fluorovaline (ACβFV). X-Ray crystallographic studies of IPNS crystals grown anaerobically with ACβFV reveal that the valinyl β-fluorine is missing from the active site region, and suggest the presence of the unsaturated tripeptide δ-(L-α-aminoadipoyl)-L-cysteinyl-D-isodehydrovaline in place of substrate ACβFV. 19F NMR studies confirm the release of fluoride from ACβFV in the presence of the active IPNS enzyme. These results suggest a new mode of reactivity for the IPNS iron centre, a mechanism of action that has not previously been reported for any of the iron oxidase enzymes.

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14

Yadav, Sushma, Anupama Asthana, Rupa Chakraborty, Bhawana Jain, Ajaya Kumar Singh, Sónia A. C. Carabineiro, and Md Abu Bin Hasan Susan. "Cationic Dye Removal Using Novel Magnetic/Activated Charcoal/β-Cyclodextrin/Alginate Polymer Nanocomposite." Nanomaterials 10, no. 1 (January 18, 2020): 170. http://dx.doi.org/10.3390/nano10010170.

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New magnetic iron oxide (Fe3O4)/activated charcoal (AC)/β-cyclodextrin (CD)/sodium alginate (Alg) polymer nanocomposite materials were prepared by direct mixing of the polymer matrix with the nanofillers. The obtained materials were utilized as nano-adsorbents for the elimination of methylene blue (MB), a hazardous water-soluble cationic dye, from aqueous solutions, and showed excellent regeneration capacity. The formation of the nanocomposites was followed by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and adsorption of N2 at −196 °C. The rate of adsorption was investigated varying several factors, namely contact time, pH, amount of adsorbent and MB concentration on the adsorption process. Studies dealing with equilibrium and kinetics were carried out in batch conditions. The obtained results indicated that the removal rate of MB was 99.53% in 90 min. Langmuir’s isotherm fitted better to the equilibrium data of MB. Fe3O4/AC/CD/Alg polymer beads shows amazing adsorption capacities in the elimination of cationic dyes (2.079 mg/g for polymer gel beads and 10.63 mg g−1 for dry powder beads), in comparison to other adsorbent materials. The obtained adsorbent is spherical with hydrophobic cross-linked surface properties that enable an easy recovery without any significant weight loss of in the adsorbent used.

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15

Klinotová, Eva, Václav Křeček, Jiří Klinot, Miloš Buděšínský, Jaroslav Podlaha, Jana Podlahová, and Jiří Ječný. "An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride." Collection of Czechoslovak Chemical Communications 56, no. 12 (1991): 2917–35. http://dx.doi.org/10.1135/cccc19912917.

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3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

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16

Williams, D. Bradley G., Judy Caddy, and Kevin Blann. "FRAGMENTATION AND CLEAVAGE REACTIONS MEDIATED BY SAMARIUM IODIDE. PART 2: α- AND β-ELIMINATION REACTIONS OF C-X SUBSTRATES." Organic Preparations and Procedures International 35, no. 3 (June 2003): 307–60. http://dx.doi.org/10.1080/00304940309356020.

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17

Sdoeung, Sayleap, Kohei Sasaki, Katsumi Kawasaki, Jun Hirabayashi, Akito Kuramata, and Makoto Kasu. "Probe-induced surface defects: Origin of leakage current in halide vapor-phase epitaxial (001) β-Ga₂O₃ Schottky barrier diodes." Applied Physics Letters 120, no. 9 (February 28, 2022): 092101. http://dx.doi.org/10.1063/5.0085057.

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The elimination of killer defects, which are responsible for the reverse leakage current and breakdown at low voltage in β-gallium oxide (β-Ga2O3) Schottky barrier diodes (SBDs), is crucial for the commercialization of the power devices. We found probe-induced surface defects, which act as a reverse leakage current path in β-Ga2O3 SBDs. Each defect corresponds to a reverse leakage current of −0.725 [Formula: see text]A at a reverse bias of −140 V. These defects are wrinkle shaped, which consists of a pair of the convex and concave structures, as observed by atomic force microscopy. The residual strain around the defects was observed as bright contrasts in the x-ray topography image. The surface defect comprised an 83 nm high convex and a 26 nm deep concave structure. A probe attachment at the pressure of 0.206 GPa induced the surface defect along with a reverse leakage current of −3.75 nA at a reverse voltage of −140 V.

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18

Klein, Hans-Friedrich, Stefan Haller, Hongjian Sun, Xiaoyan Li, Thomas Jung, Caroline Röhr, Ulrich Flörke, and Hans-Jürgen Haupt. "Hydrido(acylphenolato)cobaIt(III)-Verbindungen mit Trimethylphosphan-Liganden / Hydrido(acylphenolato)cobalt(III) Compounds Containing Trimethylphosphane Ligands." Zeitschrift für Naturforschung B 53, no. 5-6 (June 1, 1998): 587–98. http://dx.doi.org/10.1515/znb-1998-5-617.

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Abstract Salicylaldehyde derivatives and related β-hydroxo aldehydes CHO-CR=CR′-OH react with CoMe(PMe3)4 via oxidative substitution to form low-spin d6 complexes mer-CoH(CO-CR=CR-O)(PMe3)3. Reductive elimination of acyl and hydride functions from cis positions at the metal is less favourable than in carbonyl cobalt intermediates through a pronounced stabilization by neutral phosphane σ-donor and dianionic acylenolato chelate ligands. Reactions of the hydride complexes with iodomethane or with protic acids HX afford octahedral molecular complexes mer-CoX(CO-CR=CR′-O)(PMe3)3 (X =I, OAc) and mer-CoX(CO-CR=CR′-O)(PMe3)2 (X = OAc, O-CR′=CR-CHO) without opening of the acylenolato chelate ring.

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19

Reimer, Mark L. J., John B. Westmore, and Manoranjan Das. "Electron ionization mass spectrometry of aryl- and fluoroalkyl-substituted nickel(II) β-diketonates and monothio-β-diketonates." Canadian Journal of Chemistry 71, no. 9 (September 1, 1993): 1450–62. http://dx.doi.org/10.1139/v93-187.

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Electron ionization positive-ion mass spectra are reported for 18 substituted nickel(II) β-diketonates and monothio-β-diketonates, NiII(RCXCHCOR′)2, where X = O or S; R = phenyl, 2-thienyl, 5-methyl-2-thienyl, or 2-naphthyl; and R′ = difluoromethyl, trifluoromethyl, pentafluoroethyl, or n-heptafluoropropyl. Each mass spectrum contains a prominent molecular ion, [NiL2]+, which, for β-diketonates, fragments mainly by elimination of the odd-electron R′• species; the resulting ion decomposes by losses of one or more even-electron neutral species to yield ions containing nickel(II). In contrast, the major fragmentation of the molecular ion of monothio-β-diketonates is loss of NiIL to yield an abundant L+ ion. Furthermore, while most ions contain nickel(II), some prominent ions contain nickel(I); among these are [NiISC(R) = CH]+ and [NiI(HCCR)]+. Interesting ions are formed by hydrogen transfer processes. The [NiHL]+ ion is favored in the spectra of β-diketonates having a phenyl substituent, consistent with hydrogen transfer to the metal from the aryl group. On the other hand, the [Ni(L–H)]+ ion, favored for the monothio-β-diketonates, could be formed by hydrogen transfer from the central position of the chelate ring or from an aryl substituent. Alternative mechanisms of formation are discussed. Some minor ions are formed by fluorine transfer to nickel. The trends in their abundances are influenced by the hardness of nickel as an acid in its different oxidation states, under the influence of the ligand donor atoms, and by the hardness of the carbon atoms of the perfluoroalkyl substituents.

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20

Alunni, S., R. Ruzziconi, and O. Teofrasti. "Reactivity and Mechanism of 1-X-2-(O-Nitrophenyl)Ethanes in Base Induced β-Elimination Reactions With Formation of O-Nitrostyrene." Research on Chemical Intermediates 25, no. 5 (January 1, 1999): 483–95. http://dx.doi.org/10.1163/156856799x00077.

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21

Reimer, Mark L. J., John B. Westmore, and Manoranjan Das. "Electron ionization mass spectrometry of cobalt(III) β-diketonates and monothio-β-diketonates possessing aryl and fluorinated alkyl substituents." Canadian Journal of Chemistry 70, no. 3 (March 1, 1992): 952–63. http://dx.doi.org/10.1139/v92-128.

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Electron ionization positive ion mass spectra of 15 substituted cobalt(III) β-diketonates and monothio-β-diketonates, CoIIIL3, where L = RCXCHCOR′, R = phenyl, 2-thienyl, or 2-naphthyl; X = O or S; and R′ = CHF2, CF3, C2F5, or n-C3F7, show a marked dependence on the ligand. Molecular ions, [CoIIIL3]+•, are observed only for some of the more highly fluorinated complexes (R′ = C2F5 or n-C3F7). The [CoIIIL2]+• ion, possibly generated by ionization of CoIIL2 formed by thermal degradation, or by electron ionization of CoIIIL3, typically decomposes by elimination of a radical, i.e., L• or R′•, to yield ions containing Co(II); subsequent decompositions proceed preferentially by loss of even-electron neutral species, also to yield ions containing Co(II). Cobalt-containing ions in which fluorine has rearranged to the metal decrease in variety and abundance for the ligands with higher fluorine content. When metal-bonded oxygen is replaced by sulfur, fluorine migration to Co(III), rather than to Co(II), is preferred. These trends are consistent with a combination of several different concepts including the ability of the metal to undergo valency change, the principle of Hard and Soft Acids and Bases, and the inductive capabilities of the ligand donor atoms and of the R and R′ groups. Ion decomposition pathways are proposed. Keywords: mass spectrometry, cobalt complexes, β-diketonates, fluorinated chelate complexes.

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22

Kawaguchi, Tomohiro, Yung Pin Chen, R. Sean Norman, and Alan W. Decho. "Rapid Screening of Quorum-Sensing Signal N-Acyl Homoserine Lactones by an In Vitro Cell-Free Assay." Applied and Environmental Microbiology 74, no. 12 (April 18, 2008): 3667–71. http://dx.doi.org/10.1128/aem.02869-07.

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ABSTRACT A simple, sensitive, and rapid cell-free assay system was developed for detection of N-acyl homoserine lactone (AHL) autoinducers involved in bacterial quorum sensing (QS). The present approach improves upon previous whole-cell biosensor-based approaches in its utilization of a cell-free assay approach to conduct bioassays. The cell-free assay was derived from the AHL biosensor bacterium Agrobacterium tumefaciens NTL4(pCF218)(pCF372), allowing the expression of β-galactosidase upon addition of exogenous AHLs. We have shown that β-galactosidase expression is possible in cell-free solution [lysate from Agrobacterium tumefaciens NTL4(pCF218)(pCF372) culture]. Assay detection limits with the use of chromogenic substrate X-Gal (5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside) ranged from approximately 100 nM to 300 nM depending on the specific AHL. Replacement (of X-Gal) with the luminescent substrate Beta-Glo increased sensitivity to AHLs by 10-fold. A major advantage of the cell-free assay system is elimination of time-consuming steps for biosensor cell culture conditioning, which are required prior to whole-cell bioassays. This significantly reduced assay times from greater than 24 h to less than 3 h, while maintaining high sensitivity. Assay lysate may be prepared in bulk and stored (−80°C) over 6 months for future use. Finally, the present protocol may be adapted for use with other biosensor strains and be used in high-throughput AHL screening of bacteria or metagenomic libraries.

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23

Shin, Chung-gi, Takumi Obara, Shigeru Morita, and Yasuchika Yonezawa. "Dehydrooligopeptides. X. Useful Synthetic Method for (E)- and (Z)-Isomers of Dehydroaspartic Acids, and TheirΔ1,2-Dehydrodipeptides by the Base-Catalyzed β-Elimination." Bulletin of the Chemical Society of Japan 61, no. 9 (September 1988): 3265–72. http://dx.doi.org/10.1246/bcsj.61.3265.

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24

Zollner, Gernot, Martin Wagner, Tarek Moustafa, Peter Fickert, Dagmar Silbert, Judith Gumhold, Andrea Fuchsbichler, et al. "Coordinated induction of bile acid detoxification and alternative elimination in mice: role of FXR-regulated organic solute transporter-α/β in the adaptive response to bile acids." American Journal of Physiology-Gastrointestinal and Liver Physiology 290, no. 5 (May 2006): G923—G932. http://dx.doi.org/10.1152/ajpgi.00490.2005.

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The bile acid receptor farnesoid X receptor (FXR) is a key regulator of hepatic defense mechanisms against bile acids. A comprehensive study addressing the role of FXR in the coordinated regulation of adaptive mechanisms including biosynthesis, metabolism, and alternative export together with their functional significance is lacking. We therefore fed FXR knockout (FXR−/−) mice with cholic acid (CA) and ursodeoxycholic acid (UDCA). Bile acid synthesis and hydroxylation were assessed by real-time RT-PCR for cytochrome P-450 (Cyp)7a1, Cyp3a11, and Cyp2b10 and mass spectrometry-gas chromatography for determination of bile acid composition. Expression of the export systems multidrug resistance proteins (Mrp)4–6 in the liver and kidney and the recently identified basoalteral bile acid transporter, organic solute transporter (Ost-α/Ost-β), in the liver, kidney, and intestine was also investigated. CA and UDCA repressed Cyp7a1 in FXR+/+ mice and to lesser extents in FXR−/− mice and induced Cyp3a11 and Cyp2b10 independent of FXR. CA and UDCA were hydroxylated in both genotypes. CA induced Ost-α/Ost-β in the liver, kidney, and ileum in FXR+/+ but not FXR−/− mice, whereas UDCA had only minor effects. Mrp4 induction in the liver and kidney correlated with bile acid levels and was observed in UDCA-fed and CA-fed FXR−/− animals but not in CA-fed FXR+/+ animals. Mrp5/6 remained unaffected by bile acid treatment. In conclusion, we identified Ost-α/Ost-β as a novel FXR target. Absent Ost-α/Ost-β induction in CA-fed FXR−/− animals may contribute to increased liver injury in these animals. The induction of bile acid hydroxylation and Mrp4 was independent of FXR but could not counteract liver toxicity sufficiently. Limited effects of UDCA on Ost-α/Ost-β may jeopardize its therapeutic efficacy.

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Paparo, Albert, Caspar N. de Bruin-Dickason, and Cameron Jones. "Synthesis and Characterisation of Two Lithium Tetramethylberyllate Salts and a Series of β-Diketiminato Beryllium Alkyl Complexes." Australian Journal of Chemistry 73, no. 12 (2020): 1144. http://dx.doi.org/10.1071/ch20129.

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A safer route than that previously published for the synthesis of [BeI2(OEt2)2] has been developed. Reactions of beryllium dihalide complexes [BeX2(OEt2)2] (X=Br or I) with either LiMe or LiBun lead to mixtures of products, which have been shown to act as sources of ‘BeR2’ (R=Me or Bun) in previous synthetic studies. Here, a titration method has been developed to determine the quantity of metal alkyl residues in these ‘BeR2’ mixtures that are available for subsequent alkane elimination reactions. Treating ‘BeMe2’ mixtures with N,N,N′,N′-tetramethylethylenediamine (tmeda) gave two lithium tetramethylberyllate compounds, [{(tmeda)Li}2(μ-BeMe4)] and [{[(tmeda)Li](BeMe4)(μ-Li)}∞], which were crystallographically characterised. Treatment of insitu-generated ‘BeR2’ solutions with several β-diketimines (HC{C(Me)=NR}{=C(Me)N(H)R}, NacnacH, R=aryl or alkyl) yielded a series of β-diketiminato beryllium alkyl complexes, [(Nacnac)BeR], including the first chiral example of such a compound. Crystallographic studies of these reveal them to be monomeric, with planar three-coordinate beryllium centres.

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26

Martwong, Ekkachai, Santi Chuetor, and Jatupol Junthip. "Adsorption of Cationic Contaminants by Cyclodextrin Nanosponges Cross-Linked with 1,2,3,4-Butanetetracarboxylic Acid and Poly(vinyl alcohol)." Polymers 14, no. 2 (January 16, 2022): 342. http://dx.doi.org/10.3390/polym14020342.

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Cationic organic pollutants (dyes and pesticides) are mainly hydrosoluble and easily contaminate water and create a serious problem for biotic and abiotic species. The elimination of these dangerous contaminants from water was accomplished by adsorption using cyclodextrin nanosponges. These nanosponges were elaborated by the cross-linking between 1,2,3,4-butanetetracarboxylic acid and β-cyclodextrin in the presence of poly(vinyl alcohol). Their physicochemical characteristics were characterized by gravimetry, acid-base titration, TGA, 13C NMR, ATR-FTIR, Raman, X-ray diffraction, and Stereomicroscopy. The BP5 nanosponges displayed 68.4% yield, 3.31 mmol/g COOH groups, 0.16 mmol/g β-CD content, 54.2% swelling, 97.0% PQ removal, 96.7% SO removal, and 98.3% MG removal for 25 mg/L of initial concentration. The pseudo-second-order model was suitable for kinetics using 180 min of contact time. Langmuir isotherm was suitable for isotherm with the maximum adsorption of 120.5, 92.6, and 64.9 mg/g for paraquat (PQ), safranin (SO), and malachite green (MG) adsorption, respectively. Finally, the reusability performance after five regeneration times reached 94.1%, 91.6%, and 94.6% for PQ, SO, and MG adsorption, respectively.

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Ramesh, T. N., P. Vishnu Kamath, and C. Shivakumara. "Classification of stacking faults and their stepwise elimination during the disorder → order transformation of nickel hydroxide." Acta Crystallographica Section B Structural Science 62, no. 4 (July 12, 2006): 530–36. http://dx.doi.org/10.1107/s0108768106013188.

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Nickel hydroxide samples obtained by strong alkali precipitation are replete with stacking faults. The local structures of the stacking faults resemble the stacking patterns of different polytypic modifications that are theoretically possible among the layered hydroxides. This resemblance becomes a basis for the classification of stacking faults into different types. Each type of stacking fault produces a characteristic non-uniform broadening of peaks in the X-ray powder diffraction pattern of nickel hydroxide. DIFFaX simulations aid the classification and quantification of stacking faults. Hydrothermal treatment of a poorly ordered nickel hydroxide slurry at different temperatures (338–473 K) and different durations (5–48 h) shows that the stacking faults are removed in a stepwise manner. The as-precipitated sample has 17–20% stacking faults of the 3R 2 variety, which evolve into the 2H 2 type at 413 K. The 2H 2 stacking faults persist up to 443 K. The stacking faults are completely removed only at 473 K. At this temperature an ordered β-Ni(OH)2 phase is observed.

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28

Hong, Yue-Hua, Xue-Feng Zheng, Yun-Long He, Hao Zhang, Zi-Jian Yuan, Xiang-Yu Zhang, Fang Zhang, et al. "Leakage current reduction in β-Ga₂O₃ Schottky barrier diode with p-NiO_x guard ring." Applied Physics Letters 121, no. 21 (November 21, 2022): 212102. http://dx.doi.org/10.1063/5.0128736.

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A β-Ga2O3 Schottky barrier diode (SBD) with a p-type NiOx guard ring was fabricated, and the reverse leakage and subthreshold leakage current reduction was found at high temperatures from temperature-dependent I–V characteristics. The functional mechanisms of NiOx as edge termination on leakage reduction were studied. NiOx can increase the barrier height and passivate the defects at the interface, resulting in the suppression of subthreshold leakage and elimination of current crowding effect confirmed by a thermal emission microscope. From the temperature-dependent x-ray photoelectron spectroscopy characteristics, more holes generated to deplete Ga2O3 at higher temperatures were found. It leads to reduce the reverse leakage current. The small-polaron transportation in NiOx is proposed to argue the implausibility of the leakage conduction in NiOx. This work will offer critical physical insight and a valuable route for developing low-leakage Ga2O3 SBDs.

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29

Cai, Tie-Jun, Shu-Zi Lü, Chuan-Lei Zhang, Yi-lan Huang, Ren-yuan Liu, and Qian Deng. "Crystal Structure and Catalytic Properties of (C6H8N)3[PMo12O40]." Zeitschrift für Naturforschung B 66, no. 12 (December 1, 2011): 1231–36. http://dx.doi.org/10.1515/znb-2011-1206.

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The 4-picolinium salt (C6H8N)3[PMo12O40] was synthesized hydrothermally and characterized by IR spectroscopy, TG-DTA data and single-crystal X-ray diffraction. The results indicate that the compound consists of a [PMo12O40]3− heteropolyoxoanion and 4-picolinium cations [C6H8N]+. A supramolecular structure is formed via intermolecular hydrogen-bonding between the different structural units. Crystal data: monoclinic, space group P21/c, a = 19.7004(3), b = 14.0785(2), c = 33.0209(5) Å, β = 91.3590(10)°, V = 9155.8(2) Å3, Z = 8, wR2 = 0.0730. (C6H8N)3[PMo12O40] has a high catalytic activity for the oxidative elimination of acetone from gases as tested in a continuousflow fixed-bed micro-reactor. When the initial concentration is 5.2 gm−3 in air, and the flow rate is 3.3 mLmin−1, 93% of the acetone is eliminated at 70 °C.

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Fryzuk, Michael D., Paul B. Duval, and Steven J. Rettig. "Formation and reactivity of the zirconium ethylene complexes [η5-C5H3-1,3-(SiMe2CH2PR2)2]Zr(η2-CH2=CH2)(X) (R = Me, Pr i; X = Br, C5H5)." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 536–45. http://dx.doi.org/10.1139/v00-154.

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The formation and reactivity of the zirconium ethylene complexes R[P2Cp]Zr(η2-CH2=CH2)(X) (2a: R = Pri, X = Br; 2b: R = Me, X = Br; 4a: R = Pri, X = C5H5; R[P2Cp] = (η5-C5H3-1,3-(SiMe2CH2PR2)2)) are described. Ethylene complexes 2a and 2b are prepared from a reaction of R[P2Cp]ZrCl3 (1a: R = Pri; 1b: R = Me) with 2 equiv of EtMgBr, presumably via β-H elimination from the diethyl intermediate R[P2Cp]ZrCl(CH2CH3)2. The structure of 2b was determined by X-ray crystallography. Addition of carbon monoxide to 16-electron 2 displaces the ethylene ligand to generate the carbonyl complex R[P2Cp]Zr(CO)2Br (5a: R = Pri; 5b: R = Me), which is stable only under an atmosphere of CO. The corresponding CO reaction with 18-electron 4a to give the metallocene monocarbonyl analogue Pr[P2Cp]Zr(η5-C5H5)(CO) (6a) is considerably slower. 2a exhibits fluxional exchange of one carbonyl ligand with bulk 13CO in solution; the kinetic parameters for this exchange process are ΔH = 9.2(5) kcal mol1 and ΔS = 17(2) cal mol1 K1. The addition of diphenylacetylene to 2a yields the alkyne complex Pr[P2Cp]Zr(η2-PhCCPh)Br (7a), which exists in solution as two isomers in equilibrium. A solid-state X-ray structure determination for the minor isomer syn-7a was performed.Key words: zirconium, cyclopentadienyl phosphine, alkyne, metallocyclopropane.

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31

Wiles, Jason A., Steven H. Bergens, and Victor G. Young, Jr. "Stereochemistry at carbon upon protonolysis of a late transition metal-alkyl bond: a reaction of relevance to catalytic enantioselective hydrogenation of olefins." Canadian Journal of Chemistry 79, no. 5-6 (May 1, 2001): 1019–25. http://dx.doi.org/10.1139/v01-051.

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Reaction of [Ru((R)-BINAP)(H)(MeCN)n(acetone)3n](BF4) (where n = 03) (2) with 1 equiv of the olefin substrate methyl α-acetamidoacrylate (MAA) in acetone at room temperature immediately generated a mixture (72:28) of two diastereomers of the complex [Ru((R)-BINAP)(MeCN)(MAA(H))](BF4) (3). The olefinhydride insertion reaction between 2 and MAA to generate 3 was regioselective, with transfer of the hydride to the β-olefinic carbon and transfer of ruthenium to the α-carbon in both diastereomers of 3. The two diastereomers of 3 differ by the absolute configuration at the α-carbon of MAA(H) ((SCα)-3 and (RCα)-3). The absolute configuration of the major ((SCα)-3) diastereomer was determined by X-ray diffraction in conjunction with NMR spectroscopic data. Protonolysis of the rutheniumcarbon bond in 3 and in the methyl α-acetamidocinnamate (MAC) analog ([Ru((R)-BINAP)(MeCN)((S)- MAC(H))](BF4) ((SCα)-4)) by addition of 2 equiv HBF4·Et2O in CH2Cl2 at room temperature was not stereospecific and did not occur with β-hydride elimination from the methyl or benzyl groups.Key words: ruthenium, BINAP, enantioselective, hydrogenation, catalysis.

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Royo, Pascual, Javier Sánchez-Nieves, Maria Angela Pellinghelli, and Antonio Tiripicchio. "β-Elimination and insertion of CNR in transient pentamethylcyclopentadienyl-imido-tantalum dialkyl complexes. X-ray structure of [TaCp*{N(2,6-Me2C6H3)}(CH2CH2)(PMe3)]." Journal of Organometallic Chemistry 563, no. 1-2 (July 1998): 15–21. http://dx.doi.org/10.1016/s0022-328x(98)00570-1.

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HIROYAMA, Masami, and Tadaomi TAKENAWA. "Purification and characterization of a lysophosphatidic acid-specific phosphatase." Biochemical Journal 336, no. 2 (December 1, 1998): 483–89. http://dx.doi.org/10.1042/bj3360483.

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Lysophosphatidic acid (LPA)-specific phosphatase was purified 3300-fold from bovine brain cytosol. The purification was achieved by (NH4)2SO4 fractionation and several chromatography steps, such as Q-Sepharose, DEAE-5PW, Superdex 200 and heparin–Sepharose. The final enzyme preparation showed a single band of molecular mass 44 kDa on SDS/PAGE under reducing conditions. The enzyme activity was completely dependent on the presence of detergents such as Triton X-100, CHAPS, cholate and octyl-β-glucoside. The activity was independent of Mg2+; other cations were inhibitory. The enzyme hydrolysed LPA specifically but not cardiolipin, tetraoleoyl-bisphosphatidic acid, ceramide 1-phosphate or sphingosine 1-phosphate, although phosphatidic acid was hydrolysed slightly. The purified enzyme hydrolysed 1-oleoyl LPA at a rate of 1.1 µmol/min per mg of protein when assayed with LPA as Triton X-100 mixed micelles. The Km value for LPA was 38 µM. NaF and N-ethylmaleimide markedly inhibited the activity, but propranolol had a less potent inhibitory effect. The LPA-specific phosphatase might have an important role in LPA elimination.

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Payne, Nicholas C., Ravindranath Ramachandran, and Richard J. Puddephatt. "Gold-acetylide chemistry: the structure of the complex [Au2(μ-dppm) (C≡C—CMe3)2]." Canadian Journal of Chemistry 73, no. 1 (January 1, 1995): 6–11. http://dx.doi.org/10.1139/v95-002.

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The complex [Au2(μ-dppm)(C≡Ct-Bu)2], 1, dppm=Ph2PCH2PPh2, is formed by reaction of [AuC≡Ct-Bu] with dppm. Compound 1, as an acetone solvate, crystallizes in the monoclinic space group P21/c with cell dimensions a = 14.047(1), b = 16.124(1), c = 17.140(3) Å, β = 103.17(2)° and four formula units per cell. The crystal and molecular structures of this salt were solved by X-ray diffraction techniques using 2634 counter data with I > 2σ(I). Refinement of 278 variables by full-matrix least squares converged at an agreement factor R = 0.023. Thermolysis of complex 1 in refluxing toluene led to intermolecular elimination of t-BuC≡CH, by combination of a t-BuC≡C ligand of one molecule of 1 with a proton from the CH2P2 group of a second, and formation of the stable tetragold(I) complex [Au4(μ3-Ph2PCHPPh2)(μ-dppm)(C≡Ct-Bu)3], 2, which was characterized by its spectroscopic properties. Keywords: acetylide complexes, gold complexes, X-ray crystallography, nmr spectroscopy, bis(diphenylphosphino)methane.

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35

Thewalt, Ulf, Konrad Holl, Udo Demant, Ulrich Müller, and Kurt Dehnicke. "Untersuchungen zur möglichen Existenz des S4N4⊕-Radikalkations und die Kristallstruktur von S4N4[FeCl4] / Investigations Concerning the Possible Existence of the S4N4⊕ Radical Cation and the Crystal Structure of S4N4H[FeCl4]." Zeitschrift für Naturforschung B 41, no. 9 (September 1, 1986): 1061–66. http://dx.doi.org/10.1515/znb-1986-0901.

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Abstract Brom ination o f S4N 4 Cl[FeCl4], Preparation o f S4N 4 H [FeX 4] (X = Cl, Br), IR Spectra, Crystal Structure of S4N4H[FeCI4] S4N 4 H [FeC l4] as well as S4N 4 D [F eC l4] were prepared in C H 2C12 by reaction o f S4N 4 with FeC l3 and C H 3C O O H and CH 3C O O D , respectively. Bromination o f S4N 4C l[FeCl4] with M e3SiBr in C H 2 C12 yields S4N 4 H[FeBr4]; in this reaction, S4N 4 Br® is presumably formed initially; it then decom p oses by elimination o f bromine and formation of the S4N 4® radical cation; the latter reacts with the solvent, yielding the S4N 4 H® cation. Brom ination of S3N 2C l[FeCl4] with M e3SiBr affords S6N 4 [FeBr4]2. The IR spectra o f the com pounds are discussed. The crystal structure o f S4N 4 H [FeC l4] was determined by X-ray diffraction (1210 observed reflexions, R = 0.035). Crystal data: a = 803.8, b — 1003.9, c = 1507.7 pm, β = 104.52°, Z = 4, space group P 2,/c.

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Ju, Anqi, Shengfei Hou, Yuexiu Pan, Yue Wang, Yanan Zhu, and Huifang Chen. "Preparation of hollow carbon submicro-fibers with controllable wall thicknesses from acrylonitrile copolymer." Textile Research Journal 88, no. 16 (May 30, 2017): 1893–901. http://dx.doi.org/10.1177/0040517517712100.

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Most of the hollow carbon submicro-fibers (HCSFs) reported today are made from polyacrylonitrile (PAN) homopolymer. The obtained HCSFs are fragile due to the poor stabilization and spinnability of PAN. In this study, a bifunctional comonomer, β-methylhydrogen itaconate (MHI), was synthesized to prepare poly(acrylonitrile- co-β-methylhydrogen itaconate) [P(AN- co-MHI)] copolymer, which was used as a precursor to produce HCSF by coaxial electrospinning. The stabilization of P(AN- co-MHI) was studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR); the structure of HCSFs was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM). The stabilization of P(AN- co-MHI) has been improved significantly by MHI with lower cyclization temperature, broadened peak and lower activation energy, which is beneficial to producing high-performance HCSFs. HCSFs with fine and uniform structures were obtained after stabilization and carbonization; the diameter of the HCSFs shrinks due to the elimination of N and the extra H. The diameter and wall thickness of HCSFs can be controlled simply by the feeding ratio of P(AN- co-MHI) solution/styrene- co-acrylonitrile solution. The resultant HCSFs can be bent more than 280° without breaking, which has potential applications in lithium-ion rechargeable batteries, supercapacitors, fuel cells, and catalyst.

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Martin, G. C., A. N. Miller, L. A. Castle, J. W. Morris, R. O. Morris, and A. M. Dandekar. "Feasibility Studies Using β -Glucuronidase as a Gene Fusion Marker in Apple, Peach, and Radish." Journal of the American Society for Horticultural Science 115, no. 4 (July 1990): 686–91. http://dx.doi.org/10.21273/jashs.115.4.686.

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The udiA gene encoding the enzyme β -glucuronidase (GUS) appears promising as a genetic marker for early confirmation of successful plant cell transformation. Two strains of Agrobacterium rhizogenes and eight strains of A. tumefaciens were selected as hosts to carry a binary plasmid (pBI121) containing the marker gene encoding the GUS marker that is controlled by the CaMV35S promoter. Presence of plasmid pBI121 in the bacteria was confirmed by resistance to kanamycin, plasmid re-isolation, and restriction enzyme analysis. When the GUS enzyme was expressed in transformed plant cells, reaction with the histochemical substrate 5-bromo-4-chloro-3-indolylglucuronide (X-gluc) lead to blue pigment development. Expression of GUS in viable bacteria that had not been eliminated from transformed tissue caused problems with the early transformation detection in radish, peach, and apple stem sections by also producing a positive X-gluc color reaction. Putative transformation of apple xylem parenchyma callus was accomplished, as judged by resistance to kanamycin, opine analysis, GUS marker gene expression, and presence of the APH(3')11 enzyme. In this system, elimination of bacterial contamination was accomplished during multiple culture transfers on selective media. To be more useful as a marker, the GUS gene should be coupled with a promoter that will not be expressed by Agrobacterium. Parenchyma callus may serve as a primary screen to provide an efficient way of determining the ideal strain for transformation of deciduous tree fruit genera. In our studies, strain A281 consistently proved to be a vector superior to others tested.

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Jung, Hyun Min, Seung Tae Shin, Yu Hwan Kim, Mahn-Joo Kim, and Jaiwook Park. "X-ray Structure and Reactivity of (η4-tetraphenylcyclopentadienone)(CO)2Ru(HOCHMe2): Unexpected Stability of the Neutral 2-Propanol−Ruthenium(0) Complex with Respect to β-Hydride Elimination." Organometallics 20, no. 16 (August 2001): 3370–72. http://dx.doi.org/10.1021/om0103198.

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Yan, Ying, Zhoumin Niu, Boyang Wang, Shangge Zhao, Chao Sun, Yuting Wu, Yuying Li, Hao Ying, and Hongbing Liu. "Saringosterol from Sargassum fusiforme Modulates Cholesterol Metabolism and Alleviates Atherosclerosis in ApoE-Deficient Mice." Marine Drugs 19, no. 9 (August 26, 2021): 485. http://dx.doi.org/10.3390/md19090485.

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Dysregulation of cholesterol homeostasis is a major risk factor of atherosclerosis, which can lead to serious health problems, including heart attack and stroke. Liver X receptor (LXR) α and β are transcription factors belonging to the nuclear receptor superfamily, which play important roles in cholesterol homeostasis. Selectively activating LXRβ provides a promising strategy for the treatment of atherosclerosis. Here, we employed atherosclerotic apoE-knockout mice to evaluate the effects of saringosterol, a phytosterol with potent and selective action for LXRβ, which we identified previously in edible marine seaweed Sargassum fusiforme. We found that saringosterol treatment reduced the atherosclerotic plaque burden without having undesirable adverse hepatic effects in apoE-deficient mice fed an atherogenic diet. Meanwhile, reduced serum levels of cholesterol, accompanied by altered expression of LXR-regulated genes involved in cholesterol absorption, transport, efflux, excretion, and elimination, were observed in apoE-knockout mice after saringosterol treatment. Together, our study not only establishes saringosterol as an effective cholesterol-lowering and anti-atherogenic phytosterol but also provides insights into the underlying mechanism.

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Auner, Norbert, and Erika Penzenstadler. "Silaheterocyclen, XVII / Silaheterocycles, XVII." Zeitschrift für Naturforschung B 47, no. 6 (June 1, 1992): 795–804. http://dx.doi.org/10.1515/znb-1992-0607.

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The silene 2 is formed by reacting 2-chloro-1,3-bis(trimethylsilyl)-2-vinyl-1,3-diaza-2-silacyclopentane (5) with LiBut in n-pentane in the temperature range from -10 to +10°C. The reaction primarily leads to the corresponding a-lithio adduct 6 by addition of the Li-organyl to the vinyl group of 5; subsequent 1,2-LiCl elimination yields 2 as an intermediate. 2 can be trapped by polar reagents Me3SiX (X = OMe, OSO2CF3) as well as by organic dienes which add across the Si=C bond; in the absence of trapping agents, trisilacyclohexane 7 is isolated. The cycloaddition behaviour of 2 is best described by the two mesomeric formulae (a) and (β), with competitive [4+2] and [2+2] addition routes: While with butadienes and norborna-2,5-diene the [2+2] products are formed mainly in a multiple step reaction via zwitterionic intermediates (1,4 dipoles), the ratio of the [4+2]/[2+2] derivatives from 2 and cyclohexa-1,3-diene becomes nearly equivalent. 2 is thus quite comparable in its reactivity to dichloroneopentylsilene, Cl2Si = CHCH2But.

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Köster, Roland, Günter Seidel, Roland Boese, and Bernd Wrackmeyer. "Ein tricyclisches Tetraboradisiladodecan aus Dimethyl-di-1-propinylsilan und Ethyldiboranen(6) / A Tricyclic Tetraboradisiladodecane from Dimethyl-di-1-propynylsilane and Ethyldiboranes(6)." Zeitschrift für Naturforschung B 50, no. 3 (March 1, 1995): 439–47. http://dx.doi.org/10.1515/znb-1995-0319.

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The exhaustive hydroboration of the (C ≡ C )-groups in Me2Si(C ≡ CMe)2 (A ) by adding ethyldiboranes(6) at room temperature is presumed to lead initially to the formation of a mixture of the threo- and erythro-3,3,5,6-tetrakis(diethylboryl)-4,4-dimethyl-4-silaheptanes (1a , b). The threo-1a reacts further by borane catalysed intermolecular condensation to the substituted disilatetraboratricyclo[6.2.1.16.9]dodecane 2 with the formula , whose crystal structure [space group C2/c, a = 19.696(2), b = 10.371(1), c = 16.580(2) Å; β = 125.90(1)°; at 122 K] has been established by X -ray diffraction. In contrast, the erythro-1b undergoes intramolecular, thermal elimination of Et3B to give the 1,2-diethyl-2,4-bis(diethylboryl)- 3,3,5-trim ethyl-3-silaborolane (4). If A is added to an excess of undiluted B (“hydridebath”), then the two substituted diastereomers of the 1-carba-arachno-pentaboranes(10) (endo/exo-Et,SiH Me2) (3a, b), are formed preferentially as the result of an initial Si-C ≡-c le a v e d hydroboration.

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42

Jenkins, Hilary A., Stephen J. Loeb, David G. Dick, and Douglas W. Stephan. "Dihydride formation versus H2-elimination in the protonation of the heterobimetallic FePt complex (CO)3Fe(μ-H)(μ-PCy2)Pt(PEt3)2." Canadian Journal of Chemistry 68, no. 6 (June 1, 1990): 869–74. http://dx.doi.org/10.1139/v90-136.

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The reaction of Li[Fe(CO)4(PCy2)] with trans-PtCl(H)(PEt3)2 results in the formation of the hydride complex (CO)3Fe((μ-H)((μ-PCy2)Pt(PEt3)2, 1. This heterobimetallic, phosphido-bridged complex reacts with one equivalent of HBF4•Et2O to give the complex [(CO)3Fe(μ-H)2((μ-PCy2)Pt(PEt3)2][BF4], 2, which contains two bridging hydride ligands. This species is isolated and fully characterized by 31P{1H} and 1H NMR and infrared spectroscopy. In contrast, 1 reacts with one equivalent of HCl•DMA (DMA = dimethylacetamide) to give the complex (CO)3ClFe(μ-PCy2)Pt(PEt3)2, 3. This species is the result of oxidative addition of HCl with subsequent reductive elimination of H2(g). This complex is fully characterized by 31P{1H} and 1H NMR, infrared spectroscopy and an X-ray crystal structure determination. 3 crystallizes in the space group [Formula: see text] with a = 10.037(4) Å, b = 10.644(3) Å, c = 17.137(9) Å, α = 102.80(3)°, β = 76.74(3)°, γ = 103.99(3)°, V = 1702(1) Å3, and Z = 2. The structure was refined to R = 2.54% and Rw = 2.73% for 4056 reflections with Fo2 > 3σ(Fo2). Keywords: heterobimetallic, hydride, phosphide, protonation.

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Xiang, Xin, Zeng-Xia Zhao, and Hong-Xing Zhang. "A theoretical study based on DFT calculations on the different influence of functional groups on the C–H activation process via Pd-catalysed β-X elimination." RSC Advances 12, no. 40 (2022): 26116–22. http://dx.doi.org/10.1039/d2ra03506e.

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44

Jírů, Jitřenka, Vojtěch Hybášek, Petr Vlčák, and Jaroslav Fojt. "The Use of Electrochemical Methods to Determine the Effect of Nitrides of Alloying Elements on the Electrochemical Properties of Titanium β-Alloys." International Journal of Molecular Sciences 24, no. 2 (January 14, 2023): 1656. http://dx.doi.org/10.3390/ijms24021656.

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Titanium beta alloys represent the new generation of materials for the manufacturing of joint implants. Their Young’s modulus is lower and thus closer to the bone tissue compared to commonly used alloys. The surface tribological properties of these materials should be improved by ion implantation. The influence of this surface treatment on corrosion behaviour is unknown. The surface of Ti-36Nb-6Ta, Ti-36Nb-4Zr, and Ti-39Nb titanium β-alloys was modified using nitrogen ion implantation. X-ray photoelectron spectroscopy was used for surface analysis, which showed the presence of titanium, niobium, and tantalum nitrides in the treated samples and the elimination of less stable oxides. Electrochemical methods, electrochemical impedance spectra, polarisation resistance, and Mott–Schottky plot were measured in a physiological saline solution. The results of the measurements showed that ion implantation does not have a significant negative effect on the corrosion behaviour of the material. The best results of the alloys investigated were achieved by the Ti-36Nb-6Ta alloy. The combination of niobium and tantalum nitrides had a positive effect on the corrosion resistance of this alloy. After surface treatment, the polarization resistance of this alloy increased, 2.3 × 106 Ω·cm2, demonstrating higher corrosion resistance of the alloy. These results were also supported by the results of electrochemical impedance spectroscopy.

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45

El-Khoueiry, Anthony B., Yan Ning, Dongyun Yang, Sarah Cole, Michael Kahn, Marwan Zoghbi, Jennifer Berg, et al. "A phase I first-in-human study of PRI-724 in patients (pts) with advanced solid tumors." Journal of Clinical Oncology 31, no. 15_suppl (May 20, 2013): 2501. http://dx.doi.org/10.1200/jco.2013.31.15_suppl.2501.

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2501 Background: PRI-724 is a first-in-class modulator of Wnt signaling that inhibits the CREB binding protein and β-catenin interaction. In pre-clinical models, PRI-724 (active metabolite C82) increases p300/β-catenin binding and promotes stem cell differentiation thereby eliminating tumor initiating cells and increasing sensitivity to cytotoxic or targeted drugs. Methods: PRI-724 was given as a continuous infusion X 7 days q 2 wks. There was an initial accelerated dose escalation with one pt per dose level and a plan to revert to a 3+3 escalation after 640 mg/m2 unless a dose limiting toxicity (DLT) or 2 moderate toxicities occurred earlier. Eligibility criteria: adequate bone marrow function, AST/ALT <5XULN, total bilirubin<1.5 mg/dL. Survivin/BIRC5 expression was measured by immunomagnetic RT-PCR on circulating tumor cells (CTC). Results: 18 pts treated; median age: 53 years (38-71); 12 (67%) males; median number of prior therapies: 3 (1-5). There was one DLT of grade 3 hyperbilirubinemia. Grade 3 AEs were limited to hyperbilirubinemia in 2 pts, one of which did not meet DLT criteria. Grade 2 AEs were: diarrhea (2pts; 11%), bilirubin elevation (2 pts; 11%), hypophosphatemia (2pts; 11%), nausea (1pt; 6%), fatigue (1pt; 6%), anorexia (1pt; 6%), thrombocytopenia (1 pt; 6%) and alkaline phosphatase elevation (1pt; 6%). There was no MTD at the doses tested. The recommended phase 2 dose was 905 mg/m2 based on the incidence of AEs at 1280 mg/m2 and the plateau in pK parameters. The median Cmax and AUC 0-t for C-82 at 905 mg/m2/day were 887 ng/mL and 262787 h*ng/mL. Median elimination T ½ was 7.35 h. 3 pts with colon cancer had stable disease for 8, 10 and 12 weeks. Survivin expression in CTCs decreased in 72% of pts on C1D8 and 61% on C2D8. There was an inverse relationship between C82 plasma concentration and survivin expression on C1D8 (Spearman correlation coefficient r = -0.72; p=0.001). Conclusions: PRI-724 had an acceptable toxicity profile. Downregulation of survivin expression in CTCs may serve as a pharmacodynamic marker of drug-on-target effect. Studies combining PRI-724 with chemotherapy are ongoing. Clinical trial information: NCT01302405. [Table: see text]

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46

Oliaey, Ahmad Reza, Abolfazl Shiroudi, Ehsan Zahedi, and Michael S. Deleuze. "Theoretical study on the mechanisms and kinetics of the β-elimination of 2,2-dihaloethyltrihalosilanes (X = F, Cl, Br) compounds: a DFT study along with a natural bond orbital analysis." Reaction Kinetics, Mechanisms and Catalysis 124, no. 1 (December 19, 2017): 27–44. http://dx.doi.org/10.1007/s11144-017-1332-6.

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47

Shin, H. K., M. J. Hampden-Smith, E. N. Duesler, and T. T. Kodas. "The chemistry of copper(I) β-diketonate compounds. Part V. Syntheses and characterization of (β-diketonate)CuLn species where L = PBu3, PPh3, and PCy3; n = 1 and 2; crystal and molecular structures of (acac)Cu(PCy3), (tfac)Cu(PCy3), (hfac)Cu(PCy3), and (hfac)Cu(PCy3)2." Canadian Journal of Chemistry 70, no. 12 (December 1, 1992): 2954–66. http://dx.doi.org/10.1139/v92-377.

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The compounds (β-diketonate)Cu(PR3)n, where β-diketonate = 1,1,1,5,5,5-hexafluoroacetylacetonate, hfac; 1,1,1-trifluoroacetylacetonate, tfac; and acetylacetonate, acac; R = n-butyl (n-Bu), phenyl (Ph), and cyclohexyl (Cy); n = 1 and 2, have been prepared. The monotriorganophosphine adducts were prepared in high yield by the reaction of the sodium salt of the corresponding β-diketonate with [ClCu(PR3)] with elimination of sodium chloride. The bis(triorganophosphine) adducts were prepared by the reaction of (β-diketonate)Cu(PR3) with one equivalent of triorganophosphine. These species were characterized by 1H, 13C, and 31P NMR spectroscopy, FTIR spectroscopy, mass spectroscopy, and by combustion elemental analysis. Four examples were structurally characterized by single crystal X-ray diffraction in the solid state. (acac)CuPCy3 crystallizes in the triclinic crystal system, space group [Formula: see text], where a = 13.502(6) Ǻ, b = 13.691(6) Ǻ, c = 5.781(6) Ǻ, α = 71.05(3)°, β = 67.50(3)°, γ = 64.81(3)°, Z = 4, and R = 5.42%. (tfac)CuPCy3 crystallizes in the monoclinic crystal system, space group P21/n, where a = 9.639(3) Ǻ, b = 22.717(7) Ǻ, c = 12.045(5) Ǻ, β = 111.67(3)°, Z = 4, and R = 7.22%. (hfac)CuPCy3 crystallizes in the monoclinic crystal system, space group P21/c, where a = 9.870(2) Ǻ, b = 17.314(4) Ǻ, c = 15.586(3) Ǻ, β = 99.74(2)°, Z = 4, and R = 5.29%. (hfac)Cu(PCy3)2 crystallizes in the monoclinic crystal system, space group P21/n, where a = 13.645(6) Ǻ, b = 19.252(13) Ǻ, c = 16.875(9) Ǻ, β = 102.02(4)°, Z = 4, and R = 7.20%. The compounds (β-diketonate)Cu(PCy3) are all monomeric in the solid state and possess approximately trigonal-planar copper coordination environments, although (tfac)Cu(PCy3) is significantly distorted from trigonal geometry. The Cu—O bond distances are significantly different in this species. The compound (hfac)Cu(PCy3)2 is monomeric in the solid state and possesses a distorted tetrahedral copper coordination environment. The distortion is believed to be due to the large steric demands of the PCy3 ligands that result in long Cu—P bond distances of 2.251(3) and 2.277(3) Ǻ, a large P—Cu—P angle of 141.3(1)°, long Cu—O distances of 2.213(5) and 2.251(5) Ǻ, and a small O—Cu—O angle of 80.8(2)° compared to the corresponding values for (hfac)Cu(PCy3). No trends in Cu—O bond distances between the compounds can be discerned, within the limits of error on the data, that would clearly enable a comparison of thermodynamic parameters such as bond length – bond strength relationships as a function of the β-diketonate substituents. However, the spectroscopic data revealed a number of trends as a function of the β-diketonate substituents, including an increase of ν(C=O and ν(C=C) in the order acac < tfac < hfac, analogous to the increase in their Lewis acidity. An increase in shielding of the 31P resonance of the triorganophosphine ligands was observed in the order hfac < tfac < acac, consistent with expected inductive effects based on the electronegativity of the β-diketonate substituents.

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Wu, Qingli, Zierold Claudia, and Erik A. Ranheim. "Dysregulation of Frizzled 6 Is a Critical Component of B Cell Leukemogenesis in a Mouse Model of Chronic Lymphocytic Leukemia." Blood 110, no. 11 (November 16, 2007): 347. http://dx.doi.org/10.1182/blood.v110.11.347.347.

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Abstract Wnt/Fzd signaling is known to play a key role in development, tissue specific stem cell maintenance, and tumorigenesis, particularly through the canonical pathway involving stabilization of β-catenin. We have previously shown that Fzd9−/− mice exhibit a decrease in pre-B cells at a stage when self-renewing division is occurring in preference to further differentiation, prior to light chain immunoglobulin recombination. To determine whether pathologic usurpation of this pathway plays a role in B cell leukemogenesis, we examined the expression of Wnt/Fzd pathway genes in the Eμ-TCL1 mouse model of chronic lymphocytic leukemia (CLL). We find that in the course of leukemogenesis, the expression of Wnt16, Wnt10b, Fzd1, and most dramatically, Fzd6, are progressively upregulated in the transformed CD5+ B cells of these mice, as are β-catenin protein levels. Fzd6 expression is increased an average of 35-fold in tumor B cells in comparison to CD5- normal B cells in the same mouse. In 3 animals we were able to compare oligoclonal, preleukemic CD5+ B cells with monoclonally transformed CD5+ B cells and noted between 4 and 340 fold incremental increases in Fzd6 expression. Elimination of Fzd6 gene expression by crossing Eμ-TCL1 into Fzd6−/− mice significantly delays or eliminates development of CLL in this model, while crossing into Fzd9−/− mice has no effect. Greater than 50% of Fzd6+/+ X Eμ-TCL1 mice have evidence of CLL in the peripheral blood at 5 months of age, while in Fzd6−/− X Eμ-TCL1 mice, this occurs at 8 months (p < 0.001). Even at 1 yr. of age, >30% of Fzd6−/− X Eμ-TCL1 mice remain disease free while >95% of Fzd6+/+ X Eμ-TCL1 mice have leukemia at 7 months of age. Tumors that do arise in Fzd6−/− mice are morphologically similar to the usual Eμ-TCL1 CLL cells, but do not show upregulation of β-catenin protein by flow cytometry, suggesting that Fzd6 is responsible for this aberrant expression. Further, rather than upregulating Wnt16, Wnt10b, and Fzd1, these genes are down-modulated in tumor cells lacking Fzd6, suggesting a balance between positive and negative signals in CLL B cells mediated by the Wnt/Fzd pathway with Fzd6 acting as an oncogene and other family members potentially as tumor suppressors. We and others have noted increases in LEF-1, Wnt10b, Wnt16, and Fzd3 in human CLL B cells as well, mirroring the findings in the mouse model. Our findings suggest that the self-renewal signals mediated by Wnt/Fzd that are enlisted during B cell development may be pathologically reactivated in the neoplastic transformation of mature B cells; and that agents targeting specific members of the beta-catenin signaling pathway may have therapeutic impact that could be tested in the Eμ-TCL1 model.

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Stevens, Anne M., Heidi M. Hermes, Meghan M. Kiefer, Joe C. Rutledge, and J. Lee Nelson. "Chimeric Maternal Cells with Tissue-Specific Antigen Expression and Morphology Are Common in Infant Tissues." Pediatric and Developmental Pathology 12, no. 5 (September 2009): 337–46. http://dx.doi.org/10.2350/08-07-0499.1.

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Maternal microchimerism (MMc) has been purported to play a role in the pathogenesis of autoimmunity, but how a small number of foreign cells could contribute to chronic, systemic inflammation has not been explained. Reports of peripheral blood cells differentiating into tissue-specific cell types may shed light on the problem in that chimeric maternal cells could act as target cells within tissues. We investigated MMc in tissues from 7 male infants. Female cells, presumed maternal, were characterized by simultaneous immunohistochemistry and fluorescence in situ hybridization for X- and Y-chromosomes. Maternal cells constituted 0.017% to 1.9% of parenchymal cells and were found in all infants in liver, pancreas, lung, kidney, bladder, skin, and spleen. Maternal cells were differentiated: maternal hepatocytes in liver, renal tubular cells in kidney, and β-islet cells in pancreas. Maternal cells were not found in areas of tissue injury or inflammatory infiltrate. Maternal hematopoietic cells were found only in hearts from patients with neonatal lupus. Thus, differentiated maternal cells are present in multiple tissue types and occur independently of inflammation or tissue injury. Loss of tolerance to maternal parenchymal cells could lead to organ-specific “auto” inflammatory disease and elimination of maternal cells in areas of inflammation.

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Gebauer, Thorsten, Gerlinde Frenzen, and Kurt Dehnicke. "Synthese und Kristallstrukturen der Palladium(II)-Komplexe cis- und trans-PdCl2[P(OSiMe3)3]2, {PdCl[PO(OSiMe3)2][P(OSiMe3)3]2} und (NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]} / Synthesis und Crystal Structures of the Palladium(II) Complexes cis- and trans-PdCl2[P(OSiMe3)3]2, {PdCl[PO(OSiMe3)2][P(OSiMe3)3]2} and (NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]}." Zeitschrift für Naturforschung B 48, no. 11 (November 1, 1993): 1661–71. http://dx.doi.org/10.1515/znb-1993-1126.

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The molecular complex PdCl2[P(OSiMe3)3]2 was obtained both as cis- (la) and trans- (lb) isomer from palladium(II) chloride with the equivalent amount of tris(trimethylsilyl)phosphite in a THF suspension at room temperature. With excess P(OSiMe3)3 the complex {PdCI[PO(OSiMe3)2][P(OSiMe3)3]2} (2) is formed with elimination of trimethylchlorosilane. By partial hydrolysis the anionic binuclear palladium complex(NMe2H2)2{Pd2Cl4[P4O5(OSiMe3)4]} (3) is generated from palladium(II) chloride and excess P(OSiMe3)3 in THF in the presence of dimethylamine. All complexes form colourless, moisture-sensitive crystals, which were characterized by X-ray structure determinations.1a: Space group C2/c, Z = 4,2973 observed unique reflections, R = 0.044. Lattice dimensions at —80°C: a =1052.9(2), b =1675.3(5), c = 2240.1(7) pm, β = 99.88(2)°. The compound has a molecular structure with cis-arrangement of the P(OSiMe3)3 groups with Pd—P bond lengths of 222.9 pm.1b: Space group P1̄, Z = 1, 3796 observed unique reflections, R = 0.053. Lattice dimensions at-70°C: a = 959.5(2), b = 998.3(2), c =1162.6(2) pm, α=86.99(3)°, β = 81.63(3)°, γ = 62.91(3)°. The compound has a molecular structure with trans-arrangement of the P(OSiMe3)3 groups with Pd—P bond lengths of 230.4 pm.2: Space group P212121, Z = 4,4444 observed unique reflections, R = 0.055. Lattice dimensions at —70°C: a =1050.0(2), b = 2090.5(3), c = 2357.8(6) pm. The complex has a molecular structure with trans-arrangement of the P(OSiMe3)3 groups with Pd — P bond lengths of 233.6 and 232.1 pm. The Pd—P bond length of the [PO(OSiMe3)2]- ligand is 224.8 pm.3: Space group P1̄, Z = 2,4762 observed unique reflections, R = 0.071. Lattice dimensions at —80°C: a = 1169.3(6), b = 1299.6(6), c = 1641.7(12) pm, α = 69.19(4)°, β = 87.37(5)°, γ = 80.01(4)°. In the dimeric anion {Pd2Cl4[P4O5(OSiMe3)4]}2- the two cis-PdCl2 units are bridged by the four phosphorus atoms of the [P4O5(OSiMe33)4]2- ligand with average Pd— P bond lengths of 221.5 pm.

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Journal articles on the topic 'Β-X elimination'

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