Synthons for syntheses of spiro[2.4]heptane analogues of prostaglandins

Methods for the preparation of synthons for syntheses of spiro[2.4]heptane analogues of prostaglandins are described. Two of them (1a and1b) enable the syntheses of 11-deoxy-type compounds and were prepared from spiro[2.4]heptan-4-one (3) which after transformation into the 5-phenylthio-,-unsaturated ketone5 was subjected to conjugate addition of organocuprate reagent6. The third synthon (2)-a potential intermediate in syntheses of complete spiro[2.4]heptane analogues of prostaglandins-was prepared from the bicyclic ketone10 byBaeyer-Villiger oxidation followed by epoxidation.

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Ausgangsverbindungen für die Synthese von Prostaglandin-analogen Spiro[2.4]heptanen

Zusammenfassung Es werden Synthesewege für Spiro[2.4]hepane als Analoge zu Prostaglandinen beschrieben. Zwei davon (1a und1b) ermöglichen die Synthese von Verbindungen des 11-Deoxy-Typs; sie wurden aus Spiro[2.4]heptan-4-on (3) dargestellt, das nach der Umwandlung zum 5-phenylthio-,-ungesättigten Keton5 einer konjugierten Addition von Organocuprat-Reagens6 unterworfen wurde. Das dritte (2), ein potentielles Zwischenprodukt in der Synthese von vollständigen Spiro[2.4]heptan-Analogen zu Prostaglandinen, wurde aus dem bicyclischen Keton10 durchBaeyer-Villiger-Oxidation gefolgt von einer Epoxidierung dargestellt.

     

Epitope-targeted proteome analysis: towards a large-scale automated protein–protein-interaction mapping utilizing synthetic peptide arrays

We describe the development of a process for the genome-wide mapping of interactions between protein domains and peptide ligands entirely based on high-throughput biochip technologies. A phage library displaying protein domains from a randomly fragmented and cloned cDNA library will be "panned" on an array of synthetic peptide ligands. After multiplexed affinity enrichment, peptide-specific phage populations will be automatically eluted, propagated, labelled and identified by hybridisation to a DNA microarray. Peptide arrays are synthesized in situ by SPOT synthesis on a planar substrate. By utilizing a commercially available library of human brain cDNA plus a set of distinct model domains cloned into T7-phage, we could show that a single panning round on an array of known peptide ligands for these model domains synthesized on a cellulose membrane can yield an enrichment of better than a factor of 1,000. This is sufficient to detect peptide-specific enrichment of Cy3(post-panning) against Cy5(pre-panning)-labelled phage DNA inserts on a cDNA microarray. Thus, the proof-of-principle of our approach could be successfully demonstrated and first interaction data are being collected.     

Raman Spectra of Molecules Adsorbed on Ag Centers in Sol-Gel Matrices

Silica monoliths and submicron spheres containing silver nanoparticles have been obtained using the sol gel technology. The Ag inclusions were synthesized via the counterdiffusion method. The silver-doped matrices were immersed in solutions of an organic dye (indocyanine green) enabling the solute molecules to interact with surface of the Ag-doped silica matrices. Raman spectra of free solutions of the organic molecules under investigation, the impregnated Ag-doped matrices and the impregnated Ag-free matrices have been measured. The impregnated silica matrices which did not contain silver nanoparticles were used as a reference. These experiments have been performed in order to establish if Raman signal enhancement could be obtained by adsorption of organic molecules on the surface of Ag inclusions in the sol-gel matrices analogously to the standard surface-enhanced Raman spectroscopy (SERS) method.     

Spectroscopic behavior of 1,1′-diethyl-2,2′-dicarbocyanine iodide in ethanol/water solutions with high ionic strength

Absorption spectra of 1,1′-diethyl-2,2′-dicarbocyanine iodide (DDI) have been obtained in ethanol/water mixtures. Increase of ionic strength obtained by addition of salts (e.g. NaCl) to the solvent mixture containing 10% of H₂O and 90% of EtOH leads to appearance of a new absorption band at 849 nm. Intensity of this band increases with salt concentration which suggests that this spectral feature is related to a DDI aggregate. However, no emission has been observed with excitation at 850 nm indicating that this feature does not correspond to a J-type aggregate. Addition of NaCl to DDI solutions possessing the EtOH/H₂O (v:v) ratio different from 1:9 does not induce appearance of the new absorption band.     

A discrete-particle model of blood dynamics in capillary vessels

We investigate the mechanism of aggregation of red blood cells (RBC) in capillary vessels. We use a discrete-particle model in 3D to model the flow of plasma and RBCs within a capillary tube. This model can accurately capture the scales from 0.001 to 100 microm, far below the scales that can be modeled numerically with classical computational fluid dynamics. The flexible viscoelastic red blood cells and the walls of the elastic vessel are made up of solid particles held together by elastic harmonic forces. The plasma is represented by a system of dissipative fluid particles. Modeling has been carried out using 1 to 3 million solid and fluid particles. We have modeled the flow of cells with vastly different shapes, such as normal and "sickle" cells. The two situations involving a straight capillary and a pipe with a choking point have been considered. The cells can coagulate in spite of the absence of adhesive forces in the model. We conclude that aggregation of red blood cells in capillary vessels can be stimulated by depletion forces and hydrodynamic interactions. The cluster of "sickle" cells formed in the choking point of the capillary efficiently decelerates the flow, while normal cells can pass through. These qualitative results from our first numerical results accord well with the laboratory findings.     

Synthesis of poly(γ-methoxypropylmethylsilylene) and poly(γ-methoxypropylmethylsilylene-co-di-n-hexylsilylene)

The synthesis of γ;-methoxypropylmethyldichlorosilane, and its subsequent polymerization and copolymerization with di;-n;-hexyldichlorosilane through the reductive coupling with sodium has been accomplished. The resulting polymers contain methyl ether side groups that allow further synthetic transformations on the polysilane backbone. For poly (γ;-methoxypropylmethylsilylene) these groups impart solubility characteristics different than typical alkyl and aryl substituted polysilanes. These new polymers and copolymers have been characterized by GPC and ¹H-, ¹³C-, and ²⁹Si-NMR. © 1994 John Wiley & Sons, Inc.     

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. XV. Solution Properties of bis(Salicylideneaniline)Copper(II)

The complex obtained by condensation of salicylideneaniline with copper(II) acetate was studied in a variety of solvents. This deep-brown crystalline compound is soluble in common solvents, such as, chloroform, toluene, dioxane, methanol, ethanol, dimethyl formamide, dimethyl sulfoxide, and acetonitrile—a necessary condition for observing solvatochromism. The complex has been characterized by elemental analysis, molar conductivity, EPR, and ultraviolet (UV) and visible (VIS) spectroscopy. The available X-ray data shows planar coordination geometry for the copper center. Combined multi-technique experiments have been applied to confirm the structure of the complex in solution. The molar conductivities indicate nonelectrolytic properties. EPR measurements preclude the possibility of solvent coordination at the axial positions of the complex. Spectroscopic measurements were used to study the coordination properties of donor atoms and their bonding ability, as well as trichromaticity coordinate calculations. The results obtained show that the interactions of metal with donors depend on donor strength and polarity of solvent.     

Study of hydrogen electrosorption in Pd-Ni alloys by the quartz crystal microbalance

The electrochemical quartz crystal microbalance (EQCMB) method has been used to study the processes of hydrogen absorption/desorption in Pd-Ni alloy electrodes. It was found that hydrogen electrosorption is accompanied by an additional frequency shift, attributed to the stresses generated inside the alloy. The influence of stresses on the EQCMB response depends on the amount of absorbed hydrogen and the alloy composition. From the comparison of the EQCMB results with Pd-Ni alloy absorption capabilities data, it was concluded that the decrease of the hydrogen sorption capacity at a Ni content of ca. 25–30 at% is due to an excessive generation of stresses in the alloy lattice. Also, a dependency of the rate of hydrogen absorption in Pd-Ni alloys on potential is reported. Electronic Publication     

Electrochemical charging and electrocatalysis at hybrid films of polymer-interconnected polyoxometallate-stabilized carbon submicroparticles

Using the layer-by-layer technique, carbon submicroparticles, that have been modified and stabilized with monolayers of Keggin-type phosphododecamolybdate (PMo₁₂O₄₀³⁻), can be dispersed in multilayer films of organic polymers, poly(3,4-ethylenedioxythiophene), i.e., PEDOT, or poly(diallyldimethylammonium) chloride, i.e., PDDA, deposited on glassy carbon or indium-tin oxide conductive glass electrodes. The approach involves alternate treatments in the colloidal suspension of PMo₁₂O₄₀³⁻-covered carbon submicroparticles in the solution of monomer, 3,4-ethylenedioxythiophene or in solution of PDDA polymer. Electrostatic attractive interactions between anionic phosphomolybdate-modified carbon submicroparticles and cationic polymer layers permit not only uniform and controlled growth of the hybrid organic–inorganic film but also contribute to its overall stability. The system composed of PMo₁₂O₄₀³⁻-covered carbon submicroparticles dispersed in PEDOT is characterized by fast dynamics of charge transport and has been used to construct symmetric microelectrochemical redox capacitor. The PDDA-based system has occurred to be attractive for electrocatalytic reduction of hydrogen peroxide.     

Author index for volume 47

The phase diagram of the pseudo-ternary MnV₂O₆LiVMoO₆MoO₃ system has been determined with DTA and X-ray phase analysis. Its outstanding feature is the very large range of stability of the quaternary solid solution α-ML? described by the formula Mn_1?x?yLi_y?_xV_2?2x?yMo_2x+yO₆ (? = cation vacancy), and crystallizing in the monoclinic brannerite-type structure. In this solution y may vary between 0 and 1, which corresponds to the entire miscibility of MnV₂O₆ and LiVMoO₆; x may change between 0 and x_max depending on y (if, e.g., y equals 0.00, 0.40, 0.84, or 1.00, x_max is 0.45, 0.28, 0.16, or 0.00, respectively). Depending on composition, α-ML? is stable up to 540–710°C. Other features of the diagram, including the liquidus, are described in detail. The dependence of unit cell dimensions on composition of α-ML? has been determined. On passing from MnV₂O₆ to LiVMoO₆, the lattice parameter b and unit cell volume increase, c and c sin β decrease, and a changes insignificantly. These changes are interpreted by taking into account the ionic radii of the components and the specific details of the brannerite-type structure. ML? solid solutions were prepared using the amorphous citrate precursor method.