An efficient synthesis of vinylsilanes from acylsilanes and alkyl 1-phenyl-1H-tetrazol-5-yl sulfones. Brook vs Smiles rearrangement

[reaction: see text] Vinylsilanes are formed in high yields in the reaction of representative acyl(trimethyl)silanes with anions generated from Kocienski's sulfones.     

Thermal properties of pressure sintered alumina–graphene composites

Journal of Thermal Analysis and Calorimetry - The work concerns the alumina–graphene materials sintered by two different pressure methods. The different particle sizes of graphene were used....     

Tocochromanols composition in kernels recovered from different apricot varieties: RP-HPLC/FLD and RP-UPLC-ESI/MSn study

Composition of tocochromanols in kernels recovered from 16 different apricot varieties (Prunus armeniaca L.) was studied. Three tocopherol (T) homologues, namely α, γ and δ, were quantified in all tested samples by an RP-HPLC/FLD method. The γ-T was the main tocopherol homologue identified in apricot kernels and constituted approximately 93% of total detected tocopherols. The RP-UPLC-ESI/MSⁿ method detected trace amounts of two tocotrienol homologues α and γ in the apricot kernels. The concentration of individual tocopherol homologues in kernels of different apricots varieties, expressed in mg/100 g dwb, was in the following range: 1.38–4.41 (α-T), 42.48–73.27 (γ-T) and 0.77–2.09 (δ-T). Moreover, the ratio between individual tocopherol homologues α:γ:δ was nearly constant in all varieties and amounted to approximately 2:39:1.     

Synthesis of Some Aminophosphonates Bearing N‐(Fluorophenyl)‐piperazynyl Moiety and Their Activity toward Serotonin Receptors

Syntheses of a series of compounds bearing a 1‐(fluorophenyl)piperazin‐4‐ylmethyl moiety, namely dialkyl 1‐(fluorophenyl)piperazin‐4‐ylmethyl phosphonates 3a–f , diethyl 2‐[1‐(fluorophenyl)piperazin‐4‐yl]‐ethyl phosphonates 4a,b , diethyl 3‐[1‐(4‐fluorophenyl)‐piperazin‐4‐yl]‐propyl phosphonate 5 , and di[1‐(fluorophenyl)piperazin‐4‐yl]methanes 6a,b were performed, and some of them were screened for their affinity for serotonin 5‐HT_1A, 5‐HT₆, and 5‐HT₇ receptors. Moderate interactions with these receptors were demonstrated.     

Promoted ternary CuO-ZrO2-Al2O3 catalysts for methanol synthesis

Ternary CuO-ZrO₂-Al₂O₃ catalysts promoted by palladium or gold were prepared and tested in CO hydrogenation reaction at 260°C under elevated pressure (4.8 MPa). The promotion effect of palladium or gold addition on the physicochemical and catalytical properties of CuO-ZrO₂-Al₂O₃ catalysts in methanol synthesis (MS) was studied. The catalysts were characterized by BET, XRD, TPR-H₂, TPD-NH₃ methods. The BET results showed that the ternary system CuO-ZrO₂-Al₂O₃ had the largest specific surface area, cumulative pore volume and average pore size in comparison with the promoted catalysts. The yield of methanol can be given through the following sequence: 5%Pd/CuO-ZrO₂-Al₂O₃ > CuO-ZrO₂-Al₂O₃ > 2%Au/CuO-ZrO₂-Al₂O₃. We also found that the presence of gold or palladium on catalyst surface has strong influence on the reaction selectivity. The high selectivity of gold doped ternary catalyst is explained by the gold-oxide interface sites created on the catalyst surface and the acidity of those systems. The higher selectivity to methanol in the case of the palladium catalyst is explained by the spillover effect between Pd and CuO.      

Structural properties of L-X-L-Met-L-Ala phosphonate tripeptides: a combined FT-IR, FT-RS, and SERS spectroscopy studies and DFT calculations

FT-IR and FT-RS spectra of three phosphonate tripeptides containing P-terminal L-Met-L-Ala [L-Gly-L-Met-L-Ala-PO3H2 (GMA), L-Leu-L-Met-L-Ala-PO3H2 ( LMA), and L-Phe-L-Met-L-Ala-PO3H2 (PMA)] were recorded and analyzed. Vibrational wavenumbers and intensities were calculated by density functional theory (DFT) at the B3LYP/6-311++G** level of theory and compared to these molecules in solid form. On the basis of this comparison, conclusions were drawn about the molecular structures. At the same time, the experimental data served as a test for the computational results. SERS spectra were recorded in a silver colloidal dispersion. Silver colloidal dispersions prepared by simple borohydride reduction of silver nitrate were used as substrates. A comparison is made between the SERS spectra and the spectra of the solid sample. Also, the capability of SERS for spectral fingerprinting of analytes with close structural properties using easily prepared substrates and relatively simple instrumentation is illustrated. By careful analysis, we obtained information on the orientation of these tripeptides and specific-competitive interactions of their functional groups with the silver surface. For example, all molecules are thought to adsorb on a silver surface via a P=O bond and a sulfur atom. In addition, the amide bond of GMA assists in the adsorption process, adopting a tilted orientation on the surface, with the N-H unit being closer to the surface than the C=O moiety. Conversely, the C=O unit of the LMA-CONH- bond lies closer to the silver surface than the N-H moiety. The -CH 3 group and P-O bond of LMA additionally interact with the silver surface, whereas for PMA the L-Phe lies almost flat on the colloidal silver surface.     

Large-Scale Synthesis of a Niche Olefin Metathesis Catalyst Bearing an Unsymmetrical N-Heterocyclic Carbene (NHC) Ligand and its Application in a Green Pharmaceutical Context

A large-scale synthesis of known Ru olefin metathesis catalyst VII featuring an unsymmetrical N-heterocyclic carbene (NHC) ligand with one 2,5-diisopropylphenyl (DIPP) and one thiophenylmethylene N-substituent is reported. The optimised procedure does not require column chromatography in any step and allows for preparation of up to 0.5 kg batches of the catalyst from simple precursors. The application profile of the obtained catalyst was studied in environmentally friendly dimethyl carbonate (DMC). Although VII exhibited low efficiency in cross-metathesis (CM) with electron-deficient partners, good to excellent results were noted for substrates featuring easy to isomerise C−C double bonds. This includes polyfunctional substrates of medicinal chemistry interest, such as analogues of psychoactive 5F-PB-22 and NM-2201 and two PDE5 inhibitors—Sildenafil and Vardenafil. Finally, a larger scale ring-closing metathesis (RCM) of a Vardenafil derivative was conducted in DMC, allowing for straightforward isolation of the expected product (23 g) in high yield and with low Ru contamination level (7.7 ppm).