Late-stage fluorination of bridged scaffolds: Chemoselective generation of a CHF group at three positions of the bicyclo[3.3.1]nonane system

Monofluorobicyclo[3.3.1]nonane derivatives were prepared by late-stage fluorination, often proceeding with control of stereochemistry. Introduction of fluorine at the 3-, 6- or 7-position was achieved chemoselectively, the bicyclo system being constructed by a tandem one-pot Michael-aldol annulation. The major conformer was deduced for each of the fluorobicyclo compounds prepared, each possessing a unique CF orientation on a common rigid bridged scaffold that can be polysubstituted.     

Hair analysis as a new tool to monitor adherence to long-term therapy to statins

Statins are cholesterol-lowering medications which are widely prescribed as first-line treatment for hyperlipidemia, against high blood cholesterol aimed at reducing the risk of atherosclerotic diseases. Notwithstanding their undoubted efficacy, the needed long-term treatment with these drugs is characterized by a high percentage of dropout. Consequently, an effective tool to verify the patients’ compliance to statin therapy is needed. In this context, the analysis for drugs and drug metabolites in the hair may represent an almost ideal tool because, according to a sound body of forensic toxicological literature, concentrations in the hair matrix reflect the chronic intake of drugs and pharmaceuticals. In this light, in the present study, a novel, specific and sensitive ultra-performance liquid chromatography–tandem mass spectrometry method has been developed to determine six statins and their metabolites (namely atorvastatin, (p)α-OH-atorvastatin-lactone, (o)α-OH-atorvastatin-lactone, rosuvastatin, N-desmethyl rosuvastatin and pravastatin) in human hair. After optimization, the method was successfully validated in terms of selectivity, linearity, sensitivity, precision, accuracy, stability and matrix effect. Moreover, the practical applicability of this method for verifying adherence to statin therapy was assessed by testing samples of hair collected from subjects under long-term therapy with statins.     

Amperometric Detection of Ethanol Vapors by Screen Printed Electrodes Modified by Paper Crowns Soaked with Room Temperature Ionic Liquids

A convenient assembly recently proposed for screen printed gold electrodes (SPEs) suitable for measurements in gaseous samples is here tested for the analysis of the ethanol content in alcoholic drinks. This assembly involves the use of a circular crown of filter paper, soaked in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hydrogen sulfate, which is simply placed upon a disposable screen printed cell, so as to contact the outer edge of the gold disc working electrode, as well as peripheral counter and reference electrodes. The electrical contact between the paper crown soaked in RTIL and the SPE electrode is assured by a gasket and all components are installed in a polylactic acid holder. This assembly provides a portable and disposable electrochemical platform, assembled by the easy immobilization onto a porous and inexpensive supporting material such as paper of a RTIL characterized by profitable electrical conductivity and negligible vapor pressure. The electroanalytical performance of this device was assayed for the flow injection analysis of the ethanol concentration in some real samples of wine and beer and the results obtained are compared with the alcoholic degree reported in the relevant bottle-labels, thus highlighting a substantially satisfactory agreement. Repeatable sharp peaks (RSD=6–8 %) were detected for ethanol over a wide linear range (1–20 % v/v in water) and a detection and quantitation limit of 0.55 % v/v and 1.60 % v/v were inferred for a signal-to-noise ratio of 3 and 10, respectively.     

Metergoline II: structure solution from powder diffraction data with preferred orientation and from microcrystal

Metergoline is a dopamine agonist and serotonin antagonist used both in human and veterinary medicine. In addition to the previously known crystalline form, a new polymorph, which crystallizes from aqueous solution, was found. Since it was initially impossible to prepare a single crystal of quality suitable for single crystal X-ray diffraction measurements using a conventional laboratory source, the structure was solved from the powder diffraction data using synchrotron radiation. The structure determination also included solving the effects of preferred orientation. Characterization was simultaneously done by solid-state NMR spectroscopy. Finally, a small single crystal suitable for synchrotron diffraction was found after numerous tries. Crystal structure determination using this single crystal confirmed the powder-based solution. Comparison of information obtained by different experimental methods (powder diffraction, ssNMR, single crystal diffraction) was made.     

Toxic and essential metals determination in commercial seafood: Paracentrotus lividus by ICP-MS

Toxic and essential metals content was determined by inductively coupled plasma mass spectrometry in commercial sea urchins samples from the Mediterranean Sea and Pacific Ocean. Results show that Chilean samples have the highest values of Cd, As, Ni, Cr and V; Spanish samples have the maximum Hg content while Sicilian samples have the lowest content of toxic metals. The toxic metal traces were compared with the limits of European Community (EC) No. 1881/2006 for bivalve molluscs. All samples exceed Pb and Cd limit levels; regarding Hg levels, only Sicilian and Sardinian samples have Hg content below the EC limits. The dietary intake of toxic and essential elements was evaluated for an adult. Furthermore, our study highlights a correlation between the toxic elements content and the marine environmental conditions of the places of origin even though only the generic FAO fishing area is specified.     

Oppenauer oxidation of secondary alcohols with 1,1,1-trifluoroacetone as hydride acceptor

1,1,1-Trifluoroacetone (2a) reacts as a hydride-acceptor in the Oppenauer oxidation of secondary alcohols (1) in the presence of diethylethoxyaluminum. The oxidant allows for selective oxidation of secondary alcohols in the presence of primary alcohols.     

Shear flow effects on polymer melts crystallization: kinetics features

In this work the kinetics of the isothermal crystallization from the melt of isotactic polyolefins in quiescent conditions as well as after the application of a step-shear flow is investigated by means of rheological measurements. It is shown that the kinetics of the crystallization, as measured by the increase of the storage modulus, is not affected by the strain amplitude and the frequency of the oscillation, once they are properly chosen. A strong enhancement of the crystallization kinetics has been obtained when the step-shear flow was applied at the crystallization temperature T_C=92°C for two different molecular weight poly(1-butene) samples (i-PB400 and i-PB200) and at T_C=137°C for a polypropylene (i-PP). In particular, the overall-crystallization rate constants of the i-PB400 increased with increasing the applied shear rate at a constant total strain of 60. At higher shear flow temperatures slower kinetics occurred in all the cases until the effect of the applied shear flow was lost. Moreover, the effect of the molecular weight on the flow induced crystallization phenomenon is investigated on the two i-PB samples and the results have clearly shown that the higher molecular weight i-PB200 polymer is much more sensitive than the i-PB400 to the flow history.     

Biphasic Synthesis of Hydrogen Peroxide from Carbon Monoxide,Water, and Oxygen Catalyzed by Palladium Complexes with Bidentate Nitrogen Ligands

Effective and stable Pd catalysts for the biphasic synthesis of hydrogen peroxide from carbon monoxide, oxygen, and water [Eq. (a)] can be obtained by the right choice of bidentate nitrogen ligand. The best turnover numbers (578) for this reaction have been achieved with palladium complexes with 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ligands.     

Polymer-solvent interactions in thermoreversible gels of isotactic poly(methyl methacrylate) as studied by measurement of 1h NMR relaxation of the solvent

Dynamic structure and polymer-solvent interactions in solutions and gels of isotactic (i) poly(methyl methacrylate) (PMMA) in butyl acetate (BAC) were characterized by measurements of nonselective and selective ¹H NMR spin-lattice relaxation times of the solvent. In thermoreversible gels, the existence of i-PMMA-BAC complex, where the life-time of the bound solvent is − 100 ms or shorter, was confirmed. Although the correlation time of the solvent bound in i-PMMA-BAC complex is 5-10 times longer than for the free solvent, there is still a relative motional freedom for complexed solvent molecules. The same behaviour observed recently for thermoreversible gels of syndiotactic PMMA indicates the same character of polymer-solvent complexes in gels of both stereoregular forms of PMMA.