N-Chlorosuccinimide as a versatile reagent for the sulfenylation of ketones: a facile synthesis of α-ketothioethers

The sulfenylation of ketones having α-hydrogens has been achieved using N-chlorosuccinimide (NCS) under mild reaction conditions to produce α-ketothioethers in excellent yields with high selectivity. The use of NCS makes this method quite simple, convenient and practical.     

Detection of β-methylphenethylamine,a novel doping substance,by means of UPLC/MS/MS

Novel substances of expected doping activity are constantly introduced to the market. β-Methylphenethylamine (BMPEA) is classified as a doping agent by the World Anti-Doping Agency as it is a positional isomer of amphetamine. In this work, the development and application of a simple and rapid analytical procedure that enables discrimination between both isomers is described. The analytes of interest were extracted from urine by a two-step liquid–liquid extraction and then analyzed by UPLC/MS/MS under isocratic conditions. The entire analytical procedure was validated by evaluating its selectivity, discrimination capabilities, carry-over, sensitivity, and influence of matrix effects on its performance. Application of the method resulted in detection of BMPEA in eight anti-doping samples, including the first report of adverse analytical finding regarding its use. Further analysis showed that BMPEA may be eliminated unchanged along with its phase II conjugates, the hydrolysis of which may considerably improve detection capabilities of the method. Omission of the hydrolysis step may therefore, produce false-negative results. Testing laboratories should also carefully examine their LC/MS/MS-based amphetamine and BMPEA findings as both isomers fragment yielding comparable collision-induced dissociation spectra and their insufficient chromatographic separation may result in misidentification. This is of great importance in case of forensic analyses as BMPEA is not controlled by the public law, and its manufacturing, distribution, and use are legal.     

Application of the Intramolecular α-Amido-alkylation Reaction for the Synthesis of Dibenzo /a,h/ Quinolizines

5,6,9-Trihydro-8H-dibenzo [a,h] quinolizin-8-ones 6 are obtained from adducts of 3,4-dihydroiso-quinolines 1 and phenylacetyl chlorides as a result of an intramolecular α-amidoalkylation reaction.     

Photopolymerization kinetics of a thiol–enol composition determined via recording/playback of a transmission holographic diffraction grating

The kinetics of thiol–enol photopolymerization of a hybrid composition based on a tetraacrylate monomer and a thiol-siloxane oligomer was studied with the use of a holographic recording of elementary transmission phase gratings. The degrees of conversion of double bonds in the tetraacrylate monomer after the polymerization in air and in an inert atmosphere of SF₆ were measured via IR spectroscopy. It is shown that the use of the thiol-siloxane oligomer efficiently suppresses oxygen inhibition of the photopolymerization. When the photoinitiator concentration is increased to more than 10^–2 mol/L, the photopolymerization rate levels off. An increase in the thiol-siloxane oligomer concentration leads to an extremal dependence of the photopolymerization rate on the oligomer concentration; the maximum rate is reached at an oligomer concentration of about 0.07 mol/L. The kinetic scheme of photopolymerization in the hybrid photopolymer composition was analyzed, and an analytical expression for the photopolymerization rate was obtained. The correlation between the kinetic constants of the thiol–enol photopolymerization was evaluated on the basis of the obtained parameters of the kinetic model.     

Evaluation of a molecularly imprinted polymer for the isolation/enrichment of β-estradiol

The selective preconcentration of estradiol was explored using the recognition ability of a molecularly imprinted polymer (MIP) in the solid phase extraction (SPE) format. Polymeric particles were imprinted with 17β-estradiol using methacrylic acid as functional monomer and divinylbenzene as crosslinker. Binding studies of these polymeric particles towards 17β-estradiol showed selectivity over non-imprinted polymers, using acetonitrile as solvent. The imprinted polymer showed a recovery of 88% for β-estradiol in deionized water and 81% in surface water. The selectivity of the MIP over the non-imprinted polymer was relatively low, only 10% higher recovery. The results indicate that the MIP imprinted with 17β-estradiol does not appear to provide a viable approach to be used in a sample clean-up or enrichment step for the determination of estradiol in aqueous systems.     

Synthesis of α-S-galactosylceramides with a truncated sphingoid chain

We present here a convenient synthesis of the truncated sphingoid iodide 15 from d-galactose, in which Mitsunobu reaction was utilized to retrieve successfully an unwanted intermediate, thereby increasing greatly the synthetic efficiency. Subsequent reaction of 15 with the pre-prepared α-galactosyl thiol 16 led smoothly to the desired thioglycoside 17 in good yield, from which the catabolically stable thioglycoside analogs of OCH 4 and 22 were synthesized.     

Synthesis of 2,6-diaryl-1,2-dihydropyridines through a 6π-electrocyclization of N-sulfonylazatrienes

The development of an efficient synthetic method toward substituted 1,2-dihydropyridines from cinnamylideneacetophenones is reported. The key intermediates N-sulfonylazatrienes were synthesized through a TiCl₄-mediated direct condensation of primary sulfonamides with the substituted (E,E)-cinnamylideneacetophenones. The 6π-electrocyclization of these intermediates, catalyzed by a Lewis acid, selectively afforded the desired products in good yields.     

An unexpected one-pot synthesis of multi-substituted quinolines via a cascade reaction of Michael/Staudinger/aza-Wittig/aromatization of ortho-azido-β-nitro-styrenes with various carbonyl compounds

Multi-substituted quinolines 3 were unexpectedly prepared from a cascade reaction of ortho-azido-β-nitro-styrenes with various carbonyl compounds. This method takes advantages of mild condition, simple work-up, high yield as well as wide substrate scope, which makes this method powerful for one-pot synthesis of multi-substituted quinolines.     

Separation of acetone/water mixtures by a modified γ-alumina membrane via a new method

A new surface deposition method was researched to decrease pore size of ceramic membranes. CaCO₃ was chosen to modify the top layer of γ-alumina membranes prepared by sol–gel processes. Separation of gaseous acetone/water mixtures by vapor permeation was carried out to characterize the membranes. Improvement of membrane separation property after modifications and SEM photographs proved that this new method was effective to reduce the membrane pore size.     

Water/Oil Diphasic Hydroformylation of Higher Olefins over a TPPTS-Rh/SiO_2 Catalyst

A novel TPPTS-Rh/SiO2 catalyst, prepared by directly modifying a heterogeneous high-surface-area Rh/SiO2 catalyst with water-soluble TPPTS ligands, could decrease the resistance of mass transfer in water/oil biphasic media for the hydroformylation of higher olefins. The catalytic performance for hydroformylation on this biphasic TPPTS-Rh/SiO2 catalyst system was higher than those of the traditional biphasic HRhCO(TPPTS)3 systems, owing to the chemical bonds between the highly dispersed Rh metal particles and the TPPTS ligands. The catalyst system is applicable for hydroformylation of higher olefins such as 1-dodecene.     

The development of a cholesterol biosensor using a liquid crystal/aqueous interface in a SDS-included β-cyclodextrin aqueous solution

Sodium dodecyl sulphate (SDS) including β-cyclodextrin (β-CD) (β-CD_SDS) was used to detect cholesterol at the 4-cyano-4′-pentylbiphenyl (5CB)/aqueous interface in transmission electron microscopy (TEM) grid cells. The β-CD acts as a host for SDS (guest). The guest SDS enclosed within the β-CD cavity was replaced with cholesterol by injecting cholesterol solution into the TEM cell at concentrations greater than 3 μM. The replacement of SDS with cholesterol was confirmed by pH measurement and high performance liquid chromatography (HPLC). The SDS excluded from the β-CD altered the planar orientation of the 5CB confined within the TEM grid cell to a homeotropic orientation. This planar-to-homeotropic transition was observed using a polarized optical microscope under crossed polarizers. This convenient TEM grid cell provides a new method for the selective detection of cholesterol without immobilization of the detecting receptors (enzyme, antibody, or aptamer) or the use of sophisticated instruments.     

Synthesis of a Pair of Derivatives of N-Methylpyrrole Polyamide

A pair of derivatives of tetrameric N-methylpyrrole polyamide were synthesized in order to develop a new method for the study of interaction of the polyamide derivatives with DNA. Indole acetic acid and nicotinic acid were introduced to the polyamide in the synthesized compound, which showed an expected red shift in the UV spectrum. These compounds may function as a potential tool in the detection of the polyamide binding to DNA.     

Photo-assisted charge/discharge of a secondary cell of α-Fe2O3/Prussian blue–based electrodes

Journal of Solid State Electrochemistry - In this work, an assembly of FTO/α-Fe2O3/PB|M+ electrolyte|PB/α-Fe2O3/FTO (M+ = Li+, Na+, K+) secondary photocell was done to improve...     

Thermal degradation of α-pinene using a Py–GC/MS

Mediterranean forest fires may be accelerated, partly due to biogenic volatile organic compounds produced by vegetation, mainly monoterpenes largely represented by α-pinene. To model the propagation of biomass combustion, it is necessary to study the flammability of the produced gas mixture, and thus, necessary to identify the emitted volatile compounds. However, thermal degradation of monoterpenes is rarely experimented above 300 °C, whereas forest fires reach higher temperatures. Thus, in this work, we experimented a 2-min pyrolysis of α-pinene at temperatures from 300 to 800 °C using a Py–GC/MS device. Less than 1% of pyrolysis products were detected at 300 and 400 °C. The pyrolysis products increased then from 14 compounds at 500 °C to 31 compounds at 800 °C. Degradation of α-pinene started with its isomerization at 500 °C. At 800 °C, alkenes detected increased as well as aromatics produced through the Diels–Alder mechanism. These results are consistent with the literature on thermal degradation of α- and β-pinene presented in our article.

     

Crystal Structure of a New Form of Sodium Octoborate β-Na2B8O13

Single crystals of a new form of sodium octoborate, β-Na₂B₈O₁₃, were obtained fortuitously from a complex Na₂O-B₂O₃-P₂O₅ mixture, and studied. The compound is monoclinic, space group P2₁/c; the unit cell parameters are a=11.731(4) Å, b=7.880(3) Å, c=10.410(4) Å, β=99.883(3)°; Z=4. The crystal structure was solved from 1653 reflections until R₁=0.0444; it consists of two infinite, independent, and interleaved boron-oxygen networks containing a complex borate anion (B₈O₁₃)²⁻ formed by six BO₃ triangles (Δ) and two BO₄ tetrahedra (T), which can be viewed as a B₅O₁₀ group linked to a B₃O₇ group; this leads to a Fundamental Building Block (FBB) with the shorthand notation: 8: ∞³ [(5:4Δ+T)+(3:2Δ+T)]. This FBB is identical to that described in other octoborates such as α-Na₂B₈O₁₃ and Ag₂B₈O₁₃. However, some subtle differences exist in the interlinking of the octoborate anions found in these three compounds, which explains their different structure and unit cell parameters.     

DBU-mediated regioselective intramolecular cyclization/dehydration of ortho diketo phenoxyethers: a synthesis of 2,3-substituted γ-benzopyranones

The regioselective cyclization/dehydration sequence of ortho diketo phenoxyethers induced by DBU has been explored. The results demonstrated a high degree of selectivity with preference for 6-exo-trig cyclization leading to the formation of γ-benzopyranone derivatives in good yield.     

An improved synthesis of a novel α1A partial agonist including a new two-step synthesis of 4-fluoropyrazole

This Letter outlines a new two-step process for the synthesis of 4-fluoropyrazole and its application in an improved synthesis of 4-fluoro-1-[5-fluoro-1-(1H-imidazol-2-yl)-indan-4-ylmethyl]-1H-pyrazole. The original synthesis of 4-fluoro-1-[5-fluoro-1-(1H-imidazol-2-yl)-indan-4-ylmethyl]-1H-pyrazole is also described.     

Molecular recognition of a self-assembled monolayer of a polydithiocarbamate derivative of β-cyclodextrin on silver

The synthesis and molecular recognition properties of a new sulfur containing β-cyclodextrin (β-CD) derivative chemisorbed on a silver surface are described. Hepta-6-amino-6-deoxy-β-CD was allowed to react with CS₂ in the presence of ammonia to give a mixture of partially substituted dithiocarbamate derivatives with an average degree of substitution of 4.5. A modified silver electrode with this derivative is capable of discriminating between the three positional isomers of nitrobenzoate ion and nitrophenol, as determined by cyclic voltammetry. Only the meta- and para-isomers give a signal corresponding to the reduction of the nitro group. This is attributed to the different orientations of the nitro group with respect to the silver surface after inclusion in the CD cavity. Experiments in the presence of cyclohexanol showed a decrease in signal intensity of the meta- and para-isomers which is associated with the competitive complexation of this guest, suggesting that the electroactive probe is complexed to the cavity.