Mendeleev Communications最新文献

An approach to the design of pseudocyclic peptide epitopes is proposed: lipid tails are attached to both C- and N-termini of the peptide through hydrophilic spacers; thanks to two lipid anchors, the conjugate is inserted into the membrane at two sites simultaneously, and the peptide becomes conformation- constrained. Despite the presence of two long lipid regions, the high hydrophilicity of the spacer makes the entire structure water-soluble, which is crucial for integration into living cells.

A series of catalysts based on mesoporous ceria solid solutions containing NiCo active component was synthesized via co- precipitation, impregnation, hydrothermal and core–shell (sol–gel) methods and applied to partial oxidation and dry reforming of methane. In the co-precipitated and impregnated catalysts, a better NiCo dispersion and a stronger interaction between NiCo species and the ceria- based support in comparison with other catalysts were observed, which affected activity and selectivity. Thus, simpler methods of applying the active component were more advantageous owing to the manifestation of strong metal–support interactions.

1-Alkyl-3-phenylprop-2-yn-1-ones smoothly react with aromatic aldehydes in the presence of triphenylphosphine (acetonitrile, room temperature, 24 h) to regio- and stereo- selectively afford (Z)-2-benzylideneoxacyclopentan-3-ones in yields up to 93%. The proposed mechanism for the transformation involves 1,3-H proton shift from the alkyl group at the intermediate β-phosphoniovinylide species.

Reaction of 3-hydroxy-2,5-di-tert-butyl-1,4-benzoquinone with phenylhydrazine hydrochloride mainly leads to the corresponding hydrazone at the position 1 existing in tautomeric equilibrium with 3,6-di-tert-butyl-4-(phenyl- diazenyl)catechol. Thermodynamic parameters of the tautomerization were evaluated by NMR spectroscopy. The hydrazone structure was confirmed by XRD study.

Novel 6-heterylmethylidene-3a,9a-diphenylimidazo[4,5-e]-thiazolo[3,2-b][1,2,4]triazines were synthesized by the three-component condensation of imidazo[4,5-e][1,2,4]triazine-3-thione derivative with bromoacetic acid and hetero-aromatic aldehydes. The following MeONa-induced skeletal rearrangement gave the recyclized isomeric products, viz. 7-heterylmethylidene-3a,9a-diphenylimidazo-[4,5-e]thi azolo[2,3-c][1,2,4]triazines.

The behavior of cucurbit[6]uril at the electrode/solution interface in the presence of magnesium sulfate was investigated and quantified. It has been established that at the highest positive potential available for the adsorption of organic compounds, a structure is formed that consists entirely of neutral cavitand molecules.

A simple and efficient electrochemical C–H arylation of five- membered active heteroarenes involves the application of arenediazonium salts generated in situ from anilines and tert- butyl nitrite. A cathodic reduction-induced radical chain mechanism is proposed.

Iodocyclization of N-(2-alkenylphenyl)carboxamides with acetoxybenziodoxolone/NaI system gives 4-iodomethyl- 4H-3,1-benzoxazines with high efficiency. The process is triggered by the oxidation of NaI with acetoxybenziodo- xolone to afford iodine cation which is added to alkene moiety to form iodonium species, and the ultimate intra- molecular nucleophilic addition generates the final products.

A new method for the synthesis of nanosized ZSM-5 zeolite with the MFI structure in the proton form is reported. The material was synthesized by the hydrothermal-microwave method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, low-temperature nitrogen physisorption, thermal desorption of ammonia and solid- state ²⁷Al NMR. The synthesized material is formed by zeolite particles of 30–80 nm in size, which ensures its high specific surface area, pore volume and interparticle porosity.

‘Technical’ tris(trimethylsilyl) phosphite, (Me₃SiO)₃P, as a mixture with (Me₃SiO)₂P(O)H and (Me₃SiO)₃P(O) (71 : 20 : 9) was obtained upon the action of (Me Si) NH on phosphorous acid H₃PO₃ in the presence of catalytic amount of Me₃SiCl. The action of this material on acid chlorides RC(O)Cl affords (hydroxymethylene)bis(phosphonic) acids RC(OH)[P(O)(OH)₂]₂ in preparative yields.