A facile synthesis of per (poly )fluoroalkyl substituted α-amino acid derivatives

Initiated by CrCl3/Fe redox couple, per(poly)fluoroalkyl iodides added to methyl a-acetylamino acrylate, giving B-per(poly)fluoroalkyl a-amino acid derivatives in good yields.     

Conductances of some electrolytes in 2-methylpyridine-N-oxide at 55°C

Conductance measurements for fifteen uni-univalent salts in 2-methylpyridine-N-oxide (2-MPO) were made over the concentration range of 2–120×10^–4 mol-dm^–3 at 55°C. All conductance data were evaluated by the Lee-Wheaton equation. The results indicate that all of the salts studied are slightly associated in 2-MPO, which is, nevertheless, a reasonably good ionizing solvent compared to other solvents having a similar value for the dielectric constant. The tetraalkylammonium halides are weaker electrolytes than the tetraphenylborate salts in 2-MPO. Ionic limiting molar conductances were obtained by using as a reference electrolyte tris(iso-pentyl)butylammonium tetraphenylborate. Anions appear to be poorly solvated in this solvent but certain cations, particularly Na⁺ and K⁺, show evidence of specific ion-solvent interaction.This study was presented, in part, at the 6th Central Regional Meeting of the American Chemical Society, Detroit, Michigan, April 1974.     

Intermediates in the transformation of 1,2-dialkylpyrimidinium iodides in the Kost-Sagitullin rearrangement

Intermediate recyclization products were obtained in a study of the Kost-Sagitullin rearrangement of a series of 1,2-dialkylpyrimidinium iodides. The initial attack of the nucleophile leads to the formation of products of the addition of the hydroxyl group, namely, the corresponding pseudo bases. Heating one of these intermediates in ethanol or in the presence of primary amines leads to rearrangement to give a pyridone derivative. Upon heating in chloroform, the pseudo bases readily lose a water molecule and are converted to anhydro bases, namely, derivatives of 1-alkyl-1,2-dihydro-2-methylidenepyrimidine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 894–900, May, 2006.     

AIBN-initiated radical addition of gem-difluorinated alkyl iodides to alkynes and the Pd-catalyzed Sonogashira coupling reaction of E-phenyl difluoromethylene vinylic iodides with terminal alkynes

The addition of gem-difluorinated alkyl iodides to alkynes initiated by AIBN neatly gave the corresponding difluoromethylene vinyl iodides among which the stereoselectivity of aromatic acetylenes was high. The further coupling reaction of E-phenyl difluoromethylene vinyl iodides with terminal alkynes in the presence of catalytic palladium afforded the substituted difluorinated enynes.     

Untersuchungen im System LaI2/H2: Phasenverhältnisse und Fehlordnung

Investigation of the LaI₂/H₂ System: Phase Relations and Stacking Disorder Heating of LaI₂ under 1 bar hydrogen pressure to 650 °C leads to light gray LaI₂H_0.95(3), accompanied by a structural change from tetragonal to hexagonal. Sharp reflections in the XRD pattern can be indexed in P6₃/mmc with a = 4.2158(7)Å and c = 15.508(3)Å, however, diffuse reflections indicate the presence of stacking faults in the structure, which correspond to a polytypic intergrowth of MoS₂ and NbS₂ type structural fragments. Increasing the reaction temperature to 730 °C results in a better defined diffraction pattern with the peak positions close to those of the 2H‐NbS₂ structure type. An X‐ray powder study of the samples LaI₂H_n proved the miscibility gap between LaI₂ and LaI₂H_n (0 ≤ n ≤ 0.5) in agreement with previous results. With decreasing H‐content of the homogeneous phase the lattice parameters change in opposite direction, a increasing to 4.236(1)Å and c decreasing to 15.39(2)Å for the lower limit.     

An efficient palladium-catalyzed Negishi cross-coupling reaction with arylvinyl iodides: facile regioselective synthesis of E-stilbenes and their analogues

A general synthetic route for the Pd-catalyzed cross-coupling of an arylzinc reagent with arylvinyl iodides (Negishi cross-coupling) has been developed. The system permits efficient and selective preparation of E-stilbenes and their analogues. It also functions effectively at low levels of catalyst loading without the need for an additional ligand and tolerates a wide range of functional groups including heteroaromatic substrates. A systematic study of various parameters was performed and correlated with catalyst-substrate activity.     

Copper-and Silver-Mediated Cyanation of Aryl Iodides Using DDQ as Cyanide Source

A new copper and silver‐mediated cyanation of aryl iodides with DDQ as a cyanide source is achieved, providing nitriles with good yields. This new approach represents a safe method leading to aryl nitriles.     

Silica Chloride (SiO2-Cl), a New Heterogeneous Reagent,for the Selective and Efficient Conversion of Benzylic Alcohols to Their Corresponding Chlorides and Iodides

Abstract

Structurally different benzylic alcohols were efficiently converted to their corresponding chlorides by silica chloride (SiO₂-Cl) in CHCl₃ at room temperature. Silica chloride is also able to convert benzylic alcohols to their iodides in the presence of NaI in a mixture of CH₃CN/CHCl₃ in excellent yields.     

Solvent‐Free Iodination of Arenes using Iodine–Silver Nitrate Combination

A simple and environmentally safe general method of iodination of aromatic substrates under sovent‐free conditions using the I₂/AgNO₃ combination in a solid state is reported. Both activated and deactivated aromatic compounds afford the respective aryl iodides in generally high yields (80–90%).     

An efficient copper-catalyzed N-arylation of amides: synthesis of N-arylacrylamides and 4-amido-N-phenylbenzamides

Copper-catalyzed intermolecular C–N bond-forming reactions between aryl iodides and amides are described using sodium ascorbate, which is both cheap and nontoxic, as the additive. A variety of functionalized amides including some practical, unique secondary amides, such as N-arylacrylamides and 4-amido-N-phenylbenzamides, which are difficult to obtain by the classical methods, are prepared. Furthermore, some tertiary amides are prepared by using copper thiophenecarboxylate.