Reaction of Lithium Acylate α-Carbanions with Carbon Tetrabromide

Russian Journal of Organic Chemistry - Lithium acylate α-carbanions generated by metalation of acetic, butanoic, and 2-methylpropanoic acids with lithium diisopropylamide in THF under argon...     

Tin(II) chloride‐mediated synthesis of 2‐substituted benzoxazoles

2‐Aminophenols react with an array of carboxylic acids in dioxane at 180° in the presence of tin(II) chloride to afford the corresponding 2‐substituted benzoxazoles in good yields. The reaction is applicable to a wide range of alkyl, alkenyl, aryl carboxylic acids.     

Optimized synthesis of 2-substituted 1-halocyclopropane-1-carboxylic acids

The reaction of gem-dichloro- and gem-dibromocyclopropanes with n-butyllithium in THF under argon at–78°С followed by purging the reaction mixture with dry CO₂ was used to synthesize cis- and/or trans-1-halocyclopropane-1-carboxylic acids in 30–56% yields. The yields of the target products could be increased to 76–83% by the addition of an equimolar amount of LiCl to the reaction mixture. The highest salt effect was obtained with lithium chloride generated in situ (88–96%).     

Colorimetric analysis of thermal degradation of plasticized poly(vinyl chloride): Potentials and limitations

The kinetics of formation and consumption of polyenes is studied by measuring the change in color coordinates and color difference during the thermal aging of plasticized poly(vinyl chloride) at a temperature of 60–130°С under vented conditions and in a closed volume. It is shown that the initial rate of accumulation and the quasi-stationary concentration of polyenes at 100–130°С grow with temperature. The energy of activation of dehydrochlorination is 70 ± 3 kJ/mol. At a lower temperature (60–80°С), the intensity of color of the samples that are preliminarily aged at increased temperatures decreases. The reduction in the rate of this process with temperature in the range of 60–80°С and the presence of the quasi-stationary level at 100–130°С are related to competition of the processes of formation and oxidation of polyenes.     

Ruthenium‐catalyzed formal alkyl group transfer: Synthesis of quinolines from nitroarenes and alkylammonium halides

Nitroarenes are reductively cyclized with an array of tetraalkylammonium halides and trialkylarnmonium chlorides in the presence of a catalytic amount of a ruthenium catalyst along with tin(II) chloride dihydrate at 180° to afford the corresponding quinolines in moderate to good yields. The addition of tin(II) chloride dihydrate is necessary for the effective formation of quinolines and toluene is the solvent of choice. A reaction pathway involving initial reduction of nitroarenes to anilines and conversion of alkylammonium halides to alkylamines, alkyl group transfer from alkylamines to anilines to form an imine, dimerization of imine, and heteroannulation is proposed for this catalytic process.     

Reaction of α-carbanions of lithium acylates with 1,2-dibromoethane

The reaction of 1,2-dibromoethane with α-carbanions of lithium acylates generated from acetic, butyric, isobutyric, and capronic acids with lithium diisopropylamide has been studied. Anion-radical and anionic pathways of the products formation have been discussed.     

Reactions of Lithium Acylates α-Carbanions with 1,2-Diiodoethane

Russian Journal of General Chemistry - The interaction of lithium acylates α-carbanions (obtained via metallation of acetic, butyric, and isobutyric acids with lithium diisopropylamide) with...     

Electrochemical Method for the Preparation of Dibromomethyl,Bis(bromomethyl), and Bis(dibromomethyl) Arenes

Electrochemical bromination of alkyl aromatic compounds by two-phase electrolysis yields the corresponding α, α-dibrominated products. The reaction has been carried out in a single-compartment electrochemical cell using aqueous sodium bromide (40–50%), containing a catalytic amount of HBr as electrolyte, and chloroform, containing an alkyl aromatic compound, as the organic phase with a Pt plate as anode at 10–15°C. Two-phase electrolysis results in high yields (70–90%) of dibromomethyl, bis(bromomethyl), and bis(dibromomethyl) arenes, depending upon the charge passed.     

An Expedient Phase Transfer Catalyst‐Mediated Synthesis of 2‐Alkyl/Aryl‐1,8‐phenanthrolines

Several 2‐alkyl and 2‐aryl‐1,8‐phenanthrolines were synthesized efficiently from 5‐aminoisoquinoline and seven α,β‐unsaturated aldehydes in aq. HCl–toluene mixture at 100°C using benzyltriethylammonium chloride as a phase transfer catalyst.     

Reductive Cleavage of the Te—Te Bond in Diphenyl Ditelluride by the Sm—CrCl3（cat.）System： Preparation of Telluroesters and Unsymmetrical Phenyltellurides

The reduction of diphenyl ditelluride by the Sm/CrCl3(cat.) system led to a telluride anion.This species reacted with acid chlorides,alkyl halides,and α，β-unsaturated enoates or α，β-unsaturated ene nitriles to afford telluroesters and unsymmetrical phenyltellurides,respectively,in moderate to good yields under mild and neutral conditions.     

A synthesis of esters, amides, and sulfones bearing a 1-cyclopentenyl group at the α-position from cyclobutanones with one-carbon ring-expansion

Treatment of 1-chlorovinyl p-tolyl sulfoxides, derived from cyclobutanones and chloromethyl p-tolyl sulfoxide, with lithium enolate of carboxylic acid tert-butyl esters, lithium enolate of carboxylic acid N,N-dimethylamides, or lithium α-carbanion of alkyl phenyl sulfones gave adducts in high yields. The adducts were treated with isopropylmagnesium chloride or ethylmagnesium chloride in dry toluene to give esters, amides, and sulfones bearing a 1-cyclopentenyl group at the α-position in moderate to good yields with one-carbon ring-expansion via magnesium carbenoid 1,2-CC insertion reaction. The magnesium carbenoid 1,2-CC insertion reaction proved to be highly stereospecific. The reaction mechanism and origin of the specificity are described.     

Bismuth Triflate–Catalyzed Friedel–Crafts Acylations of Sydnones

Friedel–Crafts acylations of various 3-arylsydnones at the C4 position have been achieved in good yields using 4 equivalents of an alkyl anhydride and 25 mol% each of bismuth triflate and lithium perchlorate in anhydrous acetonitrile at 95 °C. Acylations appear to be faster with arylsydnones bearing electron-donating moieties and sterically unencumbered anhydrides.     

Reaction of Grignard Reagents with Diethyl Perfluoroacyl (1-Cyanoethyl)phosphonates. Synthesis of Perfluoroalkylated α,β-Unsaturated Nitriles with Predominant Z-Selectivity

ＩｎｔｒｏｄｕｃｔｉｏｎＲｅｃｅｎｔｌｙｍｕｃｈａｔｔｅｎｔｉｏｎｈａｓｂｅｅｎｄｅｖｏｔｅｄｔｏｔｈｅｓｙｎｔｈｅｓｉｓｏｆα ,β ｕｎｓａｔｕｒａｔｅｄｎｉｔｒｉｌｅｓｓｉｎｃｅｔｈｅｙａｒｅｉｍ ｐｏｒｔａｎｔｓｔｒｕｃｔｕｒａｌｆｅａｔｕｒｅｏｆｓｅｖｅｒａｌｎａｔｕｒａｌｌｙｏｃｃｕｒｒｉｎｇｂｉ ｏｌｏｇｉｃａｌｌｙａｃｔｉｖｅｃｏｍｐｏｕｎｄｓ .1,2 Ｔｈｅｉｎｔｒｏｄｕｃｔｉｏｎｏｆｆｌｕｏ ｒｉｎｅｏｒｔｒｉｆｌｕｏｒｏｍｅｔｈｙｌｇｒｏｕｐｉｎｔｏｂｉｏｌｏｇｉｃａｌｌｙａｃｔｉｖ…     

Tin oxalate as a precursor of tin dioxide and electrode materials for lithium-ion batteries

Tin(II) oxalate was studied as a novel precursor for active electrode materials in lithium-ion batteries. The discharge of lithium cells using tin oxalate electrodes takes place by three irreversible steps: tin reduction, forming a lithium oxalate matrix; solvent decomposition to form a passivating layer; and oxalate reduction in a two-electron process. These are followed by reversible alloying of tin with lithium, leading to a maximum discharge of 11 F/mol. Cycling of the cells showed reversible capacities higher than 600 mAh/g during the first five cycles and ca. 200 mAh/g after 50 cycles. Tin oxalate was converted to tin dioxide by thermal decomposition at 450 °C and also by a chemical method by dissolving tin oxalate powder in 33% v/v hydrogen peroxide at room temperature. The ultrafine nature of the tin dioxide powders obtained by this procedure allow their use as electrodes in lithium cells. The best capacity retention during the first five cycles was achieved for a sample heat treated to 250 °C to eliminate surface water. Electronic Publication     

Flash vacuum pyrolysis of 1-methoxy-1,3-bis(trimethylsiloxy)-1,3-dienes: synthesis of α-allenic acids.

Flash vacuum pyrolysis at 680–700°C of 2- and 4- substituted 1-methoxy-1,3-bis (trimethylsiloxy)-1,3-butadienes yields α-allenic silyl esters which, upon hydrolysis, provide a direct route to α-allenic acids with good overall yield.     

Synthesis of Highly Dispersed Zirconium Carbide

The reduction of zirconium oxide with nanofibrous carbon to obtain highly dispersed zirconium carbide was studied. The optimum reduction conditions were determined. The reaction products were identified using modern physicochemical methods (scanning electron microscopy, low-temperature nitrogen adsorption, sedimentation analysis, differential scanning calorimetry). The product obtained appeared to be single-phase zirconium carbide containing no more than 2 wt % impurities. The powder particles are aggregated (mean diameter 14.9–15.0 μm, specific surface area 1.5–1.7 m² g^–1). The oxidation of zirconium carbide starts at 480°С and is complete at 800°С.     

Cycloadducts of 1‐Alkyl‐1,2‐diphospholes with N‐Phenylmaleimide: Synthesis,Structure, Oxidation,and Thionation Reactions

The [4+2] cycloaddition reaction of 1‐alkyl‐1,2‐diphospholes ( 1 ) with N‐phenylmaleimide proceeds at 25°С in toluene to give 1,7‐diphosphanorbornenes ( 2 ) as anti‐endo isomer only. Oxidation of 2 with air at room temperature or thionation with excess of sulfur at 80°С results in the formation of mixed valent P^III, P^V 7‐oxo(thia)‐1,7‐diphosphanorbornenes ( 3 , 4 ) in high yield. The polycyclic compounds 3 and 4 are air stable and have small sums of valence angles at the phosphorus atoms.     

Carbon-Supported Palladium–Gold Bimetallic Disperse Systems Formed in Aqueous Solutions at 110°С

Various palladium–carbon composites have been manufactured by autoclaving at 170°С to be used as precursors for manufacturing bimetallic particles. The morphology of the manufactured items was comprehensively studied by scanning electron microscopy; the ultrafine metal palladium was found to have particles sizes lying in the range 30–120 nm. The specifics of hydrothermal reduction of gold(III) chloro complexes by palladium–carbon composites at 110°С have been studied. An appreciable increase in gold(III) reduction rate was observed with the use of a palladium–carbon composite relative to the rate observed for ultrafine metallic palladium. Gold is reduced on a palladium–carbon composite to an individual metallic phase.     

Convenient synthesis of fluoroalkyl α- and β-aminophosphonates

Addition of both alkyl phosphites and phosphonate α-carbanions to N-substituted aldimines derived from fluoroalkyl aldehydes presents a convenient method for synthesis of fluoroalkyl α- and β-aminophosphonates in good yield (55-86%) under mild conditions.     

Efficient synthesis of new imidazo[1,2-b][1,2]benzothiazine 4,4-dioxide derivatives via lateral lithiation of N-mesitylenesulfonyl hydantoins

N-Mesitylenesulfonyl hydantoins, readily available from commercial α-amino acids, undergo lateral lithiation with an excess of lithium diisopropylamide and tetramethylethylenediamine in the presence of trimethylsilyl chloride to provide new imidazo[1,2-b][1,2]benzothiazin-2-one 4,4-dioxide derivatives in yields ranging from 44-65%.