Free radical addition of carboxylic esters to unsaturated epoxy compounds

Conclusion The addition of esters to unsaturated epoxy compounds, initiated by di-t-butyl peroxide, forms esters containing an epoxy group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, pp. 2297–2300, October, 1969.     

Et3B-Mediated radical alkylation of pyrroles and indoles

An efficient Et₃B-mediated oxidative radical substitution of substituted pyrroles and indoles using xanthate based radical chemistry in the presence of iron(II) sulfate is described. Unsubstituted indole gave only low yield or failed in the process. 2-Cyanofuran and 2-benzoylthiophene did not afford the corresponding alkylated products under these conditions.     

Relative kinetics of the radical addition of benzyl bromide to unsaturated compounds

The relative rate constants of the addition of the C₆H₅CH₂ radical to unsaturated compounds CH₂=CHX (X = C₄H₉, SiMe₃, CF₃, CO₂Me, CN) were determined under the conditions of initiation by the Fe(CO)₅ + DMF system or by benzoyl peroxide. Depending on the values of the relative addition rate constants, the monomers can be arranged into the following series (X): CF₃C₄H₉32Me5 + DMF system, the addition stage proceeds by a free radical mechanism.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2017–2022, September, 1992.     

Free radical addition of F-alkyl compounds to unsaturated carboxylic anhydrides and their derivatives

Many perfluoroalkyl-substituted organic compounds have been obtained through free radical addition of F-alkyl iodides to a center of unsaturation:

X, Y, and Z may include carbon chains, rings and various substituents. During the course of these synthetic studies—done over a span of several years—significant discoveries in mechanism and structure have been made.Today I wish to report some free radical additions of F-alkyl iodides to unsaturated anhydrides and their derivatives. Among the compounds recently discovered are the norbornene products 5 to 10.

Spectroscopic properties of the adducts varied with position and nature of the substituents. Somewhat surprisingly, the chemical shift of protons on the R_F side of the molecule was affected by changes in substituents on the other side of the molecule.Various reactions of the adducts were studied. Unusual stereospecificity in lactone formation and in base- induced cyclization to nortricyclene derivatives was observed. Only when the iodo group was in an endo position did these reactions occur.Analogous free radical addition of fluorinated thiols (R_FCH₂CH₂SH) to norbornene anhydrides produced a series of 5-polyfluoroalkylthionorbornane-2,3-dicarboxylic acid anhydrides(11, 12; U S Patent 3,989,725 (1976). As in previous studies the entering group took up the exo position exclusively. Reaction with acids, esters or norbornene carboxylic imides of the fluorinated thiol also gave analogous products.Because of the hydrophobic nature of the F-alkyl groups the entire range of compounds displayed pronounced surface-activity and would appear to have utility in a wide range of applications.

     

Physical factors determining the activation energy of alkyl radical addition to unsaturated compounds

A parabolic model of the transition state is used for the analysis of experimental data (rate constants and activation energies) for reactions of addition of alkyl and phenyl radicals to multiple bonds of unsaturated compounds. The parameters describing the activation energy as a function of the enthalpy of the reactions were calculated from the experimental data. The activation energy depends also on the strength of the forming C−C bond, the presence of π-bonds in the α-position near the attacked C=C bond and the presence of polar groups in the monomer and radical. The empirical dependence of the activation energy of a thermoneutral addition reactionE _e0 on the dissociation energyD _e of the forming C−C bond was obtained:E _e0=(5.95±0.06)·10⁻⁴ D _e ² kJ mol⁻¹, indicating the important role of triplet repulsion in the formation of the transition state of radical addition. The contribution of the polar interaction to the activation energy of addition of polar radicals to polar monomers was calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 445–450, March, 1999.     

New preparation of difluoroiodomethylsulfanylbenzenes and their radical addition to unsaturated compounds initiated by sodium dithionite

Difluoroiodomethylsulfanylbenzene (3a) and 1-chloro-4-difluoroiodomethylsulfanylbenzene (3b) are novel and efficient difluoromethylating reagents via the reaction with unsaturated compounds, such as alkenes, ethynylbenzene, pent-4-en-1-ols, and pent-4-enoic acids initiated by Na₂S₂O₄, to afford the corresponding adducts, tetrahydrofuran derivatives, and γ-butyrolactones containing difluoromethylene group in moderate to good yields.     

Alkylation of benzene with 1-hexene in acidic ionic liquid systems: Et3NHCl-FeCl3and Et3NHCl-AlCl3ionic liquids

Summary The alkylation of benzene with 1-hexene has been investigated in different triethylamine hydrochloride-ferric chloride (Et₃NHCl-FeCl₃) and triethylamine hydrochloride-aluminium chloride (Et₃NHCl-AlCl₃) ionic liquids. Both high catalyst activity and monoalkylation selectivity were observed for these two type of ionic liquids. Systems prepared by modification with HCl in Et₃NHCl-FeCl₃ionic liquids prove to be very suitable solvents and catalysts for the reaction. When employing Et₃NHCl-AlCl₃ionic liquids as catalysts, the reaction takes place in biphasic mode with facile catalyst separation and catalyst recycling.     

Tributylphosphine catalyzed addition of diphenylphosphine oxide to unsubstituted and substituted electron-deficient alkenes

The PBu₃-catalyzed conjugate addition of diphenylphosphine oxide to unsubstituted and substituted electron-deficient alkenes is reported. β-Substituted α,β-unsaturated esters, trans-methyl crotonate and trans-methyl cinnamate, known for their reluctance to participate in phosphine-catalyzed transformations, also react well under the developed conditions. Mild reaction conditions, simple work-up and the ease of catalyst recovery make the proposed methodology useful for the preparation of functionalized tertiary phosphine oxides. The utility of this method was demonstrated by the gram-scale reactions of diphenylphosphine oxide with electron-deficient alkenes.     

Free radical type addition of toluenesulfonyl cyanide to unsaturated hydrocarbons

By catalysis of AIBN, tosyl cyanide adds in a regio- and stereoselective manner to unsaturated hydrocarbons, including alkenes, dienes and 1-hexyne. Accompanied intramolecular cyclization and ring cleavage were effected in reactions with norbornadiene, 1,5-cyclooctadiene and pinenes.     

Unusual reaction of β-hydroxy α-diazo carbonyl compounds with TsNHNCHCOCl/Et3N

The reaction of β-hydroxy α-diazo carbonyl compounds with TsNHNCHCOCl/Et₃N gave β-(p-tolylsulfonyl) α,β-unsaturated carbonyl compounds or β-(p-tolylsulfonyl) α-diazo esters. The reaction mechanism is discussed.     

Electrodeposition of Aluminum from AlCl3/Et3NHCl Ionic Liquids

Aluminum was successfully electrodeposited on Al electrodes from aluminum chloride (AlCl₃)/triethylamine hydrochloride (Et₃NHCl) ionic liquids by the constant potential electrolysis. Electrical conductivities of AlCl₃/Et₃NHCl ionic liquids were measured as a function of the temperature and composition. The nucleation processes and the influence of experimental conditions on the current efficiency and surface morphology of aluminum electrodeposits were studied on Al electrodes from 2:1 molar ratio AlCl₃/Et₃NHCl ionic liquid. The electrical conductivities of ionic liquids increased as the electrolyte temperature increased, following the Arrhenius behavior. Analyses of the chronoamperograms indicated that the deposition process of aluminum on Al substrates was controlled by instantaneous nucleation with diffusion-controlled growth. Constant potential deposition experiments showed that the electrodeposits obtained on Al electrodes were dense, continuous, and well adherent, and the current efficiency was 73% at −2.4 V(vs Pt) for 20 min electrolysis at room temperature. The purity of aluminum electrodeposits on Al electrodes was above 96% (w).     

Cu(OTf)2-catalyzed Et3SiH-reductive etherification of various carbonyl compounds with trimethylsilyl ethers

A triethylsilane-reductive etherification of the trimethylsilyl ethers with a variety of carbonyl compounds in good yields at room temperature employing 0.5 mol% Cu(OTf)₂ as an extremely efficient catalyst is described here.     

Synthesis of bisphenol A catalyzed by Et3NHCl-AlCl3 ionic liquids

Multi-walled carbon nanotubes supported Pt-Fe cathodic catalyst shows higher specific activity towards oxygen reduction reaction as compared to Pt/MWNTs when employed as cathodic catalyst in direct methanol fuel cell. This revised version was published online in August 2006 with corrections to the Cover Date.