Electrophilic additions involving fluoronium ions. I. Fluoroxy additions to perfluoro-olefinic bonds

The fluoroxy addition of perfluoro-t-butyl hypofluorite to hexafluoro-propene leads predominantly (> 95%) to perfluoro-n-propyl perfluoro-t-butyl ether. The unique structural orientation of this perfluoro-n-propyl product is of interest because the products of fluoride ion addition reactions have previously been reported as perfluoroisopropyl derivatives. The results obtained in this study provide a simple experimental demonstration of electrophilic attack by the O-F group, leading to the addition of the fluoronium ion to the more nucleophilic unsaturated carbon atom.The same mechanism as for a perfluoro-α-olefin applies in fluoroxy addition to a perfluorovinyl ether. The perfluoro-t-butoxy group also adds predominantly (> 95%) to the terminal unsaturated carbon atom.     

Electrophilic addition to internal perfluoroolefins

Conclusions Chlorine fluorosulfate adds nonregiospecifically to fluoroolefins having a C(2)=C(3) double bond. This reaction is probably stereospecific independently of the order of addition.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1861–1866, August, 1982.     

Electrophilic additions to allenes—II : The reaction of benzeneselenenyl chloride with some 1,3-disubstituted allenes

Benzeneselenenyl chloride reacts with 1,3-dialkyl-substituted allenes in methylene chloride solution to give 1:1-adducts. Attack by selenium is found to occur exclusively at the central allenic carbon. In contrast to the analogous reaction of arenesulphenyl chlorides, the preferential formation of the Z-alkene is observed. A mechanism involving the preequilibrium formation of alkylideneseleniranium ions and/or alkylideneepiselenuranes which, in the product-determining step, collapse to products via an anti attack of chloride at the methine carbon of the ring is proposed to account for the preferential formation of the Z-isomers.     

Electrophilic addition of 2-chloropolyfluoroalkylsulfenyl chlorides to ketene

Conclusions The reaction of 2-chloropolyfluoroalkylsulfenyl chlorides with ketene gives 2-chloropolyfluoroalkylthioacetyl chlorides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2358–2360, October, 1987.     

Radical addition of halogen-containing addends to unsaturated compounds containing electron-acceptor groups

Conclusions The radical addition of CHCl₃ to trichloroalkenes with the structure CCl₃(CH₂)_nCH=CH₂; n=0,1,2,4; that of bromotrichloromethane to 5,5,5-trichloro-1-pentene, allyl and vinyl esters of trichloroacetic acid; and the addition of hydrogen bromide to 4,4,4-trichloro-1-butene and 5,5,5-trichloro-1-pentene were studied.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1468–1472, July, 1971.     

Electrophilic additions controlled by remote substituents. Total synthesis of daunosamine.

A new route to daunosamine based on the stereospecific electrophilic addition to 2-acetoxy-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitrile is presented.     

Electrophilic addition to bicyclo[1.1.0]butane

Conclusions A study was carried out on the electrophilic addition of some divalent mercury compounds to bicyclo[1.1.0]butane and a mechanism was proposed accounting for the ratio of cyclobutyl and cyclopropylcarbinyl products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1080–1083, May, 1982.     

Exchange and addition reactions involving tin—allyl compounds

Allyltin chlorides (or bromides) may be prepared by simple exchange reactions between tetraallyltin and the corresponding tetrahalide. Hydroboration of allylttrimethyltin yields the air-reactive borane, [Me₃Sn(CH₂)₃]₃B, which is readingly oxidised to the corresponding alcohol Me₃Sn(CH₂)₃OH.     

Electrophilic addition of phenols to 1-vinyl-4,5,6,7-tetrahydroindole

Both uncatalyzed and acid-catalyzed (CH₃COOH) addition of phenols to 1-vinyl-4,5,6,7-tetrahydroindole gave 1-(1-aroxyethyl)-4,5,6,7-tetrahydroindoles. With increasing acidity of the phenol and in the presence of CF₃COOH the yield of adducts was lowered because of the oligomerization of 1-vinyl-4,5,6,7-tetrahydroindole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 604–606, May, 1989.     

Electrophilic addition of selenium and telluriom halides to methyldiethynylsilane

Regio- and stereoselective electrophilic addition reactions of SeCl₂, SeBr₂, SeCl₄, SeBr₄ to methyldiethynylsilane lead to predominant formation of the Z-isomers of 3,6-dihalo-4-methyl-1,4-selenasilafulvenes, disiloxanes on their bases, as well as disiloxanes formed upon the reaction with methyldiethynylsilane. TeCl₄ reacts with methyldiethynylsilane with predominant formation of the E-isomer of 1,1,3,6-tetrachloro-1-methyl-1-(methyldiethynylsiloxy)-1,4-tellura(IV)silafulvene as a result of the reaction of the intermediate E-isomer of 4-methyl-1,1,3,6-tetrachloro-1,4-tellura(IV)silafulvene with methyldiethynylsilane. The structure of the products was proved by the methods of ¹H, ⁷⁷Se NMR, IR spectroscopy and chromatomass spectrometry.     

Kinetics of the Conformer Reactions: II. Significance of Media in the Electrophilic addition Reactions

The kinetics of electrophilic addition reaction of bromine to a multiple bond in a series of con-formationally unhomogenous 2-substituted 1'3-dioxa-5-cycloheptenes was studied. We found that the com-pounds with trans structure are formed. The partial reaction rate constant for chair, twist forms, thereaction susceptibility parameters to the substituent electronic effect at the ^C2atom are obtained. Relativereactivity of the alternative steric structures is defined by the specific solvation of the substrate. The result obtained are compared with those achieved without accounting for conformational term.     

Radical energies and the regiochemistry of addition to heme groups. Methylperoxy and nitrite radical additions to the heme of horseradish peroxidase

The heme of hemoproteins, as exemplified by horseradish peroxidase (HRP), can undergo additions at the meso carbons and/or vinyl groups of the electrophilic or radical species generated in the catalytic oxidation of halides, pseudohalides, carboxylic acids, aryl and alkyl hydrazines, and other substrates. The determinants of the regiospecificity of these reactions, however, are unclear. We report here modification of the heme of HRP by autocatalytically generated, low-energy NO2* and CH3OO* radicals. The NO2* radical adds regioselectively to the 4- over the 2-vinyl group but does not add to the meso positions. Reaction of HRP with tert-BuOOH does not lead to heme modification; however, reaction with the F152M mutant, in which the heme vinyls are more sterically accessible, results in conversion of the heme 2-vinyl into a 1-hydroxy-2-(methylperoxy)ethyl group [-CH(OH)CH2OOCH3]. [18O]-labeling studies indicate that the hydroxyl group in this adduct derives from water and the methylperoxide oxygens from O2. Under anaerobic conditions, methyl radicals formed by fragmentation of the autocatalytically generated tert-BuO* radical add to both the delta-meso carbon and the 2-vinyl group. The regiochemistry of these and the other known additions to the heme indicate that only high-energy radicals (e.g., CH3*) add to the meso carbon. Less energetic radicals, including NO2* and CH3OO*, add to heme vinyl groups if they are small enough but do not add to the meso carbons. Electrophilic species such as HOBr, HOCl, and HOSCN add to vinyl groups but do not react with the meso carbons. This meso- versus vinyl-reactivity paradigm, which appears to be general for autocatalytic additions to heme prosthetic groups, suggests that meso hydroxylation of the heme by heme oxygenase occurs by a controlled radical reaction rather than by electrophilic addition.     

Hydrazones—III Intramolecular 1,3-dipolar additions involving nitro- and carbonyl groups

Reaction of o-nitro-ω-halobenzaldehyde arylhydrazones with bases gives 3-arylazoanthranil 1-oxides; reduction of these oxides involves rearrangement and leads to mesoionic indazole derivatives. These structures should replace the triazirinoindazole formulations (R.I. 1223, R.R.I. 2097) hitherto used to describe both classes of compounds.

A simple route to two known 1,3,4-oxadiazoles from semicarbazones is also described.     

Anti-Markovnikov additions to N-allylic derivatives involving ammonium-carbenium superelectrophiles

Anti-Markovnikov additions to non-conjugated unsaturated amines in superacid are reported. In situ NMR studies, DFT calculations and labelled substrates reactions support the involvement of new ammonium-carbenium superelectrophiles in this original process.     

The kinetics of the addition of alkyl radicals to carbonyl groups. II. The addition of methyl radicals to trifluoroacetone in the gas phase. The formation reaction of the trifluoro-t-butoxy radical

By photolyzing azomethane over the temperature range 331–491 K in the presence of trifluoroacetone the kinetics of the addition reaction (1), ?H₃ + CF₃COCH₃ → CF₃C(?)(CH₃)₂ have been studied. Detailed analyses have shown that the principal product of the adduct radical, CF₃C(?)(CH₃)₂, is CH₃COCH₃ from reaction (?2), CF₃C(?)(CH₃)₂ → CH₃COCH₃ + ?F₃. The rate constant of the addition reaction has been determined to be k₁(dm³/mol s) = (4.5 ± 1.4) × 10⁷ exp(-(3370 ± 120)/T) over the temperature range 331–491 K, based on the value k₃ = 2.2 × 10¹⁰ dm³/mol s for the reaction (3), 2?H₃ → C₂H₆. The results are discussed in relation to existing data for radical additions to groups.     

Electrophilic addition to o-ArY-substituted phenylalkynes. A highly selective cyclization controlled by heteroatoms

Treatment of -(phenyloxy)phenylalkyne with HClO₄ or HBF₄ gave dibenz(b, f)oxepin , whereas the sulfur analogue, -(phenylthio)phenylalkyne , provided 1-phenyl-1-benzothiophenium salts .