Electron transfer reactions. Reaction of dibenzobarrelenes with potassium

The results of our studies on potassium-induced transformations of several bridgehead-substituted dibenzobarrelenes are presented. The dibenzobarrelenes 1b,c,e,f having methyl, hydroxymethyl, methoxy and phenyl groups, respectively, at the bridgehead position and the bridgehead-dimethyl derivative 1g give, on treatment with potassium in THF, the corresponding anthracenes 8b,c,e-g, dihydrodibenzobarreneses 6b,c,e-g and benzoic acid (5). The dibenzobarrelenes 1b,g give, in addition to 8b,g, 6b,g and 5, the corresponding mono-debenzoylated products 7b,g, whereas the methoxy derivative 1e gives both anthraquinone (9) and an enol derivaiive 11, besides 8e, 6e and 5. In contrast, the reaction of the hydroxy derivative 1d with potassium in THF gives a mixture of 5, anthracene (8a), the anthrone 10 and the anthrol 12. To assess the role of oxygen in these reactions, if any, the reactions of some representative substrates such as 1b,d,e with potassium in THF, saturated with oxygen and with potassium superoxide have been studied. Cyclic voltammetric studies have been carried out to measuee the reduction potentials for both one electron and two electron processes, leading to the generation of the corresponding radical anions and dianion intermediates. The radical anions of 1b-g have also been generated pulse radiolytically in methanol and their spectra show absorption maxima in the regions 310-390 and 400-450 nm.     

Reaction of α,α′ - bis(trimethylsiloxy) sulfides with low valent titanium reagents

We have shown that low valent titanium reagents reductively couple α,α′ -bis-(trimethylsiloxy) sulfidees giving olefins in good yield. With unsymmetrical $\text{1}$, mixed olefins are obtained suggesting an intermolecular pathway. Finally, we have demonstrated that $\text{trans}$-episulfide $\text{3}$ is quantitatively converted to $\text{trans}$-stilbene.     

Oxygen atom transfer reactions from isolated (oxo)manganese(V) corroles to sulfides

A series of five free-base corroles were metalated and brominated to form 10 manganese(III) corroles. Two of the free-base corroles and six manganese(III) corroles were analyzed by X-ray crystallography, including one complex that may be considered a transition-state analogue of oxygen atom transfer (OAT) from (oxo)manganese(V) to thioansisole. Oxidation by ozone allowed for isolation of the 10 corresponding (oxo)manganese(V) corroles, whose characterization by (1)H and (19)F NMR spectroscopy and electrochemistry revealed a low-spin and triply bound manganese-oxygen moiety. Mechanistic insight was obtained by investigating their reactivity regarding stoichiometric OAT to a series of p-thioanisoles, revealing a magnitude difference on the order of 5 between the β-pyrrole brominated (oxo)manganese(V) corroles relative to the nonbrominated analogues. The main conclusion is that the (oxo)manganese(V) corroles are legitimate OAT agents under conditions where proposed oxidant-coordinated reaction intermediates are irrelevant. Large negative Hammett ρ constants are obtained for the more reactive (oxo)manganese(V) corroles, consistent with expectation for such electrophilic species. The least reactive complexes display very little selectivity to the electron-richness of the sulfides, as well as a non-first-order dependence on the concentration of (oxo)manganese(V) corrole. This suggests that disproportionation of the original (oxo)manganese(V) corrole to (oxo)manganese(IV) and (oxo)manganese(VI) corroles, followed by substrate oxidation by the latter complex, gains importance when the direct OAT process becomes progressively less favorable.     

Photochemical reactions of 7-aminocoumarins. 4. Reaction of 4-methyl-7-diethylaminocoumarin with compounds tending to photolytic dissociation

The photochemical reactions of 4-methyl-7-diethylaminocoumarin with a series of alkyl halides including isopropyl iodide, allyl iodide, bromoacetone -bromoethyl acetate, phenacyl bromide, p-bromophenacyl bromide, and chloroacetonitrile, and aryl iodides including iodobenzene, 2-nitroiodobenzene, 3,4-dimethoxyiodobenzene, and 3-iodo-4-methyl-7-diethylaminocoumarin proceed by a radical addition mechanism to give 3-substituted aminocoumarins. A series of 3-substituted 7-aminocoumarins was also obtained as a result of the photochemical reactions of 4-methyl-7-diethylaminocoumarin, with other reagents, having photolabile chemical bonds such as dioxanyl peroxide, phenyl iodosodiacetate, and nitromethane. The luminescence characteristics of the compounds synthesized were studied.For Communication 3, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 460–469, April, 1989.     

Reaction of polyhalopyridines 4. Reaction of mercaptopolychloropyridines with fluorine-containing xenon compounds

A method has been developed for the perfluoroalkylation of mercaptopolychloropyridines by the thermolysis of xenon(II) perfluoroalkanecarboxylates, obtained by the reaction of xenon difluoride and aperfluoroalkanecarboxylic acids, in the presence of the appropriate thiol. Perfluoroalkylthio derivatives of polychloropyridines have been synthesized. The fluorosulfonyl derivatives of tetrachloropyriidne and of tetrachloropyridine N-oxide were obtained by the action of XeF₂ on mercaptotetrachloropyridine dissolved in aqueous HF.For Communication 3 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 58–62, January, 1994.     

Substitution reactions with the participation of organoaluminum compounds. 7. Reaction of organoaluminum compounds with monochlorodimethyl ether

Conclusions The reaction of monochlorodimethyl ether with different organoaluminum compounds is only a convenient method for the isolation of alkyl methyl ethers in the case of trialkylalanes.For previous communication 6, see [12].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 425–428, February, 1988.     

Photoinduced electron transfer reactions of pyrylium derivatives with organic sulfides in acetonitrile

The photochemistry and photophysics of pyrylium derivatives with organic sulfides in acetonitrile medium are investigated. A steady decrease in the fluorescence intensity and fluorescence lifetime of the dyes was observed with increase in the quencher concentration. Bimolecular quenching constants were evaluated and correlated with the free energy of electron transfer. Laser flash photolysis investigations on the dyes in presence of quenchers were done. Observation of pyranyl radical and sulfide cation radicals as intermediates clearly illustrates the electron transfer mechanistic pathway for this reaction. The radical pair energies were calculated and found to be lower than the triplet energy of the sensitisers and hence we do not see any triplet induction in the present system.     

Photochemical reactions of 7-aminocoumarins. 10. Reaction of 3-iodo-4-methyl-7-diethylaminocoumarin with heteroaromatic compounds

Photolysis of 3-iodo-4-methyl-7-diethylaminocoumarin in the presence of N-methylpyrrole, furan, thiophene, selenophene, pyridine, indole, imidazole, and benzimidazole results in the formation of a series of 3-hetaryl-7-aminocoumarins. The spectral luminescence characteristics of these newly synthesized compounds have been investigated.For communication 9, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1469–1473, November, 1990.     

Reaction of dichlorocarbene with vinyl sulfides

Conclusions The reaction of dihalocarbenes with vinyl sulfides gave gem-dihalocyclopropyl sulfides. The relative activity of the sulfides toward dichlorocarbene is 5–6 times greater than that of the corresponding ethers. The theory was expressed that intermediate sulfur ylides are formed in the given reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1354–1358, June, 1980.     

Reaction of 2-methylphenylsulfuranylidenedimedon with sulfides

Conclusions Dibenzyl sulfide and methyl benzyl sulfide demethylate and transylidate 2-methylphenylsulfuranylidenedimedon, in which connection the demethylation predominates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1893–1895, August, 1979.The authors express their gratitude to R. G. Gainullina for taking the PMR spectra.     

Reduction of enedicarboxylate compounds with low valent titanium

The carbon—carbon double bonds of enedicarboxylate compounds can be reduced readily with TiCl₄LiAlH₄Et₃N in THF. Other double bond of the enedicarboxylate does not react during the reduction process.     

Some charge transfer reactions of excited aromatic compounds with sulphides

Photo-reductive dehalogenation of aromatic halides to their parent hydrocarbons is stimulated in the presence of electron donors such as di-ethyl sulphide. Evidence is presented for the involvement of radicals ions in these reactions.     

Electron transfer reactions. Reaction of tetracyclone,tetraphenylfuran and related substrates with potassium

The reaction of tetracyclone (1) with potassium in THF gave a mixture of benzoic acid (4), tetraphenylfuran (5) and cis-1,2-dibenzoylstilbene (6). The reaction of 1 with potassium in oxygen-saturated THF gave a mixture of 2-hydroxy-2,4,5-triphenyl-3(2H)furanone (3), 4, 5 and 6, whereas the reaction of 1 with potassium superoxide gave a moderate yield of 3,4,5,6-tetraphenyl-2-pyrartone (7), besides 3, 4, 5, and 6. The reaction of tetraphenylfuran (5) itself with potassium in THF gave a mixture of 6, 1,2,3,4-tetraphenylbutan-1-one (9), 2,3-diphenyl-1-indenone (10) and 2,3-epoxy-4-hydroxy-2,3,4-tnphenyltetralone-l (11), whereas practically no reaction occurred on treatment of 5 with potassium superoxide. Treatment of 10 with potassium in THF, however, gave a mixture of 4, dibenzo[a,c]-13-fluorenone (13), 2,3-diphenyl-2-hydroxyl-1-indanone (14) and 2,3-diphenylbenzofuran (15). A similar mixture of products consisting of 4, 13, 14 and 15 was obtained when the reaction of 10 with potassium was carried out in oxygen-saturated THF or when 10 was treated with potassium superoxide. Treatment of 2,3-diphenyl-2,3-epoxy-1-indanone (16) with potassium on the other hand, gave 10 in excellent yield. Cyclic voltammetric studies have been carried out to measure the reduction potentials of 1, 5, 10 and 16 in the generation of their radical anions. The radical anions of 1, 5, 10 and 16 were also generated pulse radiolytically in methanol and their spectra showed absorption maxima in the region 320–380 nm.     

Reaction of trichloroacetyl isocyanate with vinyl sulfides

Conclusions Trichloroacetyl isocyanate reacts with the n-butyl, isoamyl, and phenyl vinyl sulfides on the type of 1, 4-cycloaddition with the formation of 3, 1-oxazin-6-one derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2324–2325, October, 1972.