Guanamine halogen derivatives with fluoroalkyl groups

A study is made of chlorination and bromination of 4, 6-diamino-s-triazines, with the following fluoro groups at position 2: CF₃, CF₂H, CFH₂, CFClH, CClF₂, and CFCl₂. The reactions were carried out at 5–10° and with excess water (15–20 fold). A reaction mechanism is based on intermediate formation of hypochlorous and hypobromous acids, which then react with the amino group. It is shown that the hydrogen atoms are replaced stepwise. In all cases bromination is slower than chlorination, and the N-bromo-substituted compounds less stable than the corresponding chlorine ones. Free hydrogens in the fluoroalkyl radicals are substituted last of all.     

Bromination of terephthalaldehyde

Conclusions The direct bromination of terephthalaldehyde in the presence of excess anhydrous AlCl₃ leads to the formation of terephthaloyl bromide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 480–481, February, 1977.     

Oxidative halogenation of aromatic compounds in the Pb3O4-Hal−-CF3CO2H system

Conclusions Chlorination, bromination, and iodination of aromatic compounds may be carried out in the Pb₃O₄-Hal^–-CF₃CO₂H system at room temperature. Halogenation under these conditions is not complicated by side reactions which are usual when lead tetraacetate is taken as the oxidizing agent.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2609–2611, November, 1987.     

Bromination of <Emphasis Type="Italic">tert</Emphasis>-Butyl Esters of 7α-Chloro and 7-Alkylidenedeacetoxycephalosporanic Acid Sulfones

The action of N-bromosuccinimide on tert-butyl esters of 7α-chloro- and 7-alkylidenedeacetoxycephalosporanic acid sulfones upon irradiation with visible light leads to the formation of a mixture of the product of allylic bromination of the 3-methyl group, namely, 3-bromomethyldeacetoxycephalosporanate, and the product of replacement of a proton at C₍₂₎ in the latter, namely, 2-bromo-3-bromomethyldeacetoxycephalosporanate. Small amounts of E-isomers were also obtained in the case of the Z-isomer of the 7-(4-nitrobenzylidene) derivative. In the case of the 7α-chloro derivative only substitution of one or two protons at C₍₂₎ occurs during bromination without irradiation, the same as the isomerization of the double bond in the cepheme system.Dedicated to Academician N. K. Kochetkov on the occasion of this ninetieth birthday.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 767–774, May, 2005.     

Bromination of pyridine in the presence of some lewis acids

The bromination of pyridine in the form of complexes with some Lewis acids and in the presence of catalytic amounts of the latter was studied. It is shown that bromination takes place readily at 100 °C in the presence of catalysts such as AlCl₃, ZnCl₂, CuCl₂, SbCl₃, InCl₃, TeCl₄, and HgCl₂. The principal bromination products are 3-bromopyridine and 3,5-dibromopyridine. The problem of the possibility of so-called back-bonding in the case of elements of the higher periods (particularly In, Te, and Sb) is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1236–1239, September, 1981.     

Synthesis of 6-formylpterin

Conclusions A method was developed for the synthesis of 6-formylpterin by the bromination of 2-acetamldo-4-hydroxy-6-methylpteridine in AcOH in the presence of NiC1₂ and subsequent hydrolysis of the intermediate 2-acetamido-4-hydroxy-6-dibromomethylpteridine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1669–1670, July, 1981.     

Kinetics and mechanism of bromination of cyclic acetals with 1,4-dioxane dibromide

It is shown that the reactivities of cyclic formals in the case of bromination with dioxane dibromide increase in the order 1,3-dioxepane > 1,3-dioxalane 1,3-dioxane, which is explained not only by steric factors but also by the ease of cleavage of the C₄-O₃ bond of the dioxacyclane ring. The bromination of cyclic acetals takes place through prior enolization of the cyclic acetal with subsequent electrophilic addition of bromine to the double bond.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–179, February, 1981.     

Electrochemical bromination of dmso in alkaline media: The synthesis of 1,1,1-tribromo- and hexabromodimethylsulfones

Conclusions The electrochemical bromination of DMSO in alkaline media leads to the formation of (CBr₃)₂SO₂ (in the presence of Na₂CO₃) or CBr₃SO₂CH₃ (in the presence of NaHCO₃).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 471–472, February, 1988.     

Study of radical rearrangement during bromination of 3,3,3-trichloropropene

Conclusions It was shown by the EPR method that in the photochemical bromination of 3,3,3-trichloropropene at 77°K a bromine atom adds to the compound with the formation of the CCl₃CHCH₂Br radical, which is then converted to the CCl₂CHClCH₂Br radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 179–181, January, 1973.     

Functionalization of saturated hydrocarbons by means of aprotic superacids 1. Ionic bromination of alkanes and cycloalkanes

Aprotic organic superacids with the composition AcBr·2AlX₃ (X=Cl, Br) are efficient catalysts (Cat) for the bromination of n-alkanes and cycloalkanes by molecular bromine. Under the given conditions, the reactions afford (predominantly or exclusively) monobromides in high yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2028–2033, September, 1989.     

Bromination of quinoline derivatives with N-bromosuccinimide. Isomeric composition of the bromination products by PMR and GLC

The bromination of quinoline and substituted quinolines with N-bromosuccinimide in concentrated H₂SO₄ takes place exclusively in the homocyclic part. Bromo-substituted quinolines can be obtained by this method. The bromination products were identified by PMR spectroscopy. The differences among the mono-, di-, and trisubstituted (in the benzene ring) compounds were established on the basis of the type of spectrum of the protons of the homocyclic part of the molecule. The compositions of the reaction mixtures were studied by GLC.Translated from Khimiya Geterotskiklicheskikh Soedinenii, No.8, pp.1084–1090, August, 1988.     

Halogenation of the components of nucleic acids

Summary Preparative methods have been worked out for the bromination of unprotected deoxy-AMP, deoxy-GMP, and deoxy-CMP and methods have been devised for the isolation and purification of the bromine derivatives.Some physicochemical characteristics (UV spectra, R_f values on thin-layer and paper chromatography, coefficients of millimolar extinction) of the bromine derivatives of the DNA components obtained have been determined.Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 524–527, July–August, 1976.     

Bromo derivatives of 4-phenyl-2,3-dihydro-1h-1,5-benzodiazepin-2-one

Monobromo and dibromo derivatives were synthesized by bromination of 4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one with bromine under various conditions and with N-bromosuccinimide in CCl₄. 7-Bromo- and 8-bromo-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were obtained by condensation of 4-bromo-o-phenylenediamine with benzoylacetic ester in refluxing xylene. The UV and PMR spectra of the products are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 411–415, March, 1978.     

Functionalization of saturated hydrocarbons by aprotic superacids 4. Ionic bromination of ethane and other alkanes and cycloalkanes with molecular bromine in the presence of systems based on polyhalomethanes and AlBr3 under mild conditions

Aprotic organic superacids CBr₄ · 2AlBr3, CBr₄ · AIBr₃, CHBr₃ · 2AlBr₃, CCl₄ · 2AlBr3, and C₆F₅CF₃ -2AlBr3 efficiently catalyze the bromination of alkanes and cycloalkanes with Br₂. Ethane is selectively brominated at 55–65 °C to give mostly 1,2-dibromoethane (stoichiometric reaction). Propane, butane, cyclopentane, cyclohexane, and methylcyclopentane react with Br₂ at -40 to -20 °C with good selectivity affording monobromides in high yields (catalytic reactions).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1208–1213, May, 1996.     

Reactions of organogermanium derivatives of mercury with bromine

Conclusions The bromination of bis(triisopropylgermyl)mercury by bromine gives a high yield of triisopropylgermylmercury bromide. It was found that triisopropylgermylmercury bromide and other compounds of this type reduce HgX₂ to Hg₂X₂ (X=halide).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 927–929, April, 1986.     

Bromination of 1-(4-nitrophenyl)-2-formylpyrrole

Depending on the amount of bromine, the bromination of 1-(4-nitrophenyl)-2-formylpyrrole with bromine in chloroform without a catalyst gives 5-bromo and 4,5-dibromo derivatives. 4-Bromo-1-(4-nitrophenyl)-2-formylpyrrole is formed in the presence of excess AlC1₃, while a mixture of 3,4- and 4,5-dibromo derivatives with preponderance of the latter is formed with excess bromine. The results are compared with the literature data on the bromination of 2-formylpyrrole, 2-formylfuran, and 2-formylthiophene and are interpreted with allowance for the electronacceptor effect of the p-nitrophenyl substituent attached to the nitrogen atom of the pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 662–665, May, 1982.     

Electrophilic and nucleophilic substitution reactions in the series of 3-methylxanthine and its derivatives

The reactions of nitration and bromination of 3-methylxanthine were studied. Heating 3-inethyl-8-nitroxanthine with conc. HCl and HBr leads to a replacement of the nitro group by a halogen atom. The alkylation of 8-haloxanthines by alkyl halides were studied. It was shown that boiling 7-substituted 3-methyl-8-bromoxanthine derivatives with POCl₃ and PCl₅ leads to the formation of 2,6,8-trichloro-7-alkyl-purines. The structure of the synthesized compounds was confirmed by counter-synthesis, the data of elementary analysis, and mass spectrometry.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1129–1132, August, 1984.     

Stereochemistry of cyclic compounds

Conclusions The stereochemistry of the bromination of 3-methyl-4-cyclohexene-cis-1,2-dicarboxylic acid and its anhydride was studied, and the configurations of the products were proved. The observed features of the bromination were explained on the basis of the ionic mechanism of these reactions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 127–132, January, 1967.     

Condensed imidazo-1,2,4-azines. 9. Imidazo[1,2-b]-1,2,4-triazine derivatives in electrophilic substitution reactions

It is shown that, in agreement with the results of quantum-chemical calculations by the CNDO/2 (complete neglect of differential overlap) method, the bromination, nitration, formylation, and hydroxymethylation of 2,3,6-triarylimidazo[1,2-b]-1,2, 4-triazines take place at the C₍₇₎ atom.See [1] for Communication 8.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 413–416, March, 1984.     

2-Bromomethyl derivatives of benzofuran and indole and their reactions with some nucleophilic reagents

The corresponding 2-bromomethyl derivatives of benzofuran and indole were obtained by bromination of 2-methyl-3-carbethoxy-5-methoxybenzofuran and 1,2-dimethyl-3-earbethoxy-5-methoxyindole with N-bromosuccinimide. A number of alkyl(aryl)thiomethyl and dialkylaminomethyl derivatives were obtained by reaction of the 2-bromomethyl derivatives with nucleophilic reagents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 308–311, March, 1973.