Organic fluorine compounds—XXXVIII N-alkylated fluoroamino acids

Hydroxyproline methyl ester was methylated and the hydroxyl group of the product replaced by fluorine, using 1,1,2-trifluoro-2-chloroethyl-diethylamine. Analogously, the N,N-dimethyl derivatives of several β-hydroxy--amino acids were transformed into the corresponding β-fluoro compounds.     

Furano compounds—IX

Starting with the appropriate 3-hydroxybenzoxanthones and the following the sequence of reactions allylation, Claisen migration, acetylation, bromine addition and dehydrobromination, 7:8-benzo- and 5:6-benzo-3:4, 2′:3′-furanoxanthones have been synthesized.     

Silver-catalyzed decarboxylative fluorination of aliphatic carboxylic acids in aqueous solution

Although fluorinated compounds have found widespread applications in the chemical and materials industries, general and site-specific C(sp(3))-F bond formations are still a challenging task. We report here that with the catalysis of AgNO(3), various aliphatic carboxylic acids undergo efficient decarboxylative fluorination with SELECTFLUOR(?) reagent in aqueous solution, leading to the synthesis of the corresponding alkyl fluorides in satisfactory yields under mild conditions. This radical fluorination method is not only efficient and general but also chemoselective and functional-group-compatible, thus making it highly practical in the synthesis of fluorinated molecules. A mechanism involvinig Ag(III)-mediated single electron transfer followed by fluorine atom transfer is proposed for this catalytic fluorodecarboxylation.     

Heterocyclic fluorine compounds—III Monofluoroxanthones

The four monofluoroxanthones substituted in the benzene ring have been prepared by two different routes, namely by cyclisation of the appropriate carboxyfluorodiphenyl ether and by a Balz-Schiemann reaction with the corresponding aminoxanthone.     

Advances in fluorination of organic compounds with sulphur tetrafluoride

Sulphur tetrafluoride has been known since 1958 as an efficient fluorinating agent for replacing oxygen atoms in carbonyl groups by fluorines. In the past fifteen years a number of new reactions of sulphur tetrafluoride with carbonyl compounds have been discovered. These include formation of bis(1,1-difluoroalkyl) ethers from alkanecar☐ylic acids, bis(1-fluoroalkyl) ethers from aliphatic aldehydes, and cyclic fluoroethers from difunctional car☐ylic acids and aldehydes. In the reactions with branched aldehydes rearrangements of hydrogen and fluorine atoms and also of the carbon skeleton were observed. Tertiary amides were successfully converted to 1,1-difluoroamines and tertiary formamides to trifluoromethylamines. This last reaction involves simultaneous fluorination of the carbon-oxygen and carbon-hydrogen bonds.Participation of carbocations in the mechanism of fluorination of carbonyl groups has been proved and a revised mechanism proposed. Evidence for a reduction-oxidation mechanism for the replacement of formyl hydrogen by fluorine has also been found.     

Electrolysis of aliphatic nitro compounds

Conclusions Data on electrolysis in strongly acidic media have shown that, contrary to accepted belief, reduction of the un-ionized form of trinitromethane proceeds through C-N bond rupture rather than through breakage of the nitro group N-O bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1725–1729, August, 1976.     

Sonochemical fluorination of heterocyclic nitro compounds with Selectfluor

Methine and methylene groups attached to a nitro function and heterocycle (and Ph for CH) were rapidly mono- or di-fluorinated by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), preferably with ultrasonic irradiation.     

Polarographic study of aliphatic nitro compounds

Conclusions Study bas shown that the first stage in the reduction of 1,1-dinitroethane and fluorodinitromethane in strongly acidic solution is a two-electron C-N bond rupture process, the subsequent stages of the reaction being determined by the relative rates of the competing processes of protonation, nitrosation, and Neff reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 567–573, March, 1977.     

New reaction of aliphatic nitro compounds

Conclusions Primary aliphatic nitro compounds react with magnesyl derivatives of tert-butylamine with the formation of the corresponding amidooximes, while 2-nitropropane under analogous conditions gives a -aminooxime.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2873–2874, December, 1988.     

Chemical ionization of aliphatic nitro compounds

The chemical ionization mass spectra of various aliphatic nitro compounds have been studied. Almost all the nitro compounds form stable [M+H]⁺ ions in sharp contrast to the instability of their ions produced by other ionization techniques. The fragmentations of the [M+H]⁺ ions are discussed, the mechanisms and structures of fragment ions proposed being supported by quantum mechanical calculations. Correlations between chemical ionization mass spectra and structures of compounds studied are outlined. Reliable identification of mono- and polynitroalkanes and some related derivatives may be made by analysis of their chemical ionization mass spectra.     

Denitrohydrogenation of aliphatic nitro compounds and a new use of aliphatic nitro compounds as radical precursors

Aliphatic nitro groups are replaced by hydrogen on treatment with tributyltin hydride which proceeds via free radical chain processes. As the nitro group is selectively denitrated and other reducible groups are not affected with tributyltin hydride, this reaction can be used as a method for removing the nitro group from polyfunctional compounds. The radical intermediates generated via denitration can be also used for the carbon-carbon bond forming reactions.     

Polarographic study of aliphatic nitro compounds

Conclusions In polarograms of solutions of salts of CH₂(NO₂)₂, CH₃CH(NO₂)₂, FCH(NO₂)₂, and CH₃CH₂NO₂ in abs. methanol, an anodic wave is present, due to increased ionization of mercury, by the tying up of mercury ions with the anions of these compounds to form slightly dissociated organomercury compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2021–2023, September, 1980.