1201-02-1Relevant academic research and scientific papers
Disubstitution on hexafluorobenzene with N-methylformamides
Koppang, R.,Grace, D.
, p. 27 - 30 (1994)
Nucleophilic attack on hexafluorobenzene by N-methylformamide, treated with different bases, gave N-methyl-2,3,4,5,6-pentafluoroformanilide, N-formyl-N,N'-dimethyl-2,3,5,6-tetrafluorophenylene-1,4-diamine and N,N'-diformyl-N,N'-dimethyl-2,3,5,6-tetrafluorophenylene-1,4-diamine.The substituted benzenes could be hydrolyzed to N-methyl-2,3,4,5,6-pentafluoroaniline and N,N'-dimethyl-2,3,5,6-tetrafluorophenylene-1,4-diamine.
Fluoroazaindolines by an uncommon radical ipso-substitution of a C-F bond
Laot, Yann,Petit, Laurent,Tran, Ngoc Diem My,Zard, Samir Z.
experimental part, p. 416 - 425 (2011/10/09)
Trifluoroazaindoline derivatives are prepared using the first synthetically useful radical ipso-substitution of a fluorine atom. The initial procedure has been improved to allow the gram scale synthesis of these building blocks, which can be regioselectiv
Anilinic N-oxides support cytochrome P450-mediated N-dealkylation through hydrogen-atom transfer
Roberts, Kenneth M.,Jones, Jeffery P.
experimental part, p. 8096 - 8107 (2010/09/11)
The mechanism of N-dealkylation mediated by cytochrome P450 (P450) has long been studied and argued as either a single electron transfer (SET) or a hydrogen atom transfer (HAT) from the amine to the oxidant of the P450, the reputed iron-oxene. In our study, tertiary anilinic N-oxides were used as oxygen surrogates to directly generate a P450-mediated oxidant that is capable of N-dealkylating the dimethylaniline derived from oxygen donation. These surrogates were employed to probe the generated reactive oxygen species and the subsequent mechanism of N-dealkylation to distinguish between the HAT and SET mechanisms. In addition to the expected N-demethylation of the product aniline, 2,3,4,5,6-pentafluoro-N,N-dimethylaniline N-oxide (PFDMAO) was found to be capable of N-dealkylating both N,N-dimethylaniline (DMA) and N-cyclopropyl-N-methylaniline (CPMA). Rate comparisons of the N-demethylation of DMA supported by PFDMAO show a 27-fold faster rate than when supported by N,N-dimethylaniline N-oxide (DMAO). Whereas intermolecular kinetic isotope effects were masked, intramolecular measurements showed values reflective of those seen previously in DMAO- and the native NADPH/O2-supported systems (2.33 and 2.8 for the N-demethylation of PFDMA and DMA from the PFDMAO system, respectively). PFDMAO-supported N-dealkylation of CPMA led to the ring-intact product N-cyclopropylaniline (CPA), similar to that seen with the native system. The formation of CPA argues against a SET mechanism in favor of a P450-like HAT mechanism. We suggest that the similarity of KIEs, in addition to the formation of the ring-intact CPA, argues for a similar mechanism of Compound I (Cpd I) formation followed by HAT for N-dealkylation by the native and N-oxide-supported systems and demonstrate the ability of the N-oxide-generated oxidant to act as an accurate mimic of the native P450 oxidant.
[18F]/19F exchange in fluorine containing compounds for potential use in 18F-labelling strategies
Blom, Elisabeth,Karimi, Farhad,Langstroem, Bengt
experimental part, p. 504 - 511 (2010/08/07)
Exchange of [18F]fluoride with 19F in various organofluorine compounds in concentrations ranging from 0.06 to 56 mM was explored. We aimed to explore whether exchange reactions can be a potential useful labelling strategy, when there are no requirement of high specific radioactivity. Parameters such as solvents, temperature, conventional vs microwave heating, and the degree of fluorine load in some aromatic and alkyl compounds were investigated with regard to radiochemical yield and specific radioactivity. A series of fluorobenzophenones (1-6), 1-(4-fluorophenyl)ethanone (7), various activated and deactivated fluoro benzenes (8-16), N-(pentafluorophenyl)benzamide (17), (pentafluorophenyl)formamide (18), (tridecafluorohexyl)benzene (19) and tetradecafluorohexane (20) were subjected to [18F]/19F exchange. To test this strategy to label biologically active molecules containing fluorine atoms in an aryl group, two analogues of WAY-100635 (21-22), Lapatinib (23), 2,5,6,7,8-pentafluoro-3- methylnaphthoquinone (24) and 1-(2,4-difluorophenyl)-3-(4-fluorophenyl)-propan- 1-one (25) were investigated. The multi-fluorinated molecules containing an electron-withdrawing group were successfully labelled at room temperature, whereas the monofluorinated, as well as those containing an electron-donating group, required heating for the exchange reaction to take place. Copyright
Polyfluorinated arylnitramines
Platonov,Haas,Schelvis,Lieb,Dvornikova,Osina,Gatilov, Yu.V.
, p. 131 - 139 (2007/10/03)
N-methyl- and N-butylperfluoroarylamines are transformed by HNO3 into N-nitro-N-methyl- and N-nitro-N-butylperfluoroarylamines. These reactions were used to synthesise N-nitro-N-methylpentafluoroaniline and its p-CF3, -CN, -C6F5 substituted derivatives, N-nitro-N-methylperfluoro-2,4-xylidine, N-nitro-N-methyl-4-aminotetrafluoropyridine, N-nitro-N-methyl-5-aminoperfluoroindane, N-nitro-N-methyl-2-aminoheptafluoronaphthalene, 4,4′-bis(N-nitro-N-methylamino)octafluorobiphenyl from 4,4′-bis(N-methylamino)octafluorobiphenyl, N-nitro-N-n-butylpentafluoroaniline, N-nitro-N-n-butylperfluoro-p-toluidine, N-nitro-N-n-butyl-4-aminotetrafluoropyridine and N-nitro-bis(perfluoro-p-tolyl)amine. Tetrafluoro-p-benzoquinone and heptafluoro-p-toluquinol were obtained from N-methylpentafluoroaniline and N-methylperfluoro-p-toluidine, respectively, under the action of a mixture of HNO3 and H2SO4. The X-ray crystal structure of N-nitro-N-methylperfluoro-p-toluidine was determined.
Flash photolytic generation of primary, secondary, and tertiary ynamines in aqueous solution and study of their carbon-protonation reactions in that medium
Chiang,Grant,Kresge,Paine
, p. 4366 - 4372 (2007/10/03)
A group of nine phenylynamines (PhC≡CNH2, PhC≡CNHCH(CH3)2, PhC≡CNHC6H11, PhC≡CNHC6H5, PhC≡CNHC6F5, PhC≡CN(CH2)5, PhC≡CN(CH2CH2)2O, PhC≡CN(CH2CH2CN)2, and PhC≡CN(CH3)C6F5) were generated in aqueous solution by flash photolytic decarbonylation of the corresponding phenylaminocyclopropenones, and the kinetics of their facile decay in that medium were studied. This decay is catalyzed by acids for all ynamines-primary, secondary, and tertiary-and also by bases for primary and secondary ynamines. Solvent isotope effects and the form of acid-base catalysis show that the acid-catalyzed path involves formation of keteniminium ions by rate-determining proton transfer to the β-carbon atoms of the ynamines. The ions generated from primary and secondary ynamines then lose nitrogen-bound protons to give ketenimines, and the ketenimines obtained from secondary ynamines are hydrated to phenylacetamides, whereas that from the primary ynamine tautomerizes to phenylacetonitrile. Keteniminium ions formed from tertiary ynamines have no nitrogen-bound protons that can be lost, and they are therefore captured by water instead, and the amide enols thus produced then ketonize to phenylacetamides. The base-catalyzed decay of primary and secondary ynamines also generates ketenimines, but protonation on the β-carbon is now preceeded by proton removal from nitrogen. Rate constants for β-carbon protonation of PhC≡CNHCH(CH3)2 and PhC≡CN(CH2)5 by a series of carboxylic acids give linear Bronsted relations with exponents α = 0.29 and 0.28, respectively, whereas inclusion of literature data for protonation of PhC≡CN-(CH2)5 by a group of weaker acids gives a curved Bronsted relation whose exponent varies from 0.25 to 0.97. Application of Marcus rate theory to this curved Bronsted relation produces the intrinsic barrier ΔG((+))(o) = 3.26 ± 0.19 kcal mol-1 and the work term w(r) = 8.11 ± 0.15 kcal mol-1.
