- Oxygenation of hydrocarbons mediated by mixed-valent basic iron trifluoroacetate and valence-separated component species under Gif-type conditions involves carbon- and oxygen-centered radicals
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Hydrogen-atom abstraction by hydroxyl radicals takes place to generate both tert- and sec-adamantyl radicals in Gif-type oxygenation of adamantane by H2O2 in pyridine/trifluoroacetic acid when the reaction is mediated by [Fe(O2CCF3)2(py)4] or [Fe2O(O2CCF3)4(py)6], which are formed by dissociation of [Fe3O(O2CCF3)6- (L)3] in pyridine (L = H2O, DMSO; see scheme).
- Tapper, Amy E.,Long, Jeffrey R.,Staples, Richard J.,Stavropoulos, Pericles
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p. 2343 - 2346
(2007/10/03)
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- The selective functionalization of saturated hydrocarbons. Part 46. An investigation of Udenfriend's system under Gif conditions
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Under Gif conditions using ascorbic acid as reductant and oxygen as oxidant in pyridine, the selectivity for secondary hydrogen functionalization is exceptional. EDTA (ethylenediamine-tetra-acetic acid) is not needed as a ligand for iron.
- Barton, Derek H.R.,Delanghe, Nathalie C.
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p. 4471 - 4476
(2007/10/03)
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- The conversion of saturated hydrocarbons into carboxylic acids using Fe(CO)5-H2O2 oxidation
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Saturated hydrocarbons are transformed into their corresponding homologous carboxylic acids by treatment with iron pentacarbonyl and hydrogen peroxide in pyridine-acetic acid. A mechanism for this reaction is proposed. Attention is also directed to a new and convenient procedure for the determination of carbon monoxide.
- Barton, Derek H. R.,Delanghe, Nathalie C.
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p. 8137 - 8140
(2007/10/03)
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- The functionalization of saturated hydrocarbons. Part 24. The use of tert-butyl hydroperoxide: GoAggIV and GoAggV
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The use of tert-butyl hydroperoxide as an oxidant in Gif-type systems (GoAggIV and GoAgfV) catalyzed by various Fe(III) species is examined. Regioselectivity studids of these systems have revealed several characteristics similar to those observed for other prdviously reported Gif-type reactions. A common rdaction pathway for the GoAggIV and GoAggV oxidation systems and other Gif-type reactions (from alkane via alkyl hydroperoxide to ketone or alcohol) is seen.
- Barton, Derek H. R.,Chavasiri, Warinthorn
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- The Fe(II)-Fe(IV) and Fe(III)-Fe(V) manifolds in an expanded world of gif chemistry
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The species responsible for hydrocarbon activation and formation of alkyl chlorides in the Fe(II) and Fe(III)-H2O2 and tert-butyl hydroperoxide systems are identified. The importance of the Fe(II)-Fe(IV) manifold in providing a mechanism which permits the selective functionalization of saturated hydrocarbons by ionic trapping with chloride, azide, and other anions is made manifest. Comparison is made with the Fe(III)-Fe(V) manifold where ionic trapping is never seen.
- Bardin,Barton,Hu,Rojas-Wahl,Taylor
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p. 5805 - 5808
(2007/10/02)
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- The Functionalization of Saturated Hydrocarbons. Part 26. Ionic Substitution Reactions in GoAggIV Chemistry: The Construction of C-N, C-S and C-C Bonds
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Utilization of the GoAggIV system in the presence of sodium azide, sodium nitrite, sodium thiocyanate, sodium disulfide and tetraethylammonium cyanide converts saturated hydrocarbons into the corresponding alkyl azides, nitroalkanes, alkyl thiocyanates, dialkyl disulfides and alkyl cyanides, respectively.Mechanistic studies suggest an Fe-centered ligand coupling reaction pathway.Key Words: Gif systems; Selective functionalization, Iron catalysts, C-N bond formation, C-S bond formation, C-C bond formation
- Barton, Derek H. R.,Warinthorn, Chavasiri
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- The functionalization of saturated hydrocarbons. Part 25. Ionic substitution reactions in GoAggIV chemistry: The formation of carbon-halogen bonds
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GoAggIV chemistry (Fe (III) species, tert-butyl hydroperoxide in a mixture of pyridine and acetic acid) in the presence of LiCl can transform saturated hydrocarbons efficiently into the corresponding alkyl chlorides. The transformation into monosubstituted alkyl derivatives by "ionic trapping" reagents arising from the interception of the first intermediate of the system supports the presence of a high valent VFe-C species. Mechanistic studies suggest a possible pathway operating via an Fe-centered ligand coupling. In addition, the production of alkyl chlorides and alkyl bromides could also be achieved employing this system in the presence of halogenating reagents such as CCl4 and BrCCl3.
- Barton, Derek H. R.,Beviere, Stephane D.,Chavasiri, Warinthorn
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- Gif-type oxidation systems. Evidence for a second intermediate between saturated hydrocarbon and ketone
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The addition of dianisyl telluride to a Gif(IV) oxidation of adamantane has a marked effect on the ratio of ketone to secondary alcohol formed. This is interpreted as an indication of a second intermediate in the conversion of saturated hydrocarbvons into ketones. This second intermediate is probably an Fe(III) alkoxide.
- Barton,Csuhai,Ozbalik
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p. 2717 - 2820
(2007/10/02)
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- Functionalization of Saturated Hydrocarbons. 14. Further Studies on the Mechanism of Gif-Type Systems
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The photolysis (W light) of acyl derivatives of N-hydroxy-2-thiopyridone in pyridine-acetic acid permits a study of the partioning of secondary radicals between oxygen, pyridine, and the thione function.Comparison with the GifIV oxidation system for saturated hydrocarbons confirms that radicals are not involved in oxidation at secondary positions.On the contrary, radical behavior at the tertiary position in adamantane is again established.The two recently introduced Gif-type systems, GoAggI and GoAggII, have been shown to give the same overall selectivity in attack on adamantane with the usual coupling of the tertiary radical with pyridine.
- Barton, Derek H. R.,Halley, Frank,Ozbalik, Nubar,Schmitt, Martine,Young, Esme,Balavoine, Gilbert
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p. 7144 - 7149
(2007/10/02)
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- FUNCTIONALISATION OF SATURATED HYDROCARBONS. Part X. A COMPARATIVE STUDY OF CHEMICAL AND ELECTROCHEMICAL PROCESSES (GIF AND GIF-ORSAY SYSTEMS) IN PYRIDINE, IN ACETONE AND IN PYRIDINE-CO-SOLVENT MIXTURES
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Six saturated hydrocarbons (cyclohexane, 3-ethylpentane, methylcyclopentane, cis- and trans-decalin and adamantane) were oxidised by the Gif system (iron catalyst, oxygen, zinc, carboxylic acid) and its electrochemical equivalent (Gif-Orsay system).Results obtained using various solvents (pyridine, acetone, pyridine-acetone mixtures) were similar for both systems.Total or partial replacement of pyridine with acetone affects the selectivity for secondary positions and lowers the ketone/secondary alcohol ratio.The formation of the same ratio of cis- and trans-decal-9-ol from both cis- and trans-decalin clearly demonstrates that tertiary alcohols result from a mechanism essentially radical in nature.
- Belavoine, Gilbert,Barton, Derek H. R.,Boivin, Jean,Gref, Aurore,Coupanec, Pascale Le,et al.
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p. 1091 - 1106
(2007/10/02)
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- Direct Conversion of Saturated Hydrocarbons into Phenylseleno Derivatives
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Diphenyl diselenide is an efficient trap for the carbon-iron ?-bonds postulated as intermediates in the Gif system for the substitution of saturated hydrocarbons selectively at secondary positions.
- Barton, Derek H. R.,Boivin, Jean,Le Coupanec, Pascale
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p. 1379 - 1381
(2007/10/02)
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- PHOTOCHEMICAL GENERATION OF ALIPHATIC RADICALS FROM BENZOPHENONE OXIME ESTERS: SIMPLE SYNTHESIS OF ALKYLBENZENES AND ALKYLPYRIDINES
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Photolysis of benzophenone oxime esters, prepared with aliphatic carboxylic acids and benzophenone oxime, in benzene and pyridine generates various primary, secondary and tertiary aliphatic radicals selectively, and corresponding alkylbenzenes and alkylpyridines are produced in good yields, respectively.
- Hasebe, Masato,Tsuchiya, Takashi
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p. 3239 - 3242
(2007/10/02)
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- ON THE MECHANISM OF THE GIF SYSTEM FOR THE OXIDATION OF SATURATED HYDROCARBONS
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The high selectivity of the Gif system for hydrocarbon oxidation is shown to depend upon the capture of tert. radicals by pyridine; the mechanism for the secondary oxidation products has only a minor radical component as judged by competitive trapping.
- Barton, Derek H. R.,Boivin, Jean,Ozbalik, Nubar,Schwartzentruber, Kathy M.,Jankowski, Krzysztof
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p. 447 - 450
(2007/10/02)
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