Condensation of perfluoroalkyl iodides with unsaturated nitrogen compounds

Cantacuzène, D.; Wakselman, Claude; Dorme, Régine

doi:10.1039/p19770001365

Cited by 97 publications

(29 citation statements)

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“…Replacement of CFCs and halons led to an increased commercial production of trifluoromethyl iodide, in particular for application as a fire extinguishing agent, etching gas, coolant, and trifluoromethylating agent. In early works, trifluoromethyl iodide was exploited, for example, in the photochemical trifluoromethylation of steroids [121][122][123] and in the photochemical reaction with enamines to produce a-trifluoromethyl ketones [124,125].…”

Section: Trifluoromethyl Iodidementioning

confidence: 99%

Strategies for nucleophilic, electrophilic, and radical trifluoromethylations

Ma¹,

Cahard²

2007

Journal of Fluorine Chemistry

534

177

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Section: Trifluoromethyl Iodidementioning

confidence: 99%

Strategies for nucleophilic, electrophilic, and radical trifluoromethylations

Ma¹,

Cahard²

2007

Journal of Fluorine Chemistry

534

177

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“…It was of interest to elucidate whether this system is capable of activating the fluoroalkylation of nitrogen-containing nucleophiles, in particular, pyrrole. The introduction of fluoroalkyl groups into pyrrole is usually accomplished by employing iodoperfluoroalkanes and proceeds at C-2 or C-4 in the ring [26]. We were unable to find any reports concerning the fluoroalkylation of pyrrole by Freons BrCF 2 CF 2 Br or CF 2 ClCFCl 2 .…”

mentioning

confidence: 78%

Homogeneous catalytic fluoroalkylation of thiophenols, phenols and pyrrole by Freons BrCF2CF2Br and CF2ClCFCl2

2007

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The use of sulfur dioxide as an electron transfer mediator in the presence of nitrogen bases permits the rather selective fluoroalkylation of thiophenols, phenols, and pyrrole by Freons BrCF 2 CF 2 Br and CF 2 ClCFCl 2 under mild conditions. In the case of thiophenols, the fluoroalkylation occurs to give polyfluoroalkyl aryl sulfides, while phenols and pyrrole are alkylated in the ring. Effects were found for the electronic structure of the substrates and basicity of the medium (pK a of the pyridines) on the oxidation-reduction properties of the reagents and the efficiency of the reactions studied.The activation of Freons and the search for nontraditional methods for the use of these compounds are the subject of current research. A promising approach involves the use of Freons as sources of fluoroalkyl groups in the synthesis of various fluorine compounds [1][2][3][4][5]. Especial interest is found in Freons containing several other halogen atoms in addition to fluorine such as Freons F114B2 (BrCF 2 CF 2 Br), F113 (CF 2 ClCFCl 2 ), and F113B2 (BrCF 2 CFClBr), which permits not only the synthesis of a series of new derivatives but also may significantly expand the synthetic possibilities in the subsequent transformation of simple fluorine-containing substituents into complex groups as demonstrated by various workers [6][7][8]. Equally significant is that Freons as fluoroalkylating agents are much less expensive than iodoperfluoroalkanes.As inert compounds, Freons do not react under ordinary conditions even with such extremely reactive organic substrates as thiophenols, phenols, and heterocyclic nitrogen derivatives as well as many other organic compounds. Potassium salts of these substrates are usually used for fluoroalkylation [9][10][11][12], as found, in particular, in the reaction of thiophenols and phenols with halogen-containing fluoroalkanes:(1) 2ArZK + 2Hal 1 (CF 2 ) n CF 2 Hal 2 ® ArZ(CF 2 ) n CF 2 Hal 2 + ArZ(CF 2 ) n CF 2 H + 2KHal 1 (Z = S, O).However, a large amount of a side-product, ArZ(CF 2 ) n CF 2 H is formed in the condensation with replacement of a halogen atom by hydrogen along with the halogen-containing product ArZ(CF 2 ) n CF 2 Hal 2 (scheme (1)). The fraction of the hydrogen-substituted product becomes predominant and the total overall product yield of fluoroalkylation products drops with increasing electron-withdrawing properties of the substituents in the aromatic thiophenolate ring.In the present work, we attempted to elucidate the feasibility of fluoroalkylation of thiophenols, phenols, and pyrrole as starting reagents, using Freons BrCF 2 CF 2 Br and CF 2 ClCFCl 2 , avoiding formation of salts of these substrates, which would 0040-5760/07/4305-0343

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“…It has been known for some time that 2-(perfluoroalkyl)pyrroles are formed in low yields upon heating of pyrroles in the presence of perfluoroalkyl iodides under forcing conditions [433]. Application of the H 2 O 2 /Fe(II) protocol offers a practical procedure for the preparation of, for example, the perfluoroalkylpyrroles 286 from pyrrole-2-carboxaldehyde (191) and perfluoroalkyl iodides via a homolytic substitution process (Scheme 4.82) [434].…”

Section: Reactions With Radical Reagentsmentioning

confidence: 99%