Fluoroalkyl Iodides Research Articles

Copper-induced fluoroalkylation of porphyrins: solvent-dependent synthesis of fluoroalkyl chlorins and porphyrins from fluoroalkyl iodides

Treatment of copper(II) or nickel(II) porphyrins with fluoroalkyl iodides ( R f I ) in the presence of copper powder in dioxane, diglyme(DG) or tetrahydrofuran ( THF ) at 70-90°C gave β-fluoroalkyl chlorins in moderate yields. Unexpectedly, when dimethylsulphoxide ( DMSO ), hexamethylphosphoric triamide ( HMPA ) or N , N -dimethylformamide ( DMF ) was used as the solvent, with chlorobenzene as a co-solvent, the β-fluoroalkylporphyrins were obtained. In the first three solvents the reaction can be completely suppressed by p-dinitrobenzene (p- DNB ) or hydroquione ( HQ ), but not at all in the last three solvents. Apparently, a single electron-transfer mechanism may be involved in the formation of β-fluoroalkyl chlorins while fluoroalkylcopper intermediates may play a role in the production of β-fluoroalkylporphyrins. The metallofluoroalkylchlorins can be converted quantitatively to 2-hydoxyl-3-fluoroalkylchlorins by air/ SiO 2 or air/ Al 2 O 3. Additionally, the metallofluoroalkylchlorins and metallofluoroalkylporphyrins can be converted into the corresponding free-base chlorins and porphyrins, respectively, with H 2 SO 4. On the other hand, the metallohydoxyfluoroalkylchlorins under the same conditions afforded β-fluoroalkylporphyrins. Metallohydroxyfluoroalkylchlorins were readily also etherified to the corresponding metallomethoxyfluoroalkylchlorins with dimethyl sulfate ( Me 2 SO 4).

A convenient synthesis of fluoroalkylated γ-butyrolactones from polyfluoroalkyl iodides and 4-pentenoic acid catalyzed by Pd(PPh 3) 4

A convenient synthesis of fluoroalkylated γ-butyrolactones was realized through the reaction of fluoroalkyl iodides with 4-pentenoic acid in the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium and sequential treatment with triethylamine in 79–85% yields.

含フッ素ラジカルの創出と合成反応への展開

Free radical reactions leading to carbon-carbon bond formation have emerged as a powerful tool in organic synthesis. We have been investigating the fluoroalkylation of organic molecules using radical species. The main subjects in our study are how to generate fluorinated alkyl radicals, and how to control the radical reaction. The photochemical reaction of fluoroalkyl iodide with ditin was found to be a good method for the generation of fluorinated radicals, and the generated fluorinated radicals could be effectively introduced into olefinic compounds. By the use of this method, efficient synthesis of fullerene dimers containing a fluoroalkyl group and oxygenative fluoroalkylation of styrenes were accomplished. One-electron reduction of fluorinated alkyl halides using SmI2 or Na2S2O4 was also investigated. Simultaneous introduction of fluorinated radical with other radical species such as oxygen, or fluorinated radical with electrophiles into olefinic compounds could be performed by using fluorinated alkyl halides with one-electron reducing reagent.

Does alpha-fluorination affect the structural trans-influence and kinetic trans-effect of an alkyl ligand? Molecular structures of Pd(TMEDA)(CH(3))(R(F)) and a kinetic study of the trans to cis isomerization of Pt(TMEDA)(CH(3))(2)I(R(F)) [R(F) = CF(2)CF(3), CFHCF(3), CH(2)CF(3)

Reaction of Pd(TMEDA)(CH(3))(2) [TMEDA = tetramethylethylenediamine] with fluoroalkyl iodides R(F)I affords a series of square planar Pd(II) complexes Pd(TMEDA)(CH(3))(R(F)) [R(F) = CF(2)CF(3) (9), CFHCF(3) (10), CH(2)CF(3) (11)], presumably by oxidative addition followed by reductive elimination of CH(3)I. The solid-state structures of each compound have been determined by single crystal X-ray diffraction studies, allowing the effect of increasing alpha-fluorination on the structural trans-influence of alkyl ligands to be examined. In these compounds there is no significant difference observed in the trans-influence of the three fluorinated alkyl ligands toward the trans-N atom, although a significant cis-influence on the neighboring methyl ligand is apparent. Oxidative addition of the same series of fluoroalkyl ligands to the corresponding Pt(TMEDA)(CH(3))(2) affords octahedral Pt(IV) complexes trans-Pt(TMEDA)(CH(3))(2)(R(F))I [R(F) = CF(2)CF(3) (12), CFHCF(3) (13), CH(2)CF(3) (14)] as the kinetic products. In each case, subsequent isomerization to the corresponding all cis-isomers is observed; in the case of 13, the stereocenter at the alpha-carbon results in two diastereomeric cis-isomers, which are formed at different rates. The molecular structures of 13 and its more stable all cis-isomer 16b have been crystallographically determined. Kinetic studies of the trans-cis isomerization reactions show the mechanism to involve a polar transition state, presumably involving iodide dissociation, followed by rearrangement of the cation, and iodide recombination. High dielectric solvents increase the rate, but solvent coordinating ability has no effect. Dissolved salts (LiI, LiOTf) show normal accelerative salt effects, with no inhibition in the case of added iodide, consistent with the formation of an intimate ion pair intermediate. The kinetic parameters show that the trans-effects of fluoroalkyl ligands in these compounds follow the order expected from the relative sigma-donor properties of the ligands, with CF(2)CF(3) < CFHCF(3) < CH(2)CF(3).

The Transition State for Surface-Catalyzed Dehalogenation: C–I Cleavage on Pd(111)

Substituent effects have been used as a means of probing the nature of the transition state for C–I bond cleavage on the Pd(111) surface. The barriers to C–I cleavage (ΔE‡C–I) have been measured in a set of 10 different alkyl and fluoroalkyl iodides (CH3I, CF3I, CH3CH2I, CF3CH2I, CF2HCF2I, CH3CH2CH2I, CF3CH2CH2I, CF3CF2CH2I, (CH3)2CHI, and (CH3)3CI) on Pd(111). These measurements were performed by adsorbing the iodides on the Pd(111) surface at low temperature (90 K) and then heating to 250 K to induce dissociation (R–I(ad)→R(ad)+I(ad)). X-ray photoemission of the I 3d5/2 level was used to monitor the extent of reaction during heating. To influence ΔE‡C–I the different alkyl and fluoroalkyl groups were chosen to give a wide range of field effect (σF) substituent constants. By correlating ΔE‡C–I with the field effect through a linear free energy relationship (ΔΔE‡C–I=ρF·σF) it has been possible to compare the activation of C–I bonds on the Pd(111) surface with other dehalogenation reactions (C–Cl cleavage on Pd(111) and C–I cleavage on Ag(111)). In all cases the reaction constants (ρF) are very small. For C–I cleavage on the Pd(111) surface ρF=0. These results indicate that the transition state to C–I cleavage is homolytic in the sense that it occurs early in the reaction coordinate and the reaction center in the transition state [C…I]‡ is not much different from the initial state reactant. This result appears to be generally true of metal catalyzed dehalogenation reactions.

The Transition State for Metal-Catalyzed Dehalogenation: C−I Bond Cleavage on Ag(111)

The kinetics of C−I bond cleavage on the Ag(111) surface have been measured in a set of 10 alkyl and fluoroalkyl iodides. All the iodides adsorb molecularly on the Ag(111) surface at low temperatures and then dissociate during heating at temperatures below 200 K. X-ray photoemission spectroscopy was used to monitor the rate of C−I cleavage during heating. Estimation of the barrier to C−I cleavage (ΔE⧧C-I) indicates that it is sensitive to the nature of the alkyl or fluoroalkyl substituent groups bonded to the α-carbon atom. The barriers can be correlated to the field and polarizability substituent constants (σF and σα) of the alkyl groups and reveal that the reaction constants for C−I cleavage are quite low (ρF = −17 ± 1 kJ/mol and ρα = −11 ± 2 kJ/mol ). This suggests that the transition state for C−I cleavage is slightly anionic with respect to the adsorbed iodide (RC−I → [RCδ-···I]⧧) or, in other words, that the electron density on the carbon atom of the C−I bond is slightly greater in the transition state than in the reactant iodide. The magnitudes of the reaction constants, however, are relatively low. The implication is that the transition state to C−I cleavage is fairly homolytic in the sense that it occurs early in the reaction coordinate and is like the initial state iodide.

Synthesis of Poly- and the First Perfluoroalkyl-N(SO2F)2Derivatives: Improved Methods for the Preparation of XN(SO2F)2(X = H, Cl) and Single-Crystal Diffraction Studies of HN(SO2Cl)2, HN(SO2F)2, and CF3CH2N(SO2F)2

The preparation of HN(SO2F)2 was achieved conveniently by fluorination of HN(SO2Cl)2 with SbF3. Reactions of Hg[N(SO2F)2]2 with fluoroalkyl iodides RI (R = i-C3F7CH2CH2 and CF3CH2) gave i-C3F7CH2CH2N(SO2F)2 (1) and CF3CH2N(SO2F)2 (2). The chlorination of Hg[N(SO2F)2]2 provided a high-yield method of synthesizing the well-known ClN(SO2F)2. N-alkylation of ClN(SO2F)2 with fluorinated ethenes CF2CHal2 (CHal2 = CF2, CFCl, and CCl2) resulted in the formation of CF2ClCF2N(SO2F)2 (3), CF2ClCFClN(SO2F)2 (4a, major), CFCl2CF2N(SO2F)2 (4b, minor), and CCl3CF2N(SO2F)2 (5). The synthesis of the first perfluoroalkyl-N(SO2F)2 derivatives CF3N(SO2F)2 (6), C2F5N(SO2F)2 (7), n-C3F7N(SO2F)2 (8), and n-C4F9N(SO2F)2 (9) was accomplished with moderate-to-good yields by reacting ClN(SO2F)2 with iodoperfluoroalkanes RFI (RF = CF3, C2F5, n-C3F7, and n-C4F9). Similarly, ClN(SO2F)2 reacted with CF3CH2I to give 2. Photolysis of ClN(SO2F)2 with iodoperfluoroalkanes RFI (RF = n-C3F7, and n-C4F9) gave 8 and 9 in low yields. HN(SO2F)2 ...

Na 2S 2O4/NaHCO3-system promoted addition-cyclization of per( poly)fluoroalkyl iodides or perhaloalkanes with 1,6-heptadienes

An efficient and practical synthetic method for the preparation of five-membered ring compounds is reported. Carbocyclic and heterocyclic five-membered ring compounds bearing polyfluoroalkyl groups were obtained using Na 2S 2O4/NaHCO 3 promoted addition-cyclization of per(poly)fluoroalkyl iodides or perhaloalkanes with 1,6-heptadienes. The stereochemistry of hydrodehalogenation products ( 5, 6, 8, 9) was determined based on their 1H-NMR spectra. γ-Lactams and γ-lactones bearing fluoroalkyl groups were obtained using the same system promoted per(poly)fluoroalkylation reaction with N-allyl acrylamides ( 10) and allyl propiolate ( 15) under similar reaction conditions.

A facile synthesis of per(poly)fluoroalkyl substituted α‐amino acid derivatives

AbstractInitiated by CrCl3/Fe redox couple, per(poly)fluoroalkyl iodides added to methyl α‐acetylamino acrylate, giving β‐per(poly)fluoroalkyl α‐amino acid derivatives in good yields.

Pentafluoro-λ 6-sulfanyl (SF 5) fluoroalkyl iodides

Fluoroalkyl iodides are an important class of compounds used in the preparation of large numbers of fluoro-organo and fluoro-organometallic derivatives. We report the synthesis of several SF 5-containing fluoroalkyl iodides derived from an improved synthesis of SF 5CF 2CF 2I. They are: SF 5CF 2CF 2CH 2CH 2I, SF 5CF 2CF 2CF 2CF 2I, SF 5CF 2CF 2(CH 2CH 2) 2I, SF 5CF 2CF 2CH=CHI/isomer and SF 5CF 2CF 2CHFCF 2I/isomer. In addition, the higher homologs SF 5(CF 2) 6I, SF 5CF 2CF 2(CHFCF 2) 2I/isomer and SF 5CF 2CF 2(CH 2CH 2) 3I have been identified.

Ancillary Ligand-Controlled Selectivity for Metal or Cyclopentadienyl Ring Fluoroalkylation in Reactions of Fluoroalkyl Iodides with Cyclopentadienylrhodium Complexes

Reactions of [Rh(η5-C5H5)(CO)2] with isomeric primary and secondary fluoroalkyl iodides proceed by selective fluoroalkylation at the metal center to give [Rh(η5-C5H5)(CO)(RF)I], and treatment of these compounds with excess PMe3 affords cationic fluoroalkyl complexes [Rh(η5-C5H5)(PMe3)2(RF)]+I-. In contrast, reactions of [Rh(η5-C5H5)(PMe3)2] with the same fluoroalkyl iodides proceed with completely different selectivity to afford ring-exo-fluoroalkylated products [Rh(η4-C5H5RF)(PMe3)2I], which, in turn, react with Ag+BF4- to give the cationic hydrido complexes [Rh(η5-C5H4RF)(PMe3)2H]+[BF4]-.

Fluorination of diamond — C 4F 9I and CF 3I photochemistry on diamond (100)

The radiation-induced decomposition of C 4F 9I and CF 3I overlayers at 119 K on diamond (100) surfaces has been shown to be an efficient route to fluorination of the diamond surface. X-ray photoelectron spectroscopy has been used for photoactivation as well as for studying the photodecomposition of the fluoroalkyl iodide molecules, the attachment of the photofragments to the diamond surface, and the thermal decomposition of the fluoroalkyl ligands. Measured chemical shifts agree well with ab initio calculations of both C 1s and F 1s binding energies. It is found that chemisorbed CF 3 groups on diamond (100) decompose by 300 K whereas C 4F 9 groups decompose over the range 300 to ∼ 700 K and this reactivity difference is rationalized on steric grounds. Both of these thermal decomposition processes produce surface CF bonds on the diamond. The surface CF species thermally decompose over a wide temperature range extending up to 1500 K. Hydrogen passivation of the diamond surface is ineffective in preventing free radical attack from the photodissociated products of the fluoroalkyl iodides; I atoms produced photolytically abstract H from surface CH bonds to yield hydrogen iodide at 119 K allowing diamond fluorination. The attachment of chemisorbed F species to the diamond (100) surface causes band bending as the surface states are occupied as a result of chemisorption. This results in a shift to higher binding energy of the diamond-related C 1s levels present in the surface and subsurface regions which are sampled by XPS on the diamond. The use of photoactivation of fluoroalkyl iodides for the fluorination of diamond surfaces provides a convenient route compared to other methods involving the action of atomic F, molecular F 2, XeF 2 and F-containing plasmas.

The Synthesis of Phosphonate Ester Containing Fluorinated Vinyl Ethers.

Three novel perfluorovinyl ethers containing phosphonate ester groups, diethyl 1,1,2,2,3,3,5,6,6-nonafluoro-4-oxa-5-hexenylphosphonate, (EtO)(2)P(O)(CF(2))(3)OCF=CF(2) (1), diethyl 1,1,2,2,4,5,5-heptafluoro-3-oxa-4-pentenylphosphonate, (EtO)(2)P(O)(CF(2))(2)OCF=CF(2) (2), and diethyl 1,1,2,2,4,5,5,7,8,8-decafluoro-4-trifluoromethyl-3,6-dioxa-7-octenylphosphonate, CF(2)=CFOCF(2)CF(CF(3))O(CF(2))(2)P(O)(OEt)(2) (3), have been synthesized. Perfluorovinyl ethers 1 and 2 were synthesized from methyl 4-trifluoroethenoxy-2,2,3,3,4,4-hexafluorobutanoate and methyl 3-trifluoroethenoxy-2,2,3,3-tetrafluoropropanoate, respectively, while perfluorovinyl ether 3 was synthesized either from 5-trifluoroethenoxy-4-trifluoromethyl-3-oxa-1,1,2,2,4,5,5-heptafluoropentylsulfonyl fluoride or methyl 6-trifluoroethenoxy-5-trifluoromethyl-4-oxa-2,2,3,3,5,6,6-heptafluorohexanoate. The carboxylate esters were converted to the corresponding fluoroalkyl iodides via a free-radical iododecarboxylation. The sulfonyl fluoride was converted to its corresponding fluoroalkyl iodide via iododesulfination. The intermediate iodides were found to be useful precursors for the incorporation of the phosphonic ester groups via a photoreaction with tetraethyl pyrophosphite to produce diethyl fluorophosphonites. The diethyl fluorophosphonites were oxidized to the desired phosphonates, 1, 2, and 3, utilizing hydrogen peroxide as the oxidant. Moderate to good overall yields of perfluorovinyl ethers 1-3 have been achieved.

NiCl 2/Al-promoted addition of per(poly)fluoroalkyl iodides to per(poly)fluoralkyl-substituted ethenes

In the presence of NiCl 2 · 6H 2O/Al the addition of per(poly)fluoroalkyl iodides to per(poly)fluoroalkyl-substituted ethenes proceeds smoothly, giving the corresponding addition-elimination products in moderate yield.

Selective Solubility of Organometallic Complexes in Saturated Fluorocarbons. Synthesis of Cyclopentadienyl Ligands with Fluorinated Ponytails

Cyclopentadienes bearing varying length fluorinated “ponytails”, C5H5[(CH2)n(CF2)mF] ([n.m] = [0.8], [0.10], [0.12], [2.6], [2.8], and [2,10]) have been prepared by reaction of the corresponding fluoroalkyl iodides and triphenylphosphine with nickelocene. From these, the 1,1‘-bis[2.6]-, 1,1‘-bis[2.8]-, and 1,1‘-bis[2.10]-disubstituted ferrocenes and [2.10]-substituted [Mn(CO)3L], [Re(CO)3L], and [Co(CO)2L] derivatives (L = η5-C5H4[2.10]) were prepared. Although the anions of the [0.m] compounds were thermally unstable, the corresponding [0.8], [0.10], and [0.12] cobalt dicarbonyl complexes were prepared directly from the cyclopentadienes. The solubilities of these compounds in both saturated fluorocarbon (fluorous) and conventional solvents was found to depend strongly on the length of the fluoroalkyl tail and on the temperature. These compounds all dissolve in fluorous solvents, and the 1,1‘-bis[2.10]ferrocene partitions selectively into the fluorous layer of a biphasic perfluoro(methylcyclohexane)/toluene system. The oxidation potentials of the 1,1‘-, bis[2.6]-, and 1,1‘-bis[2.10]ferrocenes are only very slightly more positive than ferrocene itself, demonstrating that the C2H4 spacer effectively insulates the electron-withdrawing effect of the fluoroalkyl part of the ponytail from the metal. A similar insulating effect is noted in the carbonyl stretching frequencies of [Mn(CO)3L], [Re(CO)3L], and [Co(CO)2L] derivatives (L = η5-C5H4[2.10]), which are slightly to low energy of those in the corresponding parent cyclopentadienyl analogues. In contrast, the corresponding frequencies in [Co(CO)2L] derivatives (L = η5-C5H4[0.10]; η5-C5H4[0.12]) without the hydrocarbon spacer group are at higher energy than the parent compound.

.beta.-Fluoride Elimination Reactions of Fluorinated Alkyl Groups on the Ag(111) Surface

The surface chemistry of CF 3 CH 2 (ad) and CF 3 CF 2 CH 2 (ad) on the Ag(111) surface was studied by temperature-programmed-reaction (TPR) measurements. These species, which are generated on the surface by thermal dissociation of the C-I bond in the corresponding fluoroalkyl iodides, undergo β-fluoride elimination to give the corresponding fluoroalkenes and adsorbed fluorine. Kinetic parameters obtained from variable heating rate TPR studies show that while the pre-exponential factors for the β-fluoride elimination reaction in CF 3 CH 2 (ad) and CF 3 CF 2 CH 2 (ad) are the same, i.e., 10 14.7±0.8 s -1 , the activation energies are considerably different, i.e., 18.1 ± 0.9 and 13.9 ± 0.7 kcal/mol, respectively. Utilizing the fact that F has a greater electron-withdrawing inductive effect than CF 3 , we conclude that the charge separation in the transition state is of the form C δ+ ...F δ- . The adsorbed F generated by the β-fluoride elimination reaction desorbs as AgF at ∼850 K. Unlike adsorbed alkyl groups, which couple to produce alkanes, the hydrofluoroalkyl groups studied here react by the β-fluoride elimination pathway, probably due to the increase in the barrier to coupling caused by fluorination at the β-carbon.

ChemInform Abstract: Addition‐Cyclization of a Diallylmalonic Acid Ester and Related Compounds with Per(poly)fluoroalkyl Iodides Using a Trichlorolanthanide (LnCl3(cat.))/Zn System.

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Synthèse de télomères fluorés. Partie IL Télomérisation du trifluoroéthylène avec des iodures de perfluoroalkyle

The synthesis of highly fluorinated telomers by thermal telomerization of trifluoroethylene with branched (i-C 3F 7I, C 5F 11CFICF 3) or linear (C 4F 9I, C 4F 9CH 2CF 2I) fluoroalkyl iodides is presented. All these telomerizations led to the first three telomeric adducts with high R FI conversion. Interestingly, the monoadduct was composed of two isomers R F CF 2CFHI ( 1) and R FCFHCF 2I ( 2),the ratio of which depends upon the electrophilicity of the radical R F·. The more electrophilic this radical,the higher the amount of isomer 2, according to a mecha that responds to both the polar and the mesomeric effects for growing radicals.

Direct synthesis of per(poly)fluoroalkylmethyl‐substituted electrophilic cyclopropane derivatives

AbstractA convenient and direct per(poly)fluoroalkylmethyl‐introducing cyclopropanation reaction was described. In the presence of CrCl3/Fe, per(poly)fluoroalkyl iodides reacted with diethyl allylmalonate and its analogs to give per(poly)fluoroalkymethyl‐substituted electrophilic cyclopropane derivatives in high yields. This reaction was considered to proceed by two steps: radical addition followed by cyclopropanation.

Addition–cyclization of a diallylmalonic acid ester and related compounds with per(poly)fluoroalkyl iodides using a trichlorolanthanide [LnCl3(cat.)]/Zn system

A free-radical addition–cyclization of hepta-1,6-diene with per(poly)fluoroalkyl iodides initiated by LnCl3(cat.)/Zn yields per(poly)fluoroalkyl-substituted cyclopentanes, cis-disubstituted compounds predominating.