Fluoroalkyl Iodides Research Articles

Palladium-Initiated Radical Cascade Stereoselective Iodofluoroalkylation/Cycloisomerization of Ene-vinylidenecyclopropanes.

A novel and convenient palladium-initiated radical cascade stereoselective iodofluoroalkylation/cycloisomerization of ene-vinylidenecyclopropanes with fluoroalkyl iodides has been developed. The reaction proceeds under mild reaction conditions with high atom economy and stereoselectivity, thereby allowing an efficient access to a variety of difluoromethylated or perfluoroalkylated pyrrolidines tethered with an alkyl iodide. Two plausible radical pathways for the transformation have been proposed on the basis of the results of control experiments and previous reports, which in one case it was thought that palladium(0) was an initiator rather than a catalyst.

Fluorinated pyridinium and ammonium cationic surfactants

Abstract New classes of partially fluorinated cationic surfactants, including pyridinium sulfonates and ammonium hydrochlorides have been prepared in which a fluoroalkyl chain is interrupted either by ether oxygen ( O ), or by methylene ( CH2 ) units. These surfactants are obtained from multi-step syntheses via intermediate fluoroalkyl ethylene iodides (RfO(CF2CF2)nCH2CH2I, Rf = C3F7, C2F5, n = 1–3 or Rf(CH2CF2)m(CH2CH2)n, Rf = C4F9, C6F13m = 0–2, n = 1–2) or fluoroalkyl iodides (RfI, Rf = C3F7O(CF2CF2)3I, C6F13). The surface activities of these fluorinated cationic surfactants were examined and compared to commercially available fluorinated cationic surfactants used as additives in oil field applications. Some examples demonstrated good performance relative to controls yet are more fluorine efficient because they have lower fluorine content than their perfluoroalkyl analogues. For the ammonium hydrochlorides, the effect of different spacer groups between the cation and the fluorinated chain including ethylene, butylene and isopropylidene on surface activity was also examined.

Unique properties for self-assembly of head-to-head type 4,4⿲-dihydroxystyrene dimers bearing two fluoroalkyl end-groups

Abstract We have been investigating the synthesis of head-to-head type styrene dimers bearing two fluoroalkyl end-groups by reactions of styrenes with fluoroalkyl iodides under radical conditions. Among the various substituted styrene dimers, 4-hydroxylated styrene dimers ( 2 ) were found to exhibit unique properties owing to their self-assembly. Especially, racemic - 2 worked as host molecules for inclusion of alcohols on the recrystallization from hexane with small amount of alcohol. The racemic dimer was recrystallized from hexane with small amount of alcohol such as ethanol and 2-propanol, and the obtained crystals were dried under vacuum for three days. However, the alcohols were not removed from the crystals as observed in 1 H NMR, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Though the dimers have meso and racemic forms, only racemic form showed such a property as the host molecule.

Tetrachloromethane addition to norbornene catalyzed by lanthanide(III) compounds

Tetrachloromethane addition to olefi ns, a particular case of telomerization, is one among the methods of carbon-carbon bonds formation. Effi cient catalysts for CCl4 addition to olefi ns are complexes of transition metals of VI–VIII groups [1]. Examples of lanthanide compounds application as telomerization catalysts are rare. The addition of fluoroalkyl iodides and polyhalomethanes to olefi ns catalyzed by samarium(II) iodide was described in [2, 3]. Aiming at extension of the range of catalysts promoting the telomerization reaction we report here on the study of catalytic activity in telomerization of lanthanide complexes (complexes of praseodymium, neodymium, samarium, europium, gadolinium, terbium, and dysprosium) by an example of CCl4 addition to norbornene. In the presence of Pr(acac)3(H2O) 2 [Pr(acac)3(H2O) 2– (I)–CCl4, 0.03 : 1 : 1] at 140°С within 6 h CCl4 stereoselectively added to norbornene (I) leading to the formation of exo-2-(trichloromethyl)-endo-3chloro-bicyclo[2.2.1]heptane (II) in 26% yield. The addition of methanol [Pr(acac)3(H2O) 2–(I)–CCl4– CH3OH, 0.03 : 1 : 1 : 1] results in higher norbornene (I) conversion (up to 60%), but the presence of methanol has a negative consequence: a mixture of two isomers, exo-2-(trichloromethyl)-endo-3-chlorobicyclo[2.2.1]heptane (II) and exo-2-(trichloromethyl)exo-3-chlorobicyclo[2.2.1]heptane (III) forms in a ratio 6 : 1. Further research made it possible to optimize the ratios of reagents and the catalyst and also the reaction conditions. The increase in CCl4 concentration to 4 mmol [Pr(acac)3(H2O)2–(I)–CCl4, 0.03 : 1 : 4] favors the increase in the norbornene (I) conversion to 45%, at adding methanol [Pr(acac)3(H2O)2–(I)–CCl4–MeOH, 0.03 : 1 : 4 : 3, 140°С, 5 h] the yield of the adducts II, III mixture, 6 : 1, grows up to 90%. Yields of compounds II, III depend on temperature and are maximum (90%) at 140°С, at 130°С the yield is 60%, and at 100°С and below the reaction does not proceed. In the preceding study [4] we established that the reason of the activating effect of alcohol on the reaction between CCl4 and olefi ns was the formation of alkyl hypochlorites by reaction of alcohol with tetrachloromethane under the action of the catalyst. CH3OCl also formed in the presence of lanthanide complexes. In the reaction

ChemInform Abstract: Microwave‐Assisted Expeditious Synthesis of 5‐Fluoroalkyl‐3‐(aryl/alkyl)‐oxazolidin‐2‐ones.

An efficient and convenient protocol for synthesis of 5-fluoroalkyl-3-(aryl/alkyl)-oxazolidin-2-ones is described. The reaction of allyl (aryl/alkyl) carbamates with fluoroalkyl iodide initiated by sodium dithionite in aqueous acetonitrile resulted in adducts that undergoes a cyclization assisted by microwave irradiation to form 5-fluoroalkyl-3-(aryl/alkyl)-oxazolidin-2-ones with high yields. It was also found that the products can be more efficiently formed via an AIBN-initiated one-pot addition–cyclization sequence from benzyl allyl(aryl/alkyl) carbamates and fluoroalkyl iodide.

Microwave-assisted expeditious synthesis of 5-fluoroalkyl-3-(aryl/alkyl)-oxazolidin-2-ones

An efficient and convenient protocol for synthesis of 5-fluoroalkyl-3-(aryl/alkyl)-oxazolidin-2-ones is described. The reaction of allyl (aryl/alkyl) carbamates with fluoroalkyl iodide initiated by sodium dithionite in aqueous acetonitrile resulted in adducts that undergoes a cyclization assisted by microwave irradiation to form 5-fluoroalkyl-3-(aryl/alkyl)-oxazolidin-2-ones with high yields. It was also found that the products can be more efficiently formed via an AIBN-initiated one-pot addition–cyclization sequence from benzyl allyl(aryl/alkyl) carbamates and fluoroalkyl iodide.

ChemInform Abstract: Copper‐Mediated Aerobic Fluoroalkylation of Arylboronic Acids with Fluoroalkyl Iodides at Room Temperature.

AbstractUnder optimized conditions using a stoichiometric amount of copper powder (Cu foil is equally effective), polyfluoroalkyl iodides are coupled with a variety of arylboronic acids in the absence of a ligand.

Copper-Mediated Aerobic Fluoroalkylation of Arylboronic Acids with Fluoroalkyl Iodides at Room Temperature

A Cu-mediated ligandless aerobic fluoroalkylation of arylboronic acids under mild conditions is described for the first time. The reaction tolerates a wide range of functional groups, allowing for further transformation. Mechanistic studies suggest that [R(f)Cu] is the active Cu species that forms the desired perfluoroalkylarenes and that [R(f)Cu] is generated from [PhCu] by either an oxidative addition/reductive elimination mechanism or nucleophilic substitution via a halogen "ate" intermediate.

Fluorinated sulfonate surfactants

New classes of fluorinated sulfonate surfactants were synthesized in which a perfluoroalkyl chain is interrupted either by an ether oxygen (–O–), or by methylene (–CH 2–) units. Both classes of molecules involve multi-step syntheses. The fluoroether sulfonates (RfOCF 2CF 2CH 2CH 2SO 3H, Rf = C 2F 5, C 3F 7) were achieved in four steps including fluoroiodonation of perfluorovinyl ethers (RfCF = CF 2), ethylation, chlorination and hydrolysis. The methylene interrupted fluorosulfonates (RfCH 2CF 2CH 2CH 2SO 3H, Rf = C 4F 9, C 6F 13) were also prepared in four steps involving vinylidene fluoride insertion of fluoroalkyl iodides, ethylene insertion, chlorination and hydrolysis. All intermediates and final products were well characterized by 1H and 19F NMR. These new fluorinated surfactants were compared to a commercially available fluorosulfonate (C 6F 13CH 2CH 2SO 3H) for surface activity. These materials match the surface tensions of commercial fluorosurfactant yet are more efficient because they have lower fluorine content.

One-Pot Addition-Intramolecular N-Cyclization of Carbamates Mediated by Alkali Metallic Reagents as an Approach to 4-(Fluoroalkyl)oxazolidin-2-ones

A mild and straightforward strategy for the synthesis of 4-(fluoroalkyl)oxazolidin-2-ones via one-pot addition-intramolecular N-cyclization of allyl carbamates with fluoroalkyl iodides is presented. The reaction proceeded in moderate to good yield through regiocontrol and an increase in the reactivity of the ambident nucleophiles by the use of alkali metallic reagents.

ChemInform Abstract: Sodium Dithionite Initiated Addition—Lactonization of 2‐Acylamino‐4‐pentenoic Acids with Fluoroalkyl Iodides to Synthesize 4‐Fluoroalkyl‐2‐acylamino‐4‐butyrolactones.

AbstractOptimum reaction conditions are studied.

Sodium dithionite initiated reaction of pent-4-en-1-amines with fluoroalkyl iodides for the synthesis of 2-fluoroalkyl pyrrolidine derivatives

Pent-4-en-1-amines are reactive to fluoroalkyl iodides with respect to sodium dithionite initiated free radical addition reactions. We report here the development of a novel and efficient synthesis of 2-fluoroalkyl pyrrolidine derivatives by sodium dithionite initiated one-pot reaction of pent-4-en-1-amines bearing various protecting groups with fluoroalkyl iodides. Among which, the N-benzyl-pent-4-en-1-amine exhibited the best tolerance toward the reaction condition in the present study, affording the desired adducts 3 in moderate to good yields of 65–85%.

Sodium Dithionite Initiated Addition‐lactonization of 2‐Acyl‐ amino‐4‐pentenoic Acids with Fluoroalkyl Iodides to Synthesize 4‐Fluoroalkyl‐2‐acylamino‐4‐butyrolactones

Abstract4‐Fluoroalkyl‐2‐acylamino‐4‐butyrolactones were afforded in moderate yields by the sodium dithionite initiated one‐pot addition‐lactonization reaction of polyfluoroalkyl iodides with 2‐acylamino‐4‐pentenoic acids.

A Novel Synthesis of SO3H Type Gemini Surfactant Having Semifluoroalkyl Group as Hydrophobic Group

In this work, novel SO(3)H type Gemini surfactants having semifluoroalkyl group (RfCH(2)CH-: Rf = C(4)F(9), C(6)F(13), C(8)F(17)) as hydrophobic group were successively synthesized by the radical addition of fluoroalkyl to 1,4-pentadiene using fluoroalkyl iodide and AIBN as initiator, and the following thiocyanization (-SCN), conversion to -SH, and oxidation to SO(3)H as hydrophilic group. Similarly, the common 1+1 type semifluoroalkyl surfactants having SO(3)H were synthesized. Surfactant properties of their sodium salts (cmc, gamma(cmc), pC(20), Gamma(cmc), and A) were investigated by measuring surface tension. As expected, the cmc value of Gemini surfactant whose fluoroalkyl is C(4)F(9) was more than one order of magnitude smaller than that of the corresponding 1+1 type. Other properties also showed the excellent efficiency of Gemini structure to reduce the surface tension.

Transition State for Alkyl Group Hydrogenation on Pt(111)

Substituent effects have been used to probe the characteristics of the transition state to hydrogenation of alkyl groups on the Pt(111) surface. Eight different alkyl and fluoroalkyl groups have been formed on the Pt(111) surface by dissociative adsorption of their respective alkyl and fluoroalkyl iodides. Coadsorption of hydrogen and alkyl groups, followed by heating of the surface, results in hydrogenation of the alkyl groups to form alkanes, which then desorb into the gas phase. Temperature-programmed reaction spectroscopy was used to measure the barriers to hydrogenation, DeltaE(H)(double dagger), which are dependent on the size of the alkyl group (polarizability) and the degree of fluorination (field effect). This example is one of only two surface reactions for which the influence of the substituents on DeltaE(H)(double dagger) has been correlated with both the field and the polarizability substituent constants of the alkyl groups in the form of a linear free energy relationship. Increasing both the field and the polarizability constants of the alkyl groups increases the value of DeltaE(H)(double dagger). The substituent effects are quantified by a field reaction constant of rho(F) = 27 +/- 4 kJ/mol and a polarizability reaction constant of rho(alpha) = 19 +/- 3 kJ/mol. These suggest that the transition state for hydrogenation is slightly cationic with respect to the alkyl group on the Pt(111) surface, RC + H <--> {RC(delta+)...H}(double dagger).

Unusual Fluoroalkenylation of Porphyrins: A Highly Stereoselective Synthesis of 10,20‐Diaryl‐5‐[(E)‐fluoroalkenyl]‐15‐(fluoroalkyl)porphyrins

AbstractA series of 10,20‐diaryl‐5‐[(E)‐fluoroalkenyl]‐15‐(fluoroalkyl)porphyrins has been synthesized by the reaction of free‐base 5,15‐diarylporphyrins with fluoroalkyl iodides in the presence of Na2S2O4. Subsequent intramolecular cyclization of the corresponding (fluoroalkenyl)porphyrins occurs smoothly in refluxing toluene/H2O. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2006)

Transition State for β-Hydride Elimination in Alkyl Groups on Pt(111)

The transition state for beta-hydride elimination in alkyl groups on the Pt(111) surface has been probed by studying the effects of fluorine substitution on the barriers to beta-hydride elimination, DeltaE++(betaH). Four different fluoroalkyl groups have been formed on the Pt(111) surface by dissociative adsorption of four fluoroalkyl iodides: RCH(2)CH(2)-I (R = CF(3), CF(3)CH(2), and CF(3)CF(2)) and (CF(3))(2)CHCH(2)-I. In the absence of preadsorbed hydrogen, fluoroalkyl groups on the Pt(111) surface dehydrogenate via beta-hydride elimination to form unsaturated fluorocarbons and deposit hydrogen atoms onto the surface. Those hydrogen atoms then hydrogenate the remaining fluoroalkyl groups to produce fluoroalkanes that desorb rapidly from the surface. The kinetics of hydrogenation and fluoroalkane desorption are rate limited by the beta-hydride elimination step and thus serve as measures of the kinetics of beta-hydride elimination. The field effects of the fluorinated substituents increase the barriers to beta-hydride elimination with a reaction constant of rho(F) = 19 +/- 2 kJ/mol. The interpretation of this effect is that the beta-carbon atom in the transition state is cationic, [RC(delta+...)H]++, with respect to the reactant. The field effect of the fluorinated substituent energetically destabilizes the electron deficient beta-carbon atom in the transition state. This is consistent with observations made on the Cu(111) surface; however, the substituent effect is significantly smaller on the Pt(111) surface. On the Pt(111) surface, the transition state for beta-hydride elimination is less polarized with respect to the initial state alkyl group than on the Cu(111) surface.

Fluoroalkylation of Porphyrins: Preparation and Characterization of meso‐ and β‐Fluoroalkyl‐5,15‐diarylporphyrins.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Fluoroalkylation of porphyrins: Preparation and characterization of meso- and β-fluoroalkyl-5,15-diarylporphyrins

Treatment of zinc(II) 5,15-diphenylporphyrin or free-base 5,15-diphenylporphyrin with 1.1 eq. of fluoroalkyl iodides (R fI) in the presence of 1.1 eq. Na 2S 2O 4 in a mixture solvent of DMSO/THF at 45 °C for 1–2 h gave 2-fluoroalkyl-5,15-diphenylporphyrin and 5-fluoroalkyl-10,20-diphenylporphyrin in a ratio from 1/3 to 1/8 in almost 50% total yields. The 5-fluoroalkyl-10,20-diphenylporphyrins were further fluoroalkylated to yield bis-fluoroalkylporphyrins.

A Convenient Synthesis of Fluoroalkylated γ‐Butyrolactones from Polyfluoroalkyl Iodides and 4‐Pentenoic Acid Catalyzed by Pd(PPh3)4.

AbstractFor Abstract see ChemInform Abstract in Full Text.