- One-pot route to X-perfluoroarenes (X = Br, I) based on FeIII-assisted C-F functionalization and utilization of these arenes as building blocks for crystal engineering involving halogen bonding
-
Perfluorinated arenes (benzeneF derivatives, diphenylF, naphthaleneF) were converted into X-perfluoroarenes (X = Br, I) via the developed one-pot protocol based on [Fe(acetylacetonate)3]-assisted C-F functionalization. The syntheses proceed under mild conditions and employ readily available perfluorinated arenes, which are treated with EtMgBr followed by addition of X2/[Fe(acetylacetonate)3] (0.8 mol %); yields range from good to moderate. The σ-hole donor properties of the obtained mono- and di-X-perfluoroarenes and the significance of these species for halogen-bonding-based crystal engineering was illustrated in a series of postsynthetic experiments, all supported by density functional theory (DFT) energy calculations, molecular electrostatic potential (MEP) surface analysis, and the quantum theory of atoms in molecules (QTAIM). These include (i) a solid-state X-ray diffraction study of X-perfluoroarene self-association (dimerization) via iodine σ-hole - electron belt interactions (three X-ray structures) and (ii) verification of X-perfluoroarene σ-hole donor abilities by their interactions with iodides acting as external σ-hole acceptors (five X-ray structures); a Hirshfeld surface analysis was performed for all eight structures.
- Baykov, Sergey V.,Eliseeva, Anastasiya A.,Frontera, Antonio,Galmés, Bartomeu,Kukushkin, Vadim Yu.,Rozhkov, Anton V.
-
p. 5908 - 5921
(2020/10/13)
-
- Decarboxylative Suzuki-Miyaura coupling of (hetero)aromatic carboxylic acids using iodine as the terminal oxidant
-
A novel methodology for the decarboxylative Suzuki-Miyaura-type coupling has been established. This process uses iodine or a bromine source as both the decarboxylation mediator and the terminal oxidant, thus avoiding the need for stoichiometric amounts of transition metal salts previously required. Our new protocol allows for the construction of valuable biaryl architectures through the coupling of (hetero)aromatic carboxylic acids with arylboronic acids. The scope of this decarboxylative Suzuki reaction has been greatly diversified, allowing for previously inaccessible non-ortho-substituted aromatic acids to undergo this transformation. The procedure also benefits from low catalyst loadings and the absence of stoichiometric transition metal additives.
- Quibell, Jacob M.,Duan, Guojian,Perry, Gregory J.P.,Larrosa, Igor
-
supporting information
p. 6445 - 6448
(2019/06/07)
-
- T -BuONa-mediated direct C-H halogenation of electron-deficient (hetero)arenes
-
An efficient halogenation of electron-deficient (hetero)arenes is described. The reaction utilizes common t-BuONa as a catalyst (for iodination) or a promoter (for bromination and chlorination), and perfluorobutyl iodide, CBr4 or CCl4 as the readily-available halogenating agents, respectively. The protocol features broad scope, high efficiency, mild conditions and gram scalability. An ionic pathway involving halogen bond formation and halophilic attack is proposed. The utility of the resulting iodinated heteroarenes is demonstrated in visible light-mediated Caryl-Caryl cross-coupling reaction.
- Liu, Xia,Zhao, Xin,Liang, Fushun,Ren, Baoyi
-
supporting information
p. 886 - 890
(2018/02/19)
-
- Utilising Sodium-Mediated Ferration for Regioselective Functionalisation of Fluoroarenes via C?H and C?F Bond Activations
-
Pairing iron bis(amide) Fe(HMDS)2 with Na(HMDS) to form new sodium ferrate base [(dioxane)0.5?NaFe(HMDS)3] (1) enables regioselective mono and di-ferration (via direct Fe?H exchange) of a wide range of fluoroaromatic substrates under mild reaction conditions. Trapping of several ferrated intermediates has provided key insight into how synchronised Na/Fe cooperation operates in these transformations. Furthermore, using excess 1 at 80 °C switches on a remarkable cascade process inducing the collective twofold C?H/threefold C?F bond activations, where each C?H bond is transformed to a C?Fe bond whereas each C?F bond is transformed into a C?N bond.
- Maddock, Lewis C. H.,Nixon, Tracy,Kennedy, Alan R.,Probert, Michael R.,Clegg, William,Hevia, Eva
-
supporting information
p. 187 - 191
(2017/12/07)
-
- Unexpected reactivity of cyclic perfluorinated iodanes with electrophiles
-
We have found that cyclic perfluorinated iodanes react with electrophiles (E+ = Br, Cl, F, I) to afford perfluorinated E-RF compounds. This reactivity is unexpected since cyclic perfluorinated iodanes are considered as electrophilic reagents that normally react with nucleophiles (e.g. Nu- = SR, OR) to afford Nu-RF products. The utility of this new transformation is demonstrated for a [18F]CF3CF2-containing compound which was prepared from [18F]XeF2 obtained from cyclotron produced [18F]fluoride.
- Gruber, Stefan,Ametamey, Simon M.,Schibli, Roger
-
supporting information
p. 8999 - 9002
(2018/08/21)
-
- Method for preparing halogenated (hetero) aromatic hydrocarbons
-
The invention relates to a method for preparing halogenated (hetero) aromatic hydrocarbons. The halogenated (hetero) aromatic hydrocarbons are prepared from cheap and easily available perfluorobutyl iodide, carbon tetrabromide and carbon tetrachloride as iodinated, brominated and chlorinated reagents respectively under the action of alkali catalysis (promotion). The method comprises the following steps: firstly, (hetero) aromatic hydrocarbons, a halogenated reagent and an inorganic base are placed in an organic solvent, stirred at room temperature and monitored with TLC until a substrate disappears, and the reaction is stopped; then, a reaction mixed solution is poured into water and extracted, an organic phase is dried, and the organic solvent is removed under reduced pressure; finally, silica-gel column chromatography is performed on a crude product, and a product is obtained. Purification can also be performed by recrystallization. The method has the advantages that the synthetic route is wide in substrate range, raw materials and reagents are cheap and easily available, operation is simple, conditions are mild, yield is high, energy consumption is reduced, the reaction route is safe, gram-grade preparation can be performed and the like.
- -
-
Paragraph 0041; 0042
(2018/03/24)
-
- Preparation method of pentafluoroiodobenzene
-
The invention relates to a preparation method of pentafluoroiodobenzene and belongs to the technical field of chemical industry, particularly to the field of chemical synthesis. The preparation method enables pentafluorobenzene and iodosuccinimide to react in concentrated sulfuric acid, wherein a molar ratio of the pentafluorobenzene, the iodosuccinimide and the concentrated sulfuric acid is 1:(1-1.5):(5-7.5). The pentafluoroiodobenzene prepared by using the method provided herein has high purity and yield, and the method produces little three wastes, is simple to performance and is easy to industrialize.
- -
-
Paragraph 0022; 0023; 0024; 0025; 0026; 0027
(2017/02/24)
-
- Unexpected distinction in reactivity of pentafluorobenzenesulfonyl halides toward organolithiums and organomagnesium halides
-
C6F5SO2Cl reacts with organolithiums and organomagnesium halides RM (R = Me, Bu, Ph; M = Li, MgX) to give mainly C6F5H and C6F5Cl. C6F5SO2Br and
- Bardin, Vadim V.,Maksimov, Alexander M.
-
p. 731 - 737
(2017/10/16)
-
- Transition-Metal-Free Decarboxylative Iodination: New Routes for Decarboxylative Oxidative Cross-Couplings
-
Constructing products of high synthetic value from inexpensive and abundant starting materials is of great importance. Aryl iodides are essential building blocks for the synthesis of functional molecules, and efficient methods for their synthesis from chemical feedstocks are highly sought after. Here we report a low-cost decarboxylative iodination that occurs simply from readily available benzoic acids and I2. The reaction is scalable and the scope and robustness of the reaction is thoroughly examined. Mechanistic studies suggest that this reaction does not proceed via a radical mechanism, which is in contrast to classical Hunsdiecker-type decarboxylative halogenations. In addition, DFT studies allow comparisons to be made between our procedure and current transition-metal-catalyzed decarboxylations. The utility of this procedure is demonstrated in its application to oxidative cross-couplings of aromatics via decarboxylative/C-H or double decarboxylative activations that use I2 as the terminal oxidant. This strategy allows the preparation of biaryls previously inaccessible via decarboxylative methods and holds other advantages over existing decarboxylative oxidative couplings, as stoichiometric transition metals are avoided.
- Perry, Gregory J. P.,Quibell, Jacob M.,Panigrahi, Adyasha,Larrosa, Igor
-
supporting information
p. 11527 - 11536
(2017/08/30)
-
- Selective CH Functionalization of Methane, Ethane, and Propane by a Perfluoroarene Iodine(III) Complex
-
Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic (trifluoroacetic acid) solvent. The reaction is highly selective for ester formation (>99 %). In the case of ethane, greater than 0.5 M EtTFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism. Gas up: Direct partial oxidation of methane, ethane, and propane to their respective trifluoroacetate (TFA) esters is achieved by a homogeneous hypervalent iodine(III) complex in non-superacidic solvent (HTFA). The reaction is highly selective, and for ethane, greater than 0.5 M Et=TFA can be achieved. Preliminary kinetic analysis and density functional calculations support a nonradical electrophilic CH activation and iodine alkyl functionalization mechanism.
- Konnick, Michael M.,Hashiguchi, Brian G.,Devarajan, Deepa,Boaz, Nicholas C.,Gunnoe, T. Brent,Groves, John T.,Gunsalus, Niles,Ess, Daniel H.,Periana, Roy A.
-
supporting information
p. 10490 - 10494
(2016/02/18)
-
- Interaction of the electrophilic bis(pentafluorophenyl)iodonium cation [(C6F5)2I]+ with the ambident pseudohalogenide anions [SCN]- and [CN]-
-
The iodonium pseudohalide compounds, [(C6F5) 2I][X] (X = SCN and CN) were synthesized by means of fluoride substitution in [(C6F5)2I][F] with the Lewis acidic reagents (CH3)3Si-NCS and (CH3) 3Si-CN. The isolated iodonium pseudohalides are intrinsically unstable solids. Decomposition resulted in equimolar amounts of C 6F5I and C6F5SCN or C 6F5I and C6F5CN, respectively. In case of [(C6F5)2I][SCN] single crystals could be grown from CH2Cl2. The crystal structure revealed a dimer with an eight membered ring formed by two ambident anions bridging the iodine atoms of two cations by N and S coordination. The favored dimerization of [(C6F5)2I][SCN] and [(C6F 5)2I][CN] in the gas phase is supported by ab initio computations.
- Hirschberg, Markus E.,Barthen, Peter,Frohn, Hermann-Josef,Bl?ser, Dieter,Tobey, Briac,Jansen, Georg
-
-
- Reaction of organylxenonium(II)salts, [RXe][Y], with organyl iodides, R'I, in anhydrous HF: Scope and limitation of a new synthetic approach to iodonium salts, [RR'I][Y]
-
Perfluoroalkynylxenonium salts, [RXe][BF4] (R = CF 3C≡C, (CF3)22CFC≡C), reacted with organyl iodides, R'I (R' = 3-FC6H4, C6F 5, CF2 ≡CF, CF3CH2; no reaction with R' = CF3CF2CF2)in anhydrous HF to yield the corresponding asymmetric polyfluorinated iodonium salts, [RR'I][Y]. The action of the arylxenonium salt, [C6F5Xe]-[BF4], and the cycloalkenylxenonium salt, [cyclo-1,4-C6F7Xe]-[AsF6], on 4-FC6H4I gave [C6F5(4-FC 6H4)I][BF4] and [cyclo-1,4-C 6F7(4-FC6H4)I][AsF6], respectively, besides the symmetric iodonium salt, [(4-FC6H4)2 2I][Y]. But the aryl-, as well as the cycloalkenylxenonium salt, did not react with C6F5I, CF2 =CFI, and CF 3CH2I.
- Frohn, Hermann-Josef,Bardin, Vadim V.
-
experimental part
p. 2616 - 2620
(2012/05/31)
-
- Superelectrophilic iodination of deactivated arenes with triiodoisocyanuric acid
-
The reaction of triiodoisocyanuric acid (TICA) with deactivated arenes in acidic medium led to the efficient and regioselective formation of the corresponding iodoarenes, in 55-88% isolated yield. The acidity of the medium was found to be the most important factor influencing the electrophilic iodination of weakly nucleophilic substrates by TICA. Georg Thieme Verlag Stuttgart New York.
- Da Ribeiro, Rodrigo S.,Esteves, Pierre M.,De Mattos, Marcio C. S.
-
experimental part
p. 739 - 744
(2011/04/24)
-
- Opening of the four-membered ring in perfluorinated 1-alkyl-2-phenyl-and 1-aryl-1,2-dihydrocyclobutabenzenes in the system I2-SbF5
-
Reactions of perfluorinated 1-phenyl-, 1-(2-ethylphenyl)-, 1-(4-ethylphenyl)-, 1-methyl-2-phenyl-, and 1-ethyl-2-phenyl-1,2- dihydrocyclobutabenzenes with iodine in antimony pentafluoride at 130°C, followed by hydroysis of the reaction mixture, resulted in the formation of perfluorinated 2-methyl-, 2-ethyl-2′-methyl-, 4-ethyl-2'-methyl-, 2-ethyl-, and 2-propylbenzophenones via opening of the four-membered ring in the initial cyclobutabenzene at the C1-C2 bond. The presence of hydrogen fluoride facilitates the process and promotes profound transformations leading to anthracene derivatives.
- Mezhenkova,Karpov,Platonov
-
experimental part
p. 1026 - 1034
(2011/10/19)
-
- A first methodical approach to salts with unsymmetrical fluorophenyl(pentafluorophenyl)difluoroiodonium(V) cations [Rf(R F)IF2]+ (Rf=x-FC6H 4, x=2, 3, 4; RF=C6F5)
-
A promising approach to the unknown type of [Ar′(Ar)IF2]X salts is offered. x-FC6H4IF4 (x=2, 3, 4) reacts with C6F5BF2 in CH2Cl2 and forms [x-FC6H4(C6F5)IF 2][BF4] salts in good yields. For [4-FC6H 4(C6F5)IF2][BF4] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C6F5)3 (E=P, As, Sb, Bi) and ArI (Ar=4-FC6H4, C6F5). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC6H4)2IF2][BF4], an example with two identical aryl groups in the difluoroiodonium(V) moiety.
- Frohn, Hermann-Josef,Wenda, André,Fl?rke, Ulrich
-
experimental part
p. 5762 - 5767
(2010/10/01)
-
- New types of asymmetrical bromonium salts [RF(R F′)Br]Y where RF and/or RF′ represent perfluorinated aryl, alkenyl, and alkynyl groups
-
A series of previously unknown asymmetrical fluorinated bis(aryl)bromonium, alkenyl(aryl)bromonium, and alkynyl(aryl)bromonium salts was prepared by reactions of C6F5BrF2 or 4-CF3C 6H4BrF2 with aryl group transfer reagents Ar′SiF3 (Ar′ = C6F5, 4-FC 6H4, C6H5) or perfluoroorganyl group transfer reagents RF′BF2 (RF = C 6F5, trans-CF3CFCF, C3F 7C≡C) preferentially in weakly coordinating solvents (CCl 3F, CCl2FCClF2, CH2Cl2, CF3CH2CHF2 (PFP), CF3CH 2CF2CH3 (PFB)). The presence of the base MeCN and the influence of the adducts RF′BF2·NCMe (RF = C6F5, CF3C≡C) on reactions aside to bromonium salt formation are discussed. Reactions of C 6F5BrF2 with AlkF′BF 2 in PFP gave mainly C6F5Br and Alk F′F (AlkF′ = C6F13, C6F13CH2CH2), presumably, deriving from the unstable salts [C6F5(AlkF′)Br]Y (Y = [AlkF′BF3]-). Prototypical reactivities of selected bromonium salts were investigated with the nucleophile I-and the electrophile H+. [4-CF3C 6H4(C6F5)Br][BF4] showed the conversion into 4-CF3C6H4Br and C 6F5I when reacted with [Bu4N]I in MeCN. Perfluoroalkynylbromonium salts [CnF2n+1C≡C(R F)Br][BF4] slowly added HF when dissolved in aHF and formed [Z-CnF2n+1CFCH(RF)Br][BF4].
- Frohn, Hermann-Josef,Giesen, Matthias,Bardin, Vadim V.
-
experimental part
p. 969 - 974
(2010/12/19)
-
- A versatile and highly reactive polyfluorinated hypervalent iodine (III) compound
-
(Figure Presented) Hyper-reactive: A highly reactive, fully fluorinated hypervalent iodine reagent (see formula) mediates new transformations (e.g. the one-pot conversion of sulfides to sulfoximines) and serves as a stoichiometric oxidant in well-established reactions (e.g. C-C bond cleavage and the conversion of alcohols into aldehydes).
- Schaefer, Sascha,Wirth, Thomas
-
experimental part
p. 2786 - 2789
(2010/07/06)
-
- Thermodynamics of halogen bonding in solution: Substituent, structural, and solvent effects
-
A detailed study of the thermodynamics of the halogen-bonding interaction in organic solution is presented. 19F NMR titrations are used to determine association constants for the interactions of a variety of Lewis bases with fluorinated iodoalkanes and iodoarenes. Linear free energy relationships for the halogen bond donor ability of substituted iodoperfluoroarenes XC 6F4I are described, demonstrating that both substituent constants (σ) and calculated molecular electrostatic potential surfaces are useful for constructing such relationships. An electrostatic model is, however, limited in its ability to provide correlation with a more comprehensive data set in which both halogen bond donor and acceptor abilities are varied: the ability of computationally derived binding energies to accurately model such data is elucidated. Solvent effects also reveal limitations of a purely electrostatic depiction of halogen bonding and point to important differences between halogen bonding and hydrogen bonding.
- Sarwar, Mohammed G.,Dragisic, Bojan,Salsberg, Lee J.,Gouliaras, Christina,Taylor, Mark S.
-
supporting information; scheme or table
p. 1646 - 1653
(2010/04/04)
-
- A simple base-mediated halogenation of acidic sp2 C-H bonds under noncryogenic conditions
-
(Chemical Equation Presented) A new method has been developed for in situ halogenation of acidic sp2 carbon-hydrogen bonds in heterocycles and electron-deficient arenes. Either selective monohalogenation or one-step exhaustive polyhalogenation is possible for substrates possessing several C-H bonds that are flanked by electron-withdrawing groups. For the most acidic arenes, such as pentafluorobenzene, K3PO4 base can be employed instead of BuLi for metalation/halogenation sequences.
- Do, Hien-Quang,Daugulis, Olafs
-
supporting information; experimental part
p. 421 - 423
(2009/07/04)
-
- In situ generation and trapping of aryllithium and arylpotassium species by halogen, sulfur, and carbon electrophiles
-
(Chemical Equation Presented) A general method has been developed for in situ trapping of arylmetal intermediates by halogen, sulfur, ketone, and aldehyde electrophiles affording the functionalization of the most acidic position in arene. Pentafluorobenzene, benzothiazole, and benzoxazole can be functionalized by using K3PO4 base. For less acidic arenes, tBuOLi base is required. Arenes with DMSO pKa values of 35 or less are reactive. 2009 American Chemical Society.
- Popov, Ilya,Do, Hien-Quang,Daugulis, Olafs
-
supporting information; experimental part
p. 8309 - 8313
(2010/01/16)
-
- A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength
-
The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents.
- Frohn, Hermann-Josef,Bailly, Frank,Welting, Dirk,Bardin, Vadim V.
-
experimental part
p. 301 - 307
(2009/12/04)
-
- N-halosuccinimide/BF3-H2O, efficient electrophilic halogenating systems for aromatics
-
N-Halosuccinimides (NXS, 1) are efficiently activated in trifluoromethanesulfonic acid and BF3-H2O, allowing the halogenations of deactivated aromatics. Because BF3-H2O is more economic, easy to prepare, nonoxidizing, and offers sufficiently high acidity (-H0 ≈ 12, only slightly lower than that of trifluoromethanesulfonic acid), an efficient new electrophilic reagent combination of NXS/BF3-H2O has been developed. DFT calculations at the B3LYP/6-311++G**//B3LYP/6-31G* level suggest that protonated N-halosuccinimides undergo further protosolvation at higher acidities to reactive superelectrophilic species capable either in the transfer of X+ from the protonated forms of NXS to the aromatic substrate or in forming a highly reactive and solvated X+ which would readily react with the aromatic substrates. Structural aspects of the BF 3-H2O complex have also been investigated.
- Prakash, G. K. Surya,Mathew, Thomas,Hoole, Dushyanthi,Esteves, Pierre M.,Wang, Qi,Rasul, Golam,Olah, George A.
-
p. 15770 - 15776
(2007/10/03)
-
- Method for producing tetrakis ( fluoroaryl) borate-magnesium compound
-
Fluoroaryl magnesium halide is reacted with a boron compound so that a molar ratio of the fluoroaryl magnesium halide to the boron compound is not less than 3.0 and not more than 3.7, so as to produce a tetrakis (fluoroaryl) borate·magnesium compound. With this method, there occurs no hydrogen fluoride which corrodes a producing apparatus and requires troublesome waste water treatment.
- -
-
-
- Method for manufacturing fluoroaryl magnesium halide
-
In order to provide a method of safely, efficiently, and industrially manufacturing fluoroaryl magnesium halide containing no impurities, such as coloring components, by a relatively gradual reaction compared with the conventional reactions, and a method of readily and efficiently manufacturing a highly-pure fluoroaryl borane derivative, fluoroaryl magnesium halide expressed by General Formula (1): where each of R1-R5independently represents H, F, a hydrocarbon group, or an alkoxy group, provided that at least three of R1-R5are fluorine atoms, and Xarepresents Cl, Br, or I; is manufactured by reacting, in a solvent containing a chain ether solvent, hydrocarbon magnesium halide expressed by General Formula (2): R6MgXa??(2) where R6represents a hydrocarbon group, and Xarepresents Cl, Br, or I; with fluoroaryl halide expressed by General Formula (3): where each of R1-R5independently represents H, F, a hydrocarbon group, or an alkoxy group, provided that at least three of R1-R5are fluorine atoms and Xbrepresents Br or I.
- -
-
-
- Chlorine Abstraction Reaction from Chloroprentafluorobenzene by the CF3 Radical
-
The temperature dependence of the rate constant for the gas phase abstraction reaction of chlorine by CFj from chloropentafluorobenzene was determined in the temperature range 573-653 K by the competitive method using the recombination of CF3 radicals as reference reaction. Taking a value of 1.53-1013 cm3 mor1 s-1 for the recombination rate constant, kc, = (6.76± 1.26) 1012 exp [-(6339±103) K/7] cm3 mor1 s-1. The Arrhcnius parameters were calculated by the Bond Strength-Bond Length method (BSBL) and good agreement was obtained with the experimental values. WILEY-VCH Verlag GmbH, 1998.
- Nieto,Herrera,Lane,Oexler
-
p. 821 - 825
(2007/10/03)
-
- Fluorinated biphenyls from aromatic arylations with pentafluorobenzenediazonium and related cations. Competition between arylation and azo coupling
-
High yields of the mixed perfluorinated biaryls (C6F5-Ar) are obtained by the catalytic dediazonlatlon of the pentafluorobenzenediazonium salt (C6F5N2+BF4-) in acetonitrile solutions containing various aromatic substrates (ArH) together with small amounts of iodide salts. Activated (electron-rich) as well as deactivated (electron-poor) arenes are successfully pentafluorophenylated by this method. The arylation is distinct from the azo coupling of the same substrates, which takes place in the absence of the iodide catalyst and yields the corresponding diazene (C6F5N=N-Ar) as product. The catalytic role of iodide, and the isomeric product distributions obtained with this procedure indicate that the arylation proceeds via the pentafluorophenyl radical in a efficient homolytic chain process. Since azo coupling involves electrophilic aromatic substitution of electron-rich ArH by C6F5N2+, the two competing pathways are distinct and do not have reactive intermediates in common.
- Kosynkin, Dmitry,Bockman, T. Michael,Kochi, Jay K.
-
p. 2003 - 2012
(2007/10/03)
-
- Thermal (iodide) and photoinduced electron-transfer catalysis in biaryl synthesis via aromatic arylations with diazonium salts
-
The dediazoniative arylation of various aromatic hydrocarbons (Ar'H) with diazonium salts (ArN2+) in acetonitrile can be readily effected to biaryls (Ar-Ar') in high yields, simply by the addition of small (catalytic) amounts of sodium iodide. [In the absence of Ar'H, the competitive iodination to ArI is nearly quantitative.] Iodide catalysis of biaryl formation is efficiently mediated by aryl radicals (Ar') that participate in an efficient homolytic chain process in which ArN2+ acts as a 1-electron oxidant. The complex kinetics of such an electron-transfer chain or ETC process (Scheme I) is quantitatively verified by computer simulation of the Ar'H-dependent (a) competition between arylation vs iodination and (b) catalytic efficiency of iodide. using the GEAR algorithms. ETC catalysis also pertains to the alternative photochemical procedure for arylation (in the absence of iodide), in which the deliberate irradiation of the charge-transfer band of the precursor complex (ArN2+, Ar'H) initiates the same homolytic chain arylation. The latter underscores the mechanistic generality of the ETC formulation for various types of catalytic dediazoniations of aromatic diazonium salts.
- Kosynkin,Bockman,Kochi
-
p. 4846 - 4855
(2007/10/03)
-
- Oxidative coupling of radicals in reactions of compounds of tervalent iodine with trimethylsilyl(phenyl)acetylene
-
Reactions of trimethylsilyl(phenyl)acetylene with aryl and alkyl difluoroiodides give coupling products of substituents in high yields.
- Lermontov,Velikohat'ko,Zefirov
-
p. 977 - 978
(2007/10/03)
-
- Preparation, NMR spectra and reactivity of pentafluorophenyltetrafluorosilicates M+-
-
Pentafluorophenyltetrafluorosilicates M+ - were obtained from pentafluorophenyltrifluorosilane C6F5SiF3 and ionic fluorides MF (M=K, Cs, Me4N) in anhydrous MeCN or diglyme.The reactivity of M+ - toward electrophiles was studied.Keywords: Pentafluorophenyl; Fluorosilicate anion; Desilylation
- Frohn, H. J.,Bardin, V. V.
-
p. 155 - 160
(2007/10/02)
-
- Thermal electron attachment to C6F5X and C6H5X (X - I, Br, Cl, and F)
-
Rate constants have been measured for thermal electron attachment to C6F5X (X = I, Br, Cl, F, and H) and C6H5X (X = I, Br, Cl, and F) at room temperature in N2 buffer gas (1-100 Torr) using the pulse-radiolysis microwave cavity method.For all the compounds studied, the rate constants are of the two-body type.Unexpectedly, the values for C6F5X except C6F5H are all the same (ca. 2 x 10-7 cm3 molecule-1 s-1), which are higher than most of the previous values, while that for C6F5H, measured in Xe and Ar buffer gases, is very low (7 x 10-12 cm3 molecule-1 s-1).For C6H5X, the value decreases dramatically with varying X from I to Br to Cl as 1.0 x 10-8 to 6.5 x 10-12 to 3 x 10-14 cm3 molecule-1 s-1, and that for C6H5F must be much lower than 10-13 cm3 molecule-1 s-1.These results for the magnitude of the rate constant are rationalized by the variation in the energy of a transient negative-ion state of each molecule, which results from a combination of the electron affinities of constituents (halogen atom X and C6F5 radical) and the strength of the C6F5-X (or C6H5-X) bond.
- Shimamori, Hiroshi,Tatsumi, Yoshitsugu,Suanagawa, Takeyoshi
-
p. 7787 - 7792
(2007/10/02)
-
- Reactions of pentafluorophenylxenon(II) hexafluoroarsenate (+)(-) with aromatic compounds
-
Pentafluorophenylxenon(II) hexafluoroarsenate (+)(-) reacts (MeCN, 20 deg C) with aromatic compounds C6H5X (X=CH3, F, CF3, NO2 and CN), yielding isomeric mixtures of polyfluorinated biphenyls XC6H4C6F5.When X=I, iodopentafluorobenzene is formed in addition, whereas trimethylsilylbenzene (X=SiMe3) is only converted to C6H5C6F5 and C6F5H.These results are compared with the data for the radical pentafluorophenylation and fluorination reactions of the corresponding aromatic compounds with XeF2.Polyfluoroaromatic compounds C6F6, C6F5H, C6F5I, C6F5CN and C6F5SiMe3 do not react with (+)(-) under the same conditions.
- Frohn, H. J.,Klose, A.,Bardin, V. V.
-
p. 201 - 216
(2007/10/02)
-
- Perfluoro- and Polyfluoro-sulphonic Acids. Part 22. Polyfluorophenyl Pentafluorobenzenesulphonates and their Electron Transfer Reaction with Sodium Iodide
-
Polyfluorophenyl pentafluorobenzenesulphonates (1) have been synthesized in excellent yields by the reaction of pentafluorobenzenesulphonyl chloride with polyfluorophenoxides.Nucleophilic attack on 1 resulted in the breakage of the S-O bond accompanied by displacement of o- and /or p-fluorine.Reaction of 1 with sodium iodide (8) in a mole ratio of 1:3 (1:8) yielded polyfluorodiphenyl ethers 9 and 10 as the main products.However, p-C6F5OC6F4SO3C6F5 (12) was isolated as the major product in addition to 9 and 10 when the reactant ratio was 1:1 or 1:0.25.Reaction of 12 with sodium iodide also gave 9 and 10 when the reactant ratio was 1:3 (12:8).The reaction of 1 (or 12) with NaI is supposed to be an electron-transfer process.
- Chen, Qing-Yun,Chen, Ming-Fang
-
p. 1071 - 1075
(2007/10/02)
-
- C-I STRETCHING VIBRATIONS IN IODOBENZENES
-
Comparison of the calculated and experimental IR and Raman spectra of a series of iodobenzenes showed that the C-I stretching vibrations for these compounds correspond to a very highly polarized Raman band 150 - 270 cm-1 (ρ = 0.1).The position of this band depends on the mass of the para substituent and relative position of the fluorine and iodine atoms in the molecule.The UV absorption spectral data indicate an interaction of the iodine atom and para substituents through the ?-system.Opposite substituent effects on the change in intensity of the B-band in the UV spectra of iodobenzenes and tetrafluoroiodobenzenes were noted.
- Fugaeva, O.M.,Korobeinicheva, I.K.,Bardin, V.V.
-
p. 2309 - 2311
(2007/10/02)
-
- ON SOME NEW TRIFLUOROMETHYL IODINE(III) COMPOUNDS: REACTIONS OF CF3IF2 WITH BORON AND SILICON COMPOUNDS AND CF3ICl2 WITH SILVER SALTS
-
CF3IF2 undergoes fluorine exchange reactions with BX3 (X = Cl, Br, I, OCOCF3) to form the compounds CF3IX2.The reactions of CF3IF2 with (CF3)2BN(CH3)2, (CH3)3SiNCO and (CH3)3SiN(CH3)COCF3 yield the corresponding new trifluoromethyl iodine (III) nitrogen compounds.A preparative method for the synthesis of CF3ICl2 is found by reacting CF3IF2 with (CH3)3SiCl.CF3ICl2 reacts with AgX (X = OCOCF3, SCF3) to yield the corresponding CF3IX2 compounds and with (C6H5)4AsCl the novel ion (-) is detected.Products were identified by n.m.r. spectroscopy.
- Tyrra, Wieland,Naumann, Dieter
-
p. 401 - 416
(2007/10/02)
-
- Alkene Epoxidations Catalyzed by Iron(III), Manganese(III), and Chromium(III) Porphyrins. Effects of Metal and Porphyrin Substituents on Selectivity and Regiochemistry of Epoxidation
-
The products of epoxidation of norbornene, cyclohexene, and adamantylideneadamantane with pentafluoroiodobenzene using as catalysts variously substituted tetraphenylporphyrin complexes of chloroiron(III), chloromanganese(III), and chlorochromium(III) have been determined.All catalysts afforded the epoxide from adamantylideneadamantane, suggesting that the metallacycle intermediate, impossible in this case, is not required for epoxidation.The ratios of exo- to endo-epoxynorbornanes obtained from norbornene varied from about 1E3 for electropositively substituted Cr(III) complexes gradually through the Mn(III) and Fe(III) series to a value of about 6 for electronegatively substituted iron(III) porphyrins.Mechanisms ranging from limiting electrophilic addition to limiting electron transfer are proposed to account for these changes.The electronegatively substituted iron porphyrins show a greater tendency toward epoxidation rather than allylic oxidation and show more selectivity for cis-alkenes.
- Traylor, Teddy G.,Miksztal, Andrew R.
-
p. 7443 - 7448
(2007/10/02)
-
- NOVEL PENTAFLUOROPHENYL HYPERVALENT IODINE REAGENTS
-
The novel C6F5I(OH)OTs has been synthesized and shown to undergo ligand exchange with C6H5I,iodonium ylide formation with dimedone and iodonium salt formation with anisole.
- Moriarty, Robert M.,Penmasta, Raju,Prakash, Indra
-
p. 877 - 880
(2007/10/02)
-
- Synthesis and Reactivity of 2-Oxidodiaryliodonium Zwitterions
-
The direct synthesis of three new 2-oxidoaryliodonium zwitterions from phenols and aryliodine(III) bistrifluoroacetate and their reaction with nucleophiles and electrophiles are reported.Especially noteworthy is the reactivity of 2-methoxy-3,5-dinitrophenyl(phenyl)iodonium tetrafluoroborate (15) which is hydrolysed by water and solvolysed by alcohols at room temperature.
- Spyroudis, Spyros,Varvoglis, Anastasios
-
p. 135 - 137
(2007/10/02)
-
- Organothallium Compounds. XVIII The Effect of Antimony Pentafluoride and Fluorosulfuric Acid on the Thallation of Polyfluoroarenes
-
The polyfluoroarenes m-H2C6F4, m-O2NC6F4H, m- and p-BrC6F4H, (p-HC6F4)2, C6F5H, 1,3,5-F3C6H3 and m-FSO2C6F4H have been thallated by thallic trifluoroacetate in fluorosulfuric acid in the presence of antimony pentafluoride.Substantial dithallation of m-H2C6F4 and 1,3,5-F3C6H3 and slight trithallation of the latter have been achieved.The products were identified by conversion into the corresponding polyfluoroiodoarenes on reaction with aqueous sodium iodide.From the reaction with pentafluorobenzene, pentafluorophenylthallium(III) species have been characterized. 1,2,4,5-Tetrafluoro-3-methoxybenzene was thallated by thallic trifluoroacetate in 1,2-dichloroethane in the presence of boron trifluoride etherate, but C6F5H and p-MeC6F4H failed to react.
- Deacon, Glen B.,Smith, Richard N.M.
-
p. 1587 - 1597
(2007/10/02)
-
- Aromatic fluorine derivatives LXXXVI. Direct introduction of pentavalent iodine into fluorine-containing benzenes. Generation of pentafluorophenyltrifluoroiodonium ion
-
The reaction of 1,3,5-trifluorobenzene and pentafluorobenzene with IF4SbFnCl6-n led to the formation of compounds the hydrolysis of which gave fluorinated aromatic derivatives of pentavalent iodine.The fluorine-containing aryliodonium ion C6H5IF3+ was generated for the first time, and its structure and characteristics were compared with those of other known heteroanalogs of perfluorinated benzyl cations.
- Bardin, V. V.,Furin, G. G.,Yakobson, G. G.
-
p. 1086 - 1092
(2007/10/02)
-
