- Vinylic C-F bond activation with low-valent zirconocene: The generation and cross-coupling reactions of 1-fluorovinylzirconocene
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(p-2,2-Difluorovinyloxyphenyl)dimethylamine, readily obtained from 2,2,2-trifluoroethanol, is treated with zirconocene equivalent 'Cp2Zr' to generate thermostable 1-fluorovinylzirconocene via a C-F bond cleavage. This 1-fluorovinylzirconocene c
- Fujiwara, Masaki,Ichikawa, Junji,Okauchi, Tatsuo,Minami, Toru
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Read Online
- Fluoride-Triggered Synthesis of 1-Aryl-2,2-difluoroalkenes via Desilylative Defluorination of (1-Aryl)-2,2,2-trifluoroethyl-silanes
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An efficient route for the synthesis of 1-aryl-2,2-difluoroalkenes via 1,2-desilylative defluorination is disclosed. Only a catalytic amount of fluoride source is required to initiate the desilylation and afford gem-difluoroalkenes in very good to quantitative yields, using mild reaction conditions in dimethyl carbonate as a green solvent. This reaction uses (1-aryl)-2,2,2-trifluoroethyl-silanes, which are easily prepared via the insertion reaction of trifluoroethyl diazo alkanes into the Si-H bond of tertiary organosilanes. (1-Aryl)-perfluoroalkyl-silanes cleanly afford the corresponding (Z)-1-benzylideneperfluoroalkanes, which upon hydrodefluorination furnish the (E)-β(perfluoroalkyl)styrene derivatives with excellent yield and complete stereoselectivity. A one-pot system involving sequential insertion and desilylative-defluorination is also suitable for this transformation. This method demonstrates the usefulness of organosilanes toward the preparation of fluorinated alkenes as synthetically useful targets.
- Carreras, Virginie,Ollevier, Thierry
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p. 13160 - 13168
(2021/09/18)
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- Acid-Catalyzed Hydrothiolation of gem-Difluorostyrenes to Access α,α-Difluoroalkylthioethers
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The substitution of hydrogen atoms with fluorine in bioactive molecules can greatly impact physicochemical, pharmacokinetic, and pharmacodynamic properties. However, current synthetic methods cannot readily access many fluorinated motifs, which impedes utilization of these groups. Thus, the development of new methods to introduce fluorinated functional groups is critical for developing the next generation of biological probes and therapeutic agents. The synthesis of one such substructure, the α,α-difluoroalkylthioether, typically requires specialized conditions that necessitate early-stage installation. A late-stage and convergent approach to access α,α-difluoroalkylthioethers could involve nucleophilic addition of thiols across gem-difluorostyrenes. Unfortunately, under basic conditions, nucleophilic addition to gem-difluorostyrenes generates an anionic intermediate that can undergo facile elimination of fluoride to generate α-fluorovinylthioethers. To overcome this decomposition, we herein exploit an acid-based catalyst system to facilitate simultaneous nucleophilic addition and protonation of the unstable intermediate. Ultimately, the optimized mild conditions afford the desired α,α-difluoroalkylthioethers in high selectivity and moderate to excellent yields. These α,α-difluoroalkylthioethers are less nucleophilic and more oxidatively stable relative to nonfluorinated thioethers, suggesting the potential application of this unexplored functional group in biological probes and therapeutic agents.
- Sorrentino, Jacob P.,Orsi, Douglas L.,Altman, Ryan A.
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p. 2297 - 2311
(2021/02/06)
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- Design and Synthesis of TY-Phos and Application in Palladium-Catalyzed Enantioselective Fluoroarylation of gem-Difluoroalkenes
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The first example of highly enantioselective fluoroarylation of gem-difluoroalkenes with aryl halides is presented by using a new chiral sulfinamide phosphine (Sadphos) type ligand TY-Phos. N-Me-TY-Phos can be easily synthesized on a gram scale from readily available starting materials in three steps. Salient features of this work including readily available starting materials, good yields, high enantioselectivities as well as broad substrate scope make this approach very practical and attractive. Notably, the asymmetric synthesis of an analogue of a biologically active molecule is also reported.
- Li, Zhiming,Lin, Tao-Yan,Liu, Yu,Pan, Zhangjin,Tu, Youshao,Wu, Hai-Hong,Zhang, Junliang,Zhu, Shuai
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supporting information
p. 22957 - 22962
(2020/10/19)
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- Pd-Catalyzed Selective Carbonylation of gem-Difluoroalkenes: A Practical Synthesis of Difluoromethylated Esters
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The first catalyst for the alkoxycarbonylation of gem-difluoroalkenes is described. This novel catalytic transformation proceeds in the presence of Pd(acac)2/1,2-bis((di-tert-butylphosphan-yl)methyl)benzene (btbpx) (L4) and allows for an efficient and straightforward access to a range of difluoromethylated esters in high yields and regioselectivities. The synthetic utility of the protocol is showcased in the practical synthesis of a Cyclandelate analogue using this methodology as the key step.
- Liu, Jiawang,Yang, Ji,Ferretti, Francesco,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 4690 - 4694
(2019/03/13)
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- One-step synthesis of 2,3-difluoronaphthalene by the gas-phase co-pyrolysis of styrene with chlorodifluoromethane
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The gas-phase co-pyrolysis of styrene with CHClF2 in a flow reactor at 550–650 °C gives 2,3-difluoronaphthalene in two parallel reaction channels. The main channel includes decomposition of CHClF2 to difluorocarbene, whose subsequent
- Volchkov,Lipkind,Nefedov
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p. 1232 - 1238
(2019/07/15)
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- Copper-Catalyzed Regioselective Monodefluoroborylation of Polyfluoroalkenes en Route to Diverse Fluoroalkenes
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Monodefluoroborylation of polyfluoroalkenes has been achieved in a regioselective manner under mild conditions via copper catalysis. The method has shown an extremely broad scope of substrates, including (difluorovinyl)arenes, tetrafluoroethylene (TFE), (
- Sakaguchi, Hironobu,Uetake, Yuta,Ohashi, Masato,Niwa, Takashi,Ogoshi, Sensuke,Hosoya, Takamitsu
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supporting information
p. 12855 - 12862
(2017/09/25)
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- Production method for fluorine-containing olefin compound
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The present invention addresses the problem of providing a method for producing, from a fluorine-containing olefin that can easily be procured industrially, a different fluorine-containing olefin, in a simple and highly efficient manner. The present invention pertains to a method for producing: a metal-carbene complex compound having olefin metathesis reaction activity; and, by reacting a fluorine-containing olefin compound (21) and an olefin compound (31) in the presence of an olefin compound (41) or (42), at least one of a fluorine-containing olefin compound (51) and a fluorine-containing olefin compound (52).
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Paragraph 0209-0214; 0268-0273
(2017/12/28)
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- Method for producing fluorine-containing olefin
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A method for producing at least one compound selected from the group consisting of a compound represented by formula (10), a compound represented by formula (11), a compound represented by formula (12), and a compound represented by formula (13), by reacting a compound represented by formula (2) and a compound represented by formula (7) in the presence of at least one compound selected from the group consisting of a compound represented by formula (1), a compound represented by formula (3), a compound represented by formula (4), a compound represented by formula (8), and a compound represented by formula (9).
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Paragraph 0376; 0377; 0378; 0379; 0380; 0381
(2017/01/17)
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- METHOD FOR PRODUCING FLUORINE-CONTAINING OLEFIN
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A method for producing at least one compound selected from the group consisting of a compound represented by the following formula (10), a compound represented by the following formula (11), a compound represented by the following formula (12), and a compound represented by the following formula (13), which the method containing reacting a compound represented by the following formula (2) with a compound represented by the following formula (7), in the presence of at least one compound selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (3), a compound represented by the following formula (4), a compound represented by the following formula (8), and a compound represented by the following formula (9).
- -
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Paragraph 0235-0244
(2016/07/27)
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- One-pot synthesis of gem-difluorostyrenes from benzyl bromide via olefination of phosphonium ylide with difluorocarbene
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A new approach for the synthesis of gem-difluorostyrenes from benzyl bromide is described. Quaternization of triphenylphosphine with benzyl bromide to give phosphonium salts, deprotonation of the corresponding phosphonium salts to produce phosphonium ylide, and the subsequent olefination of phosphonium ylide with difluorocarbene generated from difluoromethylene phosphobetaine (Ph3P+CF2CO2-) by decarboxylation can occur smoothly in one-pot, furnishing the final gem-difluorostyrenes in good yields.
- Deng, Xiao-Yun,Lin, Jin-Hong,Xiao, Ji-Chang
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p. 116 - 120
(2015/11/10)
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- Copper(0)-mediated fluoroalkylation of iodobenzene with 2-bromo-1,1,2,2-tetrafluoroethyl compounds: Investigation on the influence of R substituent on the reactivity of RCF2Cu species
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We have made a systematic investigation on the copper(0)-mediated tetrafluoroethylenation of iodobenzene with structurally diverse 2-bromo-1,1,2,2-tetrafluoroethyl compounds. A comparison of this reaction with 1,2,2-trifluoro-1-phenylethylation and the known functionalized difluoroalkylation demonstrates that the substituent R of α,α-difluoroalkyl copper species RCF2Cu plays a crucial role on their reactivity, which is believed to be useful for the development of new fluoroalkylation reactions under the promotion of transition metals.
- Zhu, Jieming,Ni, Chuanfa,Gao, Bing,Hu, Jinbo
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p. 139 - 147
(2015/03/04)
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- Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine
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Background: 1,1-Difluoroalkenes cannot only be used as valuable precursors for organic synthesis, but also act as bioisosteres for enzyme inhibitors. Among various methods for their preparation, the carbonyl olefination with difluoromethylene phosphonium ylide represents one of the most straightforward methods. Results: The combination of (chlorodifluoromethyl)trimethylsilane (TMSCF2Cl) and triphenylphosphine (PPh3) can be used for the synthesis of gem-difluoroolefins from carbonyl compounds. Comparative experiments demonstrate that TMSCF2Cl is superior to (bromodifluoromethyl)trimethylsilane (TMSCF2Br) and (trifluoromethyl)trimethylsilane (TMSCF3) in this reaction. Conclusion: Similar to many other Wittig-type gem-difluoroolefination reactions in the presence of PPh3, the reaction of TMSCF2Cl with aldehydes and activated ketones is effective.
- Wang, Fei,Li, Lingchun,Ni, Chuanfa,Hu, Jinbo
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supporting information
p. 344 - 351
(2014/03/21)
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- The use of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate as the difluorocarbene source to generate an in situ source of difluoromethylene triphenylphosphonium ylide
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Under moderate conditions in the presence of a demethylating reagent, such as iodide, methyl 2,2,-difluoro-2-(fluorosulfonyl)acetate (MDFA) releases difluorocarbene, which in the presence of triphenylphosphine forms difluoromethylene triphenylphosphonium ylide. When the process is carried out also in the presence of aldehydes or activated ketones, the ensuing in situ Wittig-type reaction of the ylide with the carbonyl reactants produces 1,1-difluoroalkenes in good yield. Density Functional Theory calculations were used to provide new estimates of the energies and structures of singlet and triplet states of CH2:, CHF:, and CF2: carbenes, as well as those of their respective triphenylphosphonium ylides.
- Thomoson, Charles S.,Martinez, Henry,Dolbier Jr., William R.
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- METHOD FOR PRODUCING SUBSTITUTED FLUORINE-CONTAINING OLEFIN
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This invention relates to a method of reacting fluoroolefin with an organic magnesium compound in the presence of a catalyst comprising nickel or palladium so as to efficiently produce fluoroolefin, such as TFE, in which a fluorine (F) atom or atoms bonded to the sp2 hybridized carbon atom are substituted with an organic group.
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Page/Page column 8
(2013/02/28)
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- Ionic liquids accelerating cycloaddition between 1-aryl-2-halocyclopropenes and furan
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Treatment of a series of 1-aryl-2,2-dihalocyclopropanes with t-BuOK at-10 °C gave the corresponding 1-aryl-2-halocyclopropenes, which react with furan in a RTIL to give a fair good yield of the [4+2]-cycloadducts with more than 90% of the exo-isomer. The imidazolium type ionic liquids are able to accelerate this cycloaddition process with high steric selectivity. Neither pyrrole nor thiophene undergoes the cycloaddition with cyclopropene to form the [4+2]-cycloadduct. 1-Aryl-3,3-difluoro-2-halocyclopropenes are inert towards furan even at a temperature higher than 100 °C.
- Ding, May-Fan,Lin, Shaw-Tao,Chang, Woan-Ju
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experimental part
p. 240 - 247
(2010/09/16)
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- OPTICALLY ACTIVE (R)-ARYLOXYPROPIONIC ACID AMIDES AND HERBICIDAL COMPOSITION COMPRISING SAME
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The present invention relates to an optically active (R)-aryloxypropionic acid amide compound which has high selectivity and safety for protecting a crop such as rice, wheat, barley and soy bean, and exhibits excellent herbicidal activity against weeds, and a herbicidal composition comprising the same.
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Page/Page column 10
(2010/12/29)
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- OPTICALLY ACTIVE (R)-ARYLOXYPROPIONIC ACID AMIDES AND HERBICIDAL COMPOSITION COMPRISING SAME
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The present invention relates to an optically active (R)-aryloxypropionic acid amide compound which has high selectivity and safety for protecting a crop such as rice, wheat, barley and soy bean, and exhibits excellent herbicidal activity against weeds, and a herbicidal composition comprising the same.
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Page/Page column 28
(2009/03/07)
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- Preparation and 13C NMR study on 1-aryl-3,3-difluoro-2-(phenylethynyl)cyclopropenes: long distance Hammett substituent effect
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Coupling of 1-aryl-3,3-difluoro-2-chlorocyclopropenes and phenylacetylene using Sonogashira reaction with Pd(OAc)2 and CuI as the catalyst with K2CO3 as a base yields phenylethynylcyclopropenes in high selectivity and good yields. The 13C chemical shifts of Cε of ~105 ppm on acetylene group significantly different from phenylacetylene (84 ppm) suggest that the acetylene group possesses less sp hybrid character due to an unusual long distance Hammett substituent effect. It is also confirmed by the substituent parameter analysis, while the Cβ and Cε display the strong resonance effect (their values are 6.89 and 3.37, respectively).
- Lin, Shaw-Tao,Lee, Chuan-Chen,Wu, En-Chien
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p. 5103 - 5106
(2008/09/21)
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- Nucleophilic difluoromethylation and difluoromethylenation using bromodifluoromethyl phenyl sulfone
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Tetrakis(dimethylamino)ethylene (TDAE) was found to be an effective electron-transfer agent that promoted the reactions of bromodifluoromethyl phenyl sulfone with aldehydes to give structurally diverse (benzenesulfonyl) difluoromethylated alcohols in good yield, which can be further transformed into difluoromethyl alcohols and 1,1-difluoro-1-alkenes via reductive desulfonylation and Julia olefination, respectively.
- Surya Prakash,Wang, Ying,Hu, Jinbo,Olah, George A.
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p. 1361 - 1367
(2007/10/03)
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- Use of kinetic isotope effects in mechanism studies. Isotope effects and element effects associated with Hydron-Transfer steps during alkoxide-promoted dehydrohalogenations
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The Arrhenius behavior of the primary kinetic isotope effect, (k(H)/k(D))(Obs) and (k(H)/k(T))(Obs), associated with the methanolic sodium methoxide-promoted dehydrohalogenations of m-ClC6H4C(i)HClCH2Cl (I), m-CF3C6H4C(i)-HClCH2Cl (II) and p-CF3C6H4C(i)HClCH2F (III) has been used to calculate the internal-return parameters, a = k(-1)/K(Elim)(X), in a two-step mechanism featuring a hydrogen-bonded carbanion. This carbanion partitions between returning the hydron to carbon, k(-1), and the loss of halide, K(Elm)(X). Isotope effects at 25°C for I, (k(H)/k(D))(Obs) = 3.40 and (k(H)/ k(T))(Obs) = 6.20, and II, (k(H)/k(D))(Obs) = 3.49 and (k(H)/k(T))(Obs) = 6.55, result in similar values for a: a(H) = 0.59, a(D) = 0.13-0.14 and a(T) = 0.07. Smaller values of (k(H)/k(D))(Obs) = 2.19 and (k(H)/k(T))(Obs) = 3.56 for III are due to more internal return [a(H) = 1.9, a(D) = 0.50, and a(T) = 0.28] associated with the dehydrofluorination reaction. Calculation of k1 ( k(Obs) [a + 1]) results in similar isotope effects for hydron transfer in these reactions: k1(H)/k1(D) = 4.74 and k1(H)/K1(T) = 9.20; II, k1(H)/k1(D) = 4.91 and k1(H)/k1(T) = 9.75; III, k1(H)/k1(D) = 4.75 and k1(H)/k1(T) = 9.17. Reactions of m-ClC6H4C(i)HBrCH2Br and m-ClC6H4C(i)HClCH2Br have very small amounts of internal return, a(H) = 0.05 and a(D) = 0.01, and (k(H)/k(D))(Obs) = 4.95 results in k1(H)/k1(D) = 5.11 The measured isotope effects are therefore due to differences in the amount of internal return and not in the symmetry of transition state structures for the hydron transfer, and the element effect, (k(HBr)/ k(HCl)) = 29, for m-ClC6H4CHClCH2X is mainly due to the hydron-transfer step, k1(HBr)/k1(HCl) = 19, and not the breaking of the C-X bend. The kinetic solvent isotope effects, k(MeOD)/k(MeOH) ~ 2.5, are consistent with three methanols of solvation lost prior to the hydron-transfer step. The energetics associated with desolvation of methoxide ion are part of the measured reaction energetics of these systems.
- Koch, Heinz F.,Lodder, Gerrit,Koch, Judith G.,Bogdan, David J.,Brown, Geoffrey H.,Carlson, Carrie A.,Dean, Amy B.,Hage, Ronald,Han, Patrick,Hopman, Johan C. P.,James, Lisa A.,Knape, Petra M.,Roos, Eric C.,Sardina, Melissa L.,Sawyer, Rachael A.,Scott, Barbara O.,Testa III, Charles A.,Wickham, Steven D.
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p. 9965 - 9974
(2007/10/03)
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- A New Route for the Preparation of Substituted 2,2-Difluorostyrenes and a Convenient Route to Substituted (2,2,2-Trifluoroethyl)benzenes
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The (2,2-difluoroethenyl)zinc reagent II is coupled with aryl iodides or bromides in the presence of Pd(PPh3)4 in DMF to give the corresponding 2,2-difluorostyrenes IV. The 4-substituted (tetrafluoroaryl)copper reagents are coupled with 2,2-difluoro-1-iodoethylene (I) to produce the corresponding styrene derivatives VII. Both methods provide good yields of the coupled products. These products react with wet KF in DMF or DMSO to form the (2,2,2-trifluoroethyl)benzene derivatives VIII in good yields.
- Nguyen, Ba V.,Burton, Donald J.
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p. 7758 - 7764
(2007/10/03)
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- Novel 2,2-difluorovinylzirconocene: A facile synthesis of monosubstituted gem-difluoroolefins via its cross-coupling reaction
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2,2-Difluorovinyl p-toluenesulfonate, readily obtained from 2,2,2-trifluoroethanol, is treated with zirconocene equivalent 'Cp2Zr' to generate the remarkably thermostable nonsubstituted 2,2-difluorovinylzirconocene, which in turn couples with a
- Ichikawa, Junji,Fujiwara, Masaki,Nawata, Hideyuki,Okauchi, Tatsuo,Minami, Toru
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p. 8799 - 8802
(2007/10/03)
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- Magnesium activation by electrochemistry. Application to the synthesis of gem-difluoroalkenes by an electrochemical Wittig reaction.
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The electrochemical reduction of bromodifluoromethyl tris-(dimethylamino)phosphonium tetrafluoroborate between a carbon felt cathode and a sacrificial magnesium anode in DMF led to difluoromethylene tris-(dimethylamino)phosphorane, which was reacted with
- Jubault, Philippe,Feasson, Christian,Collignon, Noel
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p. 850 - 856
(2007/10/02)
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- Pyrolysis of cyclobutanes from styrenes, acrylonitrile and methyl acrylate and polyfluoroolefines
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The 2 + 2 cycloadduct of styrene and TFE (1) ring-expands and eliminates HF like a butadiene adduct to give 2,3-difluoronaphthalene (3).Cyclobutane 1 also cleaves to styrene and 1,1-difluorostyrene.Titania and other solid-acids accelerate the ring-expansi
- Weigert, F. J.
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- Reactivite des dienes et styrenes fluores obtenus par reaction de couplage au palladium
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Fluorodienes and fluorostyrenes undergo clean cycloaddition to form perfluorocyclobutanes.Fluorostyrenes have been prepared by a palladium-catalyzed cross-coupling reaction.Treatment of fluorodienes under acidic conditions gives various α-fluorocarbonyl c
- Tellier, Frederique,Sauvetre, Raymond,Normant, Jean F.,Dromzee, Yves,Jeannin, Yves
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p. 281 - 298
(2007/10/02)
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- ORGANOCUPRATE-INDUCED SUBSTITUTION OF THE ENOL OXYGEN MOIETY IN 2,2-DIFLUORO ENOL PHOSPHATES WITH ALLYL HALIDES: A NOVEL ROUTE TO gem-DIFLUOROOLEFINS FROM CHLORODIFLUOROMETHYL KETONES
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2,2-Difluoro-1-arylethenyl diphenyl phosphates, prepared from chlorodifluoromethyl ketones and diphenyl phosphite, reacted with dibutylcopperlithium and successively with various allyl halides to give allylated gem-difluoroolefins in moderate to excellent
- Ishihara, Takashi,Yamana, Masayuki,Ando, Teiichi
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p. 5657 - 5660
(2007/10/02)
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- Ylide-Carbene Chemistry. Synthesis of 1,1-Difluoro-1-alkenes
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The reaction between nonstabilized alkylidenetriphenylphosphoranes and chlorodifluoromethane has been found to be a useful alternative to the Wittig reaction for the synthesis of many difluoromethylene olefins.Both primary and secondary ylides which do not contain strongly electron-withdrawing substituents within the alkylidene portion of the ylide react with chlorodifluoromethane to give the corresponding difluoromethylene olefins in yields which are significantly better than those obtained by the Wittig reaction.The formation of triphenylphosphine oxide is avoided, and all phosphorus-containing moieties can be recovered and recycled.The reaction proceeds by initial dehydrochlorination of chlorodifluoromethane by the ylide to generate difluorocarbene.The intermediate difluorocarbene is then trapped by a second equivalent of the nucleophilic ylide.Mechanistic evidence indicates that either a zwitterionic intermediate or a three-membered cyclic phosphorane can account for the 1,1-difluoro-1-alkene products.The isolation of several 1-hydro-1-fluoro-1-alkene products such as FCH=CHPh, FHC=CPh2, and FHC=CHCH=CHPh after steam distillation of the reaction mixtures, however, can only be accounted for via a three-membered cyclic phosphorane.
- Wheaton, Gregory A.,Burton, Donald J.
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p. 917 - 927
(2007/10/02)
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- Proton-Transfer Reactions. 3. Differences in the Protonation of Localized and Delocalized Carbanion Intermediates
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Rates, activation parameters, and product distributions are reported for the reaction of methanolic sodium methoxide with XC6H4CH = CF2 (V) and C6F5CH = CF2 (IX) and compared to previously reported results for C6H5C(CF3) = CF2 (I).A ρ = 3.5 was calculated
- Koch, Heinz F.,Koch, Judith G.,Koch, Nanci H,,Koch, Andrew S.
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p. 2388 - 2393
(2007/10/02)
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- PREPARATION AND SYNTHETIC UTILITY OF FLUORINATED PHOSPHONIUM SALTS, BISPHOSPHONIUM SALTS AND PHOSPHORANIUM SALTS
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The reaction of tertiary phosphines with fluorohalomethanes provides a rapid and high yield synthesis of various types of fluorinated phosphonium salts, bis-phosphonium salts and phosphoranium salts.These salts are useful precursors to fluorine-containing
- Burton, Donald J.
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p. 339 - 358
(2007/10/02)
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- Proton-Transfer Reactions. 2. Effects of Internal Return on Reactivity Difference between Alkoxide-Promoted Eliminations in tert-Butyl alcohol and Ethyl Alcohol
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Kinetics of alkoxide-promoted dehydrofluorination reactions are reported for the series C6H5CH2CH2F (I), C6H5CH2CHF2 (II), C6H5CH2CF3 (III), and C6H5CH2CF2CF3 (V).Rates and activation parameters 3 (M-1 s-1)(50 deg C), ΔH* (kcal mol-1), and ΔS*, (eu)> are respectively: (a) using potassium tert-butoxide in tert-butyl alcohol, I (1.88 * 10-4, 19.1, -16.8), II (1.18 * 10-3, 20.3, -9.3), III (2.15 * 10-3, 22.1, -2.4), V (3.93 * 10-2, 16.9, -12.7); and (b) using sodium ethoxide in ethanol, I (1.32 * 10-6, 25.6, -6.5), II (5.28 * 10-7, 29.7, 3.0), III (3.45 * 10-7, 32.6, 12.5), V (5.41 * 10-5, 27.7, 7.6).The variation in tert-butoxide:ethoxide ratios of 140 (I), 2200 (II), 6200 (III), and 730 (V) are discussed in terms of a two-step mechanism with varying amounts of internal return for II, III, and V.Differences in reactivity for groups attached to the benzylic carbon (-CF3, -CF2Cl, -CHF2, -CF2CF3) and variation of ΔS* values for these reactions are also discussed in terms of a two-step mechanism.
- Koch, H. F.,Tumas, W.,Knoll, R.
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p. 5423 - 5429
(2007/10/02)
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- Preparation, Stability, Reactivity and Synthetic Utility of a Cadmium Stabilized Complex of Difluoromethylene Phosphonic Acid Ester
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Diethyl bromodifluoromethylphosphonate reacts readily with cadmium metal to form a stable cadmium complex.Depending on solvent, this functionalized organocadmium reagent exhibits stability for days to months.It reacts with a variety of electrophiles and serves as a synthetically useful source for the introduction of the difluoromethylene phosphonate group into organic compounds.
- Burton, Donald J.,Takei, Ryutaro,Shin-Ya, Seiji
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p. 197 - 202
(2007/10/02)
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- An investigation into the origins of polar substituent effects upon 19F chemical shifts, using 4-substituted β,β-difluorostyrenes
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19F, 13C, and 1H chemical shifts have been determined for β,β-difluorostyrene and eight 4-substituted derivatives.The β-fluorine chemical shift difference, ΔδF, is used to evaluate the constant in the Buckingham equation.A=3.0*10-11
- Reynolds, William F.,Gibb, Victoria G.,Plavac, Nick
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p. 839 - 845
(2007/10/02)
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