- Reversible C-F bond formation and the Au-catalyzed hydrofluorination of alkynes
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The gold(I) fluoride complex [(SIPr)AuF] [SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene] reacts reversibly with 3-hexyne to form a (β-fluorovinyl)gold(I) species. The more stable fluorovinyl complex trans-{(SIPr)Au[(Ph)C=C(F)CH3]}, formed by addition of [(SIPr)AuF] across 1-phenyl-1-propyne, has been characterized crystallographically. Both the protonolysis of a (fluorovinyl)gold complex and the reaction of a cationic (alkyne)gold(I) complex with the mild HF source Et3N?3HF result in fluoroalkene formation. Electrophilic gold(I) complexes, supported by N-heterocyclic carbene ligands and generated in situ, catalyze the trans-hydrofluorination of internal alkynes at room temperature. This catalysis represents a new, selective, and potentially versatile method for the synthesis of fluoroalkenes. Copyright
- Akana, Jennifer A.,Bhattacharyya, Koyel X.,Mueller, Peter,Sadighi, Joseph P.
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Read Online
- Divergent reactivities in fluoronation of allylic alcohols: Synthesis of: Z -fluoroalkenes via carbon-carbon bond cleavage
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An unconventional cleavage of an unstrained carbon-carbon bond in allylic alcohols can be induced by the use of N-fluorobenzenesulfonimide (NFSI) under catalyst-free conditions. By using this simple procedure, a wide range of functionalized Z-fluoroalkenes can be accessed in high yield and selectivity from cyclic and acyclic allylic alcohols.
- Liu, Tang-Lin,Wu, Ji'En,Zhao, Yu
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Read Online
- Convergent Synthesis of Fluoroalkenes Using a Dual-Reactive Unit
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Fluoroalkenes have shown importance as a metabolically stable isostere of amide compounds. To expedite the synthesis of diverse fluoroalkenes, we have developed a dual-reactive C2-unit, (Z)-1-boryl-1-fluoro-2-tosyloxyethene, containing nucleophilic and electrophilic moieties. Consecutive palladium-catalyzed cross-coupling reactions of this unit with aryl bromides and aryl boronic acids allow for the convergent synthesis of diverse trans-1,2-diaryl-substituted fluoroethenes in a chemoselective and stereoretentive manner.
- Isoda, Motoyuki,Uetake, Yuta,Takimoto, Tadashi,Tsuda, Junpei,Hosoya, Takamitsu,Niwa, Takashi
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supporting information
p. 1622 - 1632
(2021/02/05)
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- Stereodivergent Alkyne Hydrofluorination Using Protic Tetrafluoroborates as Tunable Reagents
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The discovery of safe, general, and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal-free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These reaction conditions were suitable for a diverse collection of alkynes, including several highly functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C?F bond formation through vinyl cation intermediates, with the E- and Z-hydrofluorination products forming under kinetic and thermodynamic control, respectively.
- Geaneotes, Paul,Guo, Rui,Liu, Peng,Qi, Xiaotian,Wang, Ruihan,Wang, Yi-Ming,Xiang, Hengye
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supporting information
p. 16651 - 16660
(2020/07/16)
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- Silver-Mediated Decarboxylative Fluorodiiodination of Alkynoic Acids: Synthesis of Regio- and Stereoselective Fluoroalkenes
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A variety of arylalkynoic acids reacted with 1,3-diiodo-5,5-dimethylhydantoin and HF·pyridine in the presence of AgOAc to provide the corresponding 1-fluoro-2,2-diiodovinylarenes in good yields and high regioselectivity. In addition, Pd-catalyzed cross-co
- Jayaraman, Aravindan,Lee, Sunwoo
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p. 3485 - 3489
(2019/05/24)
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- Selective Monodefluorination and Wittig Functionalization of gem-Difluoromethyl Groups to Generate Monofluoroalkenes
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Monodefluorination of gem-difluoromethyl groups is achieved using a frustrated Lewis pair (FLP) approach. Triarylphosphines and group 13 Lewis acids were surveyed as FLP components, with the combination of P(o-Tol)3 and B(C6F5)3 found to provide the best results, although the reaction is feasible with more economical components (PPh3 and BF3·OEt2). The α-fluoroalkylphosphonium products arising from the reaction were of lower activity, in regard to further fluoride abstraction, as compared to difluoride starting materials, leading to highly selective monodefluorination. The activated substrates were subject to Wittig reaction protocols to generate a variety of monofluoroalkenes in moderate to high yields.
- Mandal, Dipendu,Gupta, Richa,Young, Rowan D.
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supporting information
p. 10682 - 10686
(2018/09/10)
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- Geminal difunctionalization of α-diazo arylmethylphosphonates: Synthesis of fluorinated phosphonates
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A general approach towards diverse fluorinated phosphonates via geminal difunctionalization reactions of α-diazo arylmethylphosphonates is described. The diazo functionality (RR′CN2) is successfully converted to RR′CF2, RR′CHF, RR′CFBr or RR′CFNR′′2 groups by employing different fluorination reagents. A variety of fluorinated organophosphorus compounds were readily accessed in good to excellent yields from a common type of precursor.
- Zhou, Yujing,Zhang, Yan,Wang, Jianbo
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p. 10444 - 10453
(2016/11/18)
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- Reactivity of platinum alkyne complexes towards N-fluorobenzenesulfonimide: formation of platinum compounds bearing a β-fluorovinyl ligand
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The platinum(0) alkyne complexes [Pt(L)(η2-PhC≡CPh)] 1-4 were synthesized by reactions of [Pt(cod)2] with diphenylacetylene and a phosphine ligand precursor (1: L = dcpe, 2: L = xantphos, 3: L = κ2-(P,N)-iPr2PC
- Berger, Josefine,Braun, Thomas,Herrmann, Roy,Braun, Beatrice
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p. 19553 - 19565
(2015/11/27)
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- Regioselective Synthesis of Vinyl Halides, Vinyl Sulfones, and Alkynes: A Tandem Intermolecular Nucleophilic and Electrophilic Vinylation of Tosylhydrazones
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A diazo species is trapped in an intermolecular fashion by two independent ion species in tandem at the carbene center to install an electrophile and a nucleophile on the same carbon. This metal-free concept, which is unprecedented, has been illustrated by regioselective synthesis of a variety of vinyl halides, vinyl sulfones, and alkyne derivatives. (Chemical Equation Presented).
- Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
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- Hydrofluorination of alkynes catalysed by gold bifluorides
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We report the synthesis of nine new N-heterocyclic carbene gold bifluoride complexes starting from the corresponding N-heterocyclic carbene gold hydroxides. A new methodology to access N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) fluoride starting from N,N′-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold(I) hydroxide and readily available potassium bifluoride is also reported. These gold bifluorides were shown to be efficient catalysts in the hydrofluorination of symmetrical and unsymmetrical alkynes, thus affording fluorinated stilbene analogues and fluorovinyl thioethers in good to excellent yields with high stereo- and regioselectivity. The method is exploited further to access a fluorinated combretastatin analogue selectively in two steps starting from commercially available reagents.
- Nahra, Fady,Patrick, Scott R.,Bello, Davide,Brill, Marcel,Obled, Alan,Cordes, David B.,Slawin, Alexandra M. Z.,O'Hagan, David,Nolan, Steven P.
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p. 240 - 244
(2015/03/03)
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- Direct fluorination of styrenes
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We have developed a practical method to synthesize fluorostyrene compounds. A mild and regioselective mono-fluorination reaction occurred smoothly for various di- and trisubstituted styrenes in the presence of RuCl3 and N-fluorobenzenesulfonimide (NFSI). A tandem alkyne hydroarylation-olefin fluorination reaction was also developed using an Au catalyst.
- Shao, Qian,Huang, Yong
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supporting information
p. 6584 - 6586
(2015/04/14)
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- Designer HF-Based fluorination reagent: Highly regioselective synthesis of fluoroalkenes and gem -difluoromethylene compounds from alkynes
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Hydrogen fluoride (HF) and selected nonbasic and weakly coordinating (toward cationic metal) hydrogen-bond acceptors (e.g., DMPU) can form stable complexes through hydrogen bonding. The DMPU/HF complex is a new nucleophilic fluorination reagent that has high acidity and is compatible with cationic metal catalysts. The gold-catalyzed mono- and dihydrofluorination of alkynes using the DMPU/HF complex yields synthetically important fluoroalkenes and gem-difluoromethlylene compounds regioselectively.
- Okoromoba, Otome E.,Han, Junbin,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 14381 - 14384
(2015/01/09)
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- Preparation of fluoroalkenes via the Shapiro reaction: Direct access to fluorinated peptidomimetics
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Fluoroalkenes represent a useful class of peptidomimetics with distinct biophysical properties. Current preparations of this functional group commonly provide mixtures of E- or Z-fluoroalkene diastereomers, and/or mixtures of nonfluorinated products. To directly access fluoroalkenes in good stereoselectivity, a Shapiro fluorination reaction was developed. Fluoroalkene products were accessed in one- or two-step sequences from widely available ketones. This strategy should be useful for the preparation of fluorinated analogs of peptide-based therapeutics, many of which would be challenging to prepare by alternate strategies.
- Yang, Ming-Hsiu,Matikonda, Siddharth S.,Altman, Ryan A.
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supporting information
p. 3894 - 3897
(2013/09/02)
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- Acceleration of alkenyltrimethylsilane fluorination under mild conditions using ultrasound
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Alkenyltrimethylsilanes are selectively fluorodesilated to alkenyl fluoride very readily by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) and N-fluorobenzensulfonimids at room temperature under
- Ranjbar-Karimi, Reza
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experimental part
p. 768 - 769
(2011/10/08)
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- Asymmetric epoxidation of fluoroolefins by chiral dioxirane. Fluorine effect on enantioselectivity
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(Chemical Equation Presented) The asymmetric epoxidation of various fluoroolefins has been studied using chiral ketone catalyst, and up to 93% ee was achieved with fructose-derived ketone 1.
- Wong, O. Andrea,Shi, Yian
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supporting information; experimental part
p. 8377 - 8380
(2010/03/25)
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- Stereoselective preparation of (E)- and (Z)-α-fluorostilbenes via palladium-catalyzed cross-coupling reaction of high E/Z ratio and (Z)-1-bromo-1-fluoroalkenes
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A highly stereoselective method to prepare both (E)- and (Z)-α-fluorostilbenes is described. 1-Bromo-1-fluoroalkenes (E/Z ≈ 1:1), a readily available starting material, isomerizes to high E/Z ratios by storage at -20 °C or by photolysis at 254 nm. Stille
- Xu, Jianjun,Burton, Donald J.
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p. 3743 - 3747
(2007/10/03)
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- Stereoselective synthesis of fluoroalkenes via (Z)-2-fluoroalkenyliodonium salts
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Stereoselective synthesis of fluoroalkenes is described. (Z)-2-Fluoro-1-alkenyl(phenyl)iodonium tetrafluoroborates (1) were synthesized stereoselectively in good yields by Michael-type addition of HF to 1-alkynyl(phenyl)iodonium tetrafluoroborates (2) with a commercially available HF reagent, hydrofluoric acid or Et3N-3HF. Pd-catalyzed cross-coupling reactions using 1 gave (Z)-2-fluoro-1-alkene derivatives in moderate yields. The treatment of 1 with KI in the presence of a catalytic amount of CuI gave (Z)-2-fluoro-1-iodo-1-alkenes (3). Pd-catalyzed cross-coupling reactions of 3 gave better results than that of 1, and a variety of (Z)-2-fluoro-1-alkene derivatives were synthesized in good yields.
- Yoshida, Masanori,Komata, Ayumu,Hara, Shoji
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p. 8636 - 8645
(2007/10/03)
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- Pd-catalyzed couplings of (α-fluoro)vinyl tris(trimethylsilyl) germanes
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The (α-fluoro)vinyl tris(trimethylsilyl)germanes undergo Pd-catalyzed cross-couplings with aryl and alkenyl halides upon oxidative treatment with hydrogen peroxide under basic aqueous conditions to give access to fluoroalkenes and fluorodienes with retent
- Wang, Zhizhong,Gonzalez, Aurelio,Wnuk, Stanislaw F.
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p. 5313 - 5316
(2007/10/03)
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- Radical-mediated silyl- and germyldesulfonylation of vinyl and (α-fluoro)vinyl sulfones: Application of tris(trimethylsilyl)silanes and tris(trimethylsilyl)germanes in Pd-catalyzed couplings
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Equation presented. Radical-mediated silyl- and germyldesulfonylations of various vinyl and (α-fluoro)vinyl sulfones with tris(trimethylsilyl)silane and germanium hydrides provide access to vinyl and (α-fluoro)vinyl silanes and germanes. Upon oxidative treatment with hydrogen peroxide in basic aqueous solution, the vinyl tris(trimethylsilyl)silanes and -germanes undergo Pd-catalyzed cross-couplings with aryl halides.
- Wnuk, Stanislaw F.,Garcia Jr., Pedro I.,Wang, Zhizhong
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p. 2047 - 2049
(2007/10/03)
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- Stereospecific preparation of (Z)-α-fluorostilbenes via a kinetically controlled palladium-catalyzed cross-coupling reaction of high E/Z ratio 1-bromo-1-fluorostyrenes and aryl stannanes
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High E/Z ratios were obtained for 1-bromo-1-fluorostyrenes by isomerization from the original E/Z ratios of approximately 1:1. The palladium-catalyzed cross-coupling reaction of high E/Z ratio 1-bromo-1-fluorostyrenes with aryl stannanes gives (Z)-α-fluor
- Xu, Jianjun,Burton, Donald J
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p. 2877 - 2879
(2007/10/03)
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- New methods for the synthesis of fluoroolefins via the palladium catalyzed cross-coupling reaction of 1-fluorovinyl halides with organoboranes and organostannanes
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The palladium catalyzed cross-coupling reaction of 1-fluorovinyl halides with organoboranes and organostannanes provide two new facile methods to 1-substituted 1-fluoroolefins. The reactions proceed with retention of configuration in good to excellent yields.
- Chen, Chen,Wilcoxen, Keith,Huang, Charles Q.,Strack, Nathalie,McCarthy, James R.
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p. 285 - 290
(2007/10/03)
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- Photolysis of bromo- and chloro-substituted benzyl derivatives. Competition between ionic and radical pathways
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Photolysis of 1-fluoro-2-halo-1,2-diphenylethanes was studied in solutions of tetrahydrofuran, acetonitrile, and cyclohexane. The effect of free radical inhibitor and metal hydrides on products formation as well as their ratio was analyzed to elucidate the reaction pathway. In the first step homolytic C-X bond cleavage occurs from a single excited state, resulting in a biradical pair. Further reaction path depends on the type of the halogen bonded and on the solvent polarity. Electron transfer within the radical pair cage is apparently more rapid for bromides than for chlorides and is opposite as expected on the basis of the relative electronegativities of chlorine and bromine. As radicals approach each other, they fall into ionic or radical product channels. This is influenced by solvent polarity, resulting in the larger yield of ionic products in the case of acetonitrile as in the case of less polar cyclohexane.
- Kosmrlj,Sket
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p. 6890 - 6896
(2007/10/03)
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- Synthesis of fluorinated olefins via the palladium catalyzed cross- coupling reaction of 1-fluorovinyl halides with organoboranes
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The palladium catalyzed cross-coupling reaction of 1-fluorovinyl halides 1-4 with organoboranes proceeds under Suzuki conditions with retention on configuration to give 1-substituted 1-fluoroolefins 6-8 in good to excellent yields.
- Chen, Chen,Wilcoxen, Keith,Strack, Nathalie,McCarthy, James R.
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p. 827 - 830
(2007/10/03)
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- Coupling of 2-substituted 1-fluorovinylstannanes with organic halides catalyzed by palladium(0)/copper(I) iodide. A mild and stereospecific method to monofluoroolefins
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The palladium-catalyzed cross-coupling reactions of (E)- or (Z)-1- fluorovinylstannanes with aryl iodides and vinyl iodides provide good yields of stereoisomerically pure substituted fluoroolefins with retention of the double bond geometry. The reaction t
- Chen,Wilcoxen,Zhu,Kim,McCarthy
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p. 3476 - 3482
(2007/10/03)
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- A general and efficient route for the preparation of phenyl-substituted vinyl fluorides
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α-fluorobenzyl phosphonate (EtO)2P(O)CFHPh (2) prepared from diethyl α-hydroxyphosphonate (EtO)2P(O)CH(OH)Ph (1) and diethylaminosulfur trifluoride (DAST), reacts with bases such as butyllithium, tert- butyllithium, lithium bis(trime
- Tsai, Hou-Jen,Lin, Keh-Wen,Ting, Tzu-Hao,Burton, Donald J.
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p. 2231 - 2239
(2007/10/03)
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- Fluorination of olefins with PhSeF3, PhSeF5 and PhTeF5
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Phenyselenium trifluoride, PhSeF3 (PSTF) either oxidatively difluorinates or selenofluorinates olefins, depending on their structures. The pentafluorides PhSeF5 and PhTeF5 appear to be effective difluorinating reagents, af
- Lermontov, Sergei A.,Zavorin, Sergei I.,Bakhtin, Ilya V.,Pushin, Alexei N.,Zefirov, Nikolai S.,Stang, Peter J.
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- Palladium/copper (I) halide-cocatalyzed stereospecific coupling of 1- fluorovinylstannanes with aryl iodides and acyl chlorides
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Cross-coupling of 1-fluorovinylstannanes with aryl iodides or acyl chlorides, cocatalyzed by palladium and copper (I) iodide proceeded under mild conditions to give substituted fluoro olefins and α-fluoro-α,β- unsaturated ketones, respectively, in good yi
- Chen, Chen,Wilcoxen, Keith,Kim, Kyung-Il,McCarthy, James R.
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p. 7677 - 7680
(2007/10/03)
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- Synthesis of phenyl substituted fluoro-olefins
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The anion derived from diethyl α-fluorobenzyl phosphonate (EtO)2P(O)-CFHPh (2) and lithium diisopropylamide in THF underwent the reaction with aldehydes and ketones to afford a moderate to good yields of phenyl substituted fluoro-olefins RR'C =
- Tsai, Hou-Jen
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p. 629 - 632
(2007/10/02)
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- Phenylselenofluoration d'alcynes
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The electrophilic anti-addition of the elements of benzeneselenenyl fluoride towards carbone-carbone triple bonds is performed by a one-pot reaction of N-phenylselenophthalimide and triethylamine tris-hydrofluoride with disubstituted alkynes ; starting from monosubstituted alkynes, the reaction proceeds further to afford vinylic diselenated compounds after hydrofluoric acid elimination. Some products of mono-addition could be transformed into vinylic or allenic fluorides.
- Saluzzo, Christine,Alvernhe, Gerard,Anker, Daniel,Haufe, Guenter
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p. 2127 - 2130
(2007/10/02)
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- CHEMISTRY OF ORGANO HALOGENIC MOLECULES. PART XCIV. THE EFFECT OF FLUORINE ON PHOTOCHEMICAL CARBON-HALOGEN BOND CLEAVAGE IN Z AND E-1-FLUORO-2-HALO-1,2-DIPHENYLETHYLENES
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Irradiation of Z and E-1-fluoro-2-halo-1,2-diphenylethylenes at λ=253.7 nm gave Z and E-2-fluoro-1,2-diphenylethylene and 1,2-diphenylacetylene.The phototransformation depended on the geometry of the molecule, the halogen atom present, and the solvent used.Introduction of fluorine on the olefinic carbon atom in the β-position to a carbon-halogen bond increased the photocleavage compared to the unsubstituted substrate, and reduced the electron transfer from the caged radical-pair to cationic intermediates.Increased solvent polarity resulted in enhanced photocleavage of the carbon-halogen bond.
- Gregorcic, A.,Zupan, M.
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p. 163 - 172
(2007/10/02)
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- PHOTOCHEMISTRY OF ORGANOHALOGENO-COMPOUNDS. PART XIX THE EFFECT OF FLUORINE ON PHOTOCHEMICAL CARBON-HALOGEN BOND CLEAVAGE
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Irradiation of 1,1-diphenyl-2-fluoro-2-haloethenes at λ = 253.7 nm gave 1,1-diphenyl-2-fluoroethene and the rearranged product trans-fluorostilbene.The phototransformation depended on the halogen present and the solvent used.Introduction of fluorine on th
- Gregorcic, A.,Zupan, M.
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p. 313 - 322
(2007/10/02)
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- FURTHER STUDIES ON THE SYNTHESIS OF α-FLUORO CARBONYL COMPOUNDS
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The trimethylsilyl enol ethers of cycloalkanones and acid esters are converted in high yields (70-90percent) to the corresponding α-fluoro carbonyl derivative using XeF2 in CH2Cl2.Non-cyclic α-hydroxy ketones such as ethyl mandelate are efficiently transformed to the α-fluoro product by DAST and by Ishikawa's reagent.Nucleophilic displacement of halogen by fluoride failed in cyclic systems, giving instead, α,β-unsaturated ketones in DMF or CH3CN (18-crown-6) and 1,2-diones in DMSO, with KF acting as a base.Attempts at DMSO oxidation of I(Br)F adducts failed to give the α-fluoro ketones, but resulted in dehydrohalogenation to the trans-vinyl fluorides.
- Cantrell, Gary L.,Filler, Robert
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