Synthesis of Alkylated Monofluoroalkenes via Fe-Catalyzed Defluorinative Cross-Coupling of Donor Alkenes with <i>gem</i>-Difluoroalkenes

Yang, Libin; Ji, Weiwei; Lin, E; Li, Jilin; Fan, Wen-Xin; Li, Qingjiang; Wang, Honggen

doi:10.1021/acs.orglett.8b00471

Cited by 94 publications

(39 citation statements)

References 55 publications

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“…Wang and co-workers achieved the Fe III -catalyzed coupling of b,b-difluorostyrenes with alkenes in the presence of PhSiH 3 as ah ydrogen source through ah ydrogen atom transfer (HAT) strategy (Scheme 28). [59] In this reaction, radical intermediates are generated by HATi nvolving an in situ generated iron(III) hydride species and alkenes,a nd then add to b,b-difluorostyrenes.S ubsequent one-electron reduction by Fe II species followed by b-fluorine elimination affords b-alkylated b-fluorostyrenes.S imilar defluorinative CÀCb ond-forming reactions of fluoroalkenes,p romoted by Ir III catalysts as visible-light photoredox catalysts,w ere achieved through ar adical addition/reduction/b-fluorine elimination sequence (not shown). [60]…”

Section: Migratory Insertionmentioning

confidence: 99%

“…Wang and co‐workers achieved the Fe III ‐catalyzed coupling of β,β‐difluorostyrenes with alkenes in the presence of PhSiH 3 as a hydrogen source through a hydrogen atom transfer (HAT) strategy (Scheme ) . In this reaction, radical intermediates are generated by HAT involving an in situ generated iron(III) hydride species and alkenes, and then add to β,β‐difluorostyrenes.…”

Section: β‐Fluorine Eliminationmentioning

confidence: 99%

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Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

2018

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The activation of carbon-fluorine (C-F) bonds is an important topic in synthetic organic chemistry. Metal-mediated and -catalyzed elimination of β- or α-fluorine proceeds under milder conditions than oxidative addition to C-F bonds. The β- or α-fluorine elimination is initiated from organometallic intermediates having fluorine substituents on carbon atoms β or α to metal centers, respectively. Transformations through these elimination processes (C-F bond cleavage), which are typically preceded by carbon-carbon (or carbon-heteroatom) bond formation, have been increasingly developed in the past five years as C-F bond activation methods. In this Minireview, we summarize the applications of transition-metal-mediated and -catalyzed fluorine elimination to synthetic organic chemistry from a historical perspective with early studies and from a systematic perspective with recent studies.

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Section: Migratory Insertionmentioning

confidence: 99%

Section: β‐Fluorine Eliminationmentioning

confidence: 99%

Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

2018

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“…This strategy has delivered a small library of alkylated monofluoroalkenes with excellent Z selectivity (Scheme 14). [21] Mechanistically, HAT from the catalytically active L n Fe III H to the alkene, generated alkyl radical 55. Then, radical addition to the gem-difluoroalkene (53) produced benzyl radical 56, which underwent a single electron reduction by the L n Fe II to yield anion 57.…”

Section: Alkylation and Alkenylationmentioning

confidence: 99%

“…An Fe‐based catalyst system can also trigger cross‐coupling reaction of gem ‐difluoroalkenes with various unactivated and heteroatom substituted olefins through a hydrogen atom transfer (HAT) strategy. This strategy has delivered a small library of alkylated monofluoroalkenes with excellent Z selectivity (Scheme ) . Mechanistically, HAT from the catalytically active L n Fe III H to the alkene, generated alkyl radical 55 .…”

Section: Reactions Proceeding Via β‐Fluoride Eliminationmentioning

confidence: 99%

Recent Advances in Transition Metal‐Catalyzed Functionalization of gem‐Difluoroalkenes

Koley

Altman

2020

Israel Journal of Chemistry

123

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gem-Difluorinated alkenes are readily accessible building blocks that can undergo functionalization to provide a broad spectrum of fluorinated and non-fluorinated products. Herein, we review recent (since 2017) transition metalcatalyzed transformations of these specialized alkenes and summarize general reactivity patterns of these reactions. Many transition metal-catalyzed reactions undergo net CÀ F bond functionalization reactions to deliver monofluorinated products. These reactions typically proceed through β-fluoroalkylmetal intermediates that readily eliminate a βfluoride to deliver monofluoroalkene products. A second series of reactions exploit coinage metal fluorides to add F À to the gem-difluorinated alkene, and further functionalization delivers trifluoromethyl-containing products. In stark contrast, few transition metal-catalyzed reactions proceed in net "fluorine-retentive processes" to deliver difluoromethylenebased products. Reactions Proceeding via β-Fluoride Eliminationgem-Difluoroalkenes react with a variety of transition metalbased catalyst systems (e. g. Cu, Co, Mn, Pd, Ni, Ru, Rh) in net CÀ F functionalization reactions. These reactions typically proceed through a β-fluoroalkylmetal intermediate that readily undergoes β-fluoride elimination to form a new alkene based product (Scheme 1). At first, reaction of a substrate-ligated complex (1) to the gem-difluoroalkene 2, proceeds through a four-membered transition state 3 to generate the intermediate 4. This process involves the matching of the anionic ligand (Y) with the cationic α,α-difluorinated position of the alkene, which generates an intermediate metalalkyl bearnig two βfluoride atoms. Subsequent β-fluoride elimination generates [a] S.Scheme 3. Plausible mechanism for defluoroborylation of aliphatic gem-difluoroalkenes. Scheme 4. CÀ F Bond borylation of gem-difluoroalkenes. Scheme 5. Copper-catalyzed trans-selective monodefluoroborylation of various gem-difluoroalkenes. Scheme 6. CÀ F Bond borylation of gem-difluoroalkenes. Scheme 7. Copper-catalyzed tunable multi-borylation reactions of gem-difluoroalkenes. In parentheses the ratio of 22, 23 and 24 is reported. Scheme 8. Stereoselective defluorinative borylation and silylation of gem-difluoroalkenes. Scheme 9. a) Synthesis of fluorinated vinylsilanes from gem-difluoro/ polyfluoroalkenes. b) Cross-coupling reaction of 29 b and iodobenzene. Scheme 10. Nickel-catalyzed fluoroalkenylation of unactivated alkylbromides. rr = The regioisomeric ratio of the benzylic fluoroÀ alkenylation product to the other regioisomers. DMA = N,N-Dimethylacetamide. Scheme 14. Iron-catalyzed defluorinative cross-coupling of donor alkenes with gem-difluoroalkenes. Dibm = diisobutyrylmethane. Scheme 15. Nickel-catalyzed reductive aryl monofluoroalkenylation of alkenes. Scheme 16. Plausible mechanism for reductive aryl monofluoroalkenylation of gem-difluoroalkenes. Scheme 17. Nickel-catalyzed hydroalkenylation of alkynes through oxidative cyclization and β-fluoride elimination. Scheme 28. Ruthenium-catalyzed fluoroal...

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“…Pioneering studies to obtain alkyl-substituted monofluoroalkenes were focused on classical olefination (Wittig, Horner-Wadsworth-Emmons or Julia Kocienski reaction) [11,12], electrophilic fluorination or fluorination of alkynes [13][14][15][16]. More recently, transition metal-catalyzed defluorinative alkylation of gem-difluoroalkenes [17][18][19][20][21] or gem-difluorocyclopropanes [22][23][24] with various carbon nucleophiles has proven to be efficient strategies to access alkylated monofluoroalkenes. In the meantime, photoredox monofluoroalkenylation of gem-difluoroalkenes has also been successfully applied for their syntheses [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed Cross-Coupling of Gem-Bromofluoroalkenes with Alkylboronic Acids for the Synthesis of Alkylated Monofluoroalkenes

2020

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Monofluoroalkenes are versatile fluorinated synthons in organic synthesis, medicinal chemistry and materials science. In light of the importance of alkyl-substituted monofluoroalkenes efficient synthesis of these moieties still represents a synthetic challenge. Herein, we described a mild and efficient methodology to obtain monofluoroalkenes through a stereospecific palladium-catalyzed alkylation of gem-bromofluoroalkenes with primary and strained secondary alkylboronic acids under mild conditions. This novel strategy gives access to a wide range of functionalized tri- and tetrasubstituted monofluoroalkenes in high yield, with good functional group tolerance, independently from the gem-bromofluoroalkenes geometry.

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Synthesis of Alkylated Monofluoroalkenes via Fe-Catalyzed Defluorinative Cross-Coupling of Donor Alkenes with gem-Difluoroalkenes

Cited by 94 publications

References 55 publications

Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

Recent Advances in Transition Metal‐Catalyzed Functionalization of gem‐Difluoroalkenes

Palladium-Catalyzed Cross-Coupling of Gem-Bromofluoroalkenes with Alkylboronic Acids for the Synthesis of Alkylated Monofluoroalkenes

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