Synthesis of Fluorinated Benzo[a]quinolizidines <i>via</i> Visible Light‐induced Tandem Substitution of Two Fluorine Atoms in a CF<sub>3</sub> Group

Chen, Haoguo; Xiao, Tiebo; Li, Linyong; Anand, Devireddy; He, Yuwei; Zhou, Lei

doi:10.1002/adsc.201700852

Cited by 57 publications

(20 citation statements)

References 62 publications

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“…Interesting results were obtained for the substrates ( 5ag and 5ah ) containing tertiary and primary or secondary alkyl bromides (Scheme 1, eqn (2)). Cyclization products (as the sole product for 5ag and the main product for 5ah ) were generated firstly through allylic defluorinative alkylation of the tertiary alkyl bromide and then intramolecular cyclization at the primary or secondary sites 18. Finally, using a trifluoromethyl alkene containing an acrylamide ( 1u ) provided a mixture of mono-alkylation ( 3uba , defluorinative alkylation) and di-alkylation ( 3ubb , defluorinative alkylation and Giese addition) products (Scheme 1, eqn (3)) 19…”

Section: Resultsmentioning

confidence: 99%

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

et al. 2019

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Section: Resultsmentioning

confidence: 99%

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

et al. 2019

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“…As described in Section 3, gem-difluoroalkens can also undergo defluorinative coupling with radical precursors under visible light conditions. We have previously reported the [3 + 3] annulation of trifluoromethyl alkenes with tertiary amines [88], or dihydroisoquinoline acetic acids [89] via dual C-F bond cleavage in a CF 3 group using a single photocatalyst. However, this protocol was limited to the synthesis of N-containing heterocyclic compounds because α-aminoalkyl radicals are necessary intermediates for both steps of C-F bond cleavage.…”

Section: Trifluoromethyl Alkenesmentioning

confidence: 99%

Recent Advances in C-F Bond Cleavage Enabled by Visible Light Photoredox Catalysis

Zhou

2021

Molecules

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The creation of new bonds via C-F bond cleavage of readily available per- or oligofluorinated compounds has received growing interest. Using such a strategy, a myriad of valuable partially fluorinated products can be prepared, which otherwise are difficult to make by the conventional C-F bond formation methods. Visible light photoredox catalysis has been proven as an important and powerful tool for defluorinative reactions due to its mild, easy to handle, and environmentally benign characteristics. Compared to the classical C-F activation that proceeds via two-electron processes, radicals are the key intermediates using visible light photoredox catalysis, providing new modes for the cleavage of C-F bonds. In this review, a summary of the visible light-promoted C-F bond cleavage since 2018 was presented. The contents were classified by the fluorosubstrates, including polyfluorinated arenes, gem-difluoroalkenes, trifluoromethyl arenes, and trifluoromethyl alkenes. An emphasis is placed on the discussion of the mechanisms and limitations of these reactions. Finally, my personal perspective on the future development of this rapidly emerging field was provided.

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“…In another report, a photocatalytic reaction of dihydroisoquinoline acetic acids (151) and α-trifluoromethyl alkenes (152) formed a variety of benzo[a]quinolizidines (154) (Scheme 43). [40] By the action of visible light and a Ir III photocatalyst, dihydroisoquinoline acetic acids (151) underwent oxidative decarboxylation process to form α-amino radical 155, which reacted with trifluoromethyl alkenes (152) to form α-CF 3 radical intermediate 156. Reduction of 156 by Ir III produced α-CF 3 anion 157, which in turn eliminated one F À and formed the gem-difluoroalkene intermediate 153.…”

Section: Synthesis Of Heterocyclesmentioning

confidence: 99%

“…In another report, a photocatalytic reaction of dihydroisoquinoline acetic acids ( 151 ) and α ‐trifluoromethyl alkenes ( 152 ) formed a variety of benzo[ a ]quinolizidines ( 154 ) (Scheme ) …”

Section: Annulation Reactionsmentioning

confidence: 99%

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

Koley

Altman

2020

Israel Journal of Chemistry

131

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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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Synthesis of Fluorinated Benzo[a]quinolizidines via Visible Light‐induced Tandem Substitution of Two Fluorine Atoms in a CF₃ Group

Cited by 57 publications

References 62 publications

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Recent Advances in C-F Bond Cleavage Enabled by Visible Light Photoredox Catalysis

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

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Synthesis of Fluorinated Benzo[a]quinolizidines via Visible Light‐induced Tandem Substitution of Two Fluorine Atoms in a CF3 Group

Cited by 57 publications

References 62 publications

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Recent Advances in C-F Bond Cleavage Enabled by Visible Light Photoredox Catalysis

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

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Synthesis of Fluorinated Benzo[a]quinolizidines via Visible Light‐induced Tandem Substitution of Two Fluorine Atoms in a CF₃ Group