Metal-Free sp3 C-SCF3 Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate

Zhao, Xia; Tian, Miaomiao; Ji, Liangshuo; Liu, Junjie; Lu, Kui

doi:10.1021/acs.orglett.9b04343

Cited by 26 publications

(31 citation statements)

References 48 publications

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“…When the 1-(2-(4-methoxyphenyl)ethyl)cyclobutanol (42c) was used as a substrate, the fluorinated product (43c) was obtained in a 40% yield. The reaction was also tolerant to the benzocyclobutenol (44) and the fluorinated ketone (45) was selectively obtained in an efficient manner (85% yield). The authors suggested a radical-type mechanism for the synthesis of 43.…”

Section: Fluorination Reactionsmentioning

confidence: 99%

“…In 2020, Zhao and co-workers reported the synthesis of trifluoromethylthiolated nitriles at the -and -positions. [45] Taking benefit from -fragmentation reactivity of constrained cyclic compounds, a metal-free process based on the trifluoromethylthiolation of cycloalkanone oxime esters was developed. Similarly to the work of Hu and Shen, the S-(trifluoromethyl)-4-methylbenzenesulfonothioate (TolSO2SCF3) was used as the SCF3 source.…”

Section: Trifluoromethylthiolation Reactionsmentioning

confidence: 99%

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Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

2021

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Due to their unique properties, fluorinated scaffolds are pivotal compounds in pharmaceuticals, agrochemicals and materials science. Over the last years, the development of versatile strategies for the selective synthesis of fluorinated molecules by direct C−H bond functionalization has attracted a lot of attention. In particular, the design of novel transformations based on a radical process was a bottleneck for the distal C−H functionalization reactions, offering synthetic solutions for the selective introduction of a fluorinated group. This Minireview highlights the major contributions that have been made in this blossoming field. The development of new methodologies for the remote functionalization of aliphatic derivatives with various fluorinated groups based on a 1,5-HAT process and a -fragmentation reaction will be mainly showcased and discussed.Scheme 3. Synthesis of -fluorinated ketone derivatives via an iminyl radical generated by a photoredox process. Acr + -Mes ClO4 -= 9-mesityl-10methylacridinium perchlorate. Boc = tert-butyloxycarbonyl.Aiming at developing a general approach, the same group showed that changing the nature of the nitrogen radical, from iminyl radicals to amidyl ones, the fluorination of remote tertiary, secondary and primary C−H bonds was possible (Scheme 4, 31 examples, up to 89% yield). [11] Using an Ir (III) catalyst, in the presence of Selectfluor along with cesium carbonate, an access to fluorinated amide derivatives at the -position was developed starting from the corresponding carboxylic acid precursors 3. The reaction proved to be efficient for the remote fluorination of tertiary (3a), secondary (3b), and primary (3c) C(sp 3 ) centers leading to the corresponding fluorinated N-methyl amides (4a-c). Note that the fluorination of a benzylic position was possible and the compound 4d was synthesized in a good yield. The transformation was not limited to the functionalization of N-methyl amides as the -fluorinated N-benzyl amide (4e) or the primary amide (4f) were successfully obtained. This distal fluorination was efficient on amides containing cycloalkyls (3g-i), offering an access to potentially interesting bioactive building blocks such as a N-Boc-piperidine (4i). The methodology was extended to the selective latestage remote fluorination of protected-amino acid derivatives (3j and 3k) and the dipeptide building block 3l. Furthermore, the transformation was not restricted to amide derivatives as the synthesis of fluorinated carbamate (4m) and N-protected amines (4n-p) at the -and -positions, respectively, was also possible. When the amide (3q) or the carbamate (3r) bearing a competitive tertiary center at the -position was used, the fluorination at this position was preferentially achieved via a 1,6-HAT process. [12] However, in case of the N-Boc-protected amine 3s, a mixture of fluorinated products (4s and 4s') at the -and -positions was obtained in a 1:1 ratio, presumably due to a higher chain flexibility. The following mechanism was suggested: under basic conditi...

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Section: Fluorination Reactionsmentioning

confidence: 99%

Section: Trifluoromethylthiolation Reactionsmentioning

confidence: 99%

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

2021

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“…In 2020, Zhao and co‐workers reported the synthesis of trifluoromethylthiolated nitriles at the γ‐ and δ‐positions [45] . Taking advantage of the β‐fragmentation reactivity of constrained cyclic compounds, a metal‐free process based on the trifluoromethylthiolation of cycloalkanone oxime esters was developed.…”

Section: Remote Functionalization Via β‐Fragmentationmentioning

confidence: 99%

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

2021

View full text Add to dashboard Cite

Due to their unique properties, fluorinated scaffolds are pivotal compounds in pharmaceuticals, agrochemicals, and materials science. Over the last years, the development of versatile strategies for the selective synthesis of fluorinated molecules by direct C−H bond functionalization has attracted a lot of attention. In particular, the design of novel transformations based on a radical process was a bottleneck for distal C−H functionalization reactions, offering synthetic solutions for the selective introduction of fluorinated groups. This Minireview highlights the major contributions in this blossoming field. The development of new methodologies for the remote functionalization of aliphatic derivatives with various fluorinated groups based on a 1,5‐hydrogen atom transfer process and a β‐fragmentation reaction will be showcased and discussed.

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“…Recently, Lu and co‐workers demonstrated a metal‐free coupling of cycloketone oxime esters 115 with S ‐trifluoromethyl 4‐methylbenzenesulfonothioate 116 in DMAc at 100 °C, providing a versatile route to SCF 3 ‐substituted nitriles 117 (Scheme 41). [53] Mechanistically, DMAc was regarded as the reductant to initiate the iminyl radical formation. Moreover, EtOH played a vital role in the transformation by trapping the sulfonyl cation.…”

Section: Dmac/b2(oh)4 or Dmac‐promoted Cross‐coupling Reactionsmentioning

confidence: 99%

Recent Developments in Radical Cross‐Coupling of Redox‐Active Cycloketone Oximes

2020

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Recent years have witnessed a renaissance of radical cross‐coupling of cycloketone oximes which served as active cyanoalkyl radical via ring fragmentation in various transformations. It provided an efficient and practical strategy to introduce cyanoalkyl groups into organic compounds without using toxic cyanide sources. In this review, a comprehensive overview of recent advances in the field of redox‐active cycloketone oximes‐based cross‐couplings were covered. This review was categorized into two broad parts: non‐photocatalyzed and photocatalyzed cross‐couplings according to the reaction conditions. Moreover, the two broad parts were further divided into several sub‐sections depending on the nature of the bond formation. Some representative examples along with reaction mechanisms were also discussed.

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Metal-Free sp³ C-SCF₃ Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate

Cited by 26 publications

References 48 publications

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

Recent Developments in Radical Cross‐Coupling of Redox‐Active Cycloketone Oximes

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Metal-Free sp3 C-SCF3 Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate

Cited by 26 publications

References 48 publications

Radical‐Promoted Distal C−H Functionalization of C(sp3) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp3) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp3) Centers with Fluorinated Moieties

Recent Developments in Radical Cross‐Coupling of Redox‐Active Cycloketone Oximes

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Metal-Free sp³ C-SCF₃ Coupling Reactions between Cycloketone Oxime Esters and S-trifluoromethyl 4-Methylbenzenesulfonothioate

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties

Radical‐Promoted Distal C−H Functionalization of C(sp³) Centers with Fluorinated Moieties