C5-Regioselective C–H fluorination of 8-aminoquinoline amides and sulfonamides with Selectfluor under metal-free conditions

Zhang, Yingchao; Chen, Wen; Li, Ji‐Zhen

doi:10.1039/c7ob03059b

Cited by 34 publications

(15 citation statements)

References 61 publications

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“…This indicates that fluorination presumably occurred via SET. Based on literature evidence [21,24] and our results, we assume that the homolytic cleavage of the N–F bond results in a fluorine radical and cationic nitrogen radical 2A . The latter is protonated and intermediate 7R is formed.…”

Section: Resultssupporting

confidence: 52%

“…Different results have been observed with the same radical probe in different solvents. However, the ability of Selectfluor for homolytic cleavage of its N–F bond has recently been proved by Zhang et al, who detected the adduct of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) and the fluorine radical by LC-MS and F-NMR [24]. Based on these literature results, we investigated the mechanism of fluorination in acetonitrile and methanol by adding a radical scavenger to the reaction mixture (Scheme 5, Table 1, Entries 3, 6, 9, 12).…”

Section: Resultsmentioning

confidence: 99%

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Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors

et al. 2019

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Fluorination of 13-epimeric estrones and their 17-deoxy counterparts was performed with Selectfluor as the reagent. In acetonitrile or trifluoroacetic acid (TFA), 10β-fluoroestra-1,4-dien-3-ones were formed exclusively. Mechanistic investigations suggest that fluorinations occurred via SET in acetonitrile, but another mechanism was operative in TFA. Simultaneous application of N-chlorosuccinimide (NCS) and Selectfluor in TFA led to a 1.3:1 mixture of 10β-fluoroestra-1,4-dien-3-one and 10β-chloroestra-1,4-dien-3-one as the main products. The potential inhibitory action of the 10-fluoro- or 10-chloroestra-1,4-dien-3-one products on human aromatase was investigated via in vitro radiosubstrate incubation. The classical estrane conformation with trans ring anellations and a 13β-methyl group seems to be crucial for the inhibition of the enzyme, while test compounds bearing the 13β-methyl group exclusively displayed potent inhibitory action with submicromolar or micromolar IC50 values. Concerning molecular level explanation of biological activity or inactivity, computational simulations were performed. Docking studies reinforced that besides the well-known Met374 H-bond connection, the stereocenter in the 13 position has an important role in the binding affinity. The configuration inversion at C-13 results in weaker binding of 13α-estrone derivatives to the aromatase enzyme.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors

et al. 2019

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“…Since 2015, many papers supporting either SET or S N 2 mechanisms have appeared, including those reported by C. Liu et al (SET) in 2015 [ 154 ], Chen et al (S N 2) in 2016 [ 155 ], Tang et al (SET) in 2016 [ 156 ], F. Liu et al (SET) in 2016 [ 157 ] and 2017 [ 158 ], Mayr et al (S N 2) in 2018 [ 137 ], Hodgson et al (S N 2) in 2018 [ 138 ], Li et al (SET) in 2018 [ 159 ], Shi et al (SET) in 2018 [ 160 ], Li et al (SET) in 2019 [ 161 ], Mernyak et al (SET) in 2019 [ 162 ], and Nelson et al (S N 2) in 2019 [ 163 ].…”

Section: Reviewmentioning

confidence: 99%

Development of N-F fluorinating agents and their fluorinations: Historical perspective

Umemoto¹,

Yang²,

Hammond³

2021

Beilstein J. Org. Chem.

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This review deals with the historical development of all N-F fluorinating agents developed so far. The unique properties of fluorine make fluorinated organic compounds attractive in many research areas and therefore fluorinating agents are important. N-F agents have proven useful by virtue of their easy handling. This reagent class includes many types of N-F compounds: perfluoro-N-fluoropiperidine, N-fluoro-2-pyridone, N-fluoro-N-alkylarenesulfonamides, N-fluoropyridinium salts and derivatives, N-fluoroquinuclidium salts, N-fluoro-trifluoromethanesulfonimide, N-fluoro-sultams, N-fluoro-benzothiazole dioxides, N-fluoro-lactams, N-fluoro-o-benzenedisulfonimide, N-fluoro-benzenesulfonimide, 1-alkyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluoropyridinium-2-sulfonate derivatives, 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane salts, N-fluorodinitroimidazole, N-fluoro-trichloro-1,3,5-triazinium salt, N-F ethano-Tröger’s base derivatives, N-fluoro-methanesulfonimide, N-fluoro-N-arylarenesulfonamides, bisN-F salts such as N,N’-difluorobipyridinium salts and N,N’-difluoro-1,4-diazoniabicyclo[2.2.2]octane salts, and their many derivatives and analogs, including chiral N-F reagents such as optically active N-fluoro-sultam derivatives, N-fluoro-alkaloid derivatives, DABCO-based N-F derivatives, and N-F binaphthyldisulfonimides. The synthesis and reactions of these reagents are described chronologically and the review also discusses the relative fluorination power of each reagent and their mechanisms chronicling developments from a historical perspective.

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“…In our previous study, an efficient and facile metal-free process for the remote C-H bond uorination of 8-aminoquinoline scaffolds at the C5 position using Selectuor (1-chloromethyl-4-uoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrauoroborate)) was developed. 5 8 Also, a C-O cross-coupling reaction in the absence of metals was developed by Yao et al 9 Besides, the metal-free C5 tri-uoromethylation reactions were successively realized by Wu et al, 10 Kuninobu et al 11 and Tian et al 12 These studies inspired us to realize the metal-free and site-selective C-H functionalization of 8-aminoquinoline and aniline-derived amides without the assistance of metal catalysts.…”

Section: Introductionmentioning

confidence: 99%

Metal-free site-selective C–H cyanoalkylation of 8-aminoquinoline and aniline-derived amides with azobisisobutyronitrile

et al. 2021

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C5-Regioselective C–H fluorination of 8-aminoquinoline amides and sulfonamides with Selectfluor under metal-free conditions

Cited by 34 publications

References 61 publications

Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors

Synthesis, Biological Evaluation and Docking Studies of 13-Epimeric 10-fluoro- and 10-Chloroestra-1,4-dien-3-ones as Potential Aromatase Inhibitors

Development of N-F fluorinating agents and their fluorinations: Historical perspective

Metal-free site-selective C–H cyanoalkylation of 8-aminoquinoline and aniline-derived amides with azobisisobutyronitrile

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