Hypervalent Iodine-Promoted α-Fluorination of Acetophenone Derivatives with a Triethylamine·HF Complex

Kitamura, Tsugio; Muta, Kensuke; Muta, Kazutaka

doi:10.1021/jo500691b

Cited by 42 publications

(16 citation statements)

References 40 publications

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“…Moreover, elegant studies by Hara and co-workers have demonstrated that α-fluoroketones could be prepared by exposing silyl enol ethers to stoichiometric p -ToIIF 2 , in the presence of BF 3 ·OEt 2 and NEt 3 /HF 1:2 [ 38 ]. A report by Kitamura and co-workers in which the direct fluorination of acetophenone derivatives was achieved using iodosylarenes and commercially available NEt 3 /HF 1:5 to generate the ArIF 2 species in situ is also highly pertinent [ 39 – 40 ] ( Fig. 1 ).…”

Section: Introductionmentioning

confidence: 99%

Fluorohydration of alkynes via I(I)/I(III) catalysis

Neufeld¹,

Daniliuc²,

Gilmour³

2020

Beilstein J. Org. Chem.

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Substrate specificity is ubiquitous in biological catalysis, but less pervasive in the realm of small-molecule catalysis. Herein, we disclose an intriguing example of substrate specificity that was observed whilst exploring catalysis-based routes to generate α-fluoroketones from terminal and internal alkynes under the auspices of I(I)/I(III) catalysis. Utilising p-TolI as an inexpensive organocatalyst with Selectfluor® and amine/HF mixtures, the formation of protected α-fluoroketones from simple alkynes was realised. Whilst the transient p-TolIF2 species generated in situ productively engaged with pentynyl benzoate scaffolds to generate the desired α-fluoroketone motif, augmentation or contraction of the linker suppressed catalysis. The prerequisite for this substructure was established by molecular editing and was complemented with a physical organic investigation of possible determinants.

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Section: Introductionmentioning

confidence: 99%

Fluorohydration of alkynes via I(I)/I(III) catalysis

Neufeld¹,

Daniliuc²,

Gilmour³

2020

Beilstein J. Org. Chem.

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“…Based on the results of the above control experiments as well as the previous reports,, we postulated a plausible mechanistic pathways for this PhIO/Et 3 N ⋅ 3HF‐mediated tandem oxidation reaction, described in Scheme . Initially, the reaction between PhIO and Et 3 N ⋅ 3HF gave PhIF 2 species, which reacts with the enamine substrate 1 to give the α ‐iodo imine B .…”

Section: Methodsmentioning

confidence: 57%

PhIO/Et₃N ⋅ 3HF‐Mediated Formation of Fluorinated 2H‐Azirines via Domino Fluorination/Azirination Reaction of Enamines

et al. 2018

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A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H-azirines through reactions with PhIF 2 generated in situ by PhIO and Et 3 N · 3HF in 1,2-dichroloethane, which features the hypervalent iodine reagents-mediated introduction of fluorine atom and formation of the 2H-azirine skeleton under metal-free conditions. The domino reaction is postulated to proceed via a PhIF 2mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates.

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“…[22] First, PhIO is activated by Et 2 O • BF 3 to form an iodine(III) intermediate (50), which reacts with 48 a to give an iodonium intermediate (51), followed by intramolecular nucleophilic attack of the amino group to generate 52. Then, the hypervalent iodine(III) intermediate (52) undergoes reductive elimination to afford a cyclic carbocation intermediate (53). Subsequent combination of 53 with the in situ generated fluoride provides the final product (49 a).…”

Section: Amino- Oxy-or Carbofluorination Of Alkenesmentioning

confidence: 99%

“…Likewise, direct fluorination of acetophenone derivatives, acetonaphthones, benzyl phenyl ketone, propiophenone, butyrophenone, 1‐indanone, and phenacyl chloride ( 145 ) with iodosylarenes and TEA ⋅ 5HF (TEA=Et 3 N) gave selectively the corresponding α‐fluoroketone derivatives ( 146 ) in good yields (Scheme ) . The use of easily available iodosylarenes and a safer TEA ⋅ 5HF complex led to a greener fluorination reaction.…”

Section: Fluorination Mediated By Hypervalent Iodine Reagentsmentioning

confidence: 99%

Fluorination and Fluoroalkylation Reactions Mediated by Hypervalent Iodine Reagents

Han

Zhang

2020

Adv Synth Catal

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This review summarizes the progress in the fluorination and fluoroalkylation of electron-rich systems with diverse fluorine (F) and fluoroalkyl (R fn) reagents employing hypervalent iodine compounds as initiators in the last few decades. Because of the strong electrophilicity, high oxidizing properties, low toxicity, air and moisture stability, ready availability, ease of handling, and mild reaction conditions, the hypervalent iodine reagents have been widely utilized in modern organic chemistry. In particular, the use of hypervalent iodine reagents to initiate the CÀ F and CÀ R fn (R fn =CF 2 H, CF 3 , perfluoroalkyl, OCH 2 CF 3 , SCF 3 , SeCF 3 and etc) bond formation has been increasingly developed. In these reactions, hypervalent iodine compounds behave as powerful oxidants or electrophiles and activate the fluorination/fluoroalkylation reagents, the transitionmetal catalysts, or the substrates to in situ form electrophilic or radical intermediates, which subsequently participate in fluorination, difluoromethylation, trifluoromethylation, perfluoroalkylation, trifluoroethoxylation, fluoroalkylthiolation, trifluoromethylselenolation and others under mild conditions. Although great achievements have been made in this area, they are just the initial phase and still require a wide scope for improvement. It is anticipated that this review will draw much attention from the organic chemistry community and inspire more contributions in the development of new hyper-valent-iodine-mediated fluorination and fluoroalkylation reactions.

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Hypervalent Iodine-Promoted α-Fluorination of Acetophenone Derivatives with a Triethylamine·HF Complex

Cited by 42 publications

References 40 publications

Fluorohydration of alkynes via I(I)/I(III) catalysis

Fluorohydration of alkynes via I(I)/I(III) catalysis

PhIO/Et₃N ⋅ 3HF‐Mediated Formation of Fluorinated 2H‐Azirines via Domino Fluorination/Azirination Reaction of Enamines

Fluorination and Fluoroalkylation Reactions Mediated by Hypervalent Iodine Reagents

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Hypervalent Iodine-Promoted α-Fluorination of Acetophenone Derivatives with a Triethylamine·HF Complex

Cited by 42 publications

References 40 publications

Fluorohydration of alkynes via I(I)/I(III) catalysis

Fluorohydration of alkynes via I(I)/I(III) catalysis

PhIO/Et3N ⋅ 3HF‐Mediated Formation of Fluorinated 2H‐Azirines via Domino Fluorination/Azirination Reaction of Enamines

Fluorination and Fluoroalkylation Reactions Mediated by Hypervalent Iodine Reagents

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PhIO/Et₃N ⋅ 3HF‐Mediated Formation of Fluorinated 2H‐Azirines via Domino Fluorination/Azirination Reaction of Enamines