- Solvent-Free Fluorination of Electron-Rich Aromatic Compounds with F-TEDA-BF4: Toward “Dry” Processes
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An effective protocol for the solvent-free fluorination of electron-rich aromatic compounds with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (F-TEDA-BF4) is described. The protocol allows the easy and efficie
- Zaikin, Pavel A.,Dyan, Ok Ton,Evtushok, Darya V.,Usoltsev, Andrey N.,Borodkin, Gennady I.,Karpova, Elena V.,Shubin, Vyacheslav G.
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p. 2469 - 2474
(2017/05/12)
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- Fluorination of 4-alkyl-substituted phenols and aromatic ethers with fluoroxy and N-F reagents: Cesium fluoroxysulfate and N-fluoro-1,4-diazonia- bicyclo[2.2.2]octane dication salts case Dedicated to Prof. Dr. Boris ?emva in honor to his great contribution to fluorine chemistry.
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4-Alkyl-substituted phenols and aromatic ethers were comparatively fluorinated with electrophilic fluorinating reagents such as cesium fluoroxysulfate (CFS), Selectfluor F-TEDA-BF4, and Accufluor NFTh in MeCN or MeOH. Reactions resulted in the formation of three types of products: 2-fluoro-4-alkyl-substituted corresponding compounds (5) as a result of ortho fluorination process, 4-alkyl-4-fluoro-cyclohexa-2,5- dienone compounds (6), resulting after an addition-elimination process, and 4-fluorosubstituted corresponding compounds (7) derived from ipso attack and release of the 4-alkyl group. The distribution of products depends on the bulkiness of alkyl groups at both positions and reaction media. The reaction in methanol proved more selective toward the formation of 2-fluoro derivatives. Tyramin and l-tyrozine were transformed with NFTh reagent in methanol to their fluorophenyl-substituted derivatives in good yield.
- Pravst, Igor,Stavber, Stojan
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p. 276 - 282
(2014/01/06)
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- 4-Fluorocyclohexa-2,5-dienones as new acceptors for the Hauser annulation
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4-Fluorocyclohexa-2,5-dienones are introduced as new acceptors for the Hauser annulation. In cases where the corresponding methoxy analogs fail to undergo annulation, the former smoothly do so with phenylsulfonyl phthalides to furnish anthraquinones in go
- Pahari, Pallab,Senapati, Bidyut,Mal, Dipakranjan
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p. 2635 - 2638
(2007/10/03)
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- The role of F-N reagent and reaction conditions on fluoro functionalisation of substituted phenols
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The effect of steric interactions on the regioselectivity of fluorination of para alkyl substituted phenols was investigated and the strong effect of size of the alkyl substituent, the structure of the F-N reagent and the solvent on the site of fluorination was established. The course of reaction obeyed a second order rate equation, while the fluorination process required higher ΔH≠ activation than oxidation or oxidative demethylation. Solvent polarity variations had a small effect on the rate of functionalisation, while an excellent Hammett correlation with ρ+=-2.3 was determined.
- Pravst, Igor,Iskra, Maja Pape?,Jereb, Marjan,Zupan, Marko,Stavber, Stojan
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p. 4474 - 4481
(2007/10/03)
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- Efficient oxidative ipso-fluorination of para-substituted phenols using pyridinium polyhydrogen fluoride in combination with hypervalent iodine(III) reagents
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Diacetoxyiodobenzene (PIDA) and bis(trifluoroacetoxy)iodobenzene (PIFA) in the presence of pyridinium polyhydrogen fluoride (PPHF) are effective for the fluorination of para-substituted phenols to give a variety of 4-fluorocyclohexa-2,5-dienones in a good yield. (R,S)-1,1′-Bi-5,6,7,8- tetrahydro-2-naphthol (and its monoacetate) yields atropoisomeric fluorocyclohexadienones. The 4-substituted carbamate open-chain phenols were readily converted to fluorohydroindolenone and fluorohydroquinolenone derivatives by intramolecular conjugate addition.
- Karam, Omar,Martin-Mingot, Agnès,Jouannetaud, Marie-Paule,Jacquesy, Jean-Claude,Cousson, Alain
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p. 6629 - 6638
(2007/10/03)
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- Efficient synthesis of 4-fluorocyclohexa-2,5-dienone derivatives using n-fluoro-1,4-diazoniabicyclo[2.2.2]octane salt analogues
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4-Fluorocyclohexa-2,5-dienone derivatives were obtained in high yield by reaction of para substituted phenols with 1-fluoro-4-chloromethyl-1,4- diazoniabicyclo[2.2.2]octane bis(tetra-fluoro-borate) (1a, Selectfluor(TM) F- TEDA-BF4) or its 4-hyd
- Stavber, Stojan,Jereb, Marjan,Zupan, Marko
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p. 1375 - 1378
(2007/10/03)
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- Nucleophilic para-fluorination of 4-alkylphenols by hypervalent iodine reagent and pyridinium polyhydrogen fluoride (PPHF) a novel route to 4-fluorocyclohexa-2,5-dienones
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Ipso-fluorination of 4-alkylphenols with C6H5-I(OCOCF3)2-pyridinium polyhydrogen fluoride (PPHF) yields 4-fluorocyclohexa-2,5-dienones.
- Karam, Omar,Jacquesy, Jean-Claude,Jouannetaud, Marie-Paule
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p. 2541 - 2544
(2007/10/02)
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- Substituent modulation of mild fluorination of aromatic molecules with caesium fluoroxysulphate
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Functionalization of mono- and di-substituted benzene derivative with CsSO4F has been modulated by substituents on the benzene ring. α-Hydroxyalkylbenzenes, with a deactivated ring, were oxidized to phenones, while fluorodealkylation was achieved in high yield when electron-donating groups were present in a para position. Electron-withdrawing substituents favoured chain fluorofunctionalization in alkylbenzenes, while ring fluorination was found exclusively in acylamino-derivatized alkylbenzenes; fluoro-addition products were formed in the case of p-alkoxy-substituted alkylbenzene derivatives.
- Stavber, Stojan,Planinsek, Zdenka,Kosir, Iztok,Zupan, Marko
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p. 409 - 412
(2007/10/02)
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- Preparation of 4,4-disubstituted cyclohexadienones
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The invention provides a process for the preparation of 4,4-disubstituted cyclohexadienones of which at least one of the substituents is fluorine, which comprises reacting a compound of formula STR1 wheren X represents a hydrogen or halogen atom or an alk
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- DIRECT FLUORINATION OF PHENOL AND CRESOLS
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A study has been made of the reaction of phenol with elemental fluorine using a variety of solvents and reaction temperatures.Yields of o- and p-fluorophenol were obtained as high as 85percent.The isomer ratio changed drastically between phenol conversions of 10percent and 56percent.The o-isomer changed to unidentified polymeric substances at higher conversion, but it might also be assumed that interconversion of some isomers is occuring.The three cresols have also been succesfully fluorinated with elemental fluorine. p-Cresol gave some expected 2-fluoroderivative but also formed a fluorocyclohexadienyl ketone.
- Misaki, Susumu
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p. 159 - 172
(2007/10/02)
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