- Elemental fluorine, Part 23: Direct fluorination of β-ketoesters as an approach to enantioselective fluorination
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Attempts to develop a direct enantioselective fluorination protocol using elemental fluorine and an appropriate Lewis acid and chiral ligand system are described.
- Chambers, Richard D.,Nakano, Takashi,Okazoe, Takashi,Sandford, Graham
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- Alkylation and decarboxylation of ethyl 2-fluoro-3-oxobutanoate as a route to functionalised α-fluoro-ketones
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Alkylation and decarboxylation of α-fluoro-β-ketoesters such as ethyl 2-fluoro-3-oxobutanoate offers a versatile route to a range of fluoro-ketoalkenes, demonstrating the synthetic utility of using α-fluoro-β-ketoesters as synthons for the preparation of synthetically more sophisticated selectively fluorinated systems.
- Hutchinson,Sandford, Graham,Vaughan, Julian F.S.
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- Direct fluorination of 1,3-dicarbonyl compounds
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In acid media, 1,3-diketones and 1,3-keloesters can be fluorinated in high yield and often with high conversion mainly to the corresponding 2-fluoro- compounds. Diesters such as diethyl malonate do not react with fluorine under the same reaction conditions. The mechanism of these reactions has been investigated and while the identity of the electrophilic fluorinating species is uncertain, we believe that the essential features of the reaction pathway are understood. Copyright
- Chambers, Richard D.,Greenhall, Martin P.,Hutchinson, John
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- NEW FLUORINATING REAGENTS - I. THE FIRST ENANTIOSELECTIVE FLUORINATION REACTION
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Crystalline, optically pure N-fluoro sultams (-)-3 and (+)-5 are the first examples of enantioselective fluorinating reagents.Thus unprecedented enantiomeric excesses up to 70 percent are observed when various prochiral metal enolates are fluorinated by u
- Differding, Edmond,Lang, Robert W.
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- Chiral 1H NMR Analysis of Carbonyl Compounds Enabled by Cationic Cobalt Complex
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We report a newly prepared cationic cobalt(III) complex as a general and efficient chiral solvating agent that discriminates carbonyl compounds including esters, amides, ketones, and aldehydes. This cobalt(III) complex was further utilized to directly analyze both the conversion and the enantiomeric excess at once in the asymmetric fluorination.
- Jang, Sumin,Kim, Hyunwoo
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supporting information
(2020/06/04)
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- Reagent-controlled enantioselectivity switch for the asymmetric fluorination of β-ketocarbonyls by chiral primary amine catalysis
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A reagent-controlled enantioselectivity switch was uncovered in the asymmetric α-fluorination of β-ketocarbonyls by a chiral primary amine catalyst. By a simple swap of fluorination reagents, both enantiomers of the quaternary fluorination adducts could be obtained with good yields and high enantioselectivity. Mechanistic studies disclosed dual H-bonding and electrostatic stereocontrolling modes for the catalysis.
- You, Yang'en,Zhang, Long,Luo, Sanzhong
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p. 621 - 626
(2016/12/30)
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- Enantioselective fluorination of β-ketoesters using tartrate derived bidentate bioxazoline-Cu(II) complexes
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Enantioselective fluorination of aliphatic cyclic and acyclic β-ketoesters was achieved in excellent yield (up to 98%) with moderate to good enantioselectivities (up to 86% ee) using tartrate derived bidentate bioxazoline-Cu(II) complexes. This is the fir
- Balaraman, Kaluvu,Vasanthan, Ravichandran,Kesavan, Venkitasamy
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p. 919 - 924
(2013/09/23)
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- Substrate range of the titanium TADDOLate catalyzed asymmetric fluorination of activated carbonyl compounds
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The substrate range of the [TiCl2(TADDOLate)] (TADDOL=α,α,α′,α′-tetraaryl-1,3-dioxolane-4, 5-dimethanol)-catalyzed asymmetric α-fluorination of activated β-carbonyl compounds has been investigated. Optimal conditions for catalysis are characterized by using 5 mol-% of TiCl2(naphthalen-1- yl)-TADDOLate) as catalyst in a saturated (0.14 mol/l) MeCN solution of F-TEDA (1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis- [tetrafluoroborate]) at room temperature. A series of α-methylated β-keto esters (3-oxobutanoates, 3-oxopentanoates) with bulky benzyl ester groups (60-90% ee) or phenyl ester (67-88% ee) have been fluorinated readily, whereas α-acyl lactones were also readily fluorinated, but gave lower inductions (13-46% ee). Double stereochemical differentiation in β-keto esters with chiral ester groups raised the stereoselectivity to a diastereomeric ratio (dr) of up to 96.5:3.5. For the first time, β-keto S-thioesters were asymmetrically fluorinated (62-91.5% ee) and chlorinated (83% ee). Lower inductions were observed in fluorinations of 1,3-diketones (up to 40% ee) and β-keto amides (up to 59% ee). General strategies for preparing activated β-carbonyl compounds as important model substrates for asymmetric catalytic α-functionalizations are presented (>60 examples). Copyright
- Bertogg, Andreas,Hintermann, Lukas,Huber, Dominique P.,Perseghini, Mauro,Sanna, Maria,Togni, Antonio
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experimental part
p. 353 - 403
(2012/05/07)
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- Enantioselective α-fluorination and chlorination of β-ketoesters by cobalt catalyst
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We demonstrated the cobalt-catalyzed asymmetric a-fluorination and a-chlorination of β-ketoesters. Both reactions were achieved using a catalytic amount of Co(acac)2 with (R, R)Jacobsen's salen ligand; α-fluorinated or a-chlorinated products were thus obt
- Kawatsura, Motoi,Hayashi, Shunsuke,Komatsu, Yuji,Hayase, Shuichi,Itoh, Toshiyuki
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experimental part
p. 466 - 467
(2010/08/20)
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- Enantioselective halogenation of β-oxo esters catalyzed by a chiral sulfoximine-copper complex
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A C1-symmetric amino sulfoximine has been used as a chiral ligand in copper-catalyzed asymmetric halogenation reactions of β-oxo esters. Both the catalyst itself and the reaction conditions were optimized, and 26 fluorinated, chlorinated, and b
- Frings, Marcus,Bolm, Carsten
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supporting information; experimental part
p. 4085 - 4090
(2009/12/26)
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- Reactions of trifluoroamine oxide: A new method for selective fluorination of 1,3-diketones and β-ketoesters
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Fluorination of 1,3-diketones and β-ketoesters with trifluoroamine oxide in the presence of tetrabutylammonium hydroxide (TBAH) provides a one step route to mono- and difluoro-products selectively fluorinated at the α-position in good yields.
- Gupta, Om D.,Shreeve, Jean'ne M.
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p. 2799 - 2801
(2007/10/03)
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- Preparation of fluorinated dicarbonyls
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PCT No. PCT/GB94/02547 Sec. 371 Date Feb. 21, 1997 Sec. 102(e) Date Feb. 21, 1997 PCT Filed Nov. 18, 1994 PCT Pub. No. WO95/14646 PCT Pub. Date Jun. 1, 1995A method for the fluorination of 1,3-diketones and 1,3-ketoesters is disclosed.
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- Synthesis, Properties, and Reactivity of N,N'-Difluorobipyridinium and Related Salts and Their Applications as Reactive and Easy-To-Handle Electrophilic Fluorinating Agents with High Effective Fluorine Content
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N,N′-Difluoro-2,2′-, -2,4′-, -3,3′-, -4,4′-bipyridinium and substituted N,N′-difluoro-2,2′-bipyridinmm bis(triflates), bis(tetrafluoroborates), bis(hexafluorophosphates), and bis(hexafluoroantimonates) 1-9 were synthesized in high yields by the direct fluorination of a mixture of a bipyridyl and a Lewis acid, a Br?nsted acid, or the alkali metal salt of an acid. The higher homologues, trimer 10 and polymer 11, were also synthesized. Unsubstituted or electron-donating group-substituted N,N′- difluorobipyridinium salts are stable nonhygroscopic crystals, while the electron-withdrawing group- substituted N,N′-diflurobipyridinium salts 3, 5, and 6 are moisture-sensitive crystals. Hydrolysis of 1b in boiling water gave 3,3′-dihydroxy-2,2′-bipyridyl. The reactivity determination indicated that the fluorinating capability decreased in the order 2,2′- ? 2,4' > 3,3′- ≈ 4,4′-isomer ? N-fluoropyridinium salt and that the two N-F moieties in a molecule were effective for fluorination. This fluorination occurred in a step-by-step manner, and the reactivity difference between the first and second fluorinations was very small. N,N′-Difluoro-2,2′-bipyridinium bis(tetrafluoroborate) (1b) is thus shown to be a highly reactive and easy-to-handle electrophilic fluorinating agent with the high effective fluorine content (103.3 g/kg) for preparing many fluoro organic compounds.
- Umemoto, Teruo,Nagayoshi, Masayuki,Adachi, Kenji,Tomizawa, Ginjiro
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p. 3379 - 3385
(2007/10/03)
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- Elemental fluorine. Part 9 : Catalysis of the direct fluorination of 2-substituted carbonyl compounds
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Catalysis of the reaction between fluorine and a range of 2-substituted carbonyl compounds has been investigated. Most notably, the preparation of diethyl-2-fluoromalonate has been achieved in high yield by fluorination of diethylmalonate in the presence of hydrated copper nitrate. Reactions between fluorine and carbanions derived from 2-substituted carbonyl compounds, including phosphonates, sulphones and nitriles, are also discussed.
- Chambers, Richard D.,Hutchinson, John
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- Direct Fluorination of 1,3-Dicarbonyl Compounds
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1,3-Dicarbonyls, such as 1,3-diketones and 1,3-ketoesters, react directly with elemental fluorine at room temperature to give the corresponding 2-fluoro- and, in some cases, 2,2-difluoro-compounds in high yield.
- Chambers, Richard D.,Greenhall, Martin P.,Hutchinson, John
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- N-Fluorobisimides. Efficient reagents for the fluorination of 1,3-dicarbonyl derivatives
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Fluorination of 1,3-dicarbonyl derivatives with N-fluorobisimides, (CF3SO2)2NF (1), results in the formation of 2-fluoro- or 2,2-difluoro-1,3-dicarbonyl analogs, depending on the reaction conditions.High yields are obtained for a variety of structural types.In the case of 1,3-dicarbonyl derivatives with low enol content, only the sodium enolates react with 1.Thus 1 has been demonsrtated to be perhaps the best fluorinating reagent for the fluorination of 1,3-dicarbonyl derivatives.All of the 2-fluoro-1,3-dicarbonyl products exist predominantly as keto tautomers.
- Xu, Ze-Qi,DesMarteau, Daryl D.,Gotoh, Yoshihiko
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- N-Fluoro Perfluoroalkylsulphonimides: Efficient Reagents for the Fluorination of 1,3-Dicarbonyl Derivatives
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Fluorination of 1,3-dicarbonyl derivatives with N-fluoro sulphonimides afforded either 2-fluoro or 2,2-difluoro products in high yields.
- Xu, Ze-Qi,DesMarteau, Darryl D.,Gotoh, Yoshihiko
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p. 179 - 181
(2007/10/02)
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- A Highly Stereocontrolled Synthetic Approach to Versatile Monofluorinated Molecules
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(R)-(+)- and (S)-(-)-2-fluoro-2-substituted malonic acid monoesters were found to behave as potential synthetic reagents for the acyclic stereoselection of a variety of versatile monofluorinated molecules. (R)- and (S)-α-fluoro-α-methyl-β-keto esters have
- Kitazume, Tomoya,Kobayashi, Tadashi,Yamamoto, Takeshi,Yamazaki, Takashi
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p. 3218 - 3223
(2007/10/02)
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- SYNTHESIS OF OPTICALLY PURE (R)- OR (S)-α-FLUORO-α-METHYL-β-KETOESTERS
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A number of optically pure (R)- or (S)-α-fluoro-α-methyl-β-ketoesters were prepared by the reaction of the optically pure acid chlorides made from the corresponding (R)- or (S)-α-fluoro-α-methylmalonic acid monoethyl esters with alkyl (or aryl) cuprates.
- Kitazume, T.,Kobayashi, T.
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p. 357 - 362
(2007/10/02)
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