- Fast, solvent-free and highly enantioselective fluorination of β-keto esters catalyzed by chiral copper complexes in a ball mill
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A fast and highly enantioselective fluorination of β-keto esters catalyzed by diphenylamine linked bis(oxazoline)-Cu(OTf)2 complexes under solvent-free conditions has been developed using a planetary ball mill. High yields, high enantioselectivities and shorter reaction times were achieved with low catalyst loading.
- Wang, Yifeng,Wang, Haojiang,Jiang, Yidong,Zhang, Cheng,Shao, Juanjuan,Xu, Danqian
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supporting information
p. 1674 - 1677
(2017/06/05)
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- Enantioselective fluorination of β-ketoesters catalysed by complexes of new mono-oxazoline ligands
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A new kind of mono-oxazoline ligands which combined diaryl methyl units and chiral oxazoline units together using pyridine as linker was prepared. Their applications in enantioselective electrophilic fluorination of β-ketoesters by NFSI were investigated, and the corresponding products were obtained in excellent yield (up to 90%) and good enantioselectivity (78%) in CH2Cl2 at -60 °C.
- Niu, Teng,Han, Xiping,Huang, Danfeng,Wang, Ke-Hu,Su, Yingpeng,Hu, Yulai,Fu, Ying
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supporting information
p. 6 - 11
(2015/03/31)
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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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p. 353 - 403
(2012/05/07)
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- Recyclable fluorous cinchona alkaloid ester as a chiral promoter for asymmetric fluorination of β-ketoesters
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A fluorous cinchona alkaloid ester has been developed as a chiral promoter for the asymmetric fluorination of β-ketoesters. It has comparable reactivity and selectivity to the nonfluorous versions of cinchona alkaloids and can be easily recovered from the
- Yi, Wen-Bin,Huang, Xin,Zhang, Zijuan,Zhu, Dian-Rong,Cai, Chun,Zhang, Wei
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experimental part
p. 1233 - 1240
(2012/09/21)
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- Development of the titanium-TADDOLate-catalyzed asymmetric fluorination of β-ketoesters
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Titanium-based Lewis acids catalyze the α-fluorination of β-ketoesters by electrophilic N-F-fluorinating reagents. Asymmetric catalysis with TADDOLato-titanium(IV) dichloride (TADDOL = α,α, α',α'-tetraaryl-(1,3-dioxolane-4,5-diyl)-dimethanol) Lewis acids
- Hintermann, Lukas,Perseghini, Mauro,Togni, Antonio
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supporting information; experimental part
p. 1421 - 1435
(2011/12/15)
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- A novel enantioselective preparation of α-fluoro-β-keto acids
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A two-step method for the enantioselective preparation of α-fluorinated β-keto acids from 1,3-dioxin-4-ones having l-menthone as the chiral auxiliary at the 2-position is described. The method consists of fluorination of the dioxinones by molecular fluori
- Iwaoka,Murohashi,Sato,Kaneko
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p. 1025 - 1028
(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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