- Self-disproportionation of enantiomers of isopropyl 3,3,3-(trifluoro)lactate via sublimation: Sublimation rates vs. enantiomeric composition
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The presented results convincingly demonstrate that self-disproportionation of enantiomers via sublimation is substantially more complex phenomenon then was previously believed. We demonstrate that the racemic form of isopropyl 3,3,3-trifluoro-2-hydroxypr
- Yasumoto, Manabu,Ueki, Hisanori,Ono, Taizo,Katagiri, Toshimasa,Soloshonok, Vadim A.
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- Enantioselective Rhodium(I)-Catalyzed Hydrogenation of Trifluoromethyl Ketones
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(Matrix Presented) The asymmetric hydrogenation of trifluoromethyl ketones to yield chiral α-trifluoromethyl alcohols with enantiomeric excesses up to 98% was achieved in the presence of chiral rhodium-(amidephosphine-phosphinite) complexes.
- Kuroki, Yoshichika,Sakamaki, Yuko,Iseki, Katsuhiko
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p. 457 - 459
(2007/10/03)
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- Enantioselective synthesis of 1,1,1-trifluoroalkan-2-ols by ruthenium- catalyzed hydrogenation
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The highly enantioselective synthesis of 1,1,1-trifluoroalkan-2-ols has been achieved by hydrogenating 1,1,1-trifluoroalkan-2-one enol acetates in the presence of chiral ruthenium catalysts. An enol acetate, 2-acetoxy-3,3,3- trifluoro-1-(phenylthio)propen
- Kuroki, Yoshichika,Asada, Daisuke,Sakamaki, Yuko,Iseki, Katsuhiko
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p. 4603 - 4607
(2007/10/03)
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- Simple Access to (R)- and (S)-3,3,3-Trifluorolactic Acid and to (R)- and (S)-(Trifluoromethyl)oxirane
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Ethyl trifluoropyruvate (from hexafluoropropylene oxide) is reduced by NaBH4 to rac-trifluorolactic acid which is resolved on a 100-g scale by salt formation with (R,R)- and (S,S)-2-amino-1-phenyl-1,3-propanediol (readily available intermediates of industrial chloroamphenicol synthesis).The enantiomerically pure trifluorolactic acids (>99percent ee by GC analysis on cyclodextrin columns) are converted into (R)- and (S)-(trifluoromethyl)oxirane in an overall yield of 73percent by the following steps: esterification, THP protection of the OH group, LAH reduction and mesylation to the 2-THP-protected mesylate of 3,3,3-trifluoro-1,2-propanediol, and one-pot deprotection (Dowex 50) and cyclization (NaOCH2CH2OH) in ethylene glycol.The enantiomeric purity of the oxirane (b.p. 39 deg C, isolated on a 10-g scale) was determined by GC to be >99percent.Possible synthetic targets are mentioned which should be accessible in enantiomerically pure form from the (trifluoromethyl)oxirane described here. Key Words: Resolution by crystallization of diastereomeric salts / Perfluoropropylene oxide / Trifluoropyruvate / Capillary GC determination of ratios of enantiomers / Cyclodextrine-derived GC columns / Determination of the sense of chirality by chemical correlation / pKs of 3,3,3-trifluoro-2-hydroxypropanoic and 4,4,4-trifluoro-3-hydroxybutanoic acid
- Bussche-Huennefeld, Christoph von .,Cescato, Claudio,Seebach, Dieter
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p. 2795 - 2802
(2007/10/02)
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