- Asymmetric Synthesis of 2-Chloro- and 2-Bromo-alkanoic acids by Halogenation of α-D-Glucofuranose-Derived Silyl Ketene Acetals.
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Optically active (S)-2-bromo- and 2-chloro-alkanoic acids 6 and 7 have been obtained via the diastereoselective halogenation of chiral silyl ketene acetals 3a-f, and subsequent saponification of the resulting crude esters.Examples characterized by e.e. values up to 95percent are reported.The diastereoface selectivity is independent of the silyl ketene acetal E/Z configuration.
- Angibaud, P.,Chaumette, J. L.,Desmurs, J. R.,Duhamel, L.,Ple, G.,et al.
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p. 1919 - 1932
(2007/10/03)
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- ASYMMETRIC REDUCTION OF Z-3-CHLORO-3-ALKEN-2-ONES WITH FERMENTING BAKER'S YEAST
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Using fermenting baker's yeast, Z-RCH=CClCOCH3 (R=C2H5, n-C5H11, n-C8H17) was reduced initially to (S)-RCH2C*HClCOCH3 in 44-84percent ee, which was further reduced to RCH2C*HClC*HOHCH3 in >98percent ee with the syn(2R,3S)/anti(2S,3R) ratios of 2.6-18.3.
- Utaka, Masanori,Konishi, Satoshi,Takeda, Akira
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p. 4737 - 4740
(2007/10/02)
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- Asymmetric Transformation of 2-Phenyl- and 2-Chloroalkanoic Acids via Chiral Oxazolines
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Asymmetric transformation of racemic 2-phenyl- and 2-chloroalkanoic acids via oxazolines into the corresponding optically active acids was investigated using (S)-phenylalaninol as a chiral auxiliary.The asymmetric transformation was performed by metalatio
- Shibata, Saizo,Matsushita, Hajime,Kaneko, Hajime,Noguchi, Masao,Saburi, Masahiko,Yoshikawa, Sadao
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p. 3546 - 3551
(2007/10/02)
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