Kinetic resolution via the [2,3] stevens rearrangement of epimeric six-membered ammonium ylides: A new entry to enantio-enriched α-amino acid derivatives

Heterocycles

Volumn 66, Issue 1, 2005, Pages 95-99

  Tayama, Eiji ^a   Tanaka, Hiroyuki ^a   Nakai, Takeshi ^a  

^a NIIGATA UNIVERSITY   (Japan)

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Indexed keywords

EID: 33646891092     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/COM-05-S(K)39     Document Type: Article

References (10)

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9. 4 and evaporated. The residue was purified by column chromatography on silica gel (hexane/EtOAc=8:1 as eluent) to give (3R)-3a (colorless oil, 46 mg, 38%) and (3S)-3a (colorless oil, 6 mg, 6%).
10. To describe that our method is kinetic resolution not stereoselective protonation, epimerization of the rearrangement product (3a) was examined. A solution of 3a [(3R)/(3S)=6:1] in THF was treated with t-BuOK (1.1 equiv.) at -78°C for 2 h. The epimerized starting material 3a was recovered in 34% yield. The ratio was changed from (3R)/(3S)=6:1 to 1:9. This result indicates that the epimerization of (3R)-3a gave another isomer [(3S)-3a] preferably.