Asymmetric synthesis of alpha,alpha-disubstituted alpha-amino acids using (S,S)-cyclohexane-1,2-diol as a chiral auxiliary

Citation
M. Tanaka et al., Asymmetric synthesis of alpha,alpha-disubstituted alpha-amino acids using (S,S)-cyclohexane-1,2-diol as a chiral auxiliary, J ORG CHEM, 66(8), 2001, pp. 2667-2673
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
JOURNAL OF ORGANIC CHEMISTRY
ISSN journal
0022-3263 → ACNP
Volume
66
Issue
8
Year of publication
2001
Pages
2667 - 2673
Database
ISI
SICI code
0022-3263(20010420)66:8<2667:ASOAAA>2.0.ZU;2-0
Abstract
Diastereoselective alkylation of ethyl 2-methyl- and/or 2-ethylacetoacetate s using the (S,S)cyclohexane-1,2-diol as an acetal chiral auxiliary afforde d enol ethers (2a-f and 5a-f) of 92 - > 95% de in 31-70% yields. Removal of the cyclohexane-l,2-diol with BF3-OEt2 afforded beta -keto esters (3 and 6 ) bearing a chiral quaternary carbon. The beta -keto esters could be easily converted into optically active alpha -methylated and/or alpha -ethylated alpha,alpha -disubstituted amino acids (12 and 13) in 21-99% yields using S chmidt rearrangement.