The highly stereoselective alkylation (% de=99.6 to 97.6) of a new chiral glycine enolate synthon derived from D-2-phenylglycinol is described. Deprotection of the alkylation adducts in a one-pot, three-step procedure provides the ethyl ester hydrochloride salts of the corresponding a-amino acids wi
Enantioselective alkylation of chiral enolates
โ Scribed by D.A. Evans; J.M. Takacs
- Publisher
- Elsevier Science
- Year
- 1980
- Tongue
- French
- Weight
- 235 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0040-4039
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๐ SIMILAR VOLUMES
An efficient enantioselective alkylation of the lithium enolates of cyclohexanone and ltetralone with reactive alkyl halides was realized using a stoichiometric amount of a tetradentate chiral amine as a ligand for the lithium in the presence of lithium bromide in toluene.
Enantioselective alkylation of lactams and lactones can be realized up to 98% ee by deprotonation with a chiral tetradentate lithium amide (4b) in the presence of lithium bromide, and subsequent alkylation with active alkylating agents in non-chelating solvents.
New chiral proton sources possessing an asymmetric 2-oxazoline ring, (S,S)-imide 1 and related imides, were synthesized from Kemp's triacid and optically active 2-amino alcohols. With these ehiral imides, various lithium enolates of ct-monoalkylated cycloalkanones were effectively protonated with ex