Asymmetric synthesis of functionalized aza-cyclic amino acids with quaternary stereocenters by a phase-transfer-catalyzed alkylation strategy.
[Reaction: see text] Practical asymmetric synthesis of functionalized aza-cyclic alpha-amino acid derivatives possessing quaternary stereocenters has been achieved by the phase-transfer-catalyzed alkylation of 2 or 3 using chiral quaternary ammonium bromide 1 as catalyst. Subsequent reduction and alkylation of the 3-keto carbonyl moiety of 4 proceeded with complete diastereochemical control to afford the corresponding beta-hydroxy aza-cyclic alpha-amino acid derivatives having stereochemically defined consecutive quaternary carbon centers.
Ooi
Takashi
T
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Miki
Takashi
T
Maruoka
Keiji
K
D000478:Alkylation; D000598:Amino Acids, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D001372:Aza Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D044367:Phase Transition; D013237:Stereoisomerism
D000598:Amino Acids, Cyclic; D001372:Aza Compounds