Chiral oxime ethers in asymmetric synthesis. Part 4. Asymmetric synthesis of N-protected amines and beta-amino acids by the addition of organometallic reagents to ROPHy/SOPHy-derived aldoximes

Addition of organolithium or Grignard reagents to ( R)- or (S)-O-(1-phenylbutyl)aldehyde oximes 1 in the presence of boron trifluoride-diethyl ether results in the formation of hydroxylamines 2 in good to excellent diastereoselectivity. Subsequent cleavage of the N-O bond with zinc-acetic acid-ultrasound, and carbamate formation, gives <italics N-protected amines 3 in good enantiomeric purity (77-100% ee). When allylmagnesium bromide was used as the organometallic reagent, the resulting hydroxylamines were converted into beta-amino acid derivatives 4 and gamma-amino alcohols 5.