215236-89-8Relevant academic research and scientific papers
Asymmetric Syntheses of the Naturally Ocurring β-Amino Acids, β-Lysine, β-Leucine and β-Phenyl-β-alanine via Nitrone Cycloaddition
Keirs, David,Moffat, David,Overton, Karl,Tomanek, Richard
, p. 1041 - 1051 (2007/10/02)
A general asymmetric synthesis of β-amino acids is based on the dipolar cycloaddition of nitrones 7 (R* chiral) with vinyl acetate 8a, ketene acetals 8b or α-chloroacrylonitrile 8c.The cycloadducts 9 are converted either directly (9b) or via the isoxazolidones 10 (9a, 9c) into the free β-amino acids 11.Diastereoselectivity at C-3 in the adducts 9 ranges between 2:1 and 11:1.The natural β-amino acids, β-lysine, β-leucine and β-phenyl-β-alanine, have been prepared in this way.
An efficient C2-homologation of aromatic aldehydes via 5-hydroxyisoxazolidines
Di Nunno,Scilimati
, p. 4121 - 4132 (2007/10/02)
The reaction of lithium enolate of acetaldehyde (generated by the known cycloreversion of THF in the presence of n-BuLi) with a number of aryl N-phenylnitrones affords 2-phenyl-3-aryl-5-hydroxyisoxazolidines (trans + cis) in high yields. A low conversion or no reaction at all were instead observed with some N-alkylnitrones (methyl and t-butyl, respectively). Base (or acid) induced decomposition of 5-hydroxyisoxazolidines allows cinnamaldehydes to be obtained in high yields. Thus the combination of the synthesis and decomposition of 5-hydroxyisoxazolidines provides a new efficient way for the C2-homologation of aromatic aldehydes.
