Asymmetric synthesis of N-protected syn and anti (E)-3-amino-2-hydroxy- 4-hexenoate: A practical method for the C-α epimerization of anti β-amino- α-hydroxy acids

Article abstract of DOI:10.1016/S0040-4020(98)01051-5

A practical method to convert anti β-amino-α-hydroxy acids into the corresponding syn esters via the DCC/DMAP-HCl mediated esterification was devised, and methyl (2R,3S)-(E)-3-t-butoxycarbonylamino-2-hydroxy-4-hexenoate 15 was synthesised from the corresponding (2S,3S)-isomer 9 using the epimerization procedure developed. The α- and β-stereogenic centres of 9 were constructed by the Michael addition of a homochiral lithium amide to t- butyl sorbate and subsequent oxidation of the enolate intermediate in one pot.