The stereoselective synthesis of syn-β-amino propargylic ethers by the addition of racemic lithio 3-(methoxymethoxy)allenylcuprates, and more particularly (cyano) and (mesityl)cuprates, to enantiopure chiral N-tert-butylsulfinylimines is reported. The scope and limitations of the reaction is studied. The usefulness of the methodology for the synthesis of compounds having a syn-1,2-amino alcohol unit