Reduction of Nt-BOC-protected-N-alkyl α-aminoketones with LiEt3BH or Li (s-Bu) 3BH furnishes protected syn-β-aminoalcohols with high selectivities. In contrast, removal of the BOC group followed by reduction of the aminoketone gives anti-β-aminoalcohols with variable selectivities. With aromatic ketones, selectivities are typically high while aliphatic ketones show mediocre to high selectivities depending on steric considerations. Key ...