An efficient and convenient two step synthesis of each of the four possible diastereoisomers of the N-terminal amino acid component of nikkomycins is described. We first synthesized α-amino-β-oxo acids by aminoalkylation of ketones with iminium salts. The second step using Pearlman’s catalyst gave directly nonnatural and natural precursors 13 - 16 of nikkomycins 1 which were easily separated by chromatography on silica gel.