Dibenzyloxycarbonyl- and di-t-butyloxycarbonyl-l-β-lysine were synthesized from corresponding diacyl-l-ornithine by modified Arndt-Eistert reaction involving diazoketone preparation via the mixed carbonic carboxylic anhydride. These diacyl-β-lysine derivatives are required for total- or semi-syntheses of peptide antibiotics, tuberactinomycins or streptothricins.