Abstract The synthesis of orthogonally protected Fmoc??Dap/Dab (Boc/Z/Alloc)??OH starting from Fmoc??Asp/Glu has been described. The salient features of our synthetic strategy involved formation of Fmoc??Asp/Glu??5??oxazolidinone acids, conversion of acid function to acyl azides, Curtius rearrangement, and hydrolysis of the oxazolidinone group.