Synthesis of N(alpha)-Boc-N(epsilon)-tetrabenzyl-DTPA-L-lysine and N(alpha)-Fmoc-N(epsilon)-tetra-t-butyl-DTPA-L-lysine, building blocks for solid phase synthesis of DTPA-containing peptides.

Two building blocks, Boc-Lys(Bn4-DTPA)-OH and Fmoc-Lys(Bu4(t)-DTPA)-OH have been synthesized via the acylation of the epsilon-amino group of N(alpha)-protected lysine, using suitably protected tetra-esters of diethylene triamine pentaacetic acid (DTPA), a ligand with wide application as a chelating agent for complexing metal tons to peptides.