The synthesis of norleucine-derived phosphonopeptides was achieved by BOP-catalyzed coupling of the monobenzyl ester of a N-CBz-protected phosphonate derivative of norleucine with hydroxyl moieties of derivatized lactic or glycolic acids. The complete deprotection of the product esters/carbamates was achieved in good yields by one-step Pd-catalyzed hydrogenolysis.
In the present work, we describe in detail an efficient solution synthesis of norleucine-derived phosphonopeptides mimicking the peptide sequences Nle-Gly(Ala) and Nle-Gly(Ala)-Val. The most efficient strategy involved use of the benzyl group. The synthesis was achieved through BOP-catalysed coupling of the monobenzyl ester of the N-Cbz-protected phosphonate derivative of norleucine with the hydroxyl