Selective hydrogenolysis of the benzyloxycarbonyl protecting group of Nϵ-lysine in cyclopeptides containing a benzylic phenyl ether function. Evidence for Nϵ-methylated lysine side products.

Abstract Selective hydrogenolytic cleavage of the Nϵ-Z protecting group of lysine in cyclopeptides c[-(Glycyl)-A-B-Nϵ-Z-Lysyl-2-Phenoxymethyl-5-Aminobenzoyl-] (A = B = Glycyl, n = 2 or A = Phenylalanyl, B = Alanyl, n = 2 and 3) occurred in both acidic (MeOH/aq.AcOH) and neutral (MeOH/DMF) solvents, with Pd/C catalyst. In the latter case, a Nϵ-(bis)-methylated side product was isolated.