Synthesis of α-aminoacyl derivatives of melphalan for use in antibody directed enzyme pro-drug therapy

Article abstract of DOI:10.1016/S0040-4020(98)01139-9

L-Alanyl-, D-alanyl-, L-prolyl-, L-pyroglutamyl- and D- phenylalanylmelphalan were synthesized in 8 steps, with the reactive nitrogen mustard moiety formed at the penultimate step. After protection of p- nitrophenylalanine with benzyl ester and N-t-butyloxycarbonyl (BOC) groups, the aromatic nitro was reduced to an amine which was reacted with ethylene oxide to give a product with a bis(2-hydroxyethyl)amino moiety. After removal of BOC, it was coupled to the relevant N-benzyloxycarbonyl-α-amino acid. Chlorination of hydroxyethyl yielded the bis(2-chlorethyl)amino compound. Final removal of protecting groups was by catalytic hydrogenolysis.