URETHANE TYPE PROTECTING GROUPS FOR CARBOXAMIDE IN PEPTIDE CHEMISTRY

Abstract

Novel L-asparagine and L-glutamine derivatives with the carboxamide nitrogen (N^ca) acylated by urethane type protecting groups, tert-butyloxycarbonyl (Boc) and 4-nitrobenzyloxycarbonyl [Z(NO₂)], were synthesized through ruthenium tetroxide oxidative transformation of N^α, N^ω-diacylated L-2, 4-diaminobutyric acid and L-ornithine. N^ca-Boc and N^ca-Z (NO₂) groups can be deprotected by trifluoroacetic acid and catalytic hydrogenation respectively. N^α, N^ca-DiBoc-Asn-OH is applied to peptide synthesis by dicyclohexylcarbodiimide or mixed anhydride method without nitrile formation.