Benzyloxycarbonylarginine nitrophenyl ester salts: 1-hydroxybenzotriazole catalyzed acylations of amines.

Benzyloxycarbonylarginine p-nitrophenyl ester has been prepared by the p-nitrophenyltrifluoroacetate method. The p-nitrophenyl ester derivative was isolated as its crystalline picrate and nitrate salts. The ester salts couple with amino compounds in the presence of 1-hydroxybenzotriazole, but decompose without acylation of amines in the absence of the 1-hydroxybenzotriazole catalyst. Benzyloxycarbonylarginine p-nitrophenyl ester and other activated esters of N-a-sustituted arginine salts may be useful reagents for introduction of trypsin-labile protecting groups into peptide fragments for purpose of polypeptide semi-synthesis. At the same time, side reactions of such carboxyl-activated arginine derivatives may serve as models for side reactions in the couplings of peptide fragments with arginine residues in the carboxyl-terminal position. Peptide fragment couplings of this type may frequently be encountered in semisynthesis of polypeptides from tryptic fragments.