In addition, the aminomethylbenzamide subunit can be reacted with aldehydes derived from amino acids such as O-alkylated tyrosines, according to standard procedures, to obtain compounds such as XXX, as shown in Reaction Scheme L. When R' is an aryl group, XXX can first be hydrogenated to unmask the phenol, and the amine group deprotected with acid to produce XXXI. Alternatively, the amine protecti