Amino acid esters of phenols as prodrugs: synthesis and stability of glycine, beta-aspartic acid, and alpha-aspartic acid esters of p-acetamidophenol.

pH-rate profiles were calculated for the hydrolysis of the glycine (II), beta-aspartic acid (III), and alpha-aspartic acid (IV) esters of p-acetamidophenol (I) at 25 degrees and mu = 1.0 M. The hydrolysis of esters II and III occurred predominantly via intermolecular reactions involving water, hydroxide ion, and the various ionic forms of the substrates. The hydrolysis of ester IV occurred predominantly via intramolecular reactions. The catalytic effects of formate, acetate, and phosphate ions as well as of tromethamine on the degradation on ester II were similar to their effects on the hydrolysis of ethyl dichloroacetate. The efficient catalysis of the hydrolysis of ester II in bicarbonate buffers was consistent with a mechanism that involved carbon dioxide and the formation and decomposition of a carbamate intermediate.