Interleukin-1 beta converting enzyme. Synthesis of hydroxyethyl dipeptide surrogate-containing compounds as potential ICE inhibitors.

A series of compounds containing a hydroxyethyl-based dipeptide surrogate have been prepared as probes to evaluate the possibility of ICE being an aspartic protease. The aldehyde t-BocAsp(beta-t-butyl)H reacted with the organochromium species derived from phenethyl bromide and CrCl2 to give the expected addition product. Lactonization, reprotection of the amine and oxidation with RuCl3 gave the two protected dipeptide surrogates 7a and 7b. These were incorporated into tetra-, penta- and hexapeptide-like molecules and evaluated as inhibitors of the enzyme. The failure of these compounds to inhibit ICE indicated that this enzyme was very unlikely to be an aspartic protease.