Synthesis of P1 aspartate-based peptide acyloxymethyl and fluoromethyl ketones as inhibitors of interleukin-1β-converting enzyme

Improved procedures have been developed for the synthesis of P1 aspartate-based 2,6-dichlorobenzoyloxymethyl ketone 1 and fluoromethyl ketone 2, the prodrugs of two potent ICE-inhibitors. 1 was prepared from (R)-trans-4,5-O-isopropylidene-4,5-dihydroxy-2-pentenecarboxylic acid ethyl ester; 2 was obtained via a nitro-aldol condensation as key step from in situ generated fluoroacetaldehyde.