(1S,?2S)?-1,?2-?Cyclopropanedicarbox?ylic Acid 1,?2-?Diethyl Ester is an intermediate in synthesizing (O846925), (2S,3S)-2,3-Oxiranedicarboxylic Acid Monoethyl Ester is used in the synthesis of aza-peptidyl inhibitors of lysosomal asparaginyl endopeptidase, legumain. Also used in the synthesis of irreversible epidermal growth factor receptor inhibitors and probes for cathespins.