(RS)-Diethyl-2-benzyl-succinate was resolved using alpha-chymotrypsin. The two enantiomers were then elaborated to yield (S)-(+) and (R)-(-)-3-benzyl-N-[(methyl-sulfonyl)oxy]succinimide and the inhibitory activity of the two enantiomers toward human leukocyte elastase was subsequently determined. The k2/KI values for the R and S isomers were found to be 330 and 1500 M-1 s-1, respectively.