This invention relates to compounds of Formula I having an aziridine-2-carboxylic group and a menthol group, a process for preparing such compounds, a method for obtaining optically active aziridine-2-carboxylate derivatives by optical resolution of such compounds, and optically active aziridine-2-carboxylate derivatives obtained by the same method: ##STR00001## wherein R.sup.1 is hydrogen; alkyl; cycloalkyl; 4-chlorophenyl; 4-methoxyphenyl; s-triazinyl or pyridinyl acyl; benzyl; hydrocarbon residue which may be substituted with a substituent selected from the group consisting of hydroxy, alkoxy, dialkylamino, phenyl, 4-chlorophenyl and 4-methoxyphenyl; 2,4-dimethoxyphenyl; substituted phenyl including (1R)-phenylethyl or (1S)-phenylethyl. Preferences are given to (1R)-phenylethyl and (1S)-phenylethyl. Menthol is selected from the group consisting of (+)-menthol and (-)-menthol.