Ethyl 2-nitropropionate is used in the preparation of (-)-trans-2,5-dimethylprolineethyl ester via enantioselective Michael reaction methyl vinyl ketone using modified dihydroquinine as catalyst, novel nitrogen-15-labeled nitrone spin trap, 5-ethoxycarbonyl-5-methyl-1-pyrroline N-oxide ([15N]EMPO) for detecting superoxide anion, 2-ethoxycarbonyl-2-nitropentanal. It is used for enantioselective Michael reactions.