The stereoselective synthesis of bioactive (2 S,3 S,4 S)-3,4-dihydroxyglutamic acid hydrochloride salt was achieved. The key step involved an intramolecular nucleophilic epoxidation of homochiral γ-amino-α,β-unsaturated ester 5 containing an N-hydroperoxymethyl group followed by regioselective opening of the resulting epoxide with neighboring group participation of the N-Boc group. The diastereoselectivity was more than 20:1 by 1H NMR spectroscopy. Thus, (2 S,3 S,4 S)-3,4-dihydroxyglutamic acid hydrochloride salt was prepared from configurationally stable N-Boc- d-serinal 4 in 25% overall yield over nine steps.