Abstract N-(2-Bromopropionyl)-O-benzyl-L-serine (BPBS) was prepared using 2-bromopropionic acid
and N-Boc-O-Bzl-L-serine as the starting reagents. BPBS underwent the intra-molecular ring-closing reac-
tion in DMF/Et
3
N solvent at 80 ℃for 9 h forming a mixture of two non-enantiomers, i.e. (3S,6S)-benzyl-
oxymethyl-6-methyl-morpholine-2,5-dione [(3S,6S)-BMMD] and (3S,6R)-BMMD with a yield of 70%. Two
optically pure enantiomers of BMMD, i.e. (3S,6S)-BMMD and (3S,6R)-BMMD were obtained via 4 opera-
tion circles of “solution-partial recrystallization” by means of a differential recrystallization method using
ethyl acetate as a solvent. The single crystals of the two isomers of BMMD were grown from ethyl acetate at
room temperature. The fine molecular structures of the two isomers were determined by X-ray diffraction
analysis of the single crystals.
Keywords (3S,6S)-benzyloxymethyl-6-methyl-morpholine-2,5-dione; (3S,6R)-benzyloxymethyl-6-methyl-
 morpholine-2,5-dione; resolution; optical isomer; crystal structure