The organic layer was dried with anhydrous Na2SO4 and
concentrated to afford a residue, which was purified over Si gel CC
eluted with 50% EtOAc in n-hexane to 100% EtOAc to give (S)-PGME
amide (1b, 4.6 mg). The use of (R)-PGME gave (R)-PGME amide (1c,
6.2 mg)