Cl.CC(C1[NH:9][C:8](=[O:10])[CH2:7][NH:6]1)C.N1C2(CCCCC2)NCC1=O.C(=O)([O-])[O-].[K+].[K+].[O:28]1[CH2:36][CH:29]1[CH2:30][C:31]([O:33]CC)=O>O.CN(C=O)C.CC(C)=O>[CH2:30]1[C:31](=[O:33])[N:6]([CH2:7][C:8]([NH2:9])=[O:10])[CH2:36][CH:29]1[OH:28]5.8 g of 2-(1-methylethyl)-4-imidazolidinone hydrochloride ((5); R4 =H, R5 =isopropyl) (0.035 moles) are shaken in 10 ml water and treated with 2.4 g potassium carbonate (0.0174 moles). 4.5 g ethyl 3,4-epoxybutanoate and 6 ml acetone are added, and stirring is maintained for 45 h at 70° C. After evaporation, the residue is chromatographed on silica, eluting with 8:2 ethyl acetate/methanol. The main fractions are collected and evaporated. The oil that remains is taken up with ethyl acetate. After being left to stand overnight the white compound obtained is filtered: 1.3 g ethyl 2-(1-methylethyl)-4-oxo-1-imidazolidine-β-hydroxybutanoate m.p. 118°-122° C. 0.95 g of this compound (3.7 mmoles) are heated to boiling for 15 h in 4 ml DMF and 1 ml water. After evaporation in vacuo, the residue is taken up with methanol, and the solution is filtered. 0.37 g oxiracetam is obtained as a white crystalline powder, m.p. 167°-70° C. (63.2%).
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