[CH:1]([O:4][CH:5]1[NH:9][C:8](=[O:10])[CH2:7][CH2:6]1)([CH3:3])[CH3:2].[OH-].[K+].[CH2:13](Br)[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1>O1CCCC1>[CH2:13]([N:9]1[CH:5]([O:4][CH:1]([CH3:3])[CH3:2])[CH2:6][CH2:7][C:8]1=[O:10])[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1To a suspension of 2.5 g of 5-isopropoxy-pyrrolidin-2-one, 1.23 g of potassium hydroxide hydrated to 85%, and 0.25 g of n-tetra-butylammonium bromide in 50 cm3 of tetrahydrofuran, there is added a solution of 2.99 g of benzyl bromide, without exceeding 30° C. After agitating for 1 hour at ambient temperature, the insoluble matter is filtered off and the solvent is evaporated. The residue (4 g) is distilled at 200° C. under 0.05 mbar. The distillate is chromatographed on silica (eluent: ethyl acetate--n-hexane, 1--1). 2.9 g of the expected product is obtained.
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