630 mg (1 mM) of 1-(2-(bis-(4-fluorophenyl)-methoxy)-ethyl)-4 -(3-ketobutyl)piperazine (prepared as described in example 19) was suspended in 2 5 ml of ethanol at room temperature. A solution of hydroxylamine hydrochloride in 1 ml of water was added, followed by the dropwise addition of 240 mg of potassium hydroxide dissolved in 1 ml of water. The mixture was heated at reflux for 1 h, the solvent was evaporated, and the residue was dissolved by the addition of 5 ml of water and 5 ml of methylene chloride. The aqueous phase was extracted three times with methylene chloride, and the organic extract was washed with water, dried, and evaporated in vacuo. The residual oil was dissolved in ethanol, and a crude dimaleate salt was precipitated by addition of an ethanolic solution of 417 mg of maleic acid. The crude salt (405 mg) was recrystallized from 50 ml of hot ethanol to yield the dimaleate salt of the title compound as colourless crystals, melting at 161°-162° C. Analytical data were in accordance with the proposed structure. H-NMR spectrum indicated the presence of two stereoisomers in the ratio of 2.5:1.
