In a round bottomed flask, 2.2 mmol of 3-amino -5-methoxychroman (described in Patent EP 279,150) are dissolved in 6 ml of dimethylformamide in the presence of 2.4 mmol of N-(4-bromobutyl)phthalimide, 6.6 mmol of potassium carbonate and a catalytic amount of potassium iodide. The mixture is left stirring at 60° C. for 6 hours. After cooling, the solvent is evaporated off and, after aqueous hydrolysis, the crude reaction mixture is extracted with dichloromethane. After washing, drying and evaporation of-the organic phase, the expected product is obtained after purification by chromatography on a silica column (elution solvent: ether/petroleum ether, 5:95).
