2.85 g (7.6 mmol) of the compound from Example 59 dissolved in 30 ml of absolute tetrahydrofuran are added dropwise under a nitrogen atmosphere to 0.5 g (13.2 mmol) of lithium aluminum hydride in 20 ml of absolute tetrahydrofuran at 60° C. The mixture is heated to reflux for 1 hour, subsequently cooled to 0° C. and 1.5 ml of water and 0.3 ml of 15% strength potassium hydroxide solution are cautiously added dropwise. The solution is filtered from the deposited precipitate with suction and the latter is boiled several times with ether. The combined phases are dried over magnesium sulphate and concentrated in vacuo. The residue is chromatographed on a column (silica gel 70-230 mesh, using ethyl acetate/petroleum ether 1:9).
