1.1 g (3.9 mmol) of (RS)-1-(2-azido-propyl)-4,4,7-trimethyl-1,4-dihydro-indeno[2,1-c]pyrazole dissolved in 60 ml of anhydrous ethanol were hydrogenated over 110 mg of platinum oxide for 3 hours. The catalyst was subsequently filtered off, rinsed with ethanol and the solvent was removed in a vacuum. The colorless oil obtained was dissolved in 150 ml of anhydrous diethyl ether, filtered and treated while stirring with a solution of 453 mg (3.9 mmol) of fumaric acid in 10 ml of methanol. The mixture was stirred at room temperature for 4 hours and the white crystals were subsequently filtered off. 1 g (69%) of (RS)-2-(4,4,7-trimethyl-1,4-dihydroindeno[2,1-c]pyrazol-1-yl )-1-methyl-ethylamine fumarate (1:1) with m.p. 167° was obtained.
