1.7 g (70.8 mmol) sodium hydride are placed in 130 ml DMF and 1.0 g (54.5 mmol) 4,5-diphenylimidazole are added under cooling. The suspension is stirred for four hours at RT and, subsequently, 15.4 g (54.5 mmol) N-(4-bromobutyl)-phthalimide dissolved in DMF is added dropwise under cooling. After complete addition, the reaction mixture is stirred for 12 hours at RT, 18 ml methanol are carefully added dropwise and the suspension is filtered. The filtrate is concentrated under vacuum and the residue is distributed between 500 ml chloroform and 170 ml water. The organic phase is dried over sodium sulfate and evaporated under vacuum until dry dried. The residue is purified by chromatography on silica gel with CHCl3/CH3OH (95/5) and subsequently crystallized from methanol: Yield 16.5 g (72%).
