To a stirred mixture of 1,2-dibenzoylhexahydro-1H-1,2,5-triazepine hydrochloride (13.0 g), powdered anhydrous sodium carbonate (17.8 g) in N,N-dimethylformamide (100 ml, dried over 4A molecular sieves) under a purging nitrogen atmosphere was added 4,4-bis(4-fluorophenyl)butyl bromide (13.66 g) in N,N-dimethylformamide (30 ml) over a period of 40 minutes. The mixture was stirred under a purging nitrogen atmosphere at room temperature for 3 days. The mixture was filtered through sintered glass and the filter pad washed with N,N-dimethylformamide. The filtrate and washings were evaporated at 30° under oil pump vacuum. The residual oil was extracted with ether and the extract was filtered. The solution was slurried with 200 g of silica gel for 20 minutes. The mixture was then filtered through a sintered glass filter. The silica gel was stirred repeatedly with fresh ether (10-15 times) until no more product was removed from the silica gel. The filtrate and washings were evaporated to an oil. To the oil dissolved in 2-propanol (125 ml) was added 75 ml of a saturated solution of etheral hydrogen chloride. The hydrochloride salt of the titled product crystallized slowly on standing at room temperature; wt. 18.8 g (76%), mp=211°-212°.
