To a stirred mixture of 4.5 g of 1,2-dihydro-4-[3-(trifluoromethyl)phenyl]imidazo[1,5-a]pyrimidine-8-carbonitrile (prepared as described in Example 2) and 3.6 g of [1,8-bis(dimethylamino)naphthalene-N,N,N',N'-tetramethyl-1,8-naphthalenediamine] in 120 ml of dry tetrahydrofuran at room temperature, under nitrogen was added over a period of 12-15 minutes a solution of 3.9 g of 3-chloropropionyl chloride in 30 ml of dry tetrahydrofuran. The mixture was stirred at room temperature under nitrogen for one hour then under reflux for 4 hours. The solution was filtered hot and the filtrate was evaporated to dryness in vacuo. The residue was triturated with anhydrous ether and gave 5.95 g of the product of the example as an off-white solid. The product was recrystallized from ethyl acetate, mp 165° 166° C.
