In this example, 4.1 g of 1-methyl-2-phenyl-3-oxo-4-(3-trifluoromethylphenyl)-5-amino-4-pyrroline, was added to 100 ml of methylene chloride containing 1.0 g of sodium hydroxide, dissolved in 4.0 ml of water, and 0.28 g of benzyltriethylammonium chloride at room temperature. Dimethyl sulfate (1.17 ml) dissolved in 20 ml of methylene chloride was admixed dropwise to the aforementioned mixture at room temperature. After the addition was complete, another 0.28 g of benzyltriethylammonium was added and the mixture was stirred at room temperature for 18 hours. At the end of this time, a white precipitate was collected from the mixture by filtration. This solid was stirred with 50 ml of 1N aqueous hydrochloric acid for two hours after which it was collected with suction filtration and washed with aqueous sodium bicarbonate solution followed by water. The solid was dried affording 1.0 g of the title compound as a white powder.
