In this example about 0.36 g of solid sodium hydroxide was dissolved in a small amount of water and then added to 100 ml of methylene chloride containing 1.4 g of 2-thien-2-yl-3-oxo-4-(3-trifluoromethylphenyl)-5-amino-2,3-dihydrofuran. 0.20 g of benzyltriethylammonium chloride was added and then a mixture containing 0.84 ml of dimethyl sulfate in about 5.0 ml of methylene chloride was slowly added at room temperature. The mixture was stirred at room temperature for about one hour and then washed twice with water, twice with 1N. aqueous hydrochloric acid, twice with sodium bicarbonate, dried over magnesium sulfate and then concentrated by evaporation under vacuum. The residue was then triturated in a mixture of ethyl ether and petroleum ether affording 1.4 g of the title compound.
