About 100 parts of (3) are combined with about 109 parts of ethyl p-toluene sulfonate, 100 ml dimethylacetamide, and 5 ml p-nitrophenol (to inhibit polymerization) in a 500 ml three-necked flask equipped with a mechanical stirrer and condenser. The reaction mixture is heated at about 120° C. for about 5 hours while stirring under argon, then stirred at room temperature for about 15 hours, monitored using thin layer chromatography (TLC). After the reaction mixture is cooled to room temperature, it is poured into about 1500 ml of dry ethyl ether, decanted and stirred in fresh ethyl ether. The ethyl ether procedure is repeated until the oil product changes to a tacky solid which is then allowed to stand in ethyl ether overnight. The solid is filtered off and washed several times with butyronitrile to remove all starting material. The solid is washed further with ethyl ether and dried to yield 3-ethyl-5-acrylamido-2-methylbenzoxazolium p-toluene sulfonate (4) as a mustard-yellow solid.
