Then it is cooled again to -78° C. and a solution of 1-trityl-4-chloromethyl-5-methylimidazole 3 in 10 ml of anhydrous THF is added thereto. After stirring for an hour at -78° C. the reaction mixture is kept at -20° C. for 48 hours. Then 30 ml of an aqueous 10% ammonia solution saturated with ammonium chloride are added and the mixture is extracted with ether. The organic phase is washed with water, dried over potassium carbonate and evaporated under reduced pressure. The residual oil is dispersed in heptane and cooled with an ice bath. This causes the precipitation of a yellow solid which is recrystallised in isopropanol. The 1-trityl-4-(2,2-diphenyl ethyl)-5-methylimidazole 4 is so obtained in the form of a white solid.
