To 1 g of N-(dicyclopropylmethyl)-N-propylthiourea (Compound 88) dissolved in 25 ml of anhydrous ethanol, add 0.54 ml of triethylamine, then slowly 1 g of 2-bromo-1-(2,4-dichlorophenyl)-1-propanone (Compound 15). After two hours of heating under reflux of the ethanol, evaporate to dryness. Take up the residue in methylene chloride and wash with water until bromide ions have been removed completely. Dry the organic phase over anhydrous sodium sulphate and then evaporate to dryness. Purify the residue on a silica column, using a mixture of cyclohexane and ethyl acetate (20:1 V/V) as eluent, to obtain the expected product in the form of an oil.
