In a 25 ml single-necked round-bottomed flask, N-Methyl-N-(1-methyl-prop-2-ynyl)-formamide (223 mg) is solubilized in dry dichloromethane (4 ml) at ambient temperature (colourless solution). Under stirring a mixture of phosphorous oxide chloride (0.18 ml) in dichloromethane (1 ml) is added dropwise by syringe. Stirring at ambient temperature is continued for 1 hour. To this solution, 6-(4-Chloro-3-trifluoromethyl-phenoxy)-4-methyl-pyridin-3-ylamine (303 mg) dissolved in 10 ml of dry dichloromethane is added dropwise by syringe, giving a yellow solution. Stirring is continued at an ambient temperature for 3 hours. The mixture is then poured into ice/water (pH=2, water phase). 2 M aqueous NaOH is then added to get a pH of about 11 and stirring is continued for 10 minutes. The mixture is then extracted with dichloromethane (2×50 ml). The combined organic phases are then dried over sodium sulfate, filtered and the solvent is removed in vacuo. Purification of this gum by flash chromatography over silica gel with hexane/ethyl acetate 3:2 (v:v) gives 198 mg of the compound as a brownish oil.
