Starting with 0.71 g of [4-chloro-2-(2-chlorobenzyl)phenyl]amine dissolved in 5 ml of THF are added 0.4 ml of pyridine and 0.8 g of 3-methoxybenzenesulfonyl chloride, and the mixture is left at room temperature for 18 hours. The reaction medium is taken up in ethyl acetate and washed with water. The organic phase is dried over anhydrous sodium sulfate and concentrated. The residue is chromatographed on a column of silica gel, eluting with a 90/10 (v/v) cyclohexane/ethyl acetate solvent mixture to give 0.666 g of expected product.
