2M Oxalyl chloride solution in dichloromethane (0.9 ml) and DMF (0.025 ml) were added to a suspension of 3-[2-(tert-butoxycarbonyl-pyridin-4-yl-amino)-ethoxy]-5-chloro-benzoic acid (0.610 g) in anhydrous dichloromethane (50 ml). The reaction was stirred at room temperature for 1 h then 2-phenylamino-ethanesulfonyl fluoride(0.257 g), DMAP (0.018 g) and DIPEA (0.261 ml) were added. The reaction mixture was stirred at room temperature for 20 h and partitioned between ethyl acetate and 1M aqueous hydrochloric acid. The aqueous layer was removed and the organic phase washed with saturated aqueous sodium bicarbonate, water and dried with brine and over sodium sulphate and concentrated under reduced pressure. The residue was purified by flash column chromatography, eluting with using ethyl acetate:petroleum ether (3:1 v/v) to give the title compound as a white foam (0.40 g).
