Under argon, 550 mg (2.26 mmol) of 4-hydroxy-2-pyridinyl trifluoromethanesulfonate (Example 39A) are suspended in 15 ml of dichloromethane at room temperature. 2 ml of a 40% strength solution of tetrabutylammonium hydroxide in water are added dropwise to this. Then 476 mg (2.26 mmol) of 4,4,4-trifluoro-1-butanesulfonyl chloride are added and allowed to react for 20 minutes. Working up takes place by adding water, extracting with ethyl acetate, washing, drying and evaporating in a rotary evaporator. The residue is purified by chromatography on 20 g of silica gel (0.04-0.063 mm) with cyclohexane/ethyl acetate 2:1 to 1:1).
