[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:11])C=C)=[CH:4][CH:3]=1.[F-].[Na+].[C:14](C1C=C(C)C=C(C(C)(C)C)C=1O)(C)(C)C.[F:30][C:31]([F:43])(S(F)(=O)=O)[C:32](O[Si](C)(C)C)=O>C(OCC)(=O)C>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]([CH:32]2[CH2:14][C:31]2([F:43])[F:30])=[O:11])=[CH:4][CH:3]=1
Under argon, 91 g (546 mmol) of 1-(4-chlorophenyl)prop-2-en-1-one, 2.293 g (54.6 mmol) of sodium fluoride and 2.41 g (10.92 mmol) of 2,6-di-tert-butyl 4-methylphenol were heated in a 3 liter three-necked flask to 110° C. and stirred at this temperature for 5 min. At an internal temperature of 110°-125° C., 183 ml (928.5 mmol) of trimethylsilyl 2,2-difluoro-2-(fluorosulphonyl)acetate were then slowly added dropwise over a period of 30-35 min to the solution (careful: evolution of gas). After the addition and the evolution of gas had ended, the reaction solution was stirred for another 20 min. After cooling, the reaction mixture was taken up in several liters of ethyl acetate and extracted with saturated aqueous sodium bicarbonate solution. The phases were separated, the organic phase was then dried over magnesium sulphate and filtered and the filtrate was concentrated to dryness. The crude product obtained was purified by chromatography on silica gel (about 2 kg) (mobile phase cyclohexane/ethyl acetate 10:1). This gave 63 g of the target product (53% of theory).
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