Potassium Bromide → 1-(Tert-butoxy)-3-fluoropropan-2-one

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反応条件

反応手順

A 2.5 L 4-necked sulfonation flask equipped with mechanical stirrer, dropping funnel, thermometer and an argon in/outlet, was charged with 141 g (938.8 mmol) 1-tert-butoxy-3-fluoro-propan-2-ol, 400 mL dichloromethane, 30.02 g (357.3 mmol) sodium bicarbonate, 400 mL de-ionized water and 10.68 g (89.78 mmol) potassium bromide. The two-phase system was cooled to 0° C. and 712.1 mg (4.56 mmol) 2,2,6,6-tetramethyl-1-piperidinyloxy radical (TEMPO) were added. To the resulting light orange mixture were added within 2 h 609.1 g (1.072 mol) sodium hypochlorite solution 13.1% while vigorously stirring whereupon the internal temperature transiently rose to 15° C. The reaction mixture was quenched at 0° C. with 9.71 mL (46.8 mmol) sodium bisulfite solution 38-40% leading to disappearance of the orange color. The phases were separated and the aqueous layer was extracted twice with 350 mL dichloromethane. The combined organic phases were washed with 400 mL brine, dried over sodium sulfate, filtered and evaporated to afford 130.02 g (93.5%) crude 1-tert-butoxy-3-fluoro-propan-2-one of 98.9% GC purity. 1H-NMR (CDCl3, 300 MHz): 5.13 (d, JH,F=48, —CH2—F); 4.15 (d, J=1.5, —CH2—O); 1.22 (s, C(CH3)3).

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