4'-Fluoroacetophenone → 4-(4-Acetylphenoxy)piperidine oxalate

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Reaction Steps

To a stirred solution of dimsyl sodium, prepared from 43.2 g of NaH (0.90 mol; 50% in oil, washed 3 times with hexane) and 1200 ml of DMSO was added in aliquots, 100 g (0.989 mol) of 4-hydroxypiperidine such that the temperature remained below 23° (using an ice bath). To the mixture was then added dropwise 120 ml (0.99 mol) of p-fluoroacetophenone. The mixture was then stirred at room temperature overnight, poured into water, extracted twice with ether, washed with saturated sodium chloride and dried over potassium carbonate. Filtration followed by evaporation of the solvent provided an oil. The oil was filtered through 500 g of alumina and eluted 2×500 ml of 5% methanol/ether and 2×500 ml of 10% methanol/ether. The material was contained in fractions 2-4. Evaporation of the solvent provided an oil. The yield of the oxalate was 51.2 g (0.165 mol, 18.4%). Recrystallization from methanol provided analytically pure material, m.p. 183- 187.

Provenance & Evidence