Acetone → 6-fluoro-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

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Reaction Steps

In a 500 mL round-bottomed flask was added 1-(5-fluoro-2-hydroxyphenyl)ethanone (20.0 g, 130 mmol, Aldrich Chemical), propan-2-one (19.0 mL, 260 mmol), and pyrrolidine (21.5 mL, 260 mmol) in methanol (150 mL) to give a orange solution. The reaction mixture was stirred at ambient temperature for 48 h. The reaction mixture was poured into EtOAc (200 mL) and washed with 1N HCl (50 mL), saturated NaHCO3 (50 mL), and brine (50 mL). The organic portion was dried (Na2SO4), filtered, and concentrated to provide an orange residue which was purified by silica gel chromatography (gradient elution, 0-20% EtOAc/hexanes) to provide the title compound (14.2 g, 73.1 mmol, 56%) as a white solid. MS (DCI/NH3) m/z 208 (M+NH4)+.

Provenance & Evidence