Hydrochloric Acid → 5,7-Difluorochroman-4-one

Participants

Reaction Steps

0.5 ml of DMF and 7.35 ml (84.29 mmol) of oxalyl chloride were slowly added dropwise to a solution of 11.36 g (42.15 mmol) of the compound from Example 169A in 400 ml of dichloromethane at RT. After stirring at RT for 3 h, the solvents were removed in a rotary evaporator, and the residue was again taken up in 200 ml of dichloromethane. 6.74 g (50.57 mmol) of aluminum trichloride were added in portions to the reaction mixture, and the mixture was stirred for 1 h. 150 ml of 2N hydrochloric acid and 200 ml of dichloromethane were added, the phases were separated, and the aqueous phase was extracted twice with dichloromethane. The combined organic phases were dried over sodium sulfate and filtered, and the solvents were removed in vacuo. The crude product was purified by flash chromatography on silica gel (mobile phase: dichloromethane). 6.46 g (80% of theory) of the title compound were obtained.

Provenance & Evidence