Methanesulfonic Acid → 4-Chloro-2-fluoro-fluoren-9-one

Participants

Reaction Conditions

Reaction Steps

To a mixture of phosphorus pentoxide (133 g) and methanesulfonic acid (1300 ml) was added 2′-chloro-4′-fluoro-biphenyl-2-carboxylic acid (132.9 g), and the mixture was stirred at 80° C. for 2.5 hr. The reaction mixture was ice-cooled, water (1300 ml) was slowly added dropwise, and the mixture was further stirred at room temperature for 1 hr. This suspension was filtered, and the obtained solid was washed with water (300 ml). The solid was mixed with 50 v/v % ethanol-water (1300 ml), and the slurry was stirred at room temperature for 1.5 hr, and filtered. The obtained solid was washed with 50 v/v % ethanol-water (200 ml), air-dried for 3 hr, and dried under reduced pressure at 60° C. to give the title compound (121.6 g, 99%).

Provenance & Evidence