Sulfuric Acid → 4-Difluoromethyl-2-(4-trifluoromethyl-phenyl)-imidazo[1,5-a]pyrimidine-8-carboxylic acid

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Reaction Conditions

Reaction Steps

A mixture of 4-difluoromethyl-2-(4-trifluoromethyl-phenyl)-imidazo[1,5-a]pyrimidine-8-carboxylic acid ethyl ester (6.0 g, 15.6 mmol), potassium hydroxide 14 g (0.25 mmol) in water (62.5 ml) and methanol (125 ml) was stirred at room temperature for 2 h and at 60° C. for 1 h, cooled (ice-water), and 3N sulfuric acid (90 ml) was added. The formed precipitate (4.32 g) was collected by filtration, acetic acid (65 ml) was added and the stirred solution was heated under reflux conditions for 1 h. The reaction mixture was evaporated, ethyl acetate (30 ml) was added and the mixture was stirred for 30 min at 0° C. The precipitate was collected by filtration and dried to yield 4-difluoromethyl-2-(4-trifluoromethyl-phenyl)-imidazo[1,5-a]pyrimidine-8-carboxylic acid (2.15 g, 39%) as a yellow solid. MS (ISN) 356.0 [(M−H)−]; mp 238° C.

Provenance & Evidence