A solution of 510 mg of 5-(2-fluoro-phenoxy)-2-(4-methoxy-3,5-dimethyl-phenyl)-oxazolo[5,4-d]pyrimidine in 20 ml dichloromethane was cooled to 0° C., and over a period of 10 min 4.2 ml of a 1 M solution of boron tribromide in dichloromethane was added. The mixture was stirred at 0° C. for 1 h, and then another 2 ml of a 1 M solution of boron tribromide in dichloromethane were added. After stirring for another 1 h, 10 ml of a saturated aqueous solution of sodium hydrogencarbonate were added slowly. The aqueous layer was extracted twice with 15 ml of dichloromethane. The combined organic layers were dried over sodium sulfate, filtered and the solvents were removed in vacuo to give 445 mg of the title compound as a white solid.
