To a solution of 2-[1-(3-methoxy-2-methylbenzyl)-2-cyclohexen-2-yl]-4,5-diphenyloxazole (1.16 g) in CH2Cl2 (25 ml) was added boron tribromide (1M solution in CH2Cl2, 5.32 ml) at −60° C. and the mixture was warmed to 5° C. After stirring for 1 hour at the same temperature, the reaction mixture was stirred for further 1 hour at room temperature. To the mixture was added water under ice-cooling, extracted with EtOAc. The organic layer was washed with water, saturated sodium hydrogen carbonate, water, and brine, dried over magnesium sulfate, evaporated in vacuo. The residue was purified by silica gel column chromatography (hexane-EtOAc 5:1) to give 3-{[2-(4,5-diphenyloxazol-2-yl)-2-cyclohexen-1-yl]methyl}-2-methylphenol (903.8 mg) as an amorphous solid.
