To a mixture of tert-butyl 3-[4-(2′-formylbiphenyl-3-ylmethoxy)phenyl]propanoate (1.5 g, 3.60 mmol), sodium dihydrogenphosphate (0.43 g, 3.60 mmol), 2-methyl-2-butene (1.72 mL, 16.2 mmol), tert-butanol (7 mL), water (15 mL) and tetrahydrofuran (15 mL) was added sodium chlorite (1.22 g, 10.8 mmol) with stirring at 0° C., and the mixture was stirred at the same temperature for 2 hrs. The reaction mixture was diluted with ethyl acetate, washed with water, dried (anhydrous magnesium sulfate), and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=2/1-1/2) to give the title compound (1.12 g, 72%) as a yellow oil.
