Potassium tert-butoxide solution 0.5 mol/L in dimethyl sulfoxide (1.10 mL, 0.55 mmol) was added to and dissolved in 2-iodo-7-methoxy-3-phenyl-4-(4-pivaloyloxyphenyl)-1,2,3,4-tetrahydronaphthalene (5′, 74.4 mg, 0.138 mmol) under an argon atmosphere, and the resulting aubergine solution was stirred for 1 hour while heating at 90° C. Thereafter, the reaction mixture was cooled with ice, and then a saturated aqueous ammonium chloride solution (7 mL) was added thereto and sufficiently stirred, followed by extracting four times with a mixed liquid (4 mL) of hexane/diethyl ether (1:1). An organic layer was collected, followed by drying with anhydrous magnesium sulfate and concentration thereof. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=4/1) to obtain the title compound (7, 41.1 mg, yield 89%), the same as that of Example 4.
