Under a nitrogen atmosphere, 120 mL of dehydrated 1,2-dimethoxyethane was added to 8.00 g (18.3 mmol) of 2,7-dibromo-3,6-ditert-butyl-fluorene synthesized in Synthesis Example 1-1(i) and 1.05 g (0.909 mmol) of Pd(PPh3), and the mixture was stirred at room temperature for 20 minutes. To this solution, a solution prepared by dissolving 5.50 g (40.5 mmol) of 4-methylphenylboric acid in 20 mL of ethanol was added. The mixture was stirred at room temperature for 20 minutes, and then 36.8 mL (73.6 mmol) of a 2.0 mol/L aqueous solution of sodium carbonate was added. Subsequently, the mixture was heated to reflux for 21 hours, left to be naturally cooled, and then 1N hydrochloric acid was added in an ice bath to terminate the reaction. Dichloromethane was then added to perform a liquid-liquid phase separation, and the aqueous layer was subjected to extraction with diethyl ether twice. The resultant was combined with the organic layer obtained previously. The resultant liquid was then washed two times with a saturated aqueous solution of sodium hydrogen carbonate, two times with water, and once with saturated brine, and then dried over magnesium sulfate. Subsequently, the solvent was distilled off, and the resultant was subjected to separation by silica gel chromatography. To the whitish yellow powder obtained, small amount of a mixed solution of n-hexane and ethanol was added. The mixture was heated to 65° C., and then was left to stand for 1 hour at room temperature. Crystals Precipitated were washed 10 times with 2 mL of cold methanol and 20 times with 1 mL of cold n-hexane to obtain a target product as a white powder (yield 6.95 g (83%)). The target product was identified by 1H-NMR and FD-MS spectroscopy.
