[CH3:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[C:9]([C:14]([OH:16])=[O:15])=[CH:10][CH:11]=[CH:12][CH:13]=2)=[CH:4][CH:3]=1.O=P(Cl)(Cl)Cl.[CH2:22]=[C:23]([CH3:25])[CH3:24]>C1(C)C=CC=CC=1>[CH3:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[C:9]([C:14]([O:16][C:23]([CH3:25])([CH3:24])[CH3:22])=[O:15])=[CH:10][CH:11]=[CH:12][CH:13]=2)=[CH:4][CH:3]=1A 100-ml flask was charged with 5 ml of toluene and 2.12 g (10 mmol) of 4′-methyl-2-biphenylcarboxylic acid, and they were vigorously stirred. To this mixture was added dropwise 0.18 ml (2 mmol) of phosphorus oxytrichloride, and isobutene gas (98 mmol) was introduced to the mixture at a flow rate of 1.2 liter/min for 2 minutes. The resulting mixture was stirred at room temperature for 6 hours. After having confirmed that almost all of the peaks ascribed to 4′-methyl-2-biphenylcarboxylic acid disappeared by HPLC, the reaction solution was washed with a 1.5 M aqueous sodium hydroxide. The reaction solution was dried over anhydrous magnesium sulfate, and then the mixture was concentrated by distilling off toluene by using a rotary evaporator, to give 2.63 g of tert-butyl 4′-methyl-2-biphenylcarboxylate as crystals (yield: 98% based on 4′-methyl-2-biphenylcarboxylic acid, purity by HPLC: 99.9%). Incidentally, the obtained compound had the same physical properties as those of the compound obtained in Example II-1.
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