TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method comprises: (a) esterifying (I) to obtain methyl 2-hydroxy-4-methyl-benzoate compound of formula (II); (b) carrying out sulfonation reaction of (II) to obtain a 2-(trifluoromethylsulfonyloxy)benzoic acid of formula (III); (c) reacting (III) with a boronic acid derivative of formula (A) to obtain a 2-phenylbenzoic acid compound of formula (IV); (d) reacting (IV) with a metal compound of formula (R1aMgX) or (R1aLi) to obtain a methyl 2-phenylbenzoate compound of formula (V); (e) reacting (V) with an acidic solvent under the presence of strong acid to obtain (VI); (f) reacting (IV) with a reaction solvent under the presence of metal hydroxide of formula (M1OH) to prepare a 4-methyl-2-phenyl-benzoic acid compound of formula (VII); (g) performing acid treatment on (VII) to obtain a fluoren-9-one compound of formula (VIII); (h) reacting (VIII) with a biphenyl derivative of formula (B1) to obtain a 9-(2-phenylphenyl)fluoren-9-ol compound of formula (IX); and (i) reacting (IX) with the acidic solvent under the presence of strong acid to obtain a 9H-fluorene compound of formula (X). The step (b) is carried out in the presence of methylene chloride as a reaction solvent, triethylamine as a base and trifluoro-methanesulfonyl chloride, 1,1,1-trifluoro-N-phenyl-N-(trifluoromethylsulfonyl)methanesulfonamide, trifluoro-N-phenyl-methanesulfonamide and trifluoromethylsulfonyl trifluoromethanesulfonate as reactants. The step (e) is carried out in the presence of potassium carbonate as a base and dimethylformamide as a reaction solvent. The strong acid is hydrochloric acid. The step (f) is performed in the presence of methanol and water at a molar ratio of 1:3. The acid used in the step (g) is methanesulfonic acid. The step (g) is performed in the presence of tetrahydrofuran, hexane or n-butyl lithium. The step (i) is performed in the presence of acetic acid as a solvent.Ra1 = 1-6C alkyl, 1-6C alkenyl or 1-6C alkynyl;M1 = Li, Na or K; andp, q = 0-4. EXAMPLE - No suitable example given.