[C:1]([C:3]1[CH:8]=[CH:7][C:6]([F:9])=[CH:5][CH:4]=1)#[CH:2].Br[C:11]1[CH:12]=[C:13]([CH:23]=[CH:24][CH:25]=1)[C:14]([C:16]1[CH:21]=[CH:20][C:19]([F:22])=[CH:18][CH:17]=1)=[O:15].C1(C)C=CC=CC=1>C(N(CC)CC)C>[F:9][C:6]1[CH:7]=[CH:8][C:3]([C:1]#[C:2][C:24]2[CH:25]=[CH:11][CH:12]=[C:13]([C:14](=[O:15])[C:16]3[CH:17]=[CH:18][C:19]([F:22])=[CH:20][CH:21]=3)[CH:23]=2)=[CH:4][CH:5]=1Thus a reaction mixture is formed by dissolving appropriate amounts of 1-ethynyl-4-fluorobenzene, 3-bromo-4′-fluorobenzophenone, and tetrakis(triphenylphosphine)palladium[0] in a de-aerated aprotic solvent, for example, triethylamine. Alternatively, toluene can be used as a first solvent and triethylamine added as a cosolvent in a stoichiometric equivalent to 3-bromo-4′-fluorobenzophenone. The reaction mixture is heated to 80° C. with stirring under an inert atmosphere, e.g. argon, for approximately three hours. The reaction mixture is then allowed to cool to ambient while stirring is continued for approximately 16 hours. A white precipitate of triethylamine hydrobromide is removed by filtration and the aprotic solvents employed are removed by evaporation. The resulting solids are dissolved in a solvent, e.g. dichloromethane, or preferably toluene due to its relatively higher environmental friendliness, and then washed with water, an aqueous 2% HCl solution, brine, and then dried. After solvent evaporation, a good yield of white crystalline 4-fluoro-3′-(4-fluorobenzoyl)tolane, melting at approximately 127-128° C. is obtained. Purification by recrystallization from acetone results in a material with a melting point of 130-131° C. Alternatively, recrystallization from toluene provide a crystalline material in the form of rhombic fine needles with a melting point of 135-136° C.
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