A 100 mL three-neck round bottom flask equipped with a condenser, magnetic stir bar, thermometer, and a nitrogen inlet was dried, purged with nitrogen, then charged with 5-phenylindene (5.8 g, 0.03 mol), 3,5-di-tert-butylbromobenzene (8.1 g, 0.03 mol), sodium acetate (4.9 g, 0.06 mol), dichloropalladium (II) bis(acetonitrile) (0.026 g, 0.10 mmol), tetraphenylphosphonium chloride (0.225 g, 0.60 mmol), and anhydrous 1-methyl-2-pyrrolidinone (45 mL). The reaction mixture was heated to 60° C. for 24 hours without any conversion of starting materials. The temperature was then raised to 140° C. for 16 hours after which GC analysis showed >95% conversion of 5-phenylindene. The reaction mixture was cooled, mixed with chilled 5% aqueous HCl (250 mL) and extracted with diethyl ether (3×100 mL). The combined diethyl ether extracts were water washed and then dried over anhydrous magnesium sulfate. Rotary evaporation gave crude product (12.5 g) as a viscous red-brown oil. Crystals of 2-(3,5-di-tert-butylphenyl)-5-phenylindene (6.4 g) precipitated from a concentrated solution (˜50%) of the crude product in acetone-methanol (70:30). Three consecutive recrystallizations from acetone-methanol yielded 2-(3,5-di-tert-butylphenyl)-5-phenylindene (3.2 g, 99.9% purity by GC) as pale tan crystals (mp 122-3° C.). 1HNMR (CD2Cl2, 500MHz) 40:60 mixture of isomeric alkenes; δ7.65-7.25 (mults, 12H); 3.82, 3.80 (s, 2H); 1.30 (s, 18H).
