3-phenylindene (prepared in-house, see synthetic page 696 DOI: 10.1039/SP697

n-butyllithium (2.5 M in hexanes, Acros Organics)

heptane (99.0%, anhydrous, Sigma Aldrich)

terephthaldehyde (>97%, Sigma Aldrich)

tetrahydrofuran (>99%, anhydrous, inhibitor-free, Sigma Aldrich)

ethyl acetate (HPLC grade, Sigma Aldrich)

hexanes (HPLC grade, Sigma Aldrich)

To a dried and nitrogen flushed 50 mL flask was added: 3-phenylindene (267 mg, 1.3 mmols) and anhydrous heptane (14 mL, 0.1 M). The reaction solution was cooled to 0 ^oC via an ice bath. After stirring for 10 minutes - n-BuLi (0.590 mL, 1.4 mmol) was added dropwise. The solution turns a pale yellow, with a slight turbidity developing within minutes. The reaction was allowed to warm to RT and stirred overnight (16 h). The heptanes was removed under reduced pressure to yield a slightly yellow solid. The temperature was reduced to − 70 ^oC via a dry ice, ethyl acetate bath - THF (10 mL, anhydrous) was then added, the solution becomes a crimson red. To this solution is added, terephthaldehyde (96 mg, 0.65 mmol, dissolved in 4 mL anhydrous THF) dropwise. The reaction is allowed to warm to RT and stirred overnight (16 hours).  The reaction is quenched with NH₄Cl (10 mL, saturated, aqueous) and extracted with ethyl acetate (15 mL, 3X). The organic layer is dried over magnesium sulfate and filtered. The solvent is removed under reduced pressure.

A crude red solid is isolated and subjected to trituration (hexanes, 10 mL, 5X).  The desired product is isolated as a clean powdered red solid (199 mg, 58% yield).

1. Solubility of the benzofulvene is quite limited in most solvents. 
2. We would like to thank Dr. Lev Zakharov and Austin Erler (University of Oregon) for crystal structure analysis.
3. We would like to thank Scout Watanabe (Pacific Lutheran University) for starting material preparation.

¹H NMR (CDCl₃, 500 MHz): d ppm 7.20 (s, 2H), 7.33 (m, 4H), 7.42 (m, 2H), 7.50 (m, 4H), 7.54 (s, 2H), 7.62 (m, 2H), 7.73 (m, 4H), 7.77 (s, 4H), 7.81 (m, 2H)

¹³C NMR (CDCl₃, 125 MHz): d ppm 119.5, 120.5, 123.0, 125.6, 127.3, 127.5, 127.7, 128.3, 128.7, 130.6, 135.6, 137.2, 138.9, 139.8, 140.7, 148.0