1-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; prepared as air-free in House)

p-Tolualdehyde (97%, Sigma-Aldrich)

2-Methyltetrahydrofuran (≥99.0%, Inhibitor-free, Sigma-Aldrich)

Diethyl Ether (≥99.0%, anhydrous, ACS reagent, contains BHT as inhibitor, Sigma-Aldrich)

Hexanes, mixture of isomers (≥99.0%, anhydrous, Sigma-Aldrich)

Toluene (99.8%, anhydrous, Sigma-Aldrich)

Saturated Ammonium Chloride (Prepared in House)

Brine Solution (NaCl and deionized water, Prepared in House)

MgSO₄ (≥99.5%, anhydrous, ReagentPlus^®, Sigma-Aldrich)

The synthesis was conducted under a nitrogen atmosphere using standard Schlenk techniques. To a 15 mL scintillation vial was added: 3-phenylindene (0.150 g, 7.80 x 10^-4 mol), heptane (8.0 mL, 0.1 M) and a stir bar. The reaction was stirred at 0 °C for approximately 10 minutes.  Dropwise¹, n-Butyllithium (0.330 mL, 8.19 x 10^-4 mol) was added and the flask was allowed to return to room temperature and stirred overnight (~20 hours).

Heptane was removed under reduced pressure.  To the remaining precipitate was added: 2-methyltetrahydrofuran (8.0 mL, 0.1 M) and the reaction was cooled to 0 °C and stirred² for approximately 10 minutes at which point p-Tolualdehyde (0.100 mL, 8.58 x 10^-4 mol) was added dropwise and the reaction was stirred overnight at room temperature (≈ 20 h).

The reaction was quenched with 3 mL of aqueous NH₄Cl.  The sample was washed with brine solution (3 x 5 mL) and extracted with diethyl ether (3 x 5 mL)³.  The organic layer was dried over MgSO₄ and then gravity filtered.  The solvent was removed under reduced pressure and the crude product was purified via preparatory plate (90:10 Hexane:Toluene) yielding a highly colored yellow/orange solid (130 mg, 57% yield).

1. To ensure the lithium anion product forms, it is imperative to add the n-BuLi base drop wise after the solution has equilibrated to 0 °C in the ice bath.  This will help control for reaction selectivity since this base is very reactive.  After adding the reaction will turn from a clear, colorless solution to a cloudy, yellow color.
2. Upon re-dissolving the yellow precipitate in 2-MeTHF, the solution will turn to a deep red color. 
3. Additional washes may need to be done in order to reduce the emulsion layer if present.
4. Allowing the product to run overnight under high vacuum will remove any excess solvent remaining.
5. Reaction has been performed multiple times and resulting yields have shown method is reproducible.   
6. We would like to thank Dr. Lev Zakharov (University of Oregon) for providing crystal structure analysis.  

¹H NMR (CDCl₃, 500 MHz):  δ ppm 2.39 (s, 3H), 7.15 (s, 1H), 7.25 (d, J = 7.88 Hz, 2H), 7.29 - 7.31 (m, 2H), 7.38 (t, J = 6.62 Hz, 1H), 7.46 (t, J = 7.25 Hz, 2H), 7.50 (s, 1H), 7.57 - 7.60 (m, 3H), 7.70 (d, J = 8.20 Hz, 2H), 7.76 (d, J = 6.94 Hz, 1H)

¹³C NMR (CDCl₃, 500 MHz): δ ppm 21.4, 119.2, 120.3, 123.2, 125.4, 127.2, 127.6, 128.1, 128.4, 128.6, 129.5, 130.2, 134.3, 135.8, 138.4, 138.6, 139.0, 140.6, 147.1

GC-MS M^.+ EI calculated 294.397, found 294

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