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TCI Practical Example: Diels-Alder Reaction Using the Benzyne Precursor

We are proud to present the synthesis of 1,2,3,4-tetraphenylnaphthalene derivative with a benzyne precursor and a cyclopentadiene derivative via Diels-Alder reaction and decarbonylation.

Used Chemicals

• Phenyl[2-(trimethylsilyl)phenyl]iodonium Triflate [P1620]
• Tetraphenylcyclopentadienone [T1062]
• Tetrabutylammonium Fluoride (= TBAF) (ca. 1mol/L in Tetrahydrofuran) [T1338]
• Dichloromethane

Procedure

Under nitrogen atmosphere, tetraphenylcyclopentadienone (1.54 g, 4.0 mmol) was added to a solution of phenyl[2-(trimethylsilyl)phenyl]iodonium triflate (402 mg, 0.80 mmol) in dichloromethane (10 mL) and the reaction mixture was cooled to 0 ˚C. TBAF (ca. 1mol/L solution in Tetrahydrofuran, 0.96 mL, 0.96 mmol) was then added and the mixture was stirred at room temperature for 30 minutes. The reaction was quenched with water and extracted with dichloromethane. The organic layer was dried over anhydrous sodium sulfate and filtered. The solvent was removed under reduced pressure and the crude was purified by column chromatography (ethyl acetate:hexane = 1:99 on silica gel) to give 1 as a white solid (296 mg, 86% yield).

Experimenter’s Comments

The reaction mixture was monitored by TLC (ethyl acetate: hexane = 1:99, Rf = 0.55).
This experiment was performed in a fume hood due to the generation of carbon monoxide.

Analytical Data

1,2,3,4-Tetraphenylnaphthalene (1)

¹H NMR (270 MHz, CDCl₃); δ 7.67-7.63 (m, 2H), 7.41-7.38 (m, 2H), 7.26-7.19 (m, 10H), 6.89-6.82 (m, 10H).

Lead Reference

• A New and Efficient Hypervalent Iodine-Benzyne Precursor, (Phenyl)[o-(trimethylsilyl)phenyl]iodonium Triflate: Generation, Trapping Reaction, and Nature of Benzyne
• • T. Kitamura, M. Yamane, K. Inoue, Mi. Todaka, N. Fukatsu, Z. Meng, Y. Fujiwara, J. Am. Chem. Soc. 1999, 121, 11674.