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TCI Practical Example: Ullmann-type Coupling Reaction at Room Temperature Using N-[3',5'-Di-tert-butyl[biphenyl]-2-yl]-N'-[2-(3,5-di-tert-butylphenyl)-1-naphthyl]-1,2-benzenediamine

We are proud to present the Ullmann coupling reaction of mesityl bromide and 1-phenylpiperazine using N-[3',5'-di-tert-butyl[biphenyl]-2-yl]-N'-[2-(3,5-di-tert-butylphenyl)-1-naphthyl]-1,2-benzenediamine. This reaction has the advantage of proceeding at room temperature.

Used Chemicals

• Mesityl Bromide [B1261]
• 1-Phenylpiperazine [P0980]
• N-[3',5'-Di-tert-butyl[biphenyl]-2-yl]-N'-[2-(3,5-di-tert-butylphenyl)-1-naphthyl]-1,2-benzenediamine [D6240]
• Copper(I) Iodide [C2163]
• Sodium Methoxide [S0485]
• DMSO

Procedure

Mesityl bromide (200 mg, 1.00 mmol), 1-phenylpiperazine (196 mg, 713 µmol), N-[3',5'-di-tert-butyl[biphenyl]-2-yl]-N'-[2-(3,5-di-tert-butylphenyl)-1-naphthyl]-1,2-benzenediamine (69.0 mg, 100 µmol), copper(I) iodide (9.56 mg, 50.2 µmol) and sodium methoxide (108 mg, 2.00 mmol) were dissolved in DMSO (2 mL) and stirred at room temperature for 22 hours. The reaction was quenched with water and the aqueous layer was extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and filtered. The solvent was removed under reduced pressure and the residue was purified by silica gel column chromatography (ethyl acetate:hexane = 0:100 - 5:95) to give 1-mesityl-4-phenylpiperazine as a yellow solid (200 mg, 71% yield).

Experimenter's Comments

The reaction mixture was monitored by NMR.
The reaction was carried out under a nitrogen atmosphere.

Analytical Data

1-Mesityl-4-phenylpiperazine

¹H NMR (270 MHz, CDCl₃); δ 7.30–7.24 (m, 2H), 6.99–6.96 (m, 2H), 6.88–6.81 (m, 3H), 3.24 (s, 8H), 2.30 (s, 6H), 2.23 (s, 3H).

Lead Reference

• Room-Temperature Cu-Catalyzed Amination of Aryl Bromides Enabled by DFT-Guided Ligand Design
  • S. T. Kim, M. J. Strauss, A. Cabré, S. L. Buchwald, J. Am. Chem. Soc. 2023, 145, 6966.