Bis(tri-tert-butylphosphine)palladium(0)

Used Chemicals

• 2-Bromonaphthalene [B0619]
• Morpholine [M0465]
• Bis(tri-tert-butylphosphine)palladium(0) (= Pd(PtBu₃)₂) [B3161]
• Potassium tert-Butoxide [P1008]
• Toluene

Procedure

To a 4-necked 200 mL flask was charged with 2-bromonaphthalene (5.20 g, 25.1 mmol, 1.0 equiv.), morpholine (3.27 mL, 37.5 mmol, 1.5 equiv.) and degassed toluene (75 mL). To this solution was added bis(tri-tert-butylphosphine)palladium(0) (256 mg, 0.501 mmol, 2.0 mol%) and potassium tert-butoxide (4.21 g, 37.5 mmol, 1.5 equiv.). The reaction mixture was refluxed for 3 h under argon atmosphere. The reaction mixture was cooled to room temperature and washed with water (50 mL). The organic layer was separated and the aqueous layer was extracted with ethyl acetate (50 mL). The combined organic layers were washed with brine (50 mL), dried over Na₂SO₄ and filtered. The solvent was removed under reduced pressure. The residue was purified by column chromatography (eluent: hexane/ethyl acetate, 85/15→70/30) to obtain 1 as a white solid (5.17 g, 96.5%).

Experimenter's Comments

The reaction mixture was monitored by TLC (hexane/ethyl acetate = 9/1, Rf = 0.70).

Analytical Data（Compound 1）

¹H NMR (400 MHz, CDCl₃); δ 7.76–7.69 (m, 3H), 7.42 (t, J = 7.2 Hz, 1H), 7.31 (t, J = 6.8 Hz, 1H), 7.25–7.28 (m, 1H), 7.13 (s, 1H), 3.92 (t, J = 4.8 Hz, 2H), 3.27 (t, J = 4.8 Hz, 2H).

¹³C NMR (101 MHz, CDCl₃); δ 129.0, 127.6, 127.0, 126.5, 123.7, 119.1, 110.3, 67.1, 50.0.

Lead Reference

• Heterogeneous Rhodium‐Catalyzed Aerobic Oxidative Dehydrogenative Cross‐Coupling: Nonsymmetrical Biaryl Amines
  • K. Matsumoto, M. Yoshida, M. Shindo, Angew. Chem. Int. Ed. 2016, 55, 5272.

References

• Chain-Growth Suzuki Polymerization of n-Type Fluorene Copolymers
  • E. Elmalem, A. Kiriy, W. T. S. Huck, Macromolecules 2011, 44, 9057.
• Chain-Growth Polymerization for the Synthesis of Polyfluorene via Suzuki−Miyaura Coupling Reaction from an Externally Added Initiator Unit
  • A. Yokoyama, H. Suzuki, Y. Kubota, K. Ohuchi, H. Higashimura, T. Yokozawa, J. Am. Chem. Soc. 2007, 129, 7236.

Typical Procedure: An ampoule is charged with the thiocarbamate (0.442 mmol) and anhydrous degassed toluene (4 mL) is added via gastight syringe under nitrogen with stirring. A J. Youngs valve is fitted and the ampoule is placed into an oil bath pre-equilibrated at 100℃. After ca. 5 minutes the valve is removed and Pd(t-Bu3P)2 (2 mol%, 0.00884 mmol) is added as a solid, the valve is then replaced and the reaction mixture heated for 2.5 hours. A sample of the reaction mixture is removed via gastight syringe and found to contain the desired product (＞99%).

Reference

• The Newman–Kwart Rearrangement of O‐Aryl Thiocarbamates: Substantial Reduction in Reaction Temperatures through Palladium Catalysis
  • J. N. Harvey, J. Jover, G. C. Lloyd-Jones, J. D. Moseley, P. Murray, J. S. Renny, Angew. Chem. Int. Ed. 2009, 48, 7612.