Microwave-Assisted Ullmann-Type Coupling Reactions in Alkaline Water

Abstract

Upon microwave irradiation, homocoupling reaction of aryliodides catalyzed by Pd/C in alkaline water media can be readily accelerated to form biaryls with excellent conversions and selectivities.

GRAPHICAL ABSTRACT

Keywords:

• Aqueous media
• microwave
• Pd/C
• Ullmann-type coupling

ACKNOWLEDGMENT

This work was carried out with the support of the Development of Microspace and Nanospace Reaction Environment Technology for Materials Project under New Energy and Industrial Technology Development Organization (NEDO).

Notes

Conditions: Pd/C (50 mg, 4.8 mol%), Et₃N, H₂0 (2 mL), MW irradiation (150 °C, 30 min).

^a No Pd/C was used.

^b Bromobenzene (0.49 mmol).

^c Chlorobenzene (0.49 mmol).

^d Biphenyl (38 mg, 0.25 mmol).

Conditions: Pd/C (50 mg, 4.8 mol-%), base, H₂O (2 mL), MW irradiation (150 °C, 30 min).

^a Oilbath heating (150 °C, 30 min).

Conditions: Pd/C (50 mg, 4.8 mol%), Et₃N, H₂O (2 mL).

^a No water used.

^b Pd/C (100 mg, 9.6 mol%).

^c Zn (16 mg, 50 mol-%) added.

^d Al (7 mg, 50 mol-%) added.

^e Mg (6 mg, 50 mol-%) added.

Note: Conditions: starting aryliodide (0.49 mmol), Pd/C (50 mg, 4.8 mol%), 1 M NaOH (2 mL, 4:1 mol/mol). MW 150 °C, 60 min; side product ratio in parentheses: e.g., 2,3′-dimethoxybiphenyl.