Greener Ullmann-Type Coupling of Aryl Halides for Preparing Biaryls Using Reusable Pd/ZrO₂ Catalyst

Abstract

Biaryls with excellent yields can be prepared by the Ullmann-type coupling of aryl halides in the presence of potassium carbonate (as a base) and dimethylformamide (as a solvent), at 140 °C, using a reusable Pd (2.5 wt%)/ZrO₂ catalyst. The product yield of 4-iodoanisole coupling is strongly influenced by the catalyst preparation method, solvent, and base.

Keywords:

• Aryl halides
• biaryls
• Pd/ZrO₂
• Ullmann coupling reaction

ACKNOWLEDGMENT

V. R. C. is grateful to the National Academy of Sciences (India) for the NASI Senior Scientist Platinum Jubilee Fellowship.

Notes

^a In the absence of catalyst.

^b Fourth reuse of the catalyst.

^c At 100 °C.

^d At 0 or 50 °C.