Ultrasound-Promoted Ligand-Free Heck Reaction in Water

Abstract

An ultrasound irradiation–promoted Heck reaction catalyzed by ligand-free palladium acetate was described. The ultrasound-promoted Heck reaction was carried out under mild and environmentally friendly conditions, resulting in the corresponding products with good to excellent chemical yields (up to 96% yield) and high regioselectivities and stereoselectivities (E/Z > 99:1). Acrylamide and acrylic acid were used for the first time as substrates in the ultrasound-promoted Heck reaction. It was found that the reaction could be finished within 20 min.

Keywords:

• Aqueous media
• Heck reaction
• palladium acetate
• ultrasound

ACKNOWLEDGMENTS

We gratefully acknowledge financial support from the National Natural Science Foundation of China (No. 20772056 to Y.P.). This work was also partially supported by research funds from the Qing-Lan Program of Jiangsu Province, the Kua-Shi-Ji Program of the Education Ministry of China, and the Jiangsu 333 program (for Pan).

Notes

^a Iodobenzene (5 mmol), acrylamide (6 mmol), base (7.5 mmol), Pd(OAc)₂ (0.05 mmol), surfactant (0.5 mmol), and water (20 mL).

^b Determined by ¹H NMR. Only E-isomer was detected.

^c Isolated yield.

^a Aryl iodide (5 mmol), acrylamide (6 mmol), K₂CO₃ (7.5 mmol), Pd(OAc)₂ (0.05 mmol), sodium dodecane-1-sulfonate (0.5 mmol), and water (20 mL) at 90 °C for 20 min.

^b Determined by ¹H NMR. Only E-isomer was detected.

^c Isolated yields.

^a Iodobenzene (5 mmol), olefin (6 mmol), K₂CO₃ (7.5 mmol), Pd(OAc)₂ (0.05 mmol), sodium dodecane-1-sulfonate (0.5 mmol), and water (20 mL), at 90 °C for 20 min.

^b Determined by ¹H NMR. Only E-isomer was found.

^c Isolated yields.