Ultrasound-assisted rapid reduction of nitroaromatics to anilines using gallium metal

Abstract

The reduction of nitroaromatic compounds to anilines is widely used throughout organic synthesis. Typical methods of performing this transformation utilize hydrogenation over a pyrophoric catalyst or a finely divided reducing metal, which often affords heterogeneous mixtures that are difficult to purify. Herein, we report for the first time the use of gallium metal as a reducing agent in organic synthesis. The reaction proceeds under aerobic conditions and affords homogeneous mixtures for a convenient workup. Using this method, twelve anilines were obtained in 33% to quantitative yields with short reaction times of 10-60 minutes.

Graphical Abstract

Keywords:

• Aniline
• gallium
• metal
• nitroaromatic
• reducing
• reduction
• ultrasound

Acknowledgments

We would like to thank Hawai’i Pacific University of the use of their nuclear magnetic resonance instrument. Also, our thanks to Dr. Paul Helquist at University of Notre Dame and Dr. David Kingston at Virginia Tech for useful commentaries while preparing our manuscript.

Additional information

Funding

The work was supported by grants from the Alana Dung Research Foundation and NIH NIGMS INBRE under [Award number: P20GM103466].