TEMPO-mediated aerobic oxidative synthesis of 2-aryl benzoxazoles via ring-opening of benzoxazoles with benzylamines

Abstract

A simple and efficient TEMPO-mediated system for aerobic oxidative synthesis of 2-aryl benzoxazoles from readily available benzoxazoles and primary benzylic and hetero benzylic amines is presented in one pot. The reaction proceeds through the ring-opening of benzoxazoles and is followed by oxidative condensation with benzylamines. These metal-free, straightforward reactions worked well with a wide range of substrates, yielding moderate to good yields under mild conditions using air as an external green oxidant.

Graphical Abstract

Keywords:

• Aerobic oxidation
• amines
• benzoxazoles
• ring-opening
• TEMPO

Acknowledgments

M. S. Rao is thankful to IIT Patna for his research fellowship and research support. The authors are thankful to SAIF (IIT Patna) for the single crystal XRD facility.