Efficient and Straightforward Synthesis of Tetrahydrocarbazoles and 2,3-Dimethyl Indoles Catalyzed by CAN

Abstract

A simple protocol was established to synthesize 2,3-dialkyl indoles and various tetrahydrocarbazoles via Fischer indole synthesis. This method uses ceric ammonium nitrate as a catalyst for the Fischer indole synthesis with substituted phenyl hydrazine hydrochlorides and 2-butanone, phenyl propanal, and cyclohexanone. This process is a practical synthetic method for the preparation of various 2,3-disubstituted alkyl indoles and tetrahydrocarbazoles.

Keywords:

• CAN
• Fischer indole synthesis
• Lewis acids
• one pot
• phenylhydrazine hydrochlorides

ACKNOWLEDGMENTS

We are thankful to the Department of Postgraduate Studies and Research in Industrial Chemistry and Chemistry, Kuvempu University, Shankaraghatta, for providing laboratory facilities. The authors are also thankful to the Indian Institute of Science, Bangalore, for spectral data.

Notes

Note. All reactions were carried out at reflux temperature.

^a isolated yields.

^a All reactions were carried out at reflux temperature.

^b Isolated yields.

^a All reactions were carried out at reflux temperature.

^b Isolated yields.