Efficient Synthesis of 2-Ethoxycarbonyl Indoles

Abstract

An efficient one-pot procedure for the synthesis of 2-ethoxycarbonyl indoles from commercially available materials has been developed. The one-step procedure involves in situ formation of the hydrazones from phenylhydrazine hydrochloride and ethyl pyruvate in the presence of bismuth nitrate followed by Fischer cyclization in polyphosphoric acid and ethanol. This method is efficient and simple.

Keywords:

• Bismuth nitrate
• ethyl pyruvate
• Fisher indole synthesis
• one pot
• phenylhydrazine hydrochloride

ACKNOWLEDGMENTS

The authors are grateful to the Department of Postgraduate Studies and Research in Chemistry, School of Chemical Sciences, Kuvempu University, for providing laboratory facilities, to the Indian Institute of Science Bangalore for spectral data, and finally to Vinay K. M., lecturer Department of English, for proofreading.

Notes

^a Reaction was carried out at reflux temperature in alcohol + PPA in presence of 20 mol% of BiNO₃.

^b Isolated yields.