Antimony (III) Sulfate Catalyzed One-Pot Synthesis of 2,3-Disubstitutedindoles

Abstract

A novel one-pot Fischer indole synthesis approach has been developed by using antimony (III) sulfate as the catalyst. Good yields were obtained after reacting phenylhydrazines hydrochlorides and ketones in refluxing methanol. The exclusive formation of 2,3- disubstituted indoles was observed in the reaction of ethyl methyl ketone with phenylhydrazines. One-pot synthesis of indole-3-propanol using dihydropyran has also been described. The use of reusable antimony (III) sulfate as a catalyst makes this method both economically and environmentally friendly.

Keywords:

• Antimony (III) sulfate
• cyclohexanone
• Fischer indole synthesis
• one pot
• phenylhydrazine hydrochlorides

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

Notes

^a All reactions were carried out at reflux temperature.

^b Isolated yields.

^a Reaction was carried out at reflux temperature in MeOH in presence of 10 mol% of Sb₂(SO₄)₃.

^b Isolated yields.

^a Reaction was carried out at reflux temperature in MeOH in the presence of 10 mol% of Sb₂(SO₄)₃.

^b Isolated yields.