KHSO₄-Assisted Michael Addition–Elimination Reactions of Indole with 3-Dimethylamino-1-phenylprop-2-en-1-ones in Water: An Environmentally Friendly Synthesis of Novel 3-Indolylchalcones

Abstract

KHSO₄-assisted Michael addition–elimination reactions of 2-methylindoles and 1,2-dimethylindoles with 3-dimethylamino-1-phenylprop-2-en-1-ones (2) in water, leading to the formation of 3-(2-methyl-1H-indol-3-yl)-1-arylpropenones (3a–e) and 3-(1,2-dimethy-1H-lindol-3-yl)-1-arylpropenones (3f–j) respectively in good to excellent yields have been reported. However, cyclodehydration of adducts 3a–f to give carbazoles 4 failed to take place under the reaction conditions.

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GRAPHICAL ABSTRACT

Keywords:

• Enaminones
• indoles
• KHSO₄
• Michael addition–elimination reactions

ACKNOWLEDGMENTS

The authors thank I. Warpakma, principal of the college, for research facilities and J. Nallanatt for encouragement during the course of this investigation. Thanks are also due to B. Koikara for his help. The authors express their gratitude to the University Grants Commission (UGC), New Delhi, for financial assistance and SAIF-NEHU, Shillong, for spectral and analytical data. A.S.D. thanks the UGC for a research fellowship.

Notes

^a Melting point not reported.

Dedicated to Rev. Fr. Dr. Stephen Mavely, SDB, on his 60th birthday.