Facile and Green Syntheses of 2-(N-Methylindole-3-carbonyl)-3-(N-methylpyrrol-2-yl)acrylonitriles and a Study of Their Antimicrobial Activities

Abstract

Facile and green syntheses of substituted-2-(N-methylindole-3-carbonyl)-3-(N-methyl pyrrol-2-yl) acrylonitriles 6a–d are being reported. L-Proline has been utilized as an efficient and ecofriendly catalyst in aqueous medium for Knoevenagel condensation of pyrrole-2-carboxyaldehyde (1) and its N-methyl derivative (2) with the active methylene compounds 3-cyanoacetylindoles 3a–d at room temperature to afford substituted-2-(1H-indole-3-carbonyl)-3-(1H-pyrrol-2-yl)acrylonitriles 4a–d and substituted-2-(1H-indole-3-carbonyl)-3-(N-methylpyrrol-2-yl) acrylonitriles 5a–d respectively. Subsequently these products were treated with dimethyl sulfate (DMS) in polythylene glycol (PEG)–600 as an efficient and green solvent to afford the corresponding substituted-2-(N-methylindole-3-carbonyl)-3-(N-methylpyrrol-2-yl)acrylonitriles 6a–d. The antibacterial and antifungal activities of 4a–d, 5a–d, and 6a–d have been studied.

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GRAPHICAL ABSTRACT

Keywords:

• 3-Cyanoacetylindole
• Knoevenagel reaction
• L-proline
• PEG-600
• pyrrole-2-carboxyaldehyde
• water

ACKNOWLEDGMENTS

The authors are grateful to the Jawaharlal Nehru Technological University, Hyderabad, for providing financial support and to the principal of JNTUH College of Engineering for providing the facilities to carry out the work.

Notes

^a Reaction conditions for 4a–d and 5a–d: pyrrole-2-carboxyaldehyde, 3-cyanoacetylindole, L-proline, water, and room temperature.

^b Reaction conditions for 6a–d: PEG-600, DMS.