One-pot, green synthetic route for construction of coumarin C-4 bridged 2,6-dicyanoanilines and their photophysical study

ABSTRACT

A highly selective and more efficient green protocol has been developed via a one-pot, three-component approach for the synthesis of coumarin 2,6-dicyanoanilines in aqueous ethanol. From the mechanism, two molecules of malanonitrile condensed with aldehyde and ketone resulted in the adducts, which on intramolecular cyclization via two new C-C bonds formed to afford the title compound. The present methodology offers simplified purification and environmentally benign conditions, avoids the use of toxic solvents, and gives excellent yield with high purity. All the synthesized compounds have been characterized by spectral analysis. Optical and thermal screening studies of all newly synthesized compounds showed excellent photophysical and thermal stability properties.

GRAPHICAL ABSTRACT

KEYWORDS:

• 2,6-Dicyanoanilines
• 4-formylcoumarins
• malononitrile
• multicomponent reactions
• triethylamine

Acknowledgments

One of the authors thanks the University Grants Commission (UGC-UPE), New Delhi, for a fellowship, and anther author also thanks the NMR Research Center, Indian Institute of Science (I.I.Sc.), Bangalore, and University Sophisticated Instrumentation Center, Dharwad (USIC), for spectral analysis. Rashmi C. Kulkarni expresses her gratitude to Ashish Anand for his advice and insights.