Amine-catalyzed direct assembly of indanedione-fused spirobenzo[a]carbazoles from α,α-dicyanomethylidenecarbazoles

Abstract

An unprecedented amine-catalyzed stereoselective reaction of α,α-dicyanomethylidenecarbazoles with indane-1,3-dione and aryl/heteroaryl aldehydes afforded a series of indanedione-fused benzo[a]carbazoles. The plausible mechanism for the formation of the final products result from the above MCR is described based on successive Knoevenagel/Michael/nucleophilic reactions. The products were obtained in moderate to good yields without the use of any chromatographic techniques. The structures of the synthesized spirocycloadducts were confirmed by elemental analysis and spectral data (FT-IR, ¹H NMR, and 13C NMR).

GRAPHICAL ABSTRACT

KEYWORDS:

• Spirocarbocycles
• benzo[a]carbazoles
• indanedione
• stereoselectivity
• vinylogous Michael addition

Acknowledgments

We would like to thank the University of Mysore, for NMR data.

Additional information

Funding

Dr. K. J. Rajendra Prasad gratefully acknowledged the financial support from “UGC-Emeritus Fellowship” (Award NO.F.6-6/2015-17/EMERITUS-2015-17-OBC-7410/(SA II); dated 21.09.2015) for research. We also thank University Grant Commission (UGC-SAP), New Delhi, for BSR—Senior Research Fellowship for further financial assistance and successful completion of this work.