Aqueous NH₃-mediated syntheses of 2-styrylquinoline-4-carboxamides by domino ring opening cyclization strategy

Abstract

A straightforward and efficient protocol for the synthesis of medicinally relevant 2-styrylquinoline-4-carboxamide has been developed by aqueous ammonia-mediated domino ring-opening and cyclization strategy of 3-hydroxyoxindole. The starting precursors 3-hydroxyoxindoles were easily prepared through organocatalytic “on water” reaction of isatin and benzalacetone in high yields. The wide substrate scope with operationally simple experimental procedures provides an opportunity to create library of 2-styrylquinoline-4-carboxamide derivatives.

Graphical abstract

Keywords:

• Ammonia
• cyclization
• 3-hydroxyoxindole
• isatin
• quinoline-4-carboxamide

Acknowledgements

The authors are thankful to Dr. S. J. S. Flora, Director, NIPER, Raebareli for his support and encouragement in carrying out this research work. C. R., A. P., S. K. S., R, D.; and A. B. are thankful to the Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Govt. of India for providing fellowship. The authors are thankful to Central Instrumentation Facility (CIF), NIPER, Raebareli and SAIF, CSIR-CDRI, Lucknow for providing spectral data. NIPER, Raebareli communication no. NIPER-R/104.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

The manuscript was prepared by the contribution of all authors.