S. Reddy Yetra, Roy, T., Bhunia, A., Porwal, D., and Biju, A. T., ?Synthesis of functionalized coumarins and quinolinones by NHC-catalyzed annulation of modified enals with heterocyclic C-H acids?, Journal of Organic Chemistry, vol. 79, no. 9, pp. 4245?4251, 2014.