A Facile Synthetic Route to Biologically Relevant Substituted 1,4‐naphthoquinonyl‐2‐oxoindolinylpyrimidines under Metal‐Free Organocatalytic Conditions

A simple, straightforward, and highly efficient three-component one-pot synthesis of a series of substituted 5-(3-(3-hydroxy-1,4-naphthoquinon-2-yl)-2-oxoindolin-3-yl)pyrimidine-2,4,6(1H,3H,5H)-triones as biologically relevant molecular hybrids has been accomplished based on a tandem reaction of substituted istains, 2-hydroxy-1,4-napthoquinone and barbituric acid in the presence of sulfamic acid as a low-cost and eco-friendly organocatalyst in aqueous ethanol under reflux. High atom-economy, good yields, metal-free synthesis, eco-friendliness, and operational simplicity are some of the important features of this protocol.