Base-Dependent Cascade Synthesis of Novel Pyrano[3,2-c]coumarin Derivatives from Baylis–Hillman Bromide

Green Synthesis of 1-Aryl-1,12-Dihydrobenzo[h]Pyrano[c]Chromene Derivatives

“…6,7 Recently, syntheses of dihydropyrano[3,2-c]chromene derivatives have been reported using various methods and catalysts. [8][9][10][11] Relevant to our work was the condensation of 4-hydroxycoumarin with araldehydes and malononitrile, either using as catalyst NEt 3 in boiling EtOH 8 or DBU in boiling water. 9 As part of our continuing efforts for the expeditious synthesis of biologically relevant heterocyclic compounds, 12 we report here our recent efforts towards the synthesis of diverse 3-amino-12-oxo-1-phenyl-1,12-dihydrobenzo[h]pyrano [3,2-c] chromene-2-carbonitrile derivatives by a three-component, one-pot reaction between 4-hydroxy-2H-benzo[h]chromen-2one, araldehydes and malononitrile in the presence of NEt 3 in water at room temperature.…”