The Sequential One-Pot Reaction of Isatylidene Malononitriles and 4-Hydrazinocoumarin: Metal Catalyst-Free and Efficient Access to Coumarin-Fused Spiro[diazepin-5,3′-oxindole]

Abstract The synthesis of hybrid heterocycles (spiro and fused heterocycles) is a golden opportunity to access novel compounds with unique photophysical and pharmaceutical properties. Therefore, an efficient and metal catalyst-free procedure was designed to prepare novel coumarin-fused spiro[diazepin-5,3′-oxindole] derivatives through a three-component, sequential, one-pot reaction. This method involves the use of various isatin derivatives, malononitrile, and 4-hydrazinocoumarin. The significance of this method lies in the accessibility of the mentioned raw materials and easy purification of the products by filtering and washing with a solvent.