Molecular Iodine Catalysed One Pot Synthesis of Spirooxindoles by Tandem Knoevenagel Cyclisation
Spirooxindoles are heterocycles found in various natural and synthetic products with potent bio-, physio-, and pharmaceutical activities. Heterocyclic fused phthalazines possess antimicrobial, antifungal, anticancer, anti- inflammatory, and cardiotonic activities. Hence, an efficient multi-component method has been developed for the synthesis of pyrazolophthalazinyl spirooxindoles through tandem Knoevenagel cyclisation from isatin, malononitrile and various phthalhydrazides in presence of readily available molecular iodine as a catalyst in ethanol solvent under ultrasonic condition to afford the products in very good yield within 15 mins. The method is simple, efficient, uses readily available commercial starting materials and gives good yield of product in short reaction time.
Highly efficient, one-pot synthesis of novel bis-spirooxindoles with skeletal diversity via sequential multi-component reaction in PEG-400 as a biodegradable solvent