One-pot multicomponent green synthesis of novel series of 4-hydroxy-2-pyridone-fused spiropyrans catalyzed by acetic acid

An efficient one-pot multicomponent reaction is reported for synthesizing a novel series 4-hydroxy-2-pyridone-fused spiropyran through the reaction of 4-hydroxy-6-methylpyridine-2-ones alkaloids, malononitrile or ethyl cyanoacetate, and ninhydrin or isatin derivatives. The optimized conditions for this reaction were obtained in ethanol solvent, acetic acid as catalyst, ambient temperature (for ninhydrin) or 70 °C (for isatin), and 8 hr reaction time. Mild and safe conditions, easy work-up and separation, high to excellent yields, and eco-compatibility are the main advantages of this synthesis for affording potentially bio-effective novel products.