Readily available, non-toxic, biodegradable oleic acid was found to catalyse 4H-chromene derivatives syntheses in good yields in a water medium. A facile domino one-pot protocol was also developed for the oleic acid catalysed pyrimidine-fused heterocycle synthesis by pseudo three-component, three-component and four-component reactions. All the products were obtained in good to excellent yields. Oleic acid catalysis was further extended to the synthesis of curcumin based bioactive molecules.