Background: The agricultural waste as a source offered an excellent alternative to replace many toxic and environmentally hazardous catalysts, due to their least toxicity, ease of biodegradability, and ability to act as a greener catalytic medium. Some of the agro-waste based catalysts reported are BFE, WERSA, WEB, WEPBA. 2-Amino-4H-chromene derivatives are promising biologically potent heterocyclic compound, due to their medicinal applications such as antimicrobial, anti-inflammatory, antibacterial, antiviral, anticancer, antidiuretic, anticoagulant and anti-anaphylastic activities. The present work describes microwave accelerated, efficient, eco-friendly and economic approach synthesis of 2-amino-4H-chromenes through condensation of substituted arylaldehyde, malononitrile and resorcinol/naphthol catalyzed water extract of pomegranate peel ash (WEPPA) under microwave irradiation. The reaction completed within 3-6 min with good to excellent yield product isolation. The final product isolated by simple filtration and recrystallization gave spectroscopically pure form of product and not required further purification.
Methods: Pomegranate peel ash water extract as agro-waste derived catalyst is employed under microwave irradiation for the economic synthesis of 2-amino-4H-chromene derivatives.
Results: Reported agro-waste based catalyst proceeds in absence of external base, additives and solvent-free synthesis of 2-amino-4H-chromene using aryl aldehyde, malononitrile and resorcinol/naphthol under microwave irradiation. WEPPA act as a solvent media and catalyst, it plays dual role in the synthesis of 2-amino-4H-chromenes.
Conclusion: We have established an efficient, simple, agro-waste based catalytic approach for the synthesis of 2-amino-4H-chromene derivatives from the condensation of arylaldehyde, malononitrile and resorcinol/α-naphthol/β-naphthol employing WEPPA as an efficient catalyst under microwave synthesis. The method is found greener, economic and eco-friendly approach for the synthesis of chromene scaffolds. The advantages of the present approach are solvent-free, no external metal, chemical base free, short reaction time and isolated product in good to excellent yields. The catalyst is agro-waste derived, which has abundant in natural sources available in huge amount, thus making the present approach a greener one.