Eco-friendly Synthesis of 2-Amino-4H-Chromene Catalysed by HRSPLAE and Anti-cancer Activity Studies

Background: Several types of catalysts have been cited in the literature. However, the current work showed that a multi-component reaction involving aldehydes, malononitrile, and resorcinol or α/β-naphthol could produce 2-amino-4H-chromene in a more environmentally friendly manner. The reaction is optimized by both stirring and microwave methods, but the reaction carried out under microwave irradiation is found to be faster with easy separation of the product with high yield and purity. The catalyst is analyzed for the presence of elemental composition using Flame Photometry (FP) and SEM-EDX. The synthesis of 2-amino-4H-chromenes is catalyzed by the new, green catalyst HRSPLAE (Water Extract of Hibiscus Rosa Sinensis plant dry leaves ash) within 3-5 min. The final product is analyzed by FT-IR,¹H-, ¹³C-NMR, and mass spectrometry techniques and the product obtained is free from the use of chromatographic separation with isolation and yield of 80– 95%. Selected 2-amino-4H-chromene derivatives (4b and 4c) were screened for their anti-cancer and antimicrobial activity in vitro. Methods: The agro-waste sourced from Hibiscus rosa-sinensis plant dry leaves ash is utilized for the preparation of HRSPLAE catalyst, which is employed for the synthesis of 2-amino-4H-chromene derivatives under microwave irradiation. Results: 2-Amino-4H-chromene derivatives were obtained from aromatic aldehyde, malononitrile, and resorcinol or α/β naphthol catalyzed by HRSPLAE. They were comprehensively evaluated using flame emission spectrometry, SEM, and EDX. Conclusion: HRSPLAE outperforms expensive catalysts. An efficient simpler workup without column chromatography for increased yield through a new unique green method for the synthesis of 2- amino-4H-chromene derivatives has been developed.