An efficient catalyzed Green synthesis of substituted coumarins using Potassium dihydrogen phosphate Catalyst and study their biological activities

The Coumarine heterocyclic ring is common feature of various bioactive compounds such as calanolides, lipid-lowering agents. The Chemists all over the globe are motivated not only for the environmentally benign synthesis of new products but also to develop green synthesis for existing chemicals. Coumarins, the most important classes of fluorescent molecules constitute important structural features present in a number of bioactive natural products. Recent studies have been revealed that coumarin and the derivatives exhibit several other medicinal applications such as anti-coagulants, antifungal, insecticidal, hypnoticsphytoalexins, HIV protease & inhibitors. Coumarins act as in intermediate for the synthesis of various biologically active molecule such as coumarones, and fluorocoumarins . Thus the synthesis of coumarins is of continuing interest.Potassium dihydrogen phosphate a commercially available environmentally benign catalyst non-toxic widely used for the synthesis of the substituted coumarin .The scope of this catalyst has not been fully explored, but can be used as buffer, neutralizing agent. Owing to the numerous advantages associated with cheap and non-hazardous catalyst, and also realizing g the importance of coumarin herein we would like to focus the eco –friendly method for his synthesis of derivatives of coumarin using cheaper and commercially available acid catalysts Potassium dihydrogen phosphate and also by the Knoevenagel condensation under microwave irradiation. The synthesized coumarin derivatives were screened in Vitro anti-microbial efficacy testing. In vitro anti-microbial efficacy testing was carried out by broth dilution method by broth dilution method as mentioned in “Pharmaceutical Microbiology”. For anti-bacterial activity, MullerHintonmedium was used as the nutrient media. Test bacterial species used are Escherichia coli ,(ATCC 10148), Staphylococcus aureus(NCTC 3750), Pseudomonas aeruginosa (Fisher’Immunotype IV), test fungi species used are Aspergilliusniger(ATCC 16404) and Candida albicans (ATCC 10231) in different concentrations starting from 25ppm .All the coumarin derivatives are active against the test bacteria and fungai in different concentrations. This paper focuses is to develop environment friendly reactions, simple, highly efficient and high yielding protocol for the synthesis of coumarin derivatives using Potassium dihydrogen phosphate as a catalyst.Even though a number of modified methods have been reported, but many of them suffer from drawbacks such as unsatisfactory yields, longer reaction time, and corrosive reagents. Thus the development of an efficient and versatile method to synthesis of coumarin derivatives is an active ongoing research and there is a scope further improvement towards milder reaction condition and yield. This methodology offers significant improvements for the synthesis of derivatives of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic conventional catalysts and solvents. Therefore owing the importance of Potassium dihydrogen phosphate a facile catalyst used for the green synthesis of new derivatives of coumarin .