A simple and efficient synthesis of substituted 2H-1-benzopyran-2-ones using natural acids and their bio evaluation

Abstract

A simple and efficient route for the synthesis of coumarin derivatives (3a-3g) from reaction between substituted phenols (1a-1g) and methyl acetoacetate (2b) in presence of Citrus limon L. juice, Vitis vinifera L. juice and banana peels extract has been carried out. The homogeneity of the compounds were routinely checked by thin layer chromatography and melting points reported are uncorrected. The compounds (3a-3g) were characterized by using 1HNMR and FTIR spectral techniques and evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (3a-3g) were also screened for their fungicidal activity against Rhizoctonia solani and Colletotrichum gloeosporioides by poisoned food techniques. Antibacterial activity was also determined against Erwinia cartovora and Xanthomonas citri by inhibition zone method. From activity data, it was found that compounds 3a and 3b were most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compound 3b was found most active against R. solani fungus and Xanthomonas citri bacterium at highest concentration. Compound 3e has shown maximum percentage inhibition i.e. 83.17 against C. gloeosporioides at 2000 µg/mL concentration. Erwinia cartovora bacterium was most susceptible to compound 3 g giving 8.00 mm inhibition zone at 2000 µg/mL concentration. Less reaction time, excellent yields, simple work-up, cost effective and mild reaction conditions are some merits of present protocol.

Keywords

• Coumarins
• Citrus limon L. juice
• Vitis vinifera L. juice
• Banana peels extract