Green synthesis of bis‐coumarin derivatives using Fe(SD)3 as a catalyst and investigation of their biological activities

A convenient, practical, green, and environmentally friendly method was developed for the synthesis of biscoumarins and corresponding tetrakis products from the reaction of 4‐hydroxycoumarin and various aldehydes. The bis‐coumarins were synthesized in high yield under mild reaction conditions. Products were obtained in the presence of in situ prepared Fe(SD)3 [Iron(III) dodecyl sulfate] as a combined Lewis acid–surfactant catalyst (LASC) in water in short reaction times. Also, the antibacterial activity of compounds was screened against Pseudomonas aeruginosa and Escherichia coli as Gram‐negative bacteria and Micrococcus luteus and Staphylococcus aureus as Gram‐positive bacterial strains. Products 3g, 3k–l were most active than cefotaxime against E. coli and also compounds 3c and 3g were most active than cefotaxime against S. aureus. Green synthesis of bis‐coumarin via Fe(SD)3 and their biological activities.