Triphenyl Phosphite-mediated “Green” Synthesis of Novel Carboxycoumarin Amides

Background: A library of eleven novel coumarin carboxamides were efficiently synthesized in high yields, by triphenyl phosphite-activated direct condensation of coumarin carboxylic acids and various alkyl amines. Methods: The procedure has several advantages and addresses key “Green” chemistry issues, such as one step condensation, no prior activation of coumarin carboxylic acids by toxic chlorinating agents, no toxic by-products are produced and does not involve troublesome/hazardous disposal of the catalyst. The synthesized coumarin carboxamides were examined for their antiinflammatory activity by measuring the effect on tumour necrosis factor-α (TNF-α) induced expression of intercellular adhesion moledule-1 (ICAM-1). Conclusion: The structure-activity relationship (SAR) studies revealed that N-dodecyl-7- hydroxy-4-methyl-2-oxo-2H-chromene-8-carboxamide (23) exhibited the maximum inhibition (90%) of ICAM-1 expression at an IC50 value of 43 μM.