Microwave assisted synthesis of novel Coumarin derivatives for its Anti-Inflammatory applications

[...]occurring coumarins are found in many plants, notably in high concentration in tonka bean, woodruff, lavender, licorice, strawberries, apricots, cherries, cinnamon, sweet clover and bison grass. [23] However, these catalysts have to be used in excess; for example, sulfuric acid in ten to twelve equivalents, trifluoroacetic acid in three to four equivalents[24] and phosphorous pentoxide is required in a five-fold excess. [...]in some cases, mixtures of substituted phenols, ß-ketoesters and the acidic catalyst were allowed to stand overnight or for a number of days (depending on their reactivity) or were heated above 150°C, and undesired side-products such as chromones, in addition to coumarin were isolated.1251 As a result, the disposal of excess acid waste leads to environmental pollution. [...]there is scope for further development of milder reaction conditions, increased variation of the substituents in both components and better yields. Infra-red (IR) spectra of the intermediates and final compounds were recorded on Jasco FTIR-410 spectrophotometer using KBr pellet method and 1 H NMR spectra of intermediates and final compounds were recorded in CDCh solution and proton chemical shift are relative to tetramethylsilane as internal standard.