Improved method for synthesis of 7-amino-4-methylcoumarin
A new variant of the synthesis of 7-amino-4-methyl-coumarin from m-aminophenol via a three-step scheme is proposed. Acylation of m-aminophenyl with methoxycarbonyl chloride gave m-(N-methoxycarbonylamino)phenol, which was converted to 7-(N-methoxycarbonyl-amino)-4-methylcoumarin by condensation with acetoacetic ester in sulfuric acid. Heating of the coumarin with concentrated alkali leads to an intermediate, which, after acidification, is converted to 7-amino-4-methylcoumarin in high yield.