73097-19-5 7H-Furo(2,3-f)(1)benzopyran-2,8-dicarboxylic acid, 7-oxo-, 8-ethyl 2-methyl ester 8-Ethyl 2-methyl 7-oxo-7H-furo(2,3-f)(1)benzopyran-2,8-dicarboxylate