27267-70-5 Spiro(benzo(1,2-b:5,4-c')dipyran-2(3H),2'(3'H)-naphtho(1,2-b)furan)-7-carboxylic acid, 4,4',5',9-tetrahydro-6',10-dihydroxy-7',9'-dimethoxy-4',5',9-trioxo-, methyl ester beta-Rubromycin