63748-09-4 Nocamycin Spiro(2,9-dioxabicyclo(3.3.1)nonane-8,2'-oxirane)-3'-acetic acid, 3-(6-(2,5-dihydro-4-hydroxy-2-oxo-1H-pyrrol-3-yl)-1,3-dimethyl-6-oxo-2,4-hexadienyl)-alpha,1,4-trimethyl-6-oxo, methyl ester