20283-48-1 4,17-Dioxabicyclo[14.1.0]heptadeca-6,14-diene-5,13-dione, 2-[[(6-deoxy-2,3-di-O-methyl-.beta.-D-allopyranosyl)oxy]methyl]-9-[(4,6-dideoxy-3-O-methyl-.beta.-D-xylo-hexopyranosyl)oxy]-12-hydroxy-3,8,10,12-tetramethyl- CHALCOMYCIN NSC150439