.DELTA.13(18)-Glaucarubinone .delta.-13-Dehydroglaucarubinone 68703-94-6 GLAUCARUBINONE NSC279504 Picrasa-3,13[21]-diene-2,16-dione, 11,20-epoxy-1,11,12-trihydroxy-15-(2-hydroxy-2-methyl-1-oxobutoxy)-