Estra-4,9-diene-3,17-dione

 Dienedione (estra-4,9-diene-3,17-dione) is an anabolic steroid and a precursor to dienolone. It became a controlled substance in the US on January 4, 2010,and is classified as a Schedule III anabolic steroid under the United States Controlled Substances Act. Previous to this, it was sold as a bodybuilding supplement within the United States, and often mistakenly marketed as a prohormone for trenbolone, a veterinary steroid. Prior to its scheduling, it was part of a number of supplements that were seized during FDA enforcement of Bodybuilding.com for selling unapproved new drugs.The actual target steroid, dienolone has some structural similarity to trenbolone, but lacks the 11-carbon -ene bond.