6-Methyl-ideneandrost-4-ene-3,17-dione

In the title compound, C20H26O2, which is the 6-methylene derivative of androstenedione and a synthetic percursor of exemestane, the steroidAring approximates to a sofa (or envelope) conformation, with the methylene group adjacent to the link to theBring lying out of the plane of the other atoms. TheBandCrings have slightly flattened chair conformations and theDring is an envelope, with the CH group forming the flap. In the crystal, molecules are linked by two distinct C—H...O hydrogen bonds, involving acidic H atoms close to C=C and C=O double bonds.