title: 15-Oxa steroids.
mesh_terms: D000731:Androstanes / Q000138:chemical synthesis*; D003500:Cyclization; D004970:Estrone / Q000138:chemical synthesis*; D006868:Hydrolysis; D007664:Ketosteroids / Q000138:chemical synthesis
chemical_list: D000731:Androstanes; D007664:Ketosteroids; D004970:Estrone