ERROR opening https://cactus.nci.nih.gov/chemical/structure/N%3D1C%3DCC%3DC%28C1%29C2N%28C%29CCC2/file?format=sdf&get3d=True  -- N%3D1C%3DCC%3DC%28C1%29C2N%28C%29CCC2 could not be loaded.