ERROR opening https://cactus.nci.nih.gov/chemical/structure/CC%28C%29%28COC1%3DCN2C%28%3DC%28C%3DN2%29C/file?format=sdf&get3d=True  -- CC%28C%29%28COC1%3DCN2C%28%3DC%28C%3DN2%29C could not be loaded.