preferred_name: Propanoic acid, 2-(((2,4,5,7-tetranitro-9h-fluoren-9-ylidene)amino)oxy)-, (4s)-10-((dimethylamino)methyl)-4-ethyl-3,4,12,14-tetrahydro-9-hydroxy-3,14-dioxo-1h-pyrano(3',4':6,7)indolizino(1,2-b)quinolin-4-yl ester