8H,10H-7a,12a-(Iminomethano)indolizino[6,7-h]pyrano[3,2-a]carbazole-8,16-dione, 3,11,12,13,13a,14-hexahydro-3,3,14,14-tetramethyl-, 15-oxide, (7aS,12aS,13aS)- [ 269741-97-1 ]