Methyl (3aR,4R,5S,5aR,10bR,13aR)-4-(acetyloxy)-3a-ethyl-9-[(4RS,6S,8S)-4-ethyl-8- (methoxycarbonyl)-1,3,4,5,6,7,8,9-octahydro-2,6-methano-2H-azacyclodecino[4,3-b]indol- 8-yl]-5-hydroxy-8-methoxy-6-methyl-3a,4,5,5a,6,11,12,13a-octahydro-1H-indolizino[8,1- cd]carbazole-5-carboxylate