1H,5H,8H-dipyrido[2,1-f:3',2',1'-ij][1,6]naphthyridine-11-carboxylic acid, 2,3,6,7,7a,10,13b,13c-octahydro-10-oxo-, ethyl ester InChI=1/C18H24N2O3/c1-2-23-18(22)14-7-8-15-13-6-4-10-19-9-3-5-12(16(13)19)11-20(15)17(14)21/h7-8,12-13,16H,2-6,9-11H2,1H ethyl 15-oxo-11,12,13,14-tetradehydromatridine-14-carboxylate