3,6-dimethyl-3'-oxo-3',4'-dihydro-1H,1'H-spiro[pyridazine-4,2'-quinoxaline]-5-carboxylic acid InChI=1/C14H14N4O3/c1-7-11(12(19)20)14(8(2)18-17-7)13(21)15-9-5-3-4-6-10(9)16-14/h3-6,16-17H,1-2H3,(H,15,21)(H,19,20 spiro[pyridazine-4(1H),2'(1'H)-quinoxaline]-5-carboxylic acid, 3',4'-dihydro-3,6-dimethyl-3'-oxo-