2H-pyrimido[1,2-b]pyridazine-4-carboxylic acid, 7-chloro-2-oxo-, methyl ester InChI=1/C9H6ClN3O3/c1-16-9(15)5-4-8(14)11-7-3-2-6(10)12-13(5)7/h2-4H,1H methyl 7-chloro-2-oxo-2H-pyrimido[1,2-b]pyridazine-4-carboxylate