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