We hereby report the synthesis of a novel class of compounds, 7-aminofuro-and 7- aminothieno [2, 3-d] pyridazin-4 (5H)-one and 4-aminophthalazin-1 (2H)-ones starting from methyl 2-(2-methoxy-2-oxoethyl) furan-and thiophene-3-carboxylate and methyl 2-(2- methoxy-2-oxoethyl) benzoate. The ester functionalities connected directly to the aromatic ring were regiospecifically converted to the acid, whereas methylene groups were ...