General procedure for the synthesis of 5-methoxypyridazin-3(2H)-one from the compound (CAS: 938045-16-0): a mixture of 10% palladium/carbon (100 mg), 2-((benzyloxy)methyl)-4-chloro-5-methoxypyridazin-3(2H)-one (1.34 g), and acetic acid (10 mL) was subjected to a hydrogen atmosphere (0.8 MPa) with the addition of methanol (30 mL) and the reaction was stirred at 50 °C for 10 hours. After completion of the reaction, the insoluble material was removed by filtration and the solvent was removed by distillation under reduced pressure to afford the target product 5-methoxypyridazin-3(2H)-one (611 mg). Mass spectrometry analysis showed m/z (M + H): 127.