General procedure for the synthesis of 6-chloropyridazine-3-carboxylic acid from ethyl 6-chloropyridazine-3-carboxylate:
(Step-1) To a solution of ethyl 6-chloropyridazine-3-carboxylate (1.00 g, 5.36 mmol) in tetrahydrofuran (THF, 10 mL) was added a solution of lithium hydroxide (LiOH, 0.655 g, 26.8 mmol, 5 equiv) in water (10 mL). The reaction mixture was stirred at room temperature for 45 minutes. Upon completion of the reaction, the mixture was poured into 2 M hydrochloric acid and extracted with dichloromethane (DCM). The organic phases were combined and concentrated under reduced pressure to give 6-chloropyridazine-3-carboxylic acid as a white solid (770 mg, 91% yield).LC-MS (positive ESI): m/z 159/161 [M+H]+.
