943026-40-2

General procedure for the synthesis of 3-chloro-6,7-dihydro[1,4]dioxohexa[2,3-c]pyridazine from the compound (CAS:17284-80-9): (c) 2-[(3,6-dichloro-4-pyridazinyl)oxy]ethanol (15.46 g; 0.0703 mol) containing the bromine derivative was dissolved in anhydrous dioxane (1.2 L). Lithium hydride (2.3 g; 0.28 mol) was added in batches and stirred under argon protection at room temperature for 1 h. The reaction was then heated to 110 °C overnight. Upon completion of the reaction, the reaction was quenched with wet dioxane and then quenched with ice water. The reaction solution was concentrated to half of the original volume, the pH was adjusted to 8 with 5 M hydrochloric acid and then evaporated to dryness. After addition of water, the residue was extracted with chloroform and the organic phase was dried over sodium sulfate and concentrated to give a white solid (12.4 g, ~77% yield, containing ~15% bromine derivative). Mass spectrometric analysis (positive ion electrospray) showed m/z 173/5 (Cl MH+) and 217/9 (Br MH+).

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