Sulfuric Acid → 2,3-Dichloro-5-methyl-1H-pyrrolo[2,3-d]pyridazin-4(5H)-one

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Reaction Steps

A solution of methylhydrazine (4.72 g) and 3-carbethoxy-4,5-dichloro-2-formylpyrrole (4.72 g) in ethanol (50 ml) was refluxed for 2 hours. After cooling to room temperature, concentrated sulfuric acid (0.5 ml) was added and the mixture was refluxed for another 21 hours. The reaction mixture was cooled to room temperature and the resulting crystals were collected by filtration. The crystals were rinsed with ethanol and ether and dried in vacuo to provide the title compound as brown powder (3.29 g; yield 81%). H-NMR (DMSO-d6) δ: 3.66(3H,s), 8.11(1H,s).

Provenance & Evidence