Dichloromethane → 3-Chloro-6-hydrazinyl-4-(1-pyrrolidinyl)pyridazine

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Reaction Steps

A solution of 3,6-dichloro-4-(pyrrolidin-1-yl)pyridazine (53 g, 0.24 mol) and hydrazine monohydrate (105 ml, 2.2 mol) in 1,4-dioxane (820 ml) was heated at reflux overnight. The solution was allowed to cool, and dichloromethane was added, precipitating a solid. This was filtered off, affording the title compound as a pale yellow solid (14 g, 27%). The filtrate was concentrated in vacuo, and the residue purified by flash chromatography on silica gel, eluting with 2-5% methanol in dichloromethane containing 0.1% concentrated aqueous ammonia, yielding a further 5 g (4%) of the title compound. 1H NMR (250 MHz, CDCl3) δ1.98 (4H, m), 3.26 (2H, br s), 3.57 (4H, m), 6.11 (1H, s), 6.41 (1H, br s). MS (ES+) m/e 214 [MH]+, 216 [MH]+.

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