6-Amino-3-chloropyridazine → 6-Chloro-2-cyclopropylimidazo[1,2-b]pyridazine

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Reaction Steps

A mixture of 6-chloropyridazin-3-amine x104 (24.63 g, 0.19 mol) and 2-bromo-1-cyclopropylethanone (31 g, 0.190 mol, 1 eq) in dimethoxyethane (400 ml) is refluxed under inert atmosphere for 2 days. After cooling to room temperature, the solvent is removed under reduced pressure, the crude is taken up in water (100 ml) and extracted with ethyl acetate (2×300 ml). The cumulated organic layers are dried over MgSO4, filtered and condensed under reduced pressure to furnish 6-chloro-2-cyclopropylimidazo[1,2-b]pyridazine x105 (Yield: 42%) which is used as such in the next step. Note that further title compound x105 can be extracted from aqueous layer after neutralization to pH 5 by addition of sodium hydroxyde, extraction with dichloromethane, drying (MgSO4), filtration and condensation under reduced pressure (additional 11.13 g are then collected).

Provenance & Evidence