Cesium carbonate → 3-Chloro-6-(1-methyl-1H-pyrazol-4-yl)pyridazine

Participants

Reaction Conditions

Reaction Steps

A mixture of 3,6-dichloropyridazine (5.37 g, 33.5 mmol), 1-methyl-4-pyrazoleboronic acid pinacol ester (5 g, 24.0 mmol) and cesium carbonate (23.44 g, 72 mmol) in 1,4-dioxane (150 mL) and water (750 mL) under nitrogen was degassed by bubbling in nitrogen for 15 min. Dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) dichloromethane adduct (1 g, 1.37 mmol) was than added and nitrogen was bubbled in the mixture for another 10 min. The reaction mixture was stirred at 80° C. for 2.5 h, then cooled to room temperature and concentrated in vacuo. The residue was partitioned between 1 N aqueous potassium carbonate and ethyl acetate. The organic layer was washed with 1 N aqueous potassium carbonate and brine, dried over sodium sulfate, filtered and adsorbed on silica gel for purification. Purification by flash chromatography on silica gel using a gradient of 0-50% ethyl acetate/hexane afforded 2.8 g of the title compound as a white solid (60% yield); MS (m/z) 195 [M+H+]+.

Provenance & Evidence