Lithium Chloride → 5-(2-Butoxy-5-[2-pyridyl]-3-pyridinyl)-3-ethyl-2-(2-methoxyethyl)-2,6-dihydro-7h-pyrazolo[4,3-d]pyrimidin-7-one

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Reaction Steps

2-Tributyltin pyridine (192 mg, 0.52 mmol), lithium chloride (170 mg, 4.00 mmol), cuprous iodide (11.5 mg, 0.06 mmol), Pd(PPh3)4 (46.5 mg, 0.04 mmol) and the title compound of Example 1 (200 mg, 0.40 mmol) were stirred together in dioxan (10 mL) under a nitrogen atmosphere. The mixture was heated at reflux for 3.5 h, allowed to cool and the solvent removed in vacuo. The residue was taken up in ethyl acetate and shaken vigorously with 5% aqueous potassium fluoride solution for 10 min and the mixture filtered through Arbocel®. The organic layer was separated, washed with 5% aqueous potassium fluoride solution, saturated sodium bicarbonate solution and brine. The organics were dried (MgSO4) and concentrated. The solid was partially purified by trituration with cold ethyl acetate and further purified by flash column chromatography (elution with 50:1 dichloromethane/methanol) to give the title compound (52 mg, 29%).

Provenance & Evidence