18-Crown-6 → (E)-3-[2-(2-methoxycarbonylmethylenecyclohexyl)-3-oxo-2,3-dihydropyridazin-6-yl]-2-phenylpyrazolo[1,5-a]pyridine

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Reaction Steps

To a solution of 3-(3-oxo-2,3-dihydropyridazin-6-yl)-2-phenylpyrazolo[1,5-a]pyridine (271 mg) in N,N-dimethylformamide (6 ml) was added potassium tert-butoxide (111 mg) and 18-crown-6 (24.8 mg) at 5C. To this solution was added a solution of (E)-1-methylsulfonyloxy-2-methoxycarbonylmethylenecyclohexane (467 mg) in N,N-dimethylformamide (2 ml) was added dropwise. The reaction mixture was stirred at room temperature for 1 hour and then heated at 110° to 125° C. for 7 hours. The reaction mixture was poured into ice water (30 ml) and extracted with ethyl acetate (20 ml×2). The combined extracts were washed with water (20 ml) and brine (20 ml), dried over anhydrous magnesium sulfate, and evaporated in vacuo. The crude material was purified by column chromatography on SiO2 using a mixture of dichloromethane and ethyl acetate (20:1) as an eluant to give colorless crystals of (E)-3-[2-(2-methoxycarbonylmethylenecyclohexyl)-3-oxo-2,3-dihydropyridazin-6-yl]-2-phenylpyrazolo[1,5-a]pyridine (191.4 mg).

Provenance & Evidence