Potassium Carbonate → Ethyl 4,5-dichloro-6-(1-methyl-5-pyrazolylcarbonyl)-1,3-benzodioxole-2-carboxylate

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Reaction Steps

To a solution of 2.0 g of (1-methylpyrazol-5-yl)-(2,3-dichloro-4,5-dihydroxyphenyl)-methanone in 22 ml of dimethylformamide are added 2.12 g of powdered potassium carbonate and 3.7 g of ethyl dibromoacetate, and the mixture is stirred at 90° to 100° C. under argon gas atmosphere for 2 hours. After cooling, the mixture is poured into ice-water and the mixture is extracted with ethyl acetate. The extract is washed with an aqueous saturated sodium chloride solution, dried and evaporated to remove solvent under reduced pressure. The residue is purified by silica gel column chromatography (solvent; n-hexane-ethyl acetate) to give 1.64 g of ethyl 4,5-dichloro-6-(1-methyl-5-pyrazolylcarbonyl)-1,3-benzodioxole-2-carboxylate. Yield: 63%

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