Ethyl chloroformate → 3-Chloro-5-[[(ethoxycarbonyl)amino]sulfonyl]-1-methyl-1H-pyrazole-4-carboxylic acid ethyl ester

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Reaction Steps

Into 30 ml of dry acetone, there were added 5.35 g of 3-chloro-4-ethoxycarbonyl-1-methylpyrazole-5-sulfonamide, 2.5 g of ethyl chloroformate and 4.14 g of anhydrous potassium carbonate and the mixture was refluxed for three hours. After cooling, acetone was evaporated and the residue was added into ice-water. After separation of a trace of water insolubles, the filtrate was made acidic with hydrochloric acid. The reaction mixture was extracted with diethyl ether and organic layer was dried and the solvent was evaporated under reduced pressure to give 6.0 g of N-(ethoxycarbonyl)-3-chloro-4-ethoxycarbonyl-1-methylpyrazole-5-sulfonamide. m.p.: 82°-85° C.

Provenance & Evidence