Benzyl chloroformate → (+/-)-4,5-Dihydro-1-(benzyloxycarbonyl)-3-(2-thienyl)-1H-pyrazole-5-carboxylic acid

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Reaction Steps

To a stirred mixture of 9.8 g of (±)-4,5-dihydro-3-(2-thienyl)-1H-pyrazole-5-carboxylic acid (see example 2B) and 13.8 g of potassium carbonate in 80 ml of water and 40 ml of acetone there is added slowly 9.3 g of benzyl chloroformate dissolved in 50 ml of acetone, maintaining the temperature of the mixture at 10°-15° C. with an ice bath. After stirring at room temperature for 2 hours, the mixture is diluted with an equal volume of water and washed twice with ether. The aqueous layer containing some solids, is adjusted to pH 3.0 with 6 N HCl and cooled and filtered to obtain the title compound.

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