Ethanol → Diethyl 2-(2,4-dichloro-5-fluorobenzoyl)malonate

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Reaction Steps

24.3 g of magnesium fillings are suspended in 50 ml of anhydrous ethanol. 5 ml of carbon tetrachloride are added and, when the reaction has started, a mixture of 160 g of diethylmalonate, 100 ml of absolute ethanol and 400 ml of anhydrous ether is added dropwise, whereupon vigorous reflux is to be observed. After the reaction has subsided, the mixture is heated at the boiling point for a further 2 hours and cooled to -5° C. to -10° C. with dry ice/acetone, and a solution of 227.5 g of 2,4-dichloro-5-fluoro-benzoyl chloride (1) in 100 ml of absolute ether is slowly added dropwise at this temperature. The mixture is stirred at 0° C. to -5° C. for 1 hour and allowed to come to room temperature overnight, and a mixture of 400 ml of ice-water and 25 ml of concentrated sulphuric acid is run in, while cooling with ice. The phases are separated and subsequent extraction with ether is carried out twice. The combined ether solutions are washed with saturated NaCl solution and dried with Na2SO4 and the solvent is stripped off in vacuo. 349.5 g of diethyl 2,4-dichloro-5-fluoro-benzoyl-malonate (3) are obtained as the crude product.

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