Hydrochloric Acid → Ethyl (2,5-dichloro-1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl)acetate

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Reaction Steps

Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.59 g (3.33 mmol) of 2,5-dichloro-p-benzoquinone in 6.5 mL of THF was added dropwise while stirring at 0˜5° C. The mixture was stirred at 20˜25° C. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate, and the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.81 g of the desired product (yield 92%).

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