Hydrochloric Acid → Ethyl (3,5-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. A solution of 0.59 g (3.33 mmol) of 2,6-dichloro-p-benzoquinone in 3 mL of THF was added dropwise while stirring at 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 10 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) afforded 0.76 g of the desired product (NMR yield 74%; internal standard trioxane). As a purified product, 0.48 g of the desired product was obtained (yield 54%). 1H NMR (CDCl3), (ppm): δ 1.31 (3H, t, J=7.2 Hz), 2.77 (2H, s), 4.21-4.29 (3H, m), 7.15 (2H, s).

Provenance & Evidence