Hydrochloric Acid → Ethyl (3,5-dichloro-1-hydroxy-4-oxocyclohexa-2,5-dien-1-yl)acetate

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).

1. stirringThe mixture was stirred at 20˜25° C. for 1 hour
2. customThen, the layers were separated
3. washThe 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
4. washAfter washing
5. dry with materialthe organic layer was dried with anhydrous magnesium sulfate
6. concentrationAfter concentration
7. customunder reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3)

ORD record

ord-cd0aff46222e4abe81d53ab6c32755f5

Source dataset

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08586762B2