Hydrochloric Acid → 4-Ethyl-4-hydroxy-1H-pyrano[3,4-c]pyridine-3,8(4H,7H)-dione

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반응 단계

To a suspension of 560.0 mg of compound (15) as obtained from example 9 (1.983 mmol) in 11.2 mL dimethoxyethane were added dropwise at 0° C. 1.68 mL concentrated aqueous hydrochloric acid (36.5%) (19.83 mmol, 10.0 eq). The ice bath was removed after 15 min and the triphasic mixture was vigorously stirred. After 4 h, the mixture was evaporated to dryness in a rotary evaporator (27° C., 5 mbar, then 1 mbar). The crude product was obtained as a lightly yellow semisolid (805.4mg, 194% by weight).333.3 mg crude product were purified by trituration with 0.7 mL methanol at room temperature for 18 h furnishing the title compound (168.7 mg, 0.425 mmol, 98% by weight) as white crystals.

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