Hydrochloric Acid → (-)-4-[2-(Hydroxyamino)-2-oxoethyl]-2-[3-(4-methoxyphenyl)propyl]-3-oxo-3,4-dihydro-2h-1,4-benzothiazine-6-carboxylic acid

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Reaction Steps

To the compound of Example 1 (0.51 g) were added THF (10 ml) and water (10 ml). After the resulting mixture was ice-cooled, a 0.5N aqueous lithium hydroxide solution (4.4 ml) was slowly added dropwise thereto. The resulting mixture was slowly warmed up to room temperature and stirred overnight. Ice-cooled 1N aqueous hydrochloric acid solution and ethyl acetate were added thereto to effect extraction. The oil layer was washed twice with a 1N aqueous hydrochloric acid solution, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. Chloroform was added to the residue, and after standing for 4 days, the solid precipitated was collected by filtration and dried under reduced pressure. 4-[2-(Hydroxyamino)-2-oxoethyl]-2-[3-(4-methoxyphenyl)propyl]-3-oxo-3,4-dihydro-2H-1,4-benzothiazine-6-carboxylic acid (325 mg) was obtained as a white solid.

Provenance & Evidence