Water → 2-[3-ethoxycarbonylmethyl-6-fluoro-2(3H)-benzothiazolon-5-yl]4,5,6,7-tetrahydro-2H-isoindole-1,3-dione

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Reaction Steps

5-Amino-3-ethoxycarbonylmethyl-6-fluoro-2(3H)benzothiazolone (140 mg) and 3,4,5,6-tetrahydrophthalic anhydride (90 mg) were suspended in acetic acid (3 ml), and the resultant suspension was heated under reflux for 5 hours. After being allowed to cool, water was added thereto, and the resultant mixture was extracted with ethyl acetate. The extract was washed with water and sodium bicarbonate solution, dried and concentrated. The residue was purified by silica gel thin layer chromatography with a mixture of ethyl acetate and hexane (1:2) to give 2-[3-ethoxycarbonylmethyl-6-fluoro-2(3H)-benzothiazolon-5-yl]4,5,6,7-tetrahydro-2H-isoindole-1,3-dione (40 mg). m.p., 155.5°-156.5° C.

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