[Cl:1][C:2]1[CH:11]=[CH:10][C:5]([C:6]([NH:8]O)=[O:7])=[C:4]([OH:12])[CH:3]=1.N#N.O=S(Cl)Cl.Cl>O1CCOCC1.CCN(CC)CC.O1CCCC1>[OH:7][C:6]1[C:5]2[CH:10]=[CH:11][C:2]([Cl:1])=[CH:3][C:4]=2[O:12][N:8]=14-chloro-N,2-dihydroxy-benzamide (8 g, 42.7 mmol) is added to 10 ml of tetrahydrofuran under coverage of N2, while maintaining the temperature inside vessel lower than 30° C. and thereto is drop-added slowly 10 ml of SOCl2. After completion of drop-addition, the reaction is stirred for 30 minutes and evaporated to dryness. The residual SOCl2 is removed by azeotropic distillation with anhydrous benzene. The reaction is evaporated to dryness to obtain a yellow powder, which is dissolved in 10 ml of dioxane, while maintaining the temperature inside vessel at lower than 30° C., and thereto is drop-added slowly 5 ml of Et3N and stirred for 30 minutes, then thereto is drop-added 10% hydrochloric acid to pH=2. Under stirred, a large amount of light yellow deposit precipitates and is filtered out and recrystallized in methanol to obtain 6.50 g of 3-hydroxy-6-chloro-benzisoxazole, with a yield of 89%.
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