C(N1C=CN=C1)(N1C=CN=C1)=O.C(N(CC)CC)C.[Cl:20][C:21]1[CH:22]=[C:23]([OH:31])[C:24](=[CH:29][CH:30]=1)[C:25]([NH:27]O)=[O:26]>O1CCCC1>[Cl:20][C:21]1[CH:30]=[CH:29][C:24]2[C:25]([OH:26])=[N:27][O:31][C:23]=2[CH:22]=1A solution of 1,1'-carbonyldiimidazole (12.76 g, 78.5 mmol) and triethylamine (12.6 mL, 90 mmol) in tetrahydrofuran is slowly added to a refluxing suspension of 4-chlorosalicylohydroxamic acid (13.39 g, 71.4 mmol) in tetrahydrofuran. The reaction mixture is refluxed for 1 hour, cooled, concentrated in vacuo, diluted with water, acidified with concentrated hydrochloric acid (pH1) and filtered to obtain a solid. A solution of the solid in ether is extracted with saturated sodium hydrogen carbonate solution. The combined aqueous extracts are acidified with concentrated hydrochloric acid and the resultant precipitate is collected and dried overnight to give the title product as a white solid, mp 218°-219° C.
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