[CH:1]([C:3]1[CH:4]=[C:5]([CH:10]=[C:11]([N:13]2[CH:17]=[CH:16][CH:15]=[CH:14]2)[CH:12]=1)[C:6]([O:8][CH3:9])=[O:7])=O.Cl.[NH2:19][OH:20].C[O-].[Na+].C(OCC)(=O)C>CO.O>[OH:20][N:19]=[CH:1][C:3]1[CH:4]=[C:5]([CH:10]=[C:11]([N:13]2[CH:17]=[CH:16][CH:15]=[CH:14]2)[CH:12]=1)[C:6]([O:8][CH3:9])=[O:7]Methyl 3-formyl-5-(pyrrol-1-yl)benzoate (2.0 g) was added to a mixture of hydroxylamine hydrochloride (0.61 g) and 28% methanolic sodium methoxide (1.8 ml) in methanol (20 ml) and the whole was stirred for 22 hours at ambient temperature. The reaction mixture was poured into a mixture of ethyl acetate and water. The organic layer was successively washed with brine and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was purified by column chromatography on silica gel eluting with a mixture of chloroform and ethyl acetate (20:1). The eluted fractions containing the desired product were collected and evaporated in vacuo to give methyl 3-hydroxyiminomethyl-5-(pyrrol-1-yl)benzoate (1.69 g).
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