[C:1]([C:9]1[CH:13]=[CH:12][NH:11][CH:10]=1)(=[O:8])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[OH-].[K+].[NH2:16]OS(O)(=O)=O>CN(C)C=O.O>[NH2:16][N:11]1[CH:12]=[CH:13][C:9]([C:1]([C:2]2[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=2)=[O:8])=[CH:10]1To a solution of 3-benzoylpyrrole (4.92 g) in 50 ml of dry dimethylformamide was added milled potassium hydroxide (8.06 g). Hydroxylamine-O-sulfonic acid (4.23 g) was added to the suspension in 4 portions over a period of 1 hour with stirring at room temperature. After the addition was completed the reaction mixture was stirred for 30 minutes at room temperature, and subsequently diluted with 50 ml of water and extracted with DCM. The combined organic layers were washed with water, dried over magnesium sulfate and evaporated in vacuo. The residue was purified by flash column chromatography (silica gel, DCM/ethyl acetate, 5:1), affording starting material (1.44 g) and the desired product as the second fraction. Recrystallization from ethyl ether/hexane gave the product as crystals (1.80 g), which was combined with material obtained from a 36.9 mmol scale reaction and recrystallized from DCM/hexane affording 3.20 g of crystals, m.p. 82°-83° C.
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