[N+:1]([C:4]1[CH:5]=[C:6]([C:9]([O:11][CH2:12][CH3:13])=[O:10])[NH:7][CH:8]=1)([O-:3])=[O:2].[H-].[Na+].[CH2:16](Br)[C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1.O>CN(C)C=O>[CH2:16]([N:7]1[CH:8]=[C:4]([N+:1]([O-:3])=[O:2])[CH:5]=[C:6]1[C:9]([O:11][CH2:12][CH3:13])=[O:10])[C:17]1[CH:22]=[CH:21][CH:20]=[CH:19][CH:18]=1
To a solution of ethyl 4-nitro-1H-pyrrole-2-carboxylate (10 g) in N,N-dimethylformamide (100 mL) was slowly added sodium hydride (60%, oily, 2.4 g) at 0° C., and the mixture was stirred at room temperature for 30 min. Benzylbromide (8.0 mL) was slowly added to the reaction mixture, and the mixture was stirred at room temperature for 2 hr. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4) and concentrated. The obtained residue was subjected to silica gel column chromatography to give ethyl 1-benzyl-4-nitro-1H-pyrrole-2-carboxylate (14.3 g, yield 97%) as yellow crystals from a fraction eluted with ethyl acetate-hexane (1:3, volume ratio). melting point 73° C.
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