[Cl:1][C:2]1[C:7]([N+:8]([O-])=O)=[CH:6][CH:5]=[CH:4][N:3]=1.[CH:11]([Mg]Br)=[CH2:12]>C1COCC1>[Cl:1][C:2]1[N:3]=[CH:4][CH:5]=[C:6]2[C:7]=1[NH:8][CH:12]=[CH:11]22-Chloro-3-nitropyridine 22e (5.0 g) was dissolved in dry THF (200 ml). After the solution was cooled down to −78° C., an excess of vinyl magnesium bromide (1.0 M in THF, 100 ml) was added. Then, the reaction was left at −20° C. for eight hours before being quenched with 20% NH4Cl (150 ml). The aqueous phase was extracted with EtOAc (3×150 ml). The combined organic layer was dried over MgSO4. After filtration and concentration, the crude product was purified by silica gel column chromatography to afford 1.5 g of 7-chloro-6-azaindole 1e in 31% yield.
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