BrBr.[Mg].[Br:4][C:5]1[CH:10]=[CH:9][C:8](Br)=[CH:7][N:6]=1.C([Mg]Cl)(C)C.[Li+].[Cl-].[C:19]1([CH2:25][C:26](=[O:28])[CH3:27])[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1>>[Br:4][C:5]1[N:6]=[C:7]([C:26]([OH:28])([CH3:27])[CH2:25][C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)[CH:8]=[CH:9][CH:10]=1According to Example 2, the Grignard reagent 1d (freshly prepared via bromine-magnesium exchange[6] from 2,5-dibromopyridine (391 mg, 1.65 mmol; 1.10 equiv) and i-PrMgCl.LiCl (1.00 M in THF; 1.62 mL, 1.62 mmol, 1.08 equiv) at −10° C.) was reacted with 1-phenyl-propan-2-one (201 mg; 1.50 mmol) in the presence of LaCl3.2LiCl (0.33 M; 4.55 mL, 1.50 mmol, 1.00 equiv). The crude product was purified by flash column chromatography (silica; pentane:Et2O, 9:1, 0.2 vol-% NEt3) to give the desired product as colorless oil (355 mg, 81%).
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