C([Mg]Br)C.Br[C:6]1[N:10]([CH3:11])[CH:9]=[N:8][CH:7]=1.CON(C)[C:15]([C:17]1[CH:22]=[CH:21][N:20]=[N:19][CH:18]=1)=[O:16]>C(Cl)Cl>[CH3:11][N:10]1[C:6]([C:15]([C:17]2[CH:22]=[CH:21][N:20]=[N:19][CH:18]=2)=[O:16])=[CH:7][N:8]=[CH:9]1.[CH3:11][N:10]1[CH:6]=[CH:7][N:8]=[CH:9]1
Ethylmagnesium bromide (3 M in Et2O, 1.04 mL, 3.11 mmol) was added dropwise to a solution of 5-bromo-1-methyl-1H-imidazole (500 mg, 3.11 mmol) in DCM (6 mL) under a nitrogen atmosphere. The mixture was stirred at room temperature 15 min, then was cooled in an ice bath prior to addition of N-methoxy-N-methylpyridazine-4-carboxamide (419 mg, 2.51 mmol, Intermediate 29, step a). The resulting suspension was stirred at room temperature for 2 hours. The reaction was quenched by addition of saturated aqueous NH4Cl, diluted with water, and extracted three times with EtOAc. The aqueous phase was saturated with NaCl and back-extracted with DCM (three times). The organic phase was dried (Na2SO4), filtered, and concentrated. The residue was purified by flash column chromatography (silica gel, gradient 30-100% CH3CN-DCM, followed by isocratic 5% MeOH-acetone), affording title compound contaminated with 1-methyl-1H-imidazole, the mixture of which was used in the next reaction without further purification.
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