[Br:1][C:2]1[CH:7]=[CH:6][C:5](=[O:8])[NH:4][C:3]=1[C:9]#[N:10].[Si:11](Cl)([C:14]([CH3:17])([CH3:16])[CH3:15])([CH3:13])[CH3:12].N1C=CN=C1>CN(C=O)C.O>[Br:1][C:2]1[C:3]([C:9]#[N:10])=[N:4][C:5]([O:8][Si:11]([C:14]([CH3:17])([CH3:16])[CH3:15])([CH3:13])[CH3:12])=[CH:6][CH:7]=1A solution of 3-bromo-6-oxo-1,6-dihydropyridine-2-carbonitrile (from step 2) (1.0 eq.), tert-butyldimethylsilylchloride (TBSCl) (1.8 eq.), and imidazole (2.5 eq.) in DMF (0.2 M) was heated to 60° C. and stirred overnight. The reaction mixture was diluted with water and extracted with ether. The combined organic layers were dried over anhydrous MgSO4 and concentrated en vacuo. The residue was purified by a COMBIFLASH® system (ISCO) using 0-20% ethyl acetate in hexane to give 3-bromo-6-(tert-butyldimethylsilyloxy)picolinonitrile.
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