[C:1]([C:4]1[CH:9]=[C:8]([N:10]2[C:15](C)=[CH:14][C:13]([O:17]CC3C=CC(OC)=CC=3)=[CH:12][C:11]2=[O:27])[C:7]([CH3:28])=[CH:6][N:5]=1)(=[O:3])[CH3:2].[Cl:29]N1C(=O)CCC1=O>CC(O)C.ClC(Cl)C(O)=O>[C:1]([C:4]1[CH:9]=[C:8]([N:10]2[CH:15]=[CH:14][C:13]([OH:17])=[C:12]([Cl:29])[C:11]2=[O:27])[C:7]([CH3:28])=[CH:6][N:5]=1)(=[O:3])[CH3:2]To a solution of 2′-acetyl-4-((4-methoxybenzyl)oxy)-5′,6-dimethyl-2H-[1,4′-bipyridin]-2-one of part C (3.3 g, 8.7 mmol) in 2-propanol (100 mL) was added N-chlorosuccinimide (1.27 g, 9.6 mmol) and 10 drops of dichloroacetic acid. The slurry was heated at 60° C. for 3 h. The resulting slurry was concentrated and the residue was partitioned between ethyl acetate and water. The organic layer was washed with water and brine and dried over magnesium sulfate. The solution was concentrated in vacuo. The residue was suspended into dichloromethane and the resulting white solid was collected by vacuum filtration to provide the chlorinated deprotected product (1.16 g): MS (ES) m/e 293 (M+H).
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