[CH3:1][O:2][C:3]1[CH:8]=[CH:7][C:6]([C:9]2[CH:10]=[CH:11][C:12]([C:16]([O:18][CH2:19][C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=3)=[O:17])=[N:13][C:14]=2[CH3:15])=[CH:5][CH:4]=1.[I:26]I>CO.S([O-])([O-])(=O)=O.[Ag+2]>[I:26][C:8]1[CH:7]=[C:6]([C:9]2[CH:10]=[CH:11][C:12]([C:16]([O:18][CH2:19][C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=3)=[O:17])=[N:13][C:14]=2[CH3:15])[CH:5]=[CH:4][C:3]=1[O:2][CH3:1]Benzyl 5-(4-methoxyphenyl)-6-methylpyridine-2-carboxylate (150 mg, 0.45 mmol), iodine (228 mg, 0.898 mmol), silver sulfate (402 mg, 1.29 mmol) were stirred in methanol (3 mL) at room temperature overnight. More iodine (57 mg, 0.22 mmol) and silver sulfate (100 mg, 0.32 mmol) were added into reaction mixture after 25 hours. Added aqueous NaHSO3 solution (sat., 20 mL) into the reaction mixture after additional 1.5 hours to quench the reaction. The reaction mixture was extracted with ethyl acetate. The combined extracts were dried over Na2SO4 followed by filtration and concentration to afford a clear oil. The crude oil was purified by preparative TLC on SiO2 (eluted with 30% ethyl acetate in hexanes) to afford benzyl 5-(3-iodo-4-methoxyphenyl)-6-methylpyridine-2-carboxylate. LCMS calc.=459.03; found=460.17 (M+1)+.
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