In a round bottom flask, tert-butyl 6-amino-1-methyl-1H-imidazo[4,5-c]pyridin-4-yl(2,4-dimethoxybenzyl)carbamate (example 1D, 7.887 g, 19.08 mmol) was dissolved in MeCN (200 mL) and cooled to 0° C. N-Iodosuccinimide (4.51 g, 20.03 mmol) was dissolved in the remaining MeCN (50 mL) and added dropwise to the reaction mixture over 40 min. The reaction mixture was stirred at 0° C. for an additional 10 min and was quenched with 2 M sodium hydrogensulfite (125 mL). Stirring and temperature were maintained for 50 min. The mixture was transferred to a separatory funnel. The aqueous layer was extracted with CH2Cl2 (3×100 mL). The combined organic layers were washed with water and brine, dried over Na2SO4, filtered and concentrated in vacuo. The crude residue was purified by flash chromatography using an Isco 120 g column eluting with 20-100% ethyl acetate/CH2Cl2 to provide tert-butyl 6-amino-7-iodo-1-methyl-1H-imidazo[4,5-c]pyridin-4-yl(2,4-dimethoxybenzyl)carbamate (8.436 g, 82% yield) as a pale yellow solid.
