To a stirred suspension of 5-iodo-N-(3-methoxy-4-((6-methoxypyridin-3-yl)methoxy)benzyl)-3-nitropyridin-2-amine (14.67 g, 28.09 mmol) in acetic acid (130 mL) was added iron powder (10.98 g, 196.6 mmol). The bright yellow mixture was warmed to ˜85° C. After 15 min of heating, the reaction mixture became a gray-brown suspension and was allowed to cool to room temperature. The mixture was diluted with ethyl acetate (400 mL), and the thick mixture was filtered through Celite with the aid of additional ethyl acetate (100 mL). The filtrate was washed with water (2×150 mL) and 5N ammonium hydroxide solution (4×125 mL). The organic phase was dried over magnesium sulfate, filtered, and concentrated to provide 11.67 g (84%) of 5-iodo-N2-(3-methoxy-4-((6-methoxypyridin-3-yl)methoxy)benzyl)pyridine-2,3-diamine as a tan solid.
