To a solution of 4-chloro-N-({4-chloro-3-[(3-cyano-5-ethenylphenyl)oxy]-2-fluorophenyl}methyl)-2-methyl-1H-imidazole-5-carboxamide (0.260 g, 0.584 mmol) and sodium periodate (0.375 g, 1.752 mmol) in THF (4 ml) and water (2 ml) was added osmium tetroxide (2.5 weight % in t-butanol) (0.147 ml, 0.012 mmol) and the reaction mixture was stirred at rt for 3 hours. The reaction mixture was diluted with EtOAc and washed with water. The solvent was removed and the crude material was purified via silica gel chromatography to give 4-chloro-N-({4-chloro-3-[(3-cyano-5-formylphenyl)oxy]-2-fluorophenyl}methyl)-2-methyl-1H-imidazole-5-carboxamide (0.245 g, 0.548 mmol, 94% yield). 1H NMR (400 MHz, DMSO-d6) δ ppm 9.95 (s, 1H), 8.12 (s, 1H), 8.07 (s, 1H), 7.92 (s, 1H), 7.45-7.56 (m, 1H), 7.27-7.44 (m, 1H), 6.91 (d, 1H), 4.52 (d, 2H), 2.23 (s, 3H).
