To a solution of di-tert-butyl 2,2′-((2-(2-(((4-sulfamoylphenethyl)amino)methyl)-1H-imidazol-1-yl)acetyl)azanediyl)diacetate (283 mg, 0.50 mmol), AcOH (0.10 mL) and 2-(2-formyl-1H-imidazol-1-yl)-N-(3-iodophenyl)acetamide (178 mg, 0.50 mmol) in DCE (20 mL) at 0° C. was added NaBH(OAc)3 (0.30 g, 1.5 mmol). The reaction mixture was stirred at 0° C. for 30 minutes and at room temperature for overnight and decomposed with water. The reaction mixture was extracted with DCM. The organic layer was dried and concentrated under reduced pressure. The residue was purified by biotage over silica gel eluting with DCM to 40% MeOH in DCM to afford di-tert-butyl 2,2′-((2-(2-((((1-(2-((3-iodophenyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)methyl)(4-sulfamoylphenethyl)amino)methyl)-1H-imidazol-1-yl)acetyl)azanediyl)diacetate (254 mg, 56%).
