[Li+].[Cl-].[I:3][C:4]1[N:5]=[C:6]([C@@H:10]2[CH2:14][C@H:13]([CH3:15])[CH2:12][N:11]2[C:16]([O:18][C:19]([CH3:22])([CH3:21])[CH3:20])=[O:17])[NH:7][C:8]=1I.C[Mg]Cl.C([Mg]Cl)(C)C.[NH4+].[Cl-]>C1COCC1.O>[I:3][C:4]1[N:5]=[C:6]([C@@H:10]2[CH2:14][C@H:13]([CH3:15])[CH2:12][N:11]2[C:16]([O:18][C:19]([CH3:20])([CH3:22])[CH3:21])=[O:17])[NH:7][CH:8]=1A solution of LiCl in THF (3.9 mL of a 0.5 M solution, 1.99 mmol) is added to tert-butyl (2S,4S)-2-(4,5-diiodo-1H-imidazol-2-yl)-4-methyl-pyrrolidine-1-carboxylate (1 g, 1.99 mmol). After stirring for 5 minutes at rt the reaction mixture is cooled down to −20° C. and a solution of methyl magnesium chloride in THF (946.7 μL of 2.1 M, 1.99 mmol) is added dropwise. After stirring for 20 minutes at −20° C., a solution of isopropyl magnesium chloride in THF (3.2 mL of 1.24 M, 3.97 mmol) is added dropwise. The reaction mixture is slowly warmed up to rt and stirred for 2 hours. The reaction mixture is cooled down to 0° C. and a saturated aqueous NH4Cl solution is slowly added followed by water. This mixture is then extracted with EtOAc (3×20 mL), and the combined organic layers are washed with brine, dried over Na2SO4, filtered and concentrated to dryness. The residue is purified by flash column chromatography on silica gel (0 to 25% EtOAC/Hexane) to afford tert-butyl (2S,4S)-2-(4-iodo-1H-imidazol-2-yl)-4-methyl-pyrrolidine-1-carboxylate (636 mg, 83%) as a white solid.
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