[C:1]([O:5][C:6](=[O:20])[NH:7][CH2:8][CH2:9][N:10]1[C:14](I)=[C:13]([I:16])[N:12]=[C:11]1[CH2:17][CH2:18][CH3:19])([CH3:4])([CH3:3])[CH3:2].CC[Mg+].[Br-].O.CCOCC>C1COCC1>[C:1]([O:5][C:6](=[O:20])[NH:7][CH2:8][CH2:9][N:10]1[CH:14]=[C:13]([I:16])[N:12]=[C:11]1[CH2:17][CH2:18][CH3:19])([CH3:4])([CH3:3])[CH3:2]
A solution of [2-(4,5-diiodo-2-propyl-imidazol-1-yl)-ethyl]-carbamic acid tert-butyl ester (8.690 g; 17.204 mmol) in anhydrous THF (100 ml), under nitrogen, was cooled to −40° C., and a solution of 1M EtMgBr in THF (20.5 ml; 20.5 mmol; 1.2 eq.) was then added dropwise over 15 min. After addition, the resulting solution was stirred between −40° C. and −30° C. for 10 min. (conversion=55% according to LC-MS), and additional 1M EtMgBr in THF (13.9 ml; 13.9 mmol; 0.8 eq.) was added in order to complete the reaction. The reaction mixture was then treated with water (5 ml) at −40° C., and was allowed to warm-up to rt. Ether (200 ml) was added, and the resulting solution was washed with brine (2×200 ml). The organic layer was dried over anh. MgSO4, filtered, and concentrated to dryness under reduced pressure. The crude was purified by FC (DCM/MeOH=20/1) to give the pure product [2-(4-iodo-2-propyl-imidazol-1-yl)-ethyl]-carbamic acid tert-butyl ester as a yellow oil (6.110 g; 94%). LC-MS: tR=0.74 min.; [M+H]+=380.00 g/mol.
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